HK1256699B - Ejector and airfoil configurations - Google Patents

Description

Ejector and airfoil configuration

Copyright notice

The present disclosure is protected by the united states and international copyright laws.2016 jetpotera. All rights are reserved. A portion of the disclosure of this patent document contains material which 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 trademark office patent file or records, but otherwise reserves all copyright rights whatsoever.

Priority declaration

This application claims priority to U.S. provisional application No.62/213,465 filed on 9/2/2015, the entire disclosure of which is incorporated by reference as if fully set forth herein.

Background

Aircraft that can hover, take off, and vertically land are commonly referred to as Vertical Take Off and Landing (VTOL) aircraft. This category includes fixed wing aircraft as well as helicopters and aircraft with tiltable power rotors. Some VTOL aircraft may also operate in other modes, such as short take-off and landing (STOL). VTOL is a subset of V/STOL (vertical and/or short take-off and landing).

For purposes of illustration, an example of a current aircraft with VTOL capabilities is F-35 Lightning. Conventional methods of directing the vertical lift airflow include the use of a nozzle that can rotate in a single direction, along with the use of two sets of flat baffle blades that are arranged at 90 degrees to each other and located at the outer nozzle. Similarly, the F-35Lightning propulsion system uses a combination of vertically oriented lift fans and vector thrust from turbine engines to provide vertical lift. The lift fan is positioned behind the cockpit in a cabin (bay) with upper and lower double-leaf arc doors. The engine exhausts through a three-bearing rotary nozzle that can deflect thrust from horizontal to vertically straight ahead. A roll control duct extends from each wing and is supplied with thrust by air from an engine fan. Pitch control is affected by lift fan/engine thrust split. Yaw control is a yaw movement by rotating a nozzle by an engine. Roll control is provided by differentially opening and closing apertures at the ends of the two roll control conduits. The lift fan has a telescoping "D" shaped nozzle to provide thrust deflection in the fore and aft direction. The D-nozzle has a fixed vane at the outlet orifice.

The design of an aircraft or drone is more generally constituted by its propulsion elements and by the body into which these elements are integrated. Conventionally, the propulsion device in an aircraft may be a turbojet, a turbofan, a turboprop or turboshaft engine, a piston engine or an electric motor equipped with a propeller. The propulsion system (propeller) in small Unmanned Aerial Vehicles (UAVs) is conventionally a piston engine or an electric motor powered via an axial propeller or propellers. The propellers used for larger aircraft, whether manned or unmanned, are traditionally jet engines or turboprop engines. The propellers are typically attached to the fuselage or body or wing of the aircraft via a pylon or strut that is capable of transferring forces to the aircraft and maintaining the load. The emerging mixed jet of air and gas (outflow) is what propels the aircraft in a direction opposite to the direction of flow of the jet outflow.

Conventionally, the outflow of airflow from a large propeller is not used for lift purposes in horizontal flight, and therefore a large amount of kinetic energy is not used for the benefit of the aircraft unless it is rotating as in some applications currently available today (i.e., Bell Boeing V-22 Osprey). Of course, lift on most existing aircraft is generated by the wings and tail. Furthermore, even in those particular VTOL applications found in Osprey (e.g., take-off through transition to level flight), the lift caused by the propeller itself is minimal during level flight, and most of the lift still comes from the wing.

The current state of the art for generating lift on aircraft is to generate high velocity airflow over the wings and wing elements, which are typically airfoils. The airfoil is characterized by a chord line extending from a leading edge to a trailing edge of the airfoil primarily in an axial direction. Based on the angle of attack formed between the incident airflow and the chord line, and according to the principle of airfoil lift generation, air at a lower pressure flows over the suction (upper) side and, conversely, moves at a higher velocity than the underside (pressure side) by bernoulli's law. The lower the aircraft's airspeed, the lower the lift and the need for higher wing surface area or higher incidence angles, including at takeoff.

Large UAVs are no exception to this rule. Lift is generated by designing the airfoil of the wing with the appropriate angles of attack, chord, span and camber line. Flaps, slots and many other devices are other conventional tools for maximizing lift via increasing lift coefficient and wing surface area, but it will produce lift corresponding to the airspeed of the aircraft. (increase of area (S) and coefficient of lift (C)_L) Allowed according to the formula L ═ L¹/₂ρV²SC_LSimilar amounts of lift are produced at lower aircraft airspeeds (V0), but at the expense of higher drag and weight. ) These current techniques also perform poorly, with a significant drop in efficiency under conditions with high crosswinds.

While smaller UAVs may use the thrust generated by propellers to lift an aircraft, current technology relies strictly on control of electric motor speed, and smaller UAVs may or may not have the ability to rotate the motor to generate thrust and lift or transition to level flight by tilting the propellers. Furthermore, smaller UAVs using these propulsion elements suffer from inefficiencies associated with batteries, power densities, and large propellers that may be efficient at hovering, but inefficient in horizontal flight, and create difficulties and dangers in operation due to the rapidly moving tips of the blades. Most current quadrotors and other electric aircraft are only capable of very short flight times and are not able to efficiently lift or carry large payloads, as the weight of the electric motor system and batteries can already be far in excess of 70% of the weight of the aircraft at any time of flight. Similar aircraft using jet fuel or any other hydrocarbon fuel typically used in transportation will carry at least an order of magnitude more fuel available. This can be explained by the significantly higher energy density of hydrocarbon fuels (by at least one order of magnitude) and the lower weight of the hydrocarbon fuel-based system compared to the total aircraft weight compared to the battery system.

Thus, there is a need for improved efficiency, improved capabilities, and other technological advances in aircraft, particularly for UAVs and some manned vehicles.

Drawings

FIG. 1 is a cross-sectional view of an embodiment of the invention showing the upper half of the ejector and the velocity and temperature distribution within the internal flow;

FIG. 2 illustrates a partial perspective view of an inlet structure according to an embodiment;

FIG. 3 illustrates a side plan view of an injector placed in front of a control surface, according to an embodiment;

FIG. 4 is a perspective view of an injector placed in front of a control surface in combination with another control surface, according to an embodiment;

FIG. 5 is a top partial cross-sectional view of an alternative embodiment;

FIG. 6 is a side perspective view of an alternative embodiment;

FIG. 7 is a side view of a component of the embodiment shown in FIG. 6;

figures 8 to 9 show a further alternative embodiment of the invention; and

fig. 10 shows yet another alternative embodiment of the present invention.

Detailed Description

This application is intended to describe one or more embodiments of the invention. It is to be understood that absolute terms, such as "must," "about," and the like, as well as the use of a specific amount, are to be construed as applicable to one or more, but not necessarily all, of such embodiments. As such, embodiments of the invention may omit or include modification of one or more features or functions described in the context of such absolute terms. In addition, the headings in this application are for reference purposes only and should not affect the meaning or interpretation of the invention in any way.

One embodiment of the present invention includes an impeller that utilizes a fluid to entrain and accelerate ambient air and deliver a high velocity jet outflow of a mixture of high pressure gas (supplied to the impeller from a gas generator) and entrained ambient air. In essence, this object is achieved by venting gas in the vicinity of the convex surface. The convex surface is a so-called Coanda surface which benefits from the Coanda effect described in U.S. patent No.2,052,869 to Henri Coanda on 1/9 in 1936. In principle, the coanda effect is the tendency of the gas or liquid ejected by a jet to travel closer to the wall profile even if the wall curves in a direction away from the axis of the jet. The convex coanda surfaces discussed herein with respect to one or more embodiments need not be constructed of any particular material.

FIG. 1 shows a cross-sectional view of an upper half of a jet 200 that may be attached to an aircraft (not shown), such as, for non-limiting example, a UAV or a manned aircraft, such as a fixed wing aircraft. The plenum 211 is supplied with air hotter than ambient (i.e., a pressurized motive gas stream) from, for example, a combustion-based engine that may be employed by the aircraft. This pressurized motive gas flow, indicated by arrow 600, is directed to the interior of the ejector 200 via at least one conduit, such as the primary nozzle 203. More specifically, the primary nozzle 203 is configured to accelerate the motive fluid flow 600 as a wall jet directly above the convex coanda surface 204 to a variable predetermined desired velocity. Additionally, the primary nozzle 203 provides an adjustable volume of fluid flow 600. This wall jet, in turn, serves to entrain a secondary fluid, such as ambient air, indicated by arrow 1, through the inlet structure 206, which may be at rest or approach the ejector 200 at a non-zero velocity from the direction indicated by arrow 1. In various embodiments, the nozzles 203 may be arranged in an array in a curved orientation, a helical orientation, and/or a zig-zag orientation.

The mixture of flow 600 and air 1 may move purely axially at the throat 225 of the ejector 200. By diffusing in a diffusing structure such as diffuser 210, the mixing and smoothing process continues, so the distribution of temperature (800) and velocity (700) along the axial direction of injector 200 no longer has high and low values present at throat 225, but becomes more uniform at tip 101 of diffuser 210. As the mixture of flow 600 and air 1 approaches the exit plane of the tip 101, the temperature and velocity distribution is nearly uniform. In particular, the temperature of the mixture is low enough to be directed towards an airfoil, such as a wing or a control surface.

In embodiments, the inlet structure 206 and/or the tip 101 may have a rounded configuration. However, in different embodiments, and as best shown in fig. 2, the inlet structure 206, as well as the tip 101, may be non-circular and in fact asymmetric (i.e., not identical on both sides of at least one, or alternatively any given plane bisecting the inlet structure). For example, as shown in fig. 2, the inlet structure 206 may include a first laterally opposing edge 401 and a second laterally opposing edge 402, wherein the first laterally opposing edge has a larger radius of curvature than the second laterally opposing edge. The tip 101 may be similarly constructed.

Fig. 3 shows a propeller/injector 200, which propeller/injector 200 is placed in front of a control surface, such as an airfoil 100 having a leading edge 302 and generating a lift 400. As shown, the airfoil 100 is positioned directly behind (i.e., downstream of) an outlet structure of the injector, such as the tip 101 of the diffuser 210, such that the propulsive fluid from the injector 200 flows through the airfoil. Indeed, in embodiments, the airfoil 100 may be positioned close enough to the tip 101 such that only the propulsion fluid from the ejector 200 flows through the airfoil, excluding other ambient air. As used herein, the term "directly behind" may be interpreted to mean that at least a portion of the leading edge 302 lies within or is aligned with one of the planes (a) occupied by the surface of the tip 101 parallel to the leading edge and (b) extending in an axial direction (i.e., in the direction of arrow 300 discussed below) to the injector 200.

The local flow over the wing 100 has a higher velocity than the velocity of the aircraft due to the higher velocity of the ejector 200 exit jet outflow as indicated by arrow 300 compared to the aircraft airspeed as indicated by arrow 500. The ejector 200 vigorously mixes the hotter motive flow 600 (fig. 1) with the incoming cooler ambient air flow at a higher entrainment rate. Additional control surfaces may be implemented on the airfoil 100, for example, the elevator surface 150. In an embodiment, the entirety of any such control surface may be rotatable about an axis oriented parallel to the leading edge 302. By changing the angle of such surfaces 100 and/or 150, the attitude of the aircraft may be changed rapidly with less effort, taking into account the higher local velocity of the jet outflow 300. The mixture is sufficiently homogeneous to reduce the temperature of the injector's hot motive flow 600 to a mixture temperature distribution 800 that will not mechanically or structurally negatively impact the airfoil 100 or 150. The velocity profile 700 of the jet outflow leaving the propeller is such that it allows more lift 400 to be generated by the airfoil 100 due to the higher local velocity.

Fig. 4 shows that the propeller/injector 200 may also be placed in front of a control surface 1500 combined with another airfoil 1000 and in a different configuration than the configuration of the control surface shown in fig. 3. In the illustrated embodiment, the leading edge 1501 of the control surface 1500 is disposed at an angle of about 90 degrees relative to the leading edge 1001 of the airfoil 1000. The ejector 200 may be non-axisymmetric in shape and the control surface may be placed exactly in the wake of said ejector 200. The ejector 200 vigorously mixes the hotter motive flow 600 (fig. 1) with the incoming cooler ambient air flow at a higher entrainment rate. Similarly, the mixture is sufficiently homogeneous to reduce the temperature of the injector's hot motive flow 600 to a mixture temperature profile that will not mechanically or structurally negatively impact the control surface 1500. In this embodiment, the yaw may be controlled by changing the orientation of the control surface 1500. In a similar manner, and by changing the orientation of the control surface 1500 relative to an aircraft body, such as an aircraft fuselage, pitch and roll may also be controlled. The function of the ejector 200 is to generate thrust, but it may also provide lift or attitude control. In this embodiment, yaw control is in direction 151, resulting in rotation about the aircraft axis 10.

Fig. 5 shows an embodiment that provides an alternative to the conventional method of placing a jet engine on the wing of an aircraft to generate thrust. In fig. 5, a gas generator 501 generates a moving air stream for powering a series of injectors 502 embedded in a primary airfoil, such as an airfoil 503, for forward propulsion by injecting the gas stream directly from the trailing edge of the primary airfoil. In this embodiment, the gas generator 501 is embedded in the main body 504 of the aircraft, fluidly communicates to the jet 502 via a conduit 505, and is the only means of propelling the aircraft. The injector 502 may be circular or non-circular as in the embodiment shown in fig. 2, have a correspondingly shaped outlet configuration similar to the tip 101, and provide a flow of gas from the generator 501 and conduit 505 at a predetermined adjustable rate. Additionally, the jet 502 may be movable in a manner similar to a flap or aileron, rotatable through an angle of 180 °, and actuatable to control the attitude of the aircraft in addition to providing the desired thrust. A secondary airfoil 506 having a leading edge 507 is placed directly behind the injector 502 in series with the airfoil 503 such that the gas flow from the injector 502 flows over the secondary airfoil 506. Thus, the secondary airfoil 506 receives a significantly higher speed than the airspeed of the aircraft and as such generates a higher lift, which as stated is proportional to the square of the airspeed. The entirety of the secondary airfoil 506 may be rotatable about an axis oriented parallel to the leading edge 507.

In this embodiment of the invention, the secondary airfoil 506 will see a moderately higher temperature due to the mixing of the motive fluid (also referred to as primary fluid) produced by the gas generator 501 with the secondary fluid, which is ambient air entrained by the motive fluid at a rate of between 5 to 25 parts of secondary fluid per part of primary fluid. As such, the temperature seen by the secondary airfoil 506 is slightly above ambient temperature, but significantly below the motive fluid, allowing the material of the secondary airfoil to support and maintain the lift load, according to the following equation: t is_Mixing＝(T_{Exercise of sports}+ER*T_{Environment(s)}) V. (1+ ER), where T_MixingIs the final fluid mixture temperature of the jet outflow emerging from the eductor 502, ER is the entrainment rate in parts of ambient air entrained per part of motive air, T_{Exercise of sports}Is the hotter temperature of the motive or primary fluid, and T_{Environment(s)}Is the approximate ambient air temperature.

Fig. 6 shows a propulsion system for an aircraft 700 according to an alternative embodiment. The first augmenting airfoil 702 is coupled to the vehicle 700 and positioned downstream of the fluid flowing through the primary airfoil 701 of the vehicle. Airfoil 702 is configured to rotate about an axis 707 and is controlled by an actuator 708. As best shown in fig. 7, the first augmenting airfoil 702 comprises: a first output structure, e.g., opposing nozzle surfaces 705, 706; and at least one conduit, e.g., plenum 704, in fluid communication with a tip 703 defined by the nozzle surface. Nozzle surfaces 705, 706 may or may not include nozzles similar to nozzles 203 discussed above with reference to fig. 1. Additionally, one or more of the nozzle surfaces 705, 706 may include a convex surface, which may thus promote the coanda effect and may have a continuously rounded surface without sharp or abrupt corners. The plenum 704 is supplied with air that is warmer than ambient (i.e., a pressurized stream of motive gas) from, for example, a combustion-based engine that may be employed by the aircraft 700. The plenum 704 is configured to direct the flow of gas to an end 703, the end 703 being configured to provide an outlet for the flow of gas flowing to the primary airfoil 701 and out of the first augmenting airfoil 702.

Referring to fig. 8-9, an embodiment may include a second augmenting airfoil 902 similar to airfoil 702, each having a respective trailing edge 714, 914 diverging from the other. More specifically, second augmenting airfoil 902 is coupled to aircraft 700 and positioned downstream of the fluid flowing through primary airfoil 701 of the aircraft. The airfoil 902 is configured to rotate in a manner similar to that discussed above with reference to the airfoil 702. The airfoil 902 includes: a first output structure, e.g., opposing nozzle faces 905, 906; and at least one conduit, e.g., plenum 904, in fluid communication with the tip 903 defined by the nozzle surface. The nozzle faces 905, 906 may or may not include nozzles similar to the nozzles 203 discussed above with reference to fig. 1. Additionally, one or more of the nozzle surfaces 905, 906 may include a convex surface, which may thus promote the coanda effect. Plenum 904 is supplied with air that is warmer than ambient (i.e., a pressurized stream of motive gas) from, for example, a combustion-based engine that may be employed by aircraft 700. The plenum 904 is configured to direct the gas flow to an end 903, said end 903 being configured to provide an outlet for the gas flow to the primary airfoil 701 and out of the second augmenting airfoil 902.

Each of the first reinforced airfoil 702 and the second reinforced airfoil 902 has a leading edge 716, 916 disposed toward the primary airfoil, with the first reinforced airfoil opposing the second reinforced airfoil. In operation, the first and second augmenting airfoils 702, 902 define a diffusion region 802 therebetween and along their length, which is functionally similar to the diffuser 210 discussed above. The leading edges 716, 916 define an inlet region 804, the inlet region 804 configured to receive the flow of gas from the plenums 704, 904 and the fluid flowing over the primary airfoil 701 and direct it to the diffusion region 802. The diffusion region 802 includes a primary tip 806, the primary tip 806 configured to provide an exit from the diffusion region for the directed gas flow and fluid flowing through the primary airfoil 701.

FIG. 10 shows an alternative embodiment of the invention featuring a tandem wing. In the illustrated embodiment, the secondary airfoil 1010 is placed directly downstream of the augmenting airfoils 702, 902 such that the fluid flowing through the primary airfoil 701 and the gas flow from the augmenting airfoils flows through the secondary airfoil. The combination of the two shorter airfoils 701, 1010 produces more lift than a wing lacking the significantly larger span of the augmented airfoils 702, 902, which relies on a jet engine attached to a larger wing to produce thrust.

While the foregoing text sets forth a detailed description of numerous different embodiments, it will be understood that the scope of protection is defined by the words of the claims that follow. The detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims.

Accordingly, many modifications and variations may be made in the techniques and structures described and illustrated herein without departing from the spirit and scope of the present claims. Accordingly, it will be understood that the methods and apparatus described herein are illustrative only and do not limit the scope of the claims.

Claims (18)

1. A propulsion system coupled to an aircraft, the system comprising:

an ejector including an outlet structure from which the propelling fluid flows at a predetermined adjustable velocity; and

a first control surface having an upper surface, a lower surface, and a leading edge and located directly downstream of the outlet structure such that at least a portion of the leading edge lies in one of the following planes:

(a) a plane occupied by a surface exit structure parallel to the leading edge; and

(b) extending in an axial direction to the plane of the injector,

whereby the propelling fluid from the ejector flows over the upper surface and the lower surface;

the first control surface is positioned sufficiently close to the outlet structure such that, during operation of the system, only propulsion fluid from the ejector flows over the upper and lower surfaces; and is

The ejector further includes:

a diffusion structure;

at least one conduit coupled to the diffusing structure and configured to direct a primary fluid produced by the aircraft to the diffusing structure; and

an inlet structure coupled to the diffusing structure and configured to direct a secondary fluid accessible to the aircraft to the diffusing structure, wherein the diffusing structure includes the outlet structure and the propulsion fluid includes the primary fluid and the secondary fluid.

2. The system of claim 1, wherein the injector further comprises a convex surface, the diffusing structure is coupled to the convex surface, and the at least one conduit is coupled to the convex surface and configured to direct the primary fluid to the convex surface.

3. The system of claim 1, wherein the entirety of the first control surface is rotatable about an axis oriented parallel to the leading edge.

4. The system of claim 1, wherein the inlet structure includes a first laterally opposite edge and a second laterally opposite edge, and the first laterally opposite edge has a greater radius of curvature than the second laterally opposite edge.

5. The system of claim 4, wherein the exit structure includes a first laterally opposite edge and a second laterally opposite edge, and the first laterally opposite edge of the exit structure has a greater radius of curvature than the second laterally opposite edge of the exit structure.

6. The system of claim 1, further comprising a second control surface having a leading edge and coupled directly to the aerial vehicle, wherein the first control surface is coupled to the second control surface such that the leading edge of the first control surface is at a non-zero angle relative to the leading edge of the second control surface.

7. An aircraft, comprising:

a main body;

a primary airfoil coupled to the main body;

a gas generator coupled to the body and generating a flow of gas;

a conduit fluidly coupled to the gas generator;

an injector fluidly coupled to the duct and embedded in the primary airfoil, the injector including an outlet structure from which the gas stream flows at a predetermined adjustable velocity; and

a secondary airfoil separated from the primary airfoil, the secondary airfoil having a leading edge and being located directly downstream of the outlet structure such that a gas flow from the injector flows over the leading edge of the secondary airfoil.

8. The aircraft of claim 7, wherein the gas generator is disposed in the body.

9. The aircraft of claim 7 wherein the primary airfoil includes a trailing edge and at least one injector injects the gas stream directly from the trailing edge of the primary airfoil.

10. The aircraft of claim 7, wherein the gas flow generated by the gas generator is the only means of propelling the aircraft.

11. The aircraft of claim 7 wherein the entirety of the secondary airfoil is rotatable about an axis oriented parallel to the leading edge.

12. The aircraft of claim 7 wherein the jet is rotatable through an angle of 180 °.

13. The aircraft of claim 7 wherein the outlet structure is non-circular.

14. A propulsion system for an aircraft, the system comprising:

a primary airfoil coupled to the aircraft;

a first augmenting airfoil coupled to the vehicle and positioned downstream of fluid flowing through the primary airfoil, the first augmenting airfoil comprising a first output structure and at least one first conduit coupled to the first output structure, the at least one first conduit configured to direct primary fluid produced by the vehicle to the first output structure, the first output structure comprising a first end configured to provide an outlet for primary fluid directed toward and from the primary airfoil; and

a secondary airfoil separated from the first augmenting airfoil, the secondary airfoil being located directly downstream of the first augmenting airfoil such that fluid flowing through the primary airfoil and the primary fluid from the first augmenting airfoil flow through the secondary airfoil.

15. The system of claim 14, further comprising a second augmenting airfoil coupled to the vehicle and positioned downstream of the fluid flowing over the primary airfoil, each of the first and second augmenting airfoils having a leading edge disposed toward the primary airfoil, the first augmenting airfoil opposing the second augmenting airfoil, whereby:

the first and second reinforcing airfoils defining a diffusion region; and is

The leading edge defines an inlet region configured to receive and direct the primary fluid and fluid flowing over the primary airfoil to the diffusion region, the diffusion region including a primary tip configured to mix and provide the directed primary fluid and fluid flowing over the primary airfoil to the secondary airfoil.

16. The system of claim 15, wherein the second augmenting airfoil comprises a second output structure and at least one second conduit coupled to the second output structure, the at least one second conduit configured to direct primary fluid produced by the vehicle to the second output structure, the second output structure comprising a second tip configured to provide an outlet for primary fluid directed toward and from the primary airfoil.

17. The system of claim 14, further comprising a first actuator configured to rotate the first augmenting airfoil relative to the vehicle.

18. The system of claim 15, further comprising a second actuator configured to rotate the second augmenting airfoil relative to the vehicle.