Bracket/Spacer Optimization in Bladeless Turbines, Compressors and Pumps

FIELD OF THE INVENTION

This invention relates to the geometric shape and/or configuration of individual brackets and/or bracket/disk assemblies on the rotor(s) of bladeless (disk) turbine(s), bladeless (disk) compressor(s) and/or bladeless (disk) pump(s). This invention offers improvements in the bracket design to increase the efficiency of energy extraction or infusion between the working mechanical components and the working fluid or vice versa whether the working fluid be compressible, incompressible, Newtonian or non-Newtonian in nature.

BACKGROUND

Microturbines are gas turbines generally implemented for electrical power generation applications. Relatively small in comparison to standard power plants, they can be located on sites with space limitations for power production. Microturbines are composed at least of a compressor, combustor, turbine and alternator assembled in any number or order on one, two or three spools. Waste heat recovery can be used in combined heat and power systems to achieve energy efficiency levels greater than 80 percent. Such combinations include but are not limited to combined power and water heating cycles or combined power, heating-ventilation-air-conditioning and water heating systems. In addition to stationary and portable electrical power generation, microturbines offer an efficient and clean solution to direct mechanical drive markets such as compression, machine tools and air conditioning.

In the commercial and government electrical power markets, independence from the power grid is being sought to lessen the production burden on central power companies and traditional power sources. This move will begin to decentralize the power sources and assure service to all areas under United States sovereignty. Such decentralization protects the power supply from failure to provide for individual consumers such as homes and businesses. Furthermore, power service is commonly affected by storms, hurricanes, tornadoes, earthquakes and other natural disasters through the interruption of power service to thousands of individuals in the surrounding areas. Terrorist activities, nuclear meltdowns, acts of God or the public enemy; fires; floods; riots; strikes; shortage of labor, inability to secure fuel and/or material supplies, affect power supply and account for shortages thereof. Existing and future laws or acts of the Federal or of any State or Territorial Government (including specifically but not exclusively any orders, rules or regulations issued by any official agency or such government) or other unpredictable occurrences also provide service barriers creating situations prone to a lack of power and inappropriate service for consumers. Beyond the discomfort of the power loss, some residents find themselves in desperate circumstances fighting extreme cold or heat.

The benefits of microturbines are to provide power to individual consumers through individual micro power plants at a reasonable cost with a reasonable payback period of the consumer's investment over the life of the product. Eight benefits of microturbines as reported by the World Watch Institute (“Micropower: The next electrical era”, Worldwatch Paper 151, July 2000) are given as:

1. Modularity—By adding or removing units, micropower system size can be adjusted to match demand.
2. Short Lead Time—Small-scale power can be planned, sited and built more quickly than larger systems, reducing the risks of overshooting demand, longer construction periods and technological obsolescence.
3. Fuel Diversity and reduced volatility—Micropower's more diverse, renewables-based mix of energy sources lessens exposure to fossil fuel price fluctuations.
4. “Load-growth insurance” and load matching—Some types of small-scale power, such as cogeneration and end-use efficiency, expand with growing loads; the flow of other resources, like solar and wind, can correlate closely with electricity demand.
5. Reliability and resilience—Small plants are unlikely to all fail simultaneously; they have shorter outages, are easier to repair, and are more geographically dispersed.
6. Avoided plant and grid construction and losses—Small-scale power can displace construction of new plants, reduce grid loss, and delay or avoid adding new grid capacity or connections.
7. Local and community choice control—Micropower provides local choice and control and the option of relying on local fuels and spurring community economic development.
8. Avoid emissions and other environmental impacts—Small-scale power generally emits lower amounts of particulates, sulfur dioxide and nitrogen oxides, heavy metals, and carbon dioxide, and has a lower cumulative environmental impact on land and water supply and quality.

Technology trends as witnessed by U.S. Pat. No. 6,324,828 (Willis et al.); U.S. Pat. No. 6,363,712 (Sniegowski et al.); U.S. Pat. No. 6,392,313 (Epstein et al.); U.S. Pat. No. 6,526,757 (MacKay); and U.S. Pat. No. 6,814,537 (Olsen) demonstrate the implementation of conventional radial compressors and turbines in creating microturbines to power the electrical generation system currently on the market and in development. In particular, Olsen demonstrates a method for a rotor assembly with conventional turbine allowing interchangeability.

A bladeless turbine design was first patented by Nikola Tesla (U.S. Pat. No. 1,061,206) in 1913 for use as a steam turbine to extract energy from a working fluid. This original patent included the grouping of a series of disks and blades with identical passage holes symmetrically grouped around the rotor. The working fluid was introduced at pressure and temperature through a form of nozzle at an angle on the outer perimeter of the disks. With only the passage holes in the disks as an outlet for the working fluid, it was forced across the disks radially and angularly inward to exit through an axially located outlet which path resulted in reduction of pressure and temperature of the working fluid and the consequent rotation of the rotor assembly. This configuration is known as a Tesla turbine, bladeless turbine, disk turbine, Tesla pump, bladeless pump or disk pump. The general concept has been widely implemented as a pump, witnessed in U.S. Pat. No. 3,644,051 (Shapiro); U.S. Pat. No. 3,668,393 (Von Rauch); and U.S. Pat. No. 4,025,225 (Durant) and a turbine, witnessed in U.S. Pat. No. 1,061,206 (Tesla); U.S. Pat. No. 2,087,834 (Brown et al.); U.S. Pat. No. 4,025,225 (Durant); U.S. Pat. No. 6,290,464 (Negulescu et al.); U.S. Pat. No. 6,692,232 (Letourneau); and U.S. Pat. No. 6,726,443 (Collins et al.). In form without brackets between the disks, the bladeless turbine is referred to as a Prandtl Layer turbine as witnessed in U.S. Pat. No. 6,174,127 (Conrad et al.); U.S. Pat. No. 6,183,641 (Conrad et al.); U.S. Pat. No. 6,238,177 (Conrad et al.); U.S. Pat. No. 6,261,052 (Conrad et al.); and U.S. Pat. No. 6,238,527 (Conrad et al.)

Standard practice among individual researchers and hobbyists is to combine multiple disks each of identical outer radius and chamber size in the same turbine, compressor or pump assembly. This method is referred to as a constant—geometry disk assembly and is witnessed in U.S. Pat. No. 1,061,206 (Tesla); U.S. Pat. No. 3,644,051 (Shapiro); U.S. Pat. No. 3,668,393 (Von Rauch); U.S. Pat. No. 4,025,225 (Durant); 4,201,512 (Marynowski et al.); U.S. Pat. No. 6,227,795 (Schmoll, III); U.S. Pat. No. 6,726,442 (Letourneau); U.S. Pat. No. 6,726,443 (Collins et al.); and U.S. Pat. No. 6,779,964 (Dial).

It has been found by others that variations in the disk shape, referred to here as disk bending, gap differentiation, variation in outer diameters of disks within a single assembly and variation in diameter of flow chambers from one disk to the next alter the performances of the disk assembly. Those are listed as follows:

(1) Disk bending—U.S. Pat. No. 1,445,310 (Hall); U.S. Pat. No. 2,087,834 (Brown et al.); U.S. Pat. No. 4,036,584 (Glass); U.S. Pat. No. 4,652,207 (Brown et al.)
(2) Gap differentiation—U.S. Pat. No. 2,087,834 (Brown et al.); U.S. Pat. No. 4,402,647 (Effenberger)
(3) Outer diameter variation—U.S. Pat. No. 5,419,679 (Gaunt et al.); U.S. Pat. No. 6,261,052 (Conrad et al.)
(4) Flow chamber diameter variation—U.S. Pat. No. 2,626,135 (Serner); U.S. Pat. No. 3,273,865 (White); U.S. Pat. No. 5,446,119 (Boivin et al.); U.S. Pat. No. 6,183,641 (Conrad et al.); U.S. Pat. No. 6,238,177 (Conrad et al.); U.S. Pat. No. 6,261,052 (Conrad et al.)

The variations in the assemblies just described pertain to the disks in the assembly only. Only in U.S. Pat. No. 2,626,135 (Serner); U.S. Pat. No. 4,402,647 (Effenberger); and U.S. Pat. No. 5,466,119 (Boivin et al.) are the spacers, hereto referred as brackets, and gaps between the disks approached in design. Serner takes the arm of the disk and bends it to induce higher efficiency in energy translation from the fluid to the rotor or vice versa. Effenberger tapers the disks to achieve a desired effect on the gap, but shows no interest in deviating from standard practice in bracket design. Boivin et al. include one spacer with a knife-shaped deformable portion to compensate for adjustments when combining a turbomolecular bladeless pump with a stator.

Most of the above methods are implemented for incompressible fluids or steam. In the instance a bladeless configuration is implemented with ideal or near-ideal gases, such as air, the kinematic viscosity effect is considerably lessened. Furthermore, variations in air chamber design on the disks will not geometrically coincide with standard bracket designs.

These issues have brought about the present invention.

SUMMARY OF THE INVENTION

A bladeless turbine, compressor or pump working with a compressible or incompressible fluid relies on the viscosity of the fluid to propel the disk assembly through the extraction of energy. Likewise, when energy is added into the working fluid from the disk assembly, it is through the viscosity of the fluid the energy is transferred. Thus, as a working fluid with lower kinematic viscosity is implemented, the ability of the disks to extract or infuse energy into or from the fluid system is proportionally decreased whether this relationship be constant, linear, non-linear in nature, step-function or random in nature.

Individual researchers and hobbyists will reduce the distance between disks in a given assembly to increase the likelihood of energy exchange between the mechanical and fluid systems as the viscosity decreases. When the working fluid is no longer compressible, but incompressible the viscosity changes by several factors. For example, the kinematic viscosity of an incompressible fluid could be on the order of 1e-1 while the kinematic viscosity of a compressible fluid could be on the order of 1e-6. The inability to reduce the distance between disks by such a great factor—assuming a linear relationship between the effects—as the kinematic viscosity is reduced leads to the conclusion that the mechanical system must work harder to increase the pressure and temperature gradients to obtain similar mass flow rates as with incompressible fluids.

The most common implementation of bladeless turbines, compressors and pumps is with incompressible fluids for this very reason. One can gain satisfactory performance with an incompressible fluid running the bladeless device in a range from 0-25,000 RPM. When implementing a compressible fluid, this range of rotational speed accomplishes very little compression and mass flow. To obtain the design point of bladeless devices with compressible flow, they must be run at speeds up to 100,000 RPM and beyond.

Running a rotational device at high RPM as just described brings the outer diameter of the rotor near to stalling speed by approaching, reaching or surpassing the speed of sound under its operating conditions. For this reason, only smaller bladeless turbines, compressors and pumps ranging in size from 1 nanometer to around 150 centimeters are suited for working at high rotational speeds.

A disk working at such high rotational speeds with a compressible fluid inherently causes the arm, holding the hub of the disk to the working surface of the disk and brackets or spacers which assembly together creates flow chambers, to become objects with which the fluid will collide. Said collision is another method, perhaps the primary method at such high speeds, through which energy is exchanged from the working fluid to the mechanical system or vice versa. The low kinematic viscosity of the compressible working fluid at high RPM having a lesser effect on energy transfer. The importance of these phenomena is reversed in incompressible working fluids running with a bladeless rotor at low RPM.

An object of this invention is to define the reference system and the variables necessary to produce variation in bracket/spacer design affecting the assembly and hence the fluid flow chambers beyond those standardly used in prior art.

An object of this invention is to improve disk/bracket assembly performance at high rotational speeds through implementing variation(s), but not limiting in any fashion, from constant angular value in the centerline, median or mean of individual brackets or spacers in the assembly.

An object of this invention is to improve disk/bracket assembly performance at high rotational speeds through implementing variation in the outermost edge of the brackets and/or spacers independent of the geometry of the disks in the assembly.

A further object of this invention is to provide improved geometry to the flow chamber(s) through bracket/spacer design to maximize efficiency and improve performance at high RPM with a compressible fluid through adhering geometry similar to a teardrop for the fluid flow chamber, thus maximizing the energy extraction or infusion to and/or from the working fluid.

Further, an object of the invention is to provide a variation in width of the bracket(s) and spacer(s) geometries which, based on the implementation of the bladeless turbine, compressor or disk, will maximize the efficiency of energy transfer within various performance parameters.

Further, an object of the invention is to leading and trailing edges of the bracket(s) and spacer(s) geometries which, based on the implementation of the bladeless turbine, compressor or disk, will maximize the efficiency of energy transfer within various performance parameters.

Finally, an object of the invention is to provide a method of securing the brackets to the assembly which, based on the implementation of the bladeless turbine, compressor or disk, will maximize the efficiency of energy transfer within various performance parameters.

DESCRIPTION OF THE DRAWINGS

FIG. 1: Variables describing a bracket/spacer with a given angle from the origin, θn;

FIG. 2
a, 2b: Prior art bracket design;

FIG. 3: Improved bracket/spacer design demonstrating all possible improvements combined in one form.

DETAILED DESCRIPTION OF THE INVENTION

In order to understand prior art designs of the bracket(s) and/or spacer(s), FIG. 1 denotes the variables necessary to explain the improvements provided in this invention. The origin is placed at the center with the bracket or spacer extending radially outward in the r-direction and a nominal thickness in the x-direction. A distance, [θ_n], from the angular origin an arm of the bracket and/or spacer is located by its centerline, [℄(r)], of constant angular direction and increasing radial direction. Said arm is given a physical width, [w(r)], as a function of radial location as well as a decrease in width, [dw(r)], as it distances from the origin. Thus, the following definitions are given:

Definition List 1TermDefinitiondFirst order differential for widthmAn integer denoting the number of armsnAn integer of value 1, 2, 3, . . . k − 1, krRadial directionR_IDInner diameter of the bracket/spacerarm(s)R_ODOuter diameter of the bracket/spacerarm(s)wArm widthxAxial directionδAngular spacing distance between armson a single bracket/spacerθAngular direction

Said arm(s) may be a single unit or more than one unit. In general practice, the number of arms, m, may vary between two and six or more and are angularly spaced a distance, δ, apart. Each of the arms and consequential fluid flow chambers has a given inner diameter, R_ID, which in prior art are constant in value. Each of the bracket/spacer arms separate from the fluid flow chambers has a given outer diameter, R_OD. Each bracket/spacer arm begins with a leading edge at location δ_m-1−0.5W(r)_m-1and ends with a trailing edge at δ_m+0.5W(r)_m.

FIG. 2
a & 2b demonstrate the prior art described above for a bracket or spacer used in bladeless turbine, compressor or pump assemblies. A prior art bracket(s) and/or spacer(s) consists of one or more arms [1] & [11] whose shape and design can be described by a center, mean or median line [2] & [12] as a radially-dependent function only, such that ℄(r). Said arms in prior art are symmetrically equal to each other with leading edge [3] & [13] a constant outer diameter, R_OD, for the tips of the arms [4] & [14] as well as a trailing edge [1] & [15]. The distance between the leading and trailing edge of the arm(s), considered to be the width, w(r), of the arm, is either constant or linearly varying in the radial direction such that w(r)+dw(r)/dr where dw(r)/dr is a negative constant value as the arm extends outward. Further, each bracket and/or spacer consists of a hub [6] & [16] with an outer diameter whose radius generally coincides directly with the inner radius, R_ID, of the arm(s) [1] & [11] to which the arm(s) [1] & [11] are attached and the unit attaches to a shaft or assembly at a mount location [8] & [18]. FIG. 2b goes further to demonstrate prior art method of attaching the bracket(s), spacer(s) and/or disk(s) to the assembly with a single screw, screw hole or pin hole [19] located in each arm [1] & [11] at a given diameter [20] from the center.

FIG. 3 demonstrates a combination of improvements to the bracket and/or spacer design. In no fashion does it limit the implementation of these improvements individually, as groups or all together as depicted in FIG. 3. The improved bracket(s) and/or spacer(s) consists of one or more arms [21] whose shape and design can be described by a center, mean or median line [22] as a three-dimensional function, such that ℄(r,θ,x). Said arm(s) [21] may or may not be symmetrically equal to each other in geometry but all consitst of two edges [23] & [25] with an outer diameter, R_OD(r,θ,x), constant or varying in any of the three dimensions locating the tip of the arm(s) [24]. Said tip of the arm(s) [24] may be rounded or pointed. Which edge is determined to be the leading or trailing edge is dependent on the implementation of the unit and direction of rotation. The distance between the two edges of the arm(s) [21], considered to be the width, w(r,℄,x), of the arm, can be constant, linear or non-linear in the r, ℄, and/or x directions such that the width along the arm may be described as w(r,℄,x)+∇w(r,℄,x), remembering that ℄denotes a center, median or mean line [22] of the arm in question. Further, each bracket and/or spacer consists of a hub [26] which may have but is not limited to an outer diameter whose radius generally coincides directly with the inner radius, R_ID, of one or more arm(s) [21] to which the arm(s) [21] are attached and the unit attaches to a shaft or assembly at a mount location [28]. Further, said bracket and/or spacer may or may not have a method of attaching it to the assembly through sintering or the use of one or more screws, screw holes or pin holes [29] located in each arm [21]. Each hole may be independently located or fixed to a given radius from the center.

The above figures depict, but do not limit in concept the intention of the invention, possible flow optimizations through the combination of design and variation of individual bracket/spacer geometries in a given assembly of a bladeless compressor, pump or turbine. The geometry of the individual bracket(s)/spacer(s) themselves is recommended in this invention, but does not limit as to the possible design or configuration of the bracket(s)/spacer(s), to be maximized for compression and energy extraction purposes. These designs may be oriented in the assembly in any fashion to maximize the efficiency of energy addition or extraction to the compressible or incompressible working fluid.

Bracket/Spacer Optimization in Bladeless Turbines, Compressors and Pumps

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