Patent Application
20200340386
This disclosure is protected under United States and/or International Copyright Laws. © 2017 Jetoptera. All Rights Reserved. A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and/or Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
Combustion in a duct involves complex chemical, fluid-dynamic and thermal processes involving a fuel as well as an oxidizer in a confined geometry and a temperature that favors the ignition, flame propagation and stabilization of the reactive flow. The combustion process also generates a certain pressure drop, generating discontinuities in the process. This is particularly evident in race cars, where flames as much as one foot in length coming out from the exhaust pipe can be observed at times. A resulting loss in power of the race car is correlated to this flame emerging from the exhaust pipe.
An internal combustion engine (ICE) is often compared to an air pump. Horsepower increases with the amount of flow of air circulated through the engine system. Conversely, any backpressure formed in the exhaust system requires horsepower to overcome it, eroding the performance of the engine itself. Particularly in racing cars, one can obtain an increase in the horsepower if efficient increase of intake of air and efficient purging of gas from the engine is achieved, minimizing the horsepower spent on reducing pumping losses through the exhaust pipe. For a given engine volume, the more air supplied to it means the more power is extracted, and its efficiency is increased. In addition, the more streamlined the exhaust gas flow is, the less power is expended on pushing the exhaust gas out, hence increasing the power available to the propulsion.
A high-performance racing car typically uses an ICE. The mixture of the fuel and air is tuned to produce the maximum power at most times, but in less ideal conditions (e.g., turning curves, etc.), the stoichiometry is somewhat changed, and the chemistry, local wall temperatures, and residence time in the pipe are such that they favor ignition of the combustible mixture. As such, at different moments in the race, flames appear from the exhaust pipe. Flames are a signal of inefficiencies, i.e., the fuel is not being burned in the engine and excess fuel is leaving the cylinder and entering the exhaust system.
As discussed, the flame observed is the fuel reigniting when the conditions are appropriate (stoichiometry, residence time, and temperature). The loss of efficiency, thus, comes from the fuel burning in the wrong location. Wherever a combustion or reacting flow occurs in a confined location such as a pipe, pressure losses occur and a disturbance of the flow is observed. The upstream processes of the combustion or flame front are equally impacted, with a certain pressure loss of the flow resulting from this process. Moreover, the undesired presence of the flame inside the exhaust pipe means that the upstream conditions to and including the ICE are affected negatively, including the thermal stresses, the life of the components, and the thermodynamic efficiency of the system.
It is desirable that a streamlined flow is maintained (i.e., combustible mixture pushed out of the pipe via reduction of the residence time in the hot exhaust). The less time the combustible mixture spends inside the exhaust pipe, the lower the propensity of ignition and the higher the efficiency of the entire system.
The restrictions in the exhaust system of an automobile typically include a catalytic converter, a resonator, and a muffler. Regulations require these for both emissions and noise reduction purpose. It is important to minimize the flow losses through this system and recover some of the power spent on overcoming these flow blockages.
With every opening of an exhaust valve, pressure arises in the exhaust manifold and typically the pressure drops in the exhaust manifolds between the openings of the exhaust valves of all cylinders. This problem can be exacerbated at lower rotational speeds. Interference between the exhaust flows from multiple cylinders inside the manifold may cause a decrease in horsepower. The ideal exhaust manifold/header and exhaust system would create a lower pressure zone that effectively purges the manifold downstream resulting in an increase in horsepower.
This application is intended to describe one or more embodiments of the present invention. It is to be understood that the use of absolute terms, such as “must,” “will,” and the like, as well as specific quantities, is to be construed as being applicable to one or more of such embodiments, but not necessarily to all such embodiments. As such, embodiments of the invention may omit, or include a modification of, one or more features or functionalities described in the context of such absolute terms. In addition, the headings in this application are for reference purposes only and shall not in any way affect the meaning or interpretation of the present invention.
Embodiments of the present invention include a modified Coanda ejector that is of non-round geometry and has a 3-D inlet section which contains a plurality of primary nozzles which introduce motive fluids as wall jets. Augmentation and 3-D inlet designs are disclosed in U.S. Provisional Patent Application 62/213,465, entitled FLUIDIC PROPULSIVE SYSTEM AND THRUST AND LIFT GENERATOR FOR UNMANNED AERIAL VEHICLES, filed Sep. 2, 2015 (“the '465 Provisional Application”). The '465 Provisional Application is herein incorporated by reference in its entirety. The 3-D geometric features and other designs disclosed in '465 Provisional Application may be applied to embodiments of the present invention, such as a symmetric or non-symmetric ejector as described and adapted to an exhaust pipe of the system.
The motive fluid may be air supplied from a compressor of a turbocharger, an electric motor driven mini-compressor, or a small portion of the pressurized exhaust gas from an ICE, routed toward the said ejector. Embodiments of the ejector may be of fixed- or variable-geometry, matching the systems conditions, and operating such that it optimizes the performance at all times. One preferable embodiment has no moving parts, and may be round or non-round in nature, with its inlet and exhaust being essentially 3-D in nature (i.e., not 2-D). This 3-D feature can enable better entrainment of the incoming flow and its acceleration towards the exit of the exhaust pipe.
Embodiments of the present invention allow for rapid evacuation of exhaust gases from a confined pipe, thereby allowing for a rapid and constant (or pulsed) evacuation of the gases and streamlining the exhaust flow. As a result, the upstream processes of the combustion zone inside the confined pipe are relieved of the reaction zone blockage, and flow is rapidly evacuated towards an exit, avoiding altogether combustion occurring inside the pipe. A streamlined flow can exist and the residence time can stay at all times below a certain level.
For a given flow of air through the system and air-to-fuel ratio, the power used to evacuate the exhaust gas is inversely proportional to horsepower available at the flywheel. Other optionally advantageous benefits include the reduction of fuel consumption and the increase in miles per gallon.
Current methods of increasing the horsepower available to the driver while reducing the exhaust flow losses include: tuned headers, dual exhaust systems, resonator removals and oversizing of the exhaust gas system. Embodiments of the present invention achieve this goal via a fluidic amplifier which may be positioned inside the exhaust manifold, exhaust pipe and/or muffler, driven by a source of high pressure such as belt driven air pump, air compressor or even exhaust gas at pressure from the cylinder. Embodiments of the invention have the optionally advantageous feature of the removal of any reacting flow such as flames causing additional blockages inside the exhaust pipe. An embodiment reduces the residence time and the local stoichiometry to prevent autoignition inside the exhaust system.
For instance, NASCAR teams will generally work with a fuel injected V-8 of 725HP without the restrictor plates in the intake and will feed into an exhaust header and short pipes. In this example, dealing with the pressure waves in the exhaust is inevitable. A backfire at the outlet or in the pipe sends a disruptive (out-of-phase) pressure change back up the system, which interferes with cylinder scavenging and filling. NASCAR engines need to handle the upstream impact. The goal of a tuned header and exhaust system is to raise power output by optimally filling the cylinders at the intake end—i.e., pulling in more air/fuel mixture by exhausting more efficiently.
Embodiments of the present invention show improved entrainment by means of novel elements that rely on 3-D geometrical and fluid flow effects and utilization of separation avoidance techniques. The entrainment ratios of these embodiments are between 3-15, preferably higher. By entrainment ratio we refer to the ratio of the amount of mass flow rate entrained by the motive flow to the motive fluid flow rate. Generally, embodiments of the device will receive the motive gas from a pressurized source such as a source of pressurized fluid, exhaust gas or air; a piston engine (for pulsed operations) exhaust discharge; or a compressor or supercharger. Another optionally advantageous feature of the present invention is the ability to change the shape of the diffusor walls of the flat ejector utilized for entrainment by retracting and extending the surfaces to modify the geometry such that maximum performance is obtained at all points of the operation of the ICE.
In one embodiment, a fluidic amplifier is placed at a location inside the exhaust pipe, preferably in the center and without touching the walls of the exhaust pipe. A motive fluid supplied from the higher-pressure fluid source, such as a supercharger or any region of the system providing higher pressure fluid, is then introduced via an inlet pipe towards a plenum. Placing embodiments of the present invention inside the exhaust pipe and using a motive fluid at near-static pressure as compared to the flow inside the exhaust pipe can energize the local flow to a point where the pressure is dropped and the main reacting flow is quenched and accelerated out of the exhaust pipe.
In this embodiment, the device can be non-circular and with several 3-D features that, upon the introduction of the higher-pressure fluid, increase the number of multiple high-speed wall jets that follow along the contour of the walls of the device. The motive fluid thus moves the flow according to the internal walls of the device into an essentially axial direction. The introduction of the motive fluid at very high velocities close to sonic velocity results in a local static pressure drop according to the Bernoulli principle. In response, a large area of lower pressure forms around the 3D features of the inlet of the device, creating an effect of entrainment of the main exhaust gas flowing inside the exhaust pipe. The result is an acceleration of the flow to local speeds higher than 100 m/sec, with variations depending on the geometry of the device and the quality of the motive fluid. The high speed of the mixture emerging from the device reduces the residence time required for the ignition of the main exhaust gas upstream of the device, preventing ignition and blowing out any incipient flame that can form due to presence of additional oxygen and fuel in the exhaust. Hence, embodiments of the present invention allow for a slow- or non-reacting flow to freely be pushed at higher velocity outside the exhaust pipe, quenching any flame that may exist, and in addition, allow the forced exhaust to freely exit the conduit. This in turn enhances the operation of the system by avoiding any downstream flame or reacting flow-pressure changes that may otherwise impact the upstream ICE operation.
In this embodiment, the role of the Coanda ejector placed inside the exhaust pipe is to assure the lack of the presence of the flame via high speed local quenching and lowering the local static pressure according to the Bernoulli principle. This enhances the operation of the ICE such as those used in a racing car and operation without major disruptions related to a flame presence. Once the exhaust valve of an ICE opens, the heat carried by the gases is wasted and any re-ingestion into the engine is to be avoided.
As best illustrated in
In the embodiment illustrated in
The mix of the stream 600 and the gas 1 may be moving purely axially at a throat section 325 of the ejector 243. Through diffusion in a diffusing structure, such as diffuser 310, the mixing and smoothing out process continues so the profiles of temperature 800 and velocity 700 in the axial direction of ejector 243 no longer have the high and low values present at the throat section 325, but become more uniform at the terminal end 100 of diffuser 310. As the mixture of the stream 600 and the gas 1 approaches the exit plane of terminal end 301, the temperature and velocity profiles are almost uniform. In particular, the temperature of the mixture is low enough to prevent auto-ignition of any fuel remaining inside the exhaust pipe, and the velocity is high enough to reduce the residence time in the hot walls zone.
While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.
This application is a continuation of U.S. application Ser. No. 15/670,947 filed Aug. 7, 2017; which claims priority to U.S. Prov. Pat. Appl. No. 62/371,926 filed Aug. 8, 2016. The above-referenced applications are hereby incorporated by reference in their entireties as if fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 62371926 | Aug 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15670947 | Aug 2017 | US |
| Child | 16673514 | US |
