Aerovortex mill 2

Abstract

The invention relates to the use of Wind Turbines for power generation. It seeks to provide those areas with low winds, a pioneering way to harness efficiently the energy of the wind. In order to achieve this, it makes use of a pressure differential device given the name: VIASAD/JETIASAD. The VIASAD/JETIASAD device compresses and accelerates the Wind or Underwater current inflow (Primary Flow) and generates high-speed jet streams and vortices. The combined result of the generated high-speed jet streams and vortices is the creation of a suction flow (Secondary Flow) which can be used in the following two ways: (1) Drive the secondary air flow through a fan or impeller and (2) Laminar Flow Control (LFC/HLFC) and/or Suppress Adverse Pressure Gradients on the blades of existing wind turbines.

Description

Aerovortex Mill 2: A pressure differential device that consists of a converging nozzle and it's fitted with vortex generators (VIASAD: Vortex Induced Air Speed Amplification Device) or without vortex generators (JETIASAD: JET stream Induced Air Speed Amplification Device), generates suction. Ultimately, the generated suction can be used in the following two ways: (1) Improve the aerodynamic performance of wind turbine blades by applying Active/Laminar Flow Control (AFC/LFC) on their surface and/or (2) The air flow generated by the suction can be used to drive a wind turbine's rotor blades. This technology will help harness the energy from low-wind areas with high efficiency.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX

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BACKGROUND OF INVENTION

The invention relates to the use of wind turbines for power generation. Wind constitutes one of the major sources of renewable or “green” energy production. Wind turbines are widely used all over the world in order to harness this power from the wind.

Currently there are two types of wind turbines: vertical axis and horizontal axis machines. They both use some kind of propeller which is primarily used for extracting or converting the Kinetic Energy of the wind into mainly two types of energies: (1) Electrical energy (Power generators) and (2) Potential energy of the water (Water pumps). These propellers or rotors are either drag-based or lift-base devices. The drag-based rotors have slower rotational speeds than the lift-based devices. Generally the lift-based devices are a lot more efficient than the drag-based devices, and consequently the wind power generators are mostly lift-based devices.

A lot of research and development has been done by a number of companies around the world in order to improve the efficiency and performance of lift-based wind turbines. This lead to a number of considerable advances in this field, primarily focused on the following three areas:

• • 1. Improve the aerodynamic performance of the rotor blades using passive mechanisms. Basically the goal is to maximize the Lift-to-Drag ratio (L/D) of the rotor blades.
  • 2. Wind turbine yaw control and rotor blade pitch control.
  • 3. Improvement of the gear system which amplifies rotation from the main rotor with the blades to the generator. Lately a gearless design has been introduced. This advancement considerably drives down the maintenance costs, since the gear system is one of the most sensitive parts, and wares out the most.

How many advances have been achieved in Wind Turbine technology, even the most advanced and efficient Wind Turbines can only operate in areas with mean annual wind speeds exceeding 6.0 m/s. Only then, they can generate enough useful energy or electricity to justify their extremely high cost. As a result, areas with low mean annual wind speeds (below 6.0 m/s), are left with no reliable and efficient enough technology to harness the energy of the wind.

Current wind capacity in the U.S. is almost entirely produced by wind farms in high wind, Class 6 areas. Class 4 wind resource areas, which are significantly closer to the major load centers than Class 6 sites, are not being utilized for wind power generation. If Class 4 wind resource areas were developed to their full potential, transmission costs for wind energy would be greatly reduced, and total land area available for wind development would increase 20 times. The concept device incorporates those technological advances which promise to render the Class 4 sites economically viable for wind development.

BRIEF SUMMARY OF THE INVENTION

The proposed device will harness the energy from the wind to generate suction, that ultimately will be used to improve the aerodynamic performance of wind turbine rotor blades. The use of this device will render the conventional wind turbine a far more efficient device at low wind speeds. The generated suction can also be used to expose a turbine in an air flow with higher speed than the wind speed. This way the energy output of the air turbine will have a higher output coefficient.

The proposed device compresses and thus accelerates the incoming air flow from the wind and as result it lowers its static pressure. It can also make use of vortex generators in order to amplify the generated suction effect. It is given the name VIASAD which stands for “Vortex Induced Air Speed Amplification Device”. The device which is not fitted with vortex generators, creates high-speed jet-streams and it is given the name JETIASAD which stands for “JET stream Induced Air Speed Amplification Device”. The Wind Turbine carrying the VIASAD/JETIASAD device, is called: “Aerovortex Mill 2”.

The suction that is generated by the proposed pressure differential mechanism, enhances the aerodynamic performance of the wind turbine rotor blades, by applying Active/Laminar Flow Control (AFC/LFC) on their surface. The aerodynamic improvements can be summarized as follows:

Increase of Lift to Drag (L/D) ratio of the wind turbine rotor blades.

Noise reduction.

Current blade aerodynamic advances including advanced airfoil design and passive mechanisms for drag reduction, have reached their maximum potential. The aerodynamic benefits of the VIASAD/JETIASAD concept device constitute the next step in the direction of rotor blade aerodynamics technological advancement. This will help to efficiently harness the energy of the wind in all sites and especially the low-wind areas.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1, 2, 3: The source of inspiration for the recommended mechanisms (VIASAD/JETIASAD), consists of specific lessons from nature which can be summarized as follows: The Hydrodynamic mechanisms of Aquatic Locomotion used by fishes to propel their way through fluids and the Flight propulsion mechanisms used by birds and insects moving through Air. This idea is illustrated further in FIGS. 1, 2 and 3.

FIGS. 1 and 2 illustrate the Aquatic Locomotion which can be summarized as follows:

• • The Momentum-Impulse Couple of Vortex REAR DRIVEN Bodies:
  • The rear body parts (feet, caudal fin) can both (A) accelerate the vortex flow generated by the body moving through the water and/or (B) generate vortices:
  • A. The vortex flow generated by the body of the fish is allowed to expand laterally and eventually it is beaten by the caudal fin. This effectively restricts its path and hence the vortex flow is being accelerated.
  • B. The rear body parts preform the aquatic surroundings by applying some work on the water, which in turn stores this energy. The preformed water masses flow into the zone of the underpressure creating a rolling vortex (Ungerechts et al). Due to the high geometrical organization, vortices ‘carry a high amount of momentum in relation to the energy spent for their production’ (Lighthill, 1969). The generated trailing vortex induces a velocity field which is influencing the flow in front of the moving body.

FIG. 1. Human Swimmer.

• • Related Figures: 2, 3.
  • Part terminology: Jet stream (1), Vortex (2).
  • Description: The feet strokes up and down in the water generate ‘barrel’ like trailing vortices (2). These vortices are the cause for a backward-moving jet stream (1) in between them, and as a result the swimmer acquires forward momentum. It looks as if the human body is translating through the water between rollers.

FIG. 2. Shark Locomotion—Tail Stroke movements.

• • Related Figures: 1, 3.
  • Part terminology: Shark (1), Vortex (2), Generated Jet Stream (3), Shark Tail (4).
  • Description: The periodical (left/right) movement of the shark's caudal fin shreds vortices on each side which are rotating in an opposite sense (Blickman, 1992). Due to the lasting rotation of the generated vortices, a jet stream is produced. This jet stream flows in between the trailing vortices and with a direction opposite to the direction of travel of the shark (backwards). The thrusting impulse responsible for pushing the shark forwards is a reaction to this jet stream (similar to the jet stream behind modern aircraft).

FIG. 3. Insect Flight—Flapping Wings.

• • Related Figures: 1, 2.
  • Part terminology: Insect (1), Wing Section (2), Generated Vortex (3), Jet Stream (4).
  • Description: The very slow velocities by which insects fly in the air and hence the low Reynolds numbers associated with these velocities, do not justify the lift generated on their wings in order to keep them airborne. For this reason, insects use flapping along with rotational movement of their wings, in order to increase the airflow in the vicinity of each of their flapping wings and in this way generate the required lift so that they are able to fly. The way this is achieved is by generating wing leading-edge vortices (LEV) (3) which in turn produce a jet stream (5) on top of the wing.

FIG. 4A. Dual Air Flow Variant—Front View.

• • Related Figures: 4B, 4C.
  • Part Terminology: Throat Tube (1), Suction Flow Tubes (2), Inlet to Blower Fan (3), JETIASAD/VIASAD Inlet (4), Conical Blower Fan (5), Conical Hub (6) (For diverting air flow to the fan blades).
  • Description: In this variant, the VIASAD/JETIASAD device consists of multiple converging nozzles with circular inlets facing the wind. The incoming air is accelerated and then vortices are being generated. The accelerated vortical flow induces suction which drives a secondary flow through the fan, the fan outlet and finally through a suction flow tube which leads to the vortical and/or accelerated incoming wind flow.

FIG. 4B. Dual Air Flow Variant—Top View.

• • Related Figures: 4A, 4C.
  • Part Terminology: Outlet (1), Diffuser (2), Throat Pipe (3), Suction Flow Tube (4), Contraction (5), Inlet (6), Wind (7), Convergent Nozzle (8), Inlet to Fan (9), Fan Casing (10), Conical Blower Fan (11), Flow Deflector Wall (12).
  • Description: This is the top view of the variant described in FIG. 4A.

FIG. 4C. Dual Air Flow Variant—Side View.

• • Related Figures: 4A, 4B.
  • Part Terminology: Wind (1), Conical Blower Fan (2), Contraction (3), Air Flow Deflector (4), Shaft (5), Diffuser (6), Outlet (7), Suction Tube (8), Sucked Air (9), Fan Outflow Guide Wall (10), Inlet (11).
  • Description: This is the side view of the variant described in FIG. 4A.

FIG. 5A. Dual Air Flow Variant.

• • Related Figures: 5B, 5C, 5D, 5E.
  • Part Terminology: JETIASAD/VIASAD Inlet (1), Contraction (2), Vortex Generator (3), Suction Flow Tube (4), Fan Casing (5), Conical Blower Fan (6), Inlet to Blower Fan (7), Conical Hub Air Flow Deflector (8).
  • Description: A JETIASAD/VIASAD device consisting of two 2D contraction nozzles. The two converging nozzles guide the accelerated wind inflow past vortex generators in order to created vortices. The vortices are further being accelerated as they go through the contraction inducing suction which drives a secondary flow through the fan, the fan outlet and finally through a suction flow tube.

FIG. 5B. Dual Air Flow Variant.

• • Related Figures: 5A, 5C, 5D, 5E.
  • Part Terminology: Suction Flow Tube (1), JETIASAD/VIASAD Inlet (2), Wind (3), Intake Nozzle (4), Conical Blower Fan (5), Inlet to Fan (6), Fan Casing (7), Contraction or Converging Nozzle (8), Outflow (9), Shaft (10), Air Flow Deflector (1), Contraction Outlet (12), Diffuser (13).
  • Description: This is the top view of the variant described in FIG. 5A. The impeller shown is a conical blower fan.

FIG. 5C. Dual Air Flow Variant.

• • Related Figures: 5B, 5C, 5D, 5E.
  • Part Terminology: Suction Flow Tube (1), JETIASAD/VIASAD Inlet (2), Wind (3), Intake Nozzle (4), Multistage Axial Fan (5), Inlet to Fan (6), Fan Casing (7), Contraction or Converging Nozzle (8), Outflow (9), Shaft (10), Air Flow Deflector (11), Contraction Outlet (12), Diffuser (13).
  • Description: This is the top view of the variant described in FIG. 5A with axial fans arranged in series.

FIG. 5D. Dual Air Flow Variant.

• • Related Figures: 5A, 5B, 5C, 5E.
  • Part Terminology: Contraction (1), Suction Flow Tube (2), Diffuser (3), Conical Blower Fan (4).
  • Description: This is the side view of the variant described in FIG. 5A with one type of the contraction inlet nozzle.

FIG. 5E. Dual Air Flow Variant.

• • Related Figures: 5A, 5B, 5C, 5D.
  • Part Terminology: Contraction (1), Suction Flow Tube (2), Diffuser (3), Conical Blower Fan (4).
  • Description: This is the side view of the variant described in FIG. 5A with another type of the contraction inlet nozzle.

FIG. 6. Dual Air Flow Variant.

• • Related Figures: 7, 8, 9.
  • Part Terminology: Air Suction Tube (1), Diffusion Nozzle (2), Fan/Fan Housing (3), Branch Suction Tube (4), VIASAD/JETIASAD (5), Air Inflow (6).
  • Description: This is a 3D view of a variant with two VIASAD/JETIASAD devices. Suction induced in the VIASAD/JETIASAD devices drive the air flow through the fans which are connected to the air suction tubes.

FIG. 7. Dual Air Flow Variant.

• • Related Figures: 6, 8, 9.
  • Part Terminology: Air Suction Tube (1), Fan Inlet (2), Diffusion Nozzle (3), VIASAD/JETIASAD device (4), Fan/Fan Housing (5), Air Inflow (6).
  • Description: This is a 3D view of a variant with two VIASAD/JETIASAD devices. Suction induced in the VIASAD/JETIASAD devices drive the air flow through the fans which are connected to the air suction tubes.

FIG. 8. Dual Air Flow Variant.

• • Related Figures: 6, 7, 9.
  • Part Terminology: Air Suction Tube (1), Fan/Fan Housing (2), Fan Outlet (3), Diffusion Nozzle (4), VIASAD/JETIASAD (5), Fan Inlet (6), Air Inflow (7).
  • Description: This is a 3D view of a variant with two VIASAD/JETIASAD devices. Suction induced in the VIASAD/JETIASAD devices drive the air flow through the fans which are connected to the air suction tubes.

FIG. 9. VIASAD Device.

• • Related Figures: 6, 7, 8.
  • Part Terminology: Air Inflow (1), Contraction Nozzle (2), Vortex Generator (3), Vortex Lateral Expansion Chamber (4), Hinge (5), Air Suction Tube (6), Diffusion Nozzle (7), Low Pressure Region (8), Vortex Lateral Contraction Mechanism (9), Vortex (10).
  • Description: This is the side section view of a VIASAD device. The air inflow is initially compressed and thus its energy per unit volume increases. Vortex generators are then used to generate vortices. These vortices are allowed to expand laterally and eventually are accelerated by restricting their path towards the outlet.

FIG. 10. VIASAD—Wind Turbine APG suppressor.

• • Related Figures: 11, 12, 13, 14A/B.
  • Part Terminology: Rotor hub (1), Rotor Blade (2), VIASAD Contraction (3), VIASAD Suction Flow (4), Low Pressure Chamber (5), VIASAD Diffuser (6), Vortex (7), Vortex Generator (8), Wind (9).
  • Description: A VIASAD device is used to generate suction which is ultimately used to suppress adverse pressure gradients on the rotor blades. This is done by absorbing slow-moving air on the surface of the rotor blades close to the trailing edge. As a result the flow stays attached and smooth at higher angles of attack, increasing the blade's lift coefficient and hence enhancing its performance.

FIG. 11. VIASAD/JETIASAD—Wind Turbine APG suppressor with suction Holes.

• • Related Figures: 10, 12, 13, 14A/B.
  • Part Terminology: Blade Leading Edge (1), Rotor Hub (2), Suction Holes—APG suppressor (3), Blade Trailing Edge (4), Wind Turbine Blade (5).
  • Description: Slow moving air is sucked through the holes of the APG suppressor. As a result the flow stays attached and smooth at higher angles of attack, increasing the blade's lift coefficient and hence enhancing its performance.

FIG. 12. VIASAD/JETIASAD—Wind Turbine APG suppressor with trailing edge suction inlet.

• • Related Figures: 10, 11, 13, 14A/B.
  • Part Terminology: Blade Leading Edge (1), Rotor Hub (2), Suction Inlet—APG suppressor (3), Blade Trailing Edge (4), Wind Turbine Blade (5).
  • Description: Slow moving air is sucked through the trailing edge inlet of the APG suppressor. As a result the flow stays attached and smooth at higher angles of attack, increasing the blade's lift coefficient and hence enhancing its performance.

FIG. 13. VIASAD/JETIASAD—Wind Turbine APG suppressor with trailing edge suction vanes.

• • Related Figures: 10, 11, 12, 14A/B.
  • Part Terminology: Blade Leading Edge (1), Rotor Hub (2), Suction Vanes—APG suppressor (3), Blade Trailing Edge (4), Wind Turbine Blade (5).
  • Description: Slow moving air is sucked through the trailing edge vanes of the APG suppressor. As a result the flow stays attached and smooth at higher angles of attack, increasing the blade's lift coefficient and hence enhancing its performance.

FIG. 14A. VIASAD/JETIASAD—Wind Turbine APG suppressor with suction inlet—Blade airfoil section with suction flow.

• • Related Figures: 10, 11, 12, 13, 14B.
  • Part Terminology: Air Flow over the Blade (1), Suction Inlet opening (2), Suction Inlet APG suppressor (3), Blade Trailing Edge (4), Hinge (5), Suction Flow (6), Blade Airfoil Section (7), Suction Tube (8), Blade Leading Edge (9).
  • Description: Slow moving air is sucked through the trailing edge inlet of the APG suppressor. As a result the flow stays attached and smooth at higher angles of attack, increasing the blade's lift coefficient and hence enhancing its performance.

FIG. 14B. VIASAD/JETIASAD—Wind Turbine APG suppressor with suction holes—Blade airfoil section with suction flow.

• • Related Figures: 10, 11, 12, 13, 14A.
  • Part Terminology: Air Flow over the Blade (1), Suction Flow through the APG holes (2), Blade Trailing Edge (3), Suction Flow (4), Suction Tube (5), Blade Leading Edge (6).
  • Description: Slow moving air is sucked through the suction holes of the APG suppressor. As a result the flow stays attached and smooth at higher angles of attack, increasing the blade's lift coefficient and hence enhancing its performance.

FIG. 15. Offshore Wind Turbine with VIASAD/JETIASAD device which works with underwater currents.

• • Related Figures: All.
  • Part Terminology: Underwater current (1), Water surface (2), VIASAD/JETIASAD device (3), Suction Flow—Secondary Flow (4), Wind (5), Tower base (6), Wind Turbine blade (7), Wind Turbine Tower (8), Wind Turbine nacelle (9).
  • Description: The VIASAD/JETIASAD device generates suction (low pressure) by the use of underwater currents. This is used to suck the slow moving air in the boundary layer on the low-pressure surface of the rotor blades. As a result the flow remains attached even at high angles of attack and also transition to turbulent flow is delayed by enhancing the laminar flow. This improves the Lift to Drag (L/D) ratio and ultimately the aerodynamic performance of the blade is improved.

FIG. 16. Wind Turbine fitted with a VIASAD/JETIASAD device.

• • Related Figures: All.
  • Part Terminology: Rotor Blade (1), Wind Turbine (2), Wind Turbine Tower (3), Suction Flow—Secondary Flow (4), VIASAD/JETIASAD device (5), Wind (6).
  • Description: The VIASAD/JETIASAD device is attached to a single wind turbine. The suction or secondary flow that generates drives the Active/Laminar Flow Control on the rotor blades.

FIG. 17. Wind Turbine fitted with a VIASAD/JETIASAD device.

• • Related Figures: All.
  • Part Terminology: Wind Turbine (1), VIASAD/JETIASAD device (2), Wind (3).
  • Description: The VIASAD/JETIASAD device is attached to a single wind turbine. The suction or secondary flow that generates drives the Active/Laminar Flow Control on the rotor blades. The size of the VIASAD/JETIASAD device is a little bit exaggerated here.

FIG. 18. A VIASAD/JETIASAD device driving Active Flow Control on multiple wind turbines.

• • Related Figures: All.
  • Part Terminology: Wind Turbine (1), VIASAD/JETIASAD device (2).
  • Description: The VIASAD/JETIASAD device is supporting multiple wind turbines or a whole wind farm. The suction or secondary flow that is generated by the VIASAD/JETIASAD device, drives the Active/Laminar Flow Control on the rotor blades of the wind turbines.

DETAILED DESCRIPTION OF THE INVENTION THE INSPIRATION

The source of inspiration for the recommended concept device (VIASAD/JETIASAD), consists of specific lessons from nature which can be summarized as follows: The Hydrodynamic mechanisms of Aquatic Locomotion used by fish to propel their way through water and the Flight propulsion mechanisms used by birds and insects moving through Air.

1. Aquatic Locomotion

The Momentum-Impulse Couple of Vortex REAR DRIVEN Bodies:

• • The rear body parts (feet, caudal fin) can both (A) accelerate the vortex flow generated by the body moving through the water and/or (B) generate vortices.
    • A. The vortex flow generated by the body of the fish is allowed to expand laterally and eventually it is beaten by the caudal fin. This effectively restricts its path and hence the vortex flow is being accelerated.
    • B. The rear body parts preform the aquatic surroundings by applying some work on the water, which in turn stores this energy. The preformed water masses flow into the zone of the underpressure creating a rolling vortex (Ungerechts et al). Due to the high geometrical organization, vortex ‘carry a high amount of momentum in relation to the energy spent for their production’ (Lighthill, 1969). This generated trailing vortex induces a velocity field which is influencing the flow in front of the moving body.

1.1 Human Swimmer

• • The feet strokes up and down in the water generate ‘barrel’ like trailing vortices. It looks as if the human body is translating through the water between rollers. See FIG. 1.

1.2 Shark

• • The periodical (left/right) movement of the shark's caudal fin shreds vortices on each side which are rotating in an opposite sense (Blickman, 1992). Due to the lasting rotation of the generated vortices, a jet stream is produced. This jet stream flows in between the trailing vortices and with a direction opposite to the direction of travel of the shark (backwards). The thrusting impulse responsible for pushing the shark forwards is a reaction to this jet stream (similar to the jet stream behind modern aircraft). See FIG. 2.

2. Flight Propulsion

2.1 Insect Flapping Flight

• • The very slow velocities by which insects fly in the air and hence the low Reynolds numbers associated with these velocities, do not justify the lift generated on their wings in order to keep them airborne. For this reason, insects use flapping along with rotational movement of their wings, in order to increase the airflow in the vicinity of each of their flapping wings and in this way generate the required lift so that they are able to fly. The way this is achieved is by generating wing leading-edge vortices (LEV) which in turn produce a jet stream on top of the wing. See FIG. 3. The Wind as an Energy Resource

Large areas of the world appear to have mean annual windspeeds below 3.0 m/s, and are unsuitable for wind power systems, and almost equally large areas have wind speeds in the intermediate range of 3.0-7.0 m/s where wind power may or may not be an option. These areas, are mainly unexploited for harnessing the wind energy, because technology does not exist to serve this purpose yet.

Those areas with mean annual wind speeds exceeding 7.0 m/s are the most economically viable for power generation. In these areas, existing technology of wind turbines or lift-based devices are being used, because they are usually more efficient than drag-based devices.

In summary, the most efficient current technology based on lift-generating rotor wind turbines, can operate in areas with mean annual wind speeds exceeding 7.0 m/s and generate enough useful energy or electricity to justify their extremely high cost. On the other hand, areas with low mean annual wind speeds (below 7.0 m/s), are left with no reliable and efficient enough technology to harness the energy of the wind. The invention seeks to provide those areas with low winds, a pioneering way to harness efficiently the energy of the wind.

The Invention

The invention makes use of the following mechanisms/devices in order to achieve its high efficiency at low winds:

1. VIASAD: Vortex Induced Air Speed Amplification Device.

2. JETIASAD: Jet stream Induced Air Speed Amplification Device.

The above mechanisms are basically pressure differential devices. They consist of contractions or converging nozzles which accelerate incoming air from the wind or incoming water from underwater currents and generate high-speed jets and/or high-speed vortices (Primary Flow).

The combined effect of the generated high-speed jet stream and vortices is the decrease in static pressure and hence inducing a suction effect, which gives rise to a Secondary Air Flow.

The generated secondary air flow can be used in the following ways in order to enhance the efficiency of harnessing the wind energy, especially at low wind speeds:

• • (1) Accelerated air flow (Secondary Flow) is passed through the rotating blades of axial impellers or centrifugal impellers placed within a housing. The housing efficiently directs air through an inlet into the rotating impellers and then through an outlet into a duct which eventually leads to the region where suction takes place.
  • (2) Use of the Secondary Flow as an Adverse Pressure Gradient suppressor or to drive Active/Laminar Flow Control or Hybrid Laminar Flow Control (HLFC/LFC) on wings or lifting surfaces used by Air Turbines. Basically, low pressure generated by a VIASAD/JETIASAD device sucks slow-moving air from the low-pressure surface of the rotor blade and/or wing. This results in smooth (laminar) and attached air flow at higher angles of attack and hence higher lift coefficients and lower drag coefficients (Higher Lift to Drag L/D ratio).

Currently, the mechanical efficiency of commercial wind turbines is maximized at wind speeds above 7 m/s, usually around some 9 m/s. The thinking behind this, is that efficiency is not important at low wind speeds since there is not much energy to harvest at low winds. Consequently, in low wind areas the choices available are to either not harness the wind energy at all, or harness it with very low mechanical efficiency using existing wind turbine technology. Aerovortex Mill 2 will help close this gap by allowing the efficient harnessing of energy from the wind at very low wind speeds. Even more, it will improve performance at high wind speeds too.

Aerovortex Mill 2 or a wind turbine using a VIASAD/JETIASAD device, makes use of a contraction or a converging nozzle in combination with vortex generators, in order to increase the density of the input energy of the wind and as a result improve its efficiency at low winds. By carefully selecting the design characteristics of the converging nozzle (Inlet Area, Ratio of Inlet to Outlet cross-sectional Areas), the invention can render a wind turbine to start generating electricity at a very low cut-in wind speed.

On the contrary to the Aerovortex Mill 2, current commercial wind turbine technology makes use of large rotor blades in order to maximize the area being swept when they operate, and hence maximize the amount of energy harnessed. Note that the power available in the wind is given by the formula: P=0.5*(Density)*A*V3. However, the use of large blades, increases the inertial forces on the rotor, which results in:

(1) Higher cut-in wind speeds than expected and

(2) Poor overall performance (low efficiency) at low wind speeds.

The solution of using taller towers on which to install the Wind Turbines so that they can reach for higher wind speeds, is very costly and technologically challenging. The invention can eliminate the need for excessive tower heights by increasing the performance of existing wind turbines.

As mentioned above, current commercial wind turbines are optimized for a single design wind speed where they achieve maximum output performance efficiently. Consequently, most of the time, at all other wind speeds, they operate at low efficiency. Aerovortex Mill 2 will operate with comparable efficiency over a wide range of wind speeds.

Also there is another benefit of using the proposed VIASAD/JETIASAD device in combination with an air turbine enclosed in a casing or housing: The air turbine is protected from the rapid flactuations in the speed of the wind. As mentioned above, the VIASAD/JETIASAD device generates the suction or secondary flow which flows through the impeller of the air turbine that is enclosed in a housing. The isolation of the impeller from wind gusts, protects the gear box connected to the impeller through a shaft from excessive loads. As a result, the reliability and maintenability of the wind turbine, improves dramatically.

Claims

1. VIASAD: Vortex Induced Air Speed Amplification Device. VIASAD is a pressure differential mechanism or device which makes use of the wind or underwater currents and generates a system or pattern of air/water vortices, of ANY TYPE or CONFIGURATION. The generated air/water vortices induce a suction effect. It consists of the following parts: (1) Contraction or Converging nozzle. The purpose of this part is to accelerate the incoming air flow from the wind by contracting or compressing it. The intake of the contraction is facing the wind. The ratio of the Intake to the Exhaust Area (Ain/Aout) is optimized to achieve maximum acceleration of air inflow. The contracting walls can take various shapes and they are not limited to only one shape (FIG. 13D/E). The goal here is to minimize friction losses and keep boundary layer as thin as possible. The contraction of the nozzle walls can take different forms: It might be 1-D along the direction of the incoming flow, either on the vertical plane or on the horizontal plane. It might also be 2-D and thus the contraction takes place on both the horizontal and vertical planes. Or the contraction can be multi-D like for example the case of a venturi tube where the contraction takes place on multiple planes along the direction of the wind. The Converging nozzles facing the wind can be set to operate either Horizontally or Vertically. (2) Vortex Generators. The purpose of this part is to generate a system or pattern of air vortices of ANY TYPE or CONFIGURATION. The geometrical shape of the vortex generators can take ANY FORM to maximize its performance for their intended purpose. ALL different types of vortex generators can be used. Some of the options are the following: Fences or walls or grooves or extrusions or lifting bodies placed at different angles of attack to the air flow. They can be located inside the converging nozzle, but they can also extend outside from both the inlet and outlet of the nozzle. (3) Vortex Lateral Expansion Chamber/Area. The purpose of this part is to allow the lateral expansion of the generated vortices in a controllable way. It is basically a closed area which gives space to the generated vortices to expand laterally as they propagate towards the exhaust nozzle of the VIASAD device. (4) Vortex Lateral Contraction Mechanism—Low Pressure Region The purpose of this part is to accelerate the vortical flow by laterally contracting the generated vortices (On a plane perpendicular to the direction of propagation). It can be either of variable geometry or fixed geometry. It can take many different forms. Two options are the following: Moving flaps or converging nozzles. (5) Air Suction Tube/Channel. The purpose of this part is to efficiently guide the air inflow induced by suction into the low pressure region of the VIASAD device. This region is where the generated vortices along with the high-speed jet stream are compressed and thus inducing the suction effect. The Air Suction Tube communicates with the low pressure region via a system of holes and/or vanes. Location: These vanes sit on the walls of the Vortex Lateral Contraction Mechanism or the walls of the low pressure region. This region is between the converging nozzle and the diffusion nozzle. (6) Diffusion or Exhaust Nozzle. The purpose of this part is to allow for the gradual expansion of the accelerated flow (jet stream and vortices) and hence minimize pressure losses for the generated suction. The operation of the VIASAD device is characterized by two types of flows: (1) Primary Flow. It can be either Air/Wind Flow or water/Underwater Current Flow. (2) Secondary Flow. It is the Air Flow induced by suction generated in the Primary Flow. Primary Flow The Primary Flow consists of the following multiple stages: Stage 1: Use of a contraction or a converging nozzle in order to accelerate the incoming wind/water flow. Stage 2: Produce a pattern of high-speed vortices by the use of vortex generators. The air/water flow accelerated in stage 1 is guided past vortex generators. Stage 3: Allow the generated vortices to expand laterally. Stage 4: Generate suction by restricting the flow path of the generated high-speed vortices. Stage 5: Diffusion or expansion of the accelerated air/water flow and the generated vortices through a diverging nozzle. Secondary Flow It can only exist in tandem with the Primary Flow. It is the result of suction produced by the Primary Flow. It constitutes the useful energy output of the VIASAD device which can be used in the following ways: (1) Directly drive an Air Turbine. The Air Turbine is basically a Fan or an Impeller, preferably enclosed in a casing in order to efficiently harness the energy content of the Secondary Air Flow. A single VIASAD device can be used to drive the flow in multiple air turbines or just a single air turbine. (FIGS. 4A/B/C, 5A/B/C/D/E, 6, 7, 8) (2) Enhance the performance of Wind Turbines/Wind Mills. This is achieved by using the Secondary Flow to suppress or smooth the Adverse Pressure Gradients or drive Active/Laminar Flow Control or Hybrid Laminar Flow Control on the low-pressure surface of the airfoil blades or the lift-generating wing devices used by Wind Turbines. Basically, slow-moving air is sucked in through holes and inlets along or close to the trailing edge of the wing. A single VIASAD device can be used to support simultaneously multiple wind turbines or it can be fitted to a single wind turbine. (FIGS. 11, 12, 13, 14A/B, 15, 16, 17, 18)

2. An Air Turbine with a fan or an impeller or a rotor of ANY TYPE or CONFIGURATION (Axial or Centrifugal) which is enclosed in a casing and it is primarily driven by Air Flow Suction induced by the use of the mechanism claimed in claim 1:VIASAD: Vortex Induced Air Speed Amplification Device. The Air Turbine/Mill consists of the following parts: (1) VIASAD Device. The purpose of this part is to generate a suction effect which drives the air through a casing or housing enclosing the wind mill fan. (2) Fan Casing or Housing. This part encloses or covers the fan of the wind mill/turbine. The purpose of this part is to efficiently guide the incoming air flow through the blades of the wind mill/turbine fan and ultimately release the air through discharge tubes into the Air Suction Tubes of the VIASAD device. (3) Rotor or Fan or Impeller. This part can be of ANY TYPE or CONFIGURATION with ANY number of blades which will best serve its intended purpose by maximizing its output performance. Its output performance is measured as the ratio of the output power delivered through a shaft to the input power content of the incoming airflow (Primary Flow). Two options for the type of the fan used are the following: Axial or Centrifugal. (4) Rotor Shaft. This part is used to deliver the output power developed by the wind mill rotor to an outside power consuming device or a generator. (5) Rotor Air Flow Exhaust Tubes (FIGS. 4B/C, 5B/C/D/E). They are used for guiding the air outflow from the rotor casing into the Air Suction Tubes of the VIASAD device. (6) Rotor Casing Exhaust Outlets (FIGS. 4B/C, 5B/C/D/E). They constitute air flow communication gateways between the rotor casing and the exhaust tubes. (7) Wind Mill Yaw Control Mechanism. A mechanism used for directing the intakes of the converging nozzles of the VIASAD device as well as the intake of the rotor casing towards the wind. (8) Wind Mill Tower. This a structure that supports the whole wind mill at a certain height above the ground at the site where it is installed. The functionality of the proposed wind turbine, unlike any existing conventional technology, is based on the following main principles: Principle 1: Accelerate the incoming wind/water flow (Primary Flow). Principle 2: Generate high-speed air/water vortices. Principle 3: Give rise to a suction effect as a result of the generated pattern of high-speed air/waterjet streams along with high-speed air/water vortices. Principle 4: Make use of the low pressure suction effect to induce or drive an artificially generated high-speed air flow (Secondary Flow) through the blades of the wind mill rotor or fan. The air flow through the rotor blades has a lot higher concentration of power per unit volume than the wind. In summary, this claim states that the wind mill/turbine is using the VIASAD device to compress the energy content of the incoming wind or underwater current (Primary Flow), in order to induce by suction an air flow (Secondary Flow) with highly concentrated energy content which is ultimately used to efficiently drive the wind mill/turbine rotor.

3. VIASAD—APG suppressor: Adverse Pressure Gradient suppressor. It consists of a VIASAD device claimed in claim 1, a system of air suction pipes/ducts or channels and a suction porous area on the surface of the wings or wind turbine rotor blades. The suction generated by the VIASAD device is used for Laminar Flow Control (LFC) or Hybrid LFC (HLFC) and/or to suppress adverse pressure gradients of the flow close to the surface of wings or rotor blades or other lifting surfaces used by Wind/Air/Underwater Turbines. The slow-moving air in the boundary layer close to the surface of the wings/blades is sucked through different types of porous openings that lead to air pipes or ducts which are eventually connected to the low-pressure region of the VIASAD device. These porous openings can have any type of shape and configuration and they can be arranged in any type of pattern that will serve their purpose best. They can also be placed at any chord length from the leading edge of the blade/wing or of a wind turbine. This claim is characterized by higher lift coefficients, enhanced lift over a wider range of angles of attack, delayed stall and reduced drag coefficients of the wings/blades. Generally, higher Lift to Drag ratio (L/D) is achieved. This is a direct consequence of the suction of slow-moving air which suppresses the adverse pressure gradients close to the low pressure surface of the wings/blades.

4. VIASAD—Variant 1 Wind Turbine Blade APG suppressor: Adverse Pressure Gradient suppressor. It consists of the VIASAD device claimed in claim 1 and a variant of the Adverse Pressure Gradient suppressor claimed in claim 3. It is characterized by a system of holes arranged on the surface of a Wind Turbine blade. A VIASAD device is used to suck slow-moving air through this system of holes. The holes can have ANY type of SHAPE, and they can be arranged in ANY type of PATTERN along the span and on the low pressure surface of each blade. The width of this pattern of holes along the chord of each turbine blade, can be as large as required in order to maximize its performance. The suction air flow-rate can vary by adjusting the number of holes that are open at any time or by restricting the air flow through the suction channels or otherwise.

5. VIASAD—Variant 2 Wind Turbine Blade APG suppressor: Adverse Pressure Gradient suppressor. It consists of the VIASAD device claimed in claim 1 and a variant of the Adverse Pressure Gradient suppressor claimed in claim 3. It is characterized by a single inlet or a system of multiple inlets serially arranged along the span of each Wind Turbine blade. A VIASAD device is used to suck slow-moving air through these inlets. The inlets can have ANY type of SHAPE, and they are placed along the span on the low pressure surface of the blade, and at any chord length needed from the leading edge. The inlets can be of variable geometry: the cross-sectional area exposed to the incoming flow is variable. Also the inlets can be arranged in ANY type of pattern which will maximize the performance of the device.

6. VIASAD—Variant 3 Oscillating Wing APG suppressor: Adverse Pressure Gradient suppressor. It consists of the VIASAD device claimed in claim 1 and a variant of the Adverse Pressure Gradient suppressor claimed in claim 3. It is characterized by a system of holes arranged along the span of an oscillating wing on both its top and bottom surfaces. The position of the holes is at any chord length required from the leading edge of the oscillating wing. The holes on each surface (bottom/top) open intermittently to allow the suction of slow-moving air based on the direction of movement of the oscillating wing: (1) Oscillating wing moving Up: Compression and hence pressure drop occurs on the top surface of the wing. Holes on the top surface open up and those on the bottom surface are closed. (2) Oscillating wing moving Down: Compression and hence pressure drop occurs on the bottom surface of the wing. Holes on the bottom surface open up and those on the top surface are closed. A VIASAD device is used to suck slow-moving air through this system of holes. The holes can have ANY type of SHAPE, and they can be arranged in ANY type of PATTERN along the span of the oscillating wing. The width of this pattern of holes as measured along the chord of the wing, can have ANY value that maximizes its performance. The suction air flow-rate can vary by adjusting the number of holes that are open at any time or by restricting the air flow through the suction channels.

7. VIASAD—Variant 4 Oscillating Wing APG suppressor: Adverse Pressure Gradient suppressor. It consists of the VIASAD device claimed in claim 1 and a variant of the Adverse Pressure Gradient suppressor claimed in claim 3. It is characterized by a single inlet or a system of multiple inlets serially arranged along the span of an oscillating wing on both its top and bottom surfaces. The inlets on each surface (bottom/top) open intermittently to allow the suction of slow-moving air based on the direction of movement of the oscillating wing: (1) Oscillating wing moving Up: Compression and hence pressure drop occurs on the top surface of the wing. Inlets on the top surface open up and those on the bottom surface are closed. (2) Oscillating wing moving Down: Compression and hence pressure drop occurs on the bottom surface of the wing. Inlets on the bottom surface open up and those on the top surface are closed. A VIASAD device is used to suck slow-moving air through this system of inlets. The inlets can be of variable geometry: the cross-sectional area exposed to the incoming flow is variable. Also the inlets can be arranged in ANY type of pattern which will maximize the performance of the device.

8. JETIASAD: Jet stream Induced Air Speed Amplification Device. JETIASAD is a pressure differential mechanism or device which makes use of the wind or underwater currents and generates a single high-speed air/water jet stream or a pattern of multiple high speed air/water jet streams, of ANY TYPE or CONFIGURATION. The generated high-speed air/water jet streams induce a suction effect. JETIASAD is very similar to VIASAD in that it accelerates incoming wind/water flow, but it is a lot simpler with no vortex generators. It consists of the following parts: (1) Contraction or Converging Nozzle. The purpose of this part is to accelerate the incoming air flow from the wind by contracting or compressing it. The intake of the contraction is facing the wind. The intake can take many forms or shapes with different combinations of Intake to Exhaust Area ratios, different wall shapes and set to operate in different modes (e.g. Horizontally or Vertically). (2) Low Pressure Region. The purpose of this part is to maintain high-speed air flow before the final discharge of the compressed wind through the diffusion nozzle. The compressed high-speed air creates a low pressure region which gives rise to a suction effect, ultimately driving the air inflow through the Air Suction Tube. (3) Air Suction Tube/Channel. The purpose of this part is to efficiently guide the air inflow induced by suction into the low pressure region of the JETIASAD device. This region is where the high-speed jet streams of compressed incoming wind flow are generated and thus inducing the suction effect. The Air Suction Tube communicates with the low pressure region via a system of holes and/or vanes. Location: These vanes sit on the walls of the low pressure region. This region is between the converging nozzle and the diffusion nozzle. (4) Diffusion or Exhaust Nozzle. The purpose of this part is to allow for the gradual expansion of the accelerated jet stream and hence minimize pressure losses for the generated suction. The operation of the JETIASAD device is characterized by two types of flows: 1. Primary Flow. It can be either Air/Wind Flow or water/Underwater Current Flow. 2. Secondary Flow. It is the Air Flow induced by suction generated in the Primary Flow. Primary Flow The Primary Flow consists of the following multiple stages: Stage 1: Use of a contraction or a converging nozzle in order to accelerate the incoming wind flow. Stage 2: Maintain a low pressure region by restricting the flow path of the generated high-speed jet-streams and thus give rise to a suction effect. Stage 3: Diffusion or expansion of the accelerated air flow through a diverging nozzle. Secondary Flow It can only exist in tandem with the Primary Flow. It is the result of suction produced by the Primary Flow. It constitutes the useful energy output of the JETIASAD device which can be used in the following ways: (1) Directly drive a Wind Turbine. The Wind Turbine can be either a Fan or an Impeller, preferably enclosed in a casing in order to efficiently harness the energy content of the Secondary Air Flow. A single JETIASAD device can be used to drive the flow in multiple air turbines or just a single air turbine. (FIGS. 4A/B/C, 5A/B/C/D/E, 6, 7, 8) (2) Enhance the performance of Wind Turbines/Wind Mills. This is achieved by using the Secondary Flow to suppress or smooth the Adverse Pressure Gradients close to the trailing edge of the airfoil blades or the lift-generating wing devices used by Wind Turbines. Basically, slow-moving air is sucked in through holes and inlets along or close to the trailing edge of the wing. A single JETIASAD device can be used to support simultaneously multiple wind turbines or it can be fitted to a single wind turbine. (FIGS. 11, 12, 13, 14A/B, 15, 16, 17, 18).

9. An Air Turbine with a fan or an impeller or a rotor of ANY TYPE or CONFIGURATION (Axial or Centrifugal) which is enclosed in a casing and it is primarily driven by Air Flow Suction induced by the use of the following mechanism: JETIASAD: Jet stream Induced Air Speed Amplification Device. JETIASAD is claimed in claim 8. The Air Turbine consists of the following main parts: (1) JETIASAD Device. The purpose of this part is to generate a suction effect which drives the air through a casing or housing enclosing the air turbine fan. (2) Fan Casing or Housing. This part encloses or covers the fan of the air turbine. The purpose of this part is to efficiently guide the incoming air flow through the blades of the turbine fan and ultimately release the air through discharge tubes into the Air Suction Tubes of the JETIASAD device. (3) Rotor or Fan or Impeller. This part can be of ANY TYPE or CONFIGURATION with ANY number of blades which will best serve its intended purpose by maximizing its output performance. Its output performance is measured as the ratio of the output power delivered through a shaft to the input power content of the incoming airflow (Primary Flow). Two options for the type of the fan used are the following: Axial or Centrifugal. (4) Rotor Shaft. This part is used to deliver the output power developed by the turbine rotor to an outside power-consuming device or a generator. (5) Rotor Air Flow Exhaust Tubes (FIGS. 4B/C, 5B/C/D/E). They are used for guiding the air outflow from the rotor casing into the Air Suction Tubes of the JETIASAD device. (6) Rotor Casing Exhaust Outlets (FIGS. 4B/C, 5B/C/D/E). They constitute air flow communication gateways between the rotor casing and the exhaust tubes. The functionality of the proposed air turbine, unlike any existing conventional technology, is based on the following main principles: Principle 1: Accelerate the incoming wind/water flow (Primary Flow). Principle 2: Generate high-speed air/water jet streams. Principle 3: Give rise to a suction effect as a result of the generated pattern of high-speed air/water jet streams. Principle 4: Make use of the low pressure suction effect to induce or drive an artificially generated high-speed air flow (Secondary Flow) through the blades of the air turbine rotor or fan. The air flow through the rotor blades has a lot higher concentration of power per unit volume than the wind. In summary, this claim states that the wind/air turbine is using the JETIASAD device to compress the energy content of the incoming wind/underwater current (Primary Flow), in order to induce by suction an air flow (Secondary Flow) with highly concentrated energy content which is ultimately used to efficiently drive the wind mill rotor.

10. JETIASAD—APG suppressor: Adverse Pressure Gradient suppressor. It consists of a JETIASAD device claimed in claim 8 and a system of air pipes/ducts along with inlets and outlets. The suction generated by the JETIASAD device is used for Laminar Flow Control (LFC) or Hybrid LFC (HLFC) and/or to suppress adverse pressure gradients of the flow close to the surface of wings or rotor blades or other lifting surfaces used by Wind/Air/Underwater Turbines. The slow-moving air in the boundary layer close to the surface of the wings/blades is sucked through different types of porous openings that lead to air pipes or ducts which are eventually connected to the low-pressure region of the JETIASAD device. These openings can have any type of shape and configuration and they can be arranged in any type of pattern that will serve their purpose best. They can also be placed at any chord length from the leading edge of the blade/wing or lift-generating surface of a wind turbine. This claim is characterized by higher lift coefficients, enhanced lift over a wider range of angles of attack, delayed stall and reduced drag coefficients of the wings/blades. Generally, higher Lift to Drag ratio (L/D) is achieved. This is a direct consequence of the suction of slow-moving air which suppresses the adverse pressure gradients close to the surface of the wings/blades.

11. JETIASAD—Variant 1 Wind Turbine APG suppressor: Adverse Pressure Gradient suppressor. It consists of the JETIASAD device claimed in claim 8 and a variant of the Adverse Pressure Gradient suppressor claimed in claim 10. It is characterized by a system of holes arranged on the surface of each Wind Turbine blade. A JETIASAD device is used to suck slow-moving air through this system of holes. The holes can have ANY type of SHAPE, and they can be arranged in ANY type of PATTERN along the span and on the low pressure surface of each blade. The width of this pattern of holes along the chord of each turbine blade, can be as large as required in order to maximize its performance. The suction air flow-rate can vary by adjusting the number of holes that are open at any time or by restricting the air flow through the suction channels or otherwise.

12. JETIASAD—Variant 2 Wind Turbine APG suppressor: Adverse Pressure Gradient suppressor. It consists of the JETIASAD device claimed in claim 8 and a variant of the Adverse Pressure Gradient suppressor claimed in claim 10. It is characterized by a single inlet or a system of multiple inlets serially arranged along the span of each Wind Turbine blade. A JETIASAD device is used to suck slow-moving air through these inlets. The inlets can have ANY type of SHAPE, and they are placed along the span on the low pressure surface of the blade, and at any chord length needed from the leading edge. The inlets can be of variable geometry: the cross-sectional area exposed to the incoming flow is variable. Also the inlets can be arranged in ANY type of pattern which will maximize the performance of the device.

13. JETIASAD—Variant 3 Oscillating Wing APG suppressor: Adverse Pressure Gradient suppressor. It consists of the JETIASAD device claimed in claim 8 and a variant of the Adverse Pressure Gradient suppressor claimed in claim 10. It is characterized by a system of holes arranged along the span of an oscillating wing on both its top and bottom surfaces. The position of the holes is at any chord length required from the leading edge of the oscillating wing. The holes on each surface (bottom/top) open intermittently to allow the suction of slow-moving air based on the direction of movement of the oscillating wing: (1) Oscillating wing moving Up: Compression and hence pressure drop occurs on the top surface of the wing. Holes on the top surface open up and those on the bottom surface are closed. (2) Oscillating wing moving Down: Compression and hence pressure drop occurs on the bottom surface of the wing. Holes on the bottom surface open up and those on the top surface are closed. A JETIASAD device is used to suck slow-moving air through this system of holes. The holes can have ANY type of SHAPE, and they can be arranged in ANY type of PATTERN along the span of the oscillating wing. The width of this pattern of holes as measured along the chord of the wing, can have ANY value that maximizes its performance. The suction air flow-rate can vary by adjusting the number of holes that are open at any time or by restricting the air flow through the suction channels or otherwise.

14. JETIASAD—Variant 4 Oscillating Wing APG suppressor: Adverse Pressure Gradient suppressor. It consists of the JETIASAD device claimed in claim 8 and a variant of the Adverse Pressure Gradient suppressor claimed in claim 10. It is characterized by a single inlet or a system of multiple inlets serially arranged along the span of an oscillating wing on both its top and bottom surfaces. The position of the inlets is at any chord length required from the leading edge of the oscillating wing. The inlets on each surface (bottom/top) open intermittently to allow the suction of slow-moving air based on the direction of movement of the oscillating wing: (1) Oscillating wing moving Up: Compression and hence pressure drop occurs on the top surface of the wing. Inlets on the top surface open up and those on the bottom surface are closed. (2) Oscillating wing moving Down: Compression and hence pressure drop occurs on the bottom surface of the wing. Inlets on the bottom surface open up and those on the top surface are closed. A JETIASAD device is used to suck slow-moving air through this system of inlets. The inlets can be of variable geometry: the cross-sectional area exposed to the incoming flow is variable. Also the inlets can be arranged in ANY type of pattern which will maximize the performance of the device.