Abstract:
A device for controlling the direction of flow of a primary fluid includes one or more injectors oriented to inject a secondary fluid against the direction of flow of the primary fluid. The injector is formed by drilling or otherwise forming a hole at an angle to the surface of one or more sidewalls of an engine nozzle or other device. A feedback controller regulates the amount and duration of the secondary fluid injection to achieve the commanded attitude or attitude rate. The controller is coupled to one or more plenums attached to the sidewall(s). The plenums can be arranged to deliver secondary fluid to one or more of the injectors. Secondary fluid delivery to each plenum can be controlled independently to control the flow of the primary fluid in one or more directions. The device can be used to provide thrust vectoring in an aircraft or other type of vehicle, as well as other applications where it is desired to control the direction of a primary fluid.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 09/695,691 entitled “High Aspect Ratio, Fluidic Thrust Vectoring Nozzle”, filed Oct. 24, 2000, now abandoned, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to deflecting the flow direction of a primary fluid, and more particularly to apparatus and method whereby a secondary fluid is injected into the primary fluid stream to change the direction of flow of the primary fluid stream. 
     DESCRIPTION OF THE RELATED ART 
     Thrust vectored aircraft have many advantages over aircraft using conventional aerodynamic control surfaces. They can lead to tactical advantages in the aircraft&#39;s agility and maneuverability and also to improved take-off and landing performance, e.g. on battle-damaged runways or aircraft carriers. Thrust vectored aircraft can also operate outside of the conventional flight envelope, i.e., in the post-stall regime thus giving the pilot a significant advantage leading to improved survivability. 
     Designing aircraft without tails offers the potential for reduced weight and increased performance, efficiency and stealth. Aircraft such as the X-31 have demonstrated flight without a tail through a supersonic in-flight experiment in which the flight control system reacted as though the aircraft had no tail. The thrust vectoring capability was used to provide necessary aircraft stability, trim and control. 
     Most of the research in this field has been directed at designing and developing mechanically based systems. Although these systems are effective and may also lead to the removal of conventional moving surfaces and hence to a reduction in drag, they carry many disadvantages. For example, they often involve the use of complex mechanical actuation systems. They are also usually very expensive, difficult to integrate and aerodynamically inefficient. Further, as stealth requirements become ever more important, the radar cross section (RCS) and infra-red radiation (IR) signatures of military aircraft must be minimized. 
     One alternative to mechanical systems is known as fluidic thrust vectoring, which uses a secondary fluid stream to change the vector angle of a primary exhaust fluid stream from an engine nozzle, thus leading to a change in the overall orientation of the aircraft. Fluidic thrust vectoring involves no external moving parts thus leading to a decrease in radar cross section and infrared signature. Additionally it is lightweight, inexpensive, and easy to implement. 
     Extensive research of different nozzle shapes and aspect ratios has previously been conducted in connection with future aircraft configurations. Some of the prior innovations focus on the integration and aerodynamic efficiency of the exhaust system. Other innovations focus on mechanical configurations that are intended to effect thrust vectoring. Still other innovations have incorporated fluidic principles with the objectives of generating thrust vectoring power or controlling the effective flow area of a nozzle. 
     For example, U.S. Pat. No. 5,996,936 to Mueller discloses an exhaust nozzle for a gas turbine engine which includes a converging inlet duct in flow communication with a diverging outlet duct at a throat therebetween. Compressed air from the engine is selectively injected through a slot at the throat for fluidically varying flow area at the throat. 
     U.S. Pat. No. 6,112,512 to Miller et al. discloses an apparatus and method for varying the effective cross sectional area of an opening through a fixed geometry nozzle to provide a fluidic cross flow with an injector incorporated in the throat of the nozzle proximate to the subsonic portion of the flow through the nozzle. One or more injectors are directed at an angle in opposition to the subsonic portion of the flow. The opposed cross flow from the injectors interacts with a primary flow through the nozzle to partially block the nozzle&#39;s opening, thereby effectively decreasing the cross sectional area of the nozzle throat. A plurality of cross flows proximate to a nozzle&#39;s throat permits effective afterburner operations even with a fixed geometry nozzle by allowing throttling of the primary flow. Further, variations in the cross flow&#39;s mass flow characteristics or injection angle can allow vectoring of the primary flow. 
     U.S. Pat. No. 4,018,384 to Fitzgerald et al. teaches deflection of only a portion of the fluid thrust emanating from a nozzle, but the deflection takes place as a result of mechanical devices rather than another fluid stream. U.S. Pat. No. 4,686,824 to Dunaway et al. discloses apparatus for modulating the thrust vector of a rocket motor by injecting gas into the divergent section of the rocket nozzle and modulating injection of the hot gas by varying the flow from a solid propellant gas generator by controlling its flow rate with a vortex throttling valve arrangement. And U.S. Pat. No. 5,694,766 to Smereczniak et al. discloses a method and apparatus for controlling the throat area, expansion ratio and thrust vector of an aircraft turbine engine exhaust nozzle, using means, such as deflectors and/or injected air, for producing and controlling regions of locally separated flow, as well as control of the thrust vector angle defined by the gas exiting the nozzle to provide increased directional control of the aircraft. 
     The nozzle shapes studied in the patents mentioned above tend to be circular or of low aspect ratio. Fluidic injection from the top, bottom, and sidewall surfaces of nozzles and combinations of the three have also been analyzed, but have failed to produce the high levels of thrust vectoring and aerodynamic performance thought to be needed for quick maneuverability and efficient performance. Until recently, the amount of thrust vector angle generated with fluidics has not been high, typically less than eight degrees, and therefore, thrust vectoring through fluidics alone has only been found to be applicable to a very limited range of vehicle designs. Moreover, the efficiency of prior nozzle designs which used fluid injection or secondary flow to generate thrust vectoring has been quite low, typically on the order of 1.6 degrees of vector angle or less per each percent of secondary flow F 2  extracted from the primary flow F 1  at a primary nozzle pressure equal to 4 times the free-stream static pressure (Nozzle Pressure Ratio (NPR)). Thus, since it typically is not desirable to extract more than 10 percent of the primary flow to provide secondary flow, peak thrust vector angles have been low while inefficiently utilizing high secondary flow rates in nozzle shapes that are limited in their applicability to advanced designs and requirements. 
     It is therefore desirable to provide increased fluidic thrust vectoring capability to enhance vehicle maneuverability, as well as decrease radar and infrared cross section, and minimize requirements for additional moving parts, thereby improving reliability while reducing weight, cost, and complexity. 
     SUMMARY 
     Against this background of known technology, an apparatus to develop relatively high thrust vectoring power and efficiency in a broad range of configurations is provided. Some embodiments of such an apparatus include a nozzle with one or more injectors that introduce a secondary fluid against the direction of flow of a primary thrust fluid, thereby providing an apparatus with high thrust vectoring capability that can be easily integrated into a wide variety of vehicle configurations. The thrust vectoring nozzle can exert forces in one or more directions simultaneously to maneuver and control the vehicle about one or more axes of movement including pitch, roll and/or yaw. 
     In one embodiment, the injector(s) are formed in the sidewalls of the nozzle by drilling or otherwise forming a hole at an angle relative to the surface of the sidewall. A plenum is attached to one side of the nozzle sidewall to deliver the secondary fluid to the injector(s). Any number, size, and configuration of injectors can be disposed in each sidewall to provide the desired amount of maneuvering control. In general, the injectors can be disposed at any position, but are typically positioned as close to the exit area of the primary flow as possible. 
     A controller can be included to regulate the amount and duration of secondary flow delivered. The controller can be coupled to regulate the secondary flow to one or more plenums simultaneously. An operator or an autonomous control system can provide attitude or attitude rate commands, which are translated to secondary flow injections by the controller. Attitude and attitude rate feedback can be provided to the controller to allow the controller to refine the amount of secondary flow injected over time. 
     A variety of nozzle shapes and sizes can be configured to accommodate the injectors in their sidewalls, including high aspect ratio nozzles capable of generating thrust vectoring capability beyond that available in the prior art. 
     The secondary fluid can be provided by extracting some of the primary fluid, or by providing an independent source of secondary fluid. 
     While various configurations of the nozzles can be utilized in air vehicles, it is expected that embodiments of a device for altering the direction of flow of a primary fluid using secondary fluid injection can be utilized in other types of vehicles as well. The primary and secondary fluids can be in gaseous, solid particle, or liquid form. Other advantages and features of the invention will become more apparent, as will equivalent structures which are intended to be covered herein, with the teaching of the principles of embodiments of the present invention as disclosed in the following description, claims, and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the present invention and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings in which like reference numbers indicate like features and wherein: 
     FIG. 1A is a perspective view of an embodiment of a thrust vectoring nozzle. 
     FIG. 1B is a perspective view of the nozzle of FIG. 1A including a plenum for supplying secondary fluid flow attached to the nozzle. 
     FIG. 2 depicts a side sectional view of an embodiment of a thrust vectoring engine. 
     FIG. 3A depicts an embodiment of a nozzle showing an exhaust stream of unvectored primary fluid flow. 
     FIG. 3B depicts an embodiment of the nozzle of FIG. 3A showing a secondary fluid flow injected in the exhaust stream of the primary fluid to effect thrust vectoring. 
     FIGS. 4A through 4G depict end views of some examples of nozzle configurations in which secondary fluid injection can be utilized to provide thrust vectoring. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS. 1A and 1B, an embodiment of nozzle  100  is shown including thrust vectoring features that enhance vehicle maneuverability without requiring complex moving parts or increasing radar or infrared signatures. One or more injectors  102  are provided, such as by drilling holes in one or more of the sidewalls of nozzle  100 . Injectors  102  are oriented to inject a secondary fluid flow F 2  at an angle opposing the direction of the primary fluid flow F 1 . The force of the injected secondary fluid flow F 2  on the primary fluid flow F 1  changes the direction of the exhaust thrust vector. Nozzle  100  accordingly provides a reliable, low cost, highly effective thrust vectoring solution that can be easily implemented with minimal additional weight as further described herein. 
     Sidewalls  106  to  112  of nozzle  100  enclose a cavity centered about thrust axis  114 . A convergent inlet area  116  forms the upstream end of nozzle  100 , and a divergent exit area  118  forms the downstream end of nozzle  100 . During operation, primary fluid flow F 1  enters inlet area  116  and is exhausted through exit area  118 . Nozzle  100  also includes a throat area  120  positioned between inlet area  116  and exit area  118 . Throat area  120  is the point or section in nozzle  100  having the smallest cross sectional area. In some embodiments, exit area  118  is a two-dimensional nozzle configuration in which the sidewalls  106  to  112  form a substantially rectangular shape. The term aspect ratio as used herein refers to the ratio of the length a of sidewall  108  or  112  to the length b of sidewall  106  or  110 . The thrust-vectoring control moments are proportional to the thrust vector deflection angle and the force exerted by the vectored primary fluid flow F 1 . As the aspect ratio of exit area  118  increases, the force of the injected secondary fluid flow F 2  influences primary flow F 1  more efficiently, thus increasing the thrust vector deflection angle per unit secondary flow. The aspect ratio, along with other design variables, can therefore be selected to achieve desired thrust vectoring moments. Secondary fluid flow F 2  can be injected continuously. Alternatively, secondary fluid flow F 2  can be injected at regular or irregular pulsed intervals. 
     Injectors  102  are formed in at least one of sidewalls  106  to  112  through which secondary fluid flow F 2  can be injected into the divergent exhaust area  118 . Thrust-vectoring can generate pitch, roll, and yaw control moments by deflecting the primary flow F 1  vertically and horizontally. For single nozzle configurations, vertical deflections cause pitching moments, and horizontal deflections cause yawing moments. Multiple nozzles  100  can be positioned at desired locations relative to the axes of the vehicle so that vertical deflections cause pitching moments, differential vertical deflections cause rolling moments, and horizontal deflections cause yawing moments. In some embodiments, injector(s)  102  are disposed on opposing sidewalls  106  and  110 . In other embodiments, one or more injectors  102  can be formed in only one of sidewalls  106  or  110 . Injectors  102  can be arranged in rows having the same or a different number of injectors  102  in each row. Groups of injectors  102  can be arranged in sidewalls  106  to  112  to meet the requirements for a particular use. 
     While injectors  102  can be positioned at various locations on sidewalls  106 ,  108 ,  110 , and/or  112 , the greatest amount of thrust vectoring is typically achieved by positioning injectors  102  as close to the free stream edge of exit area  118  as possible. The force exerted by secondary fluid flow F 2  is also dependent on the diameter of injectors  102  and the pressure of secondary fluid flow F 2 . Injectors  102  with larger diameters and lower pressure can achieve the same overall fluid mass flow as smaller diameters with higher pressure secondary fluid flow F 2 . Any combination of number, size, and location of injectors  102 , and rate of secondary fluid flow F 2 , can be configured to provide the desired thrust vectoring capability. 
     FIG. 1B is a perspective view of nozzle  100  including plenum  130  for supplying secondary fluid flow F 2  to injectors  102 . Plenum  130  includes a compartment or chamber  132  to which one or more air ducts  134  are connected to form part of the distribution system for secondary fluid flow F 2 . Plenum  130  can be attached to sidewall  106  using any suitable method or mechanism, such as welding, mechanical fastener(s) or structure, and bonding. A gasket (not shown) or other device can be included between sidewall  106  and plenum  130  to provide an airtight seal. Plenum  130  can be configured to supply secondary fluid flow F 2  to one or more injectors  102  on one or more sidewalls  106 ,  108 ,  110 , and/or  112 . Alternatively, two or more plenums  130  can be included to supply secondary fluid flow F 2  to different subsets of a group of injectors  102  on a single sidewall  106 ,  108 ,  110 ,  112 . Such a configuration could be used to supply secondary fluid flow F 2  at the same or at different pressures to different injectors  102 . In some configurations, subsets of injectors  102  having the same or different diameters can receive secondary fluid flow F 2  from different plenums  130  to provide flexibility in supplying secondary fluid flow F 2  required to achieve the desired thrust vectoring forces. 
     FIG. 2 depicts a side cross-sectional view of an embodiment of jet engine  200  equipped with nozzle  100  and plenum  130 . In general, secondary fluid flow F 2  can be generated by extracting off a controlled amount of primary fluid flow F 1 , however it is usually desirable to extract as little of primary fluid flow F 1  as possible to preserve forward thrust. The amount of secondary fluid flow F 2  utilized in a particular situation can be selected based on the amount of forward thrust versus the amount of thrust vectoring capability desired. 
     Primary fluid flow F 1  of air enters jet engine  200  through intake  202 . Fan section  204 , comprised of a plurality of rotating fan blades  206 , pushes flow F 1  into bypass section  208  and compressor section  210 . Compressor section  210  is comprised of a plurality of compressor blades  212  which compress flow F 1  into combustion chamber  214 . Fuel is mixed with flow F 1  in combustion chamber  214  and ignited, thereby adding energy to flow F 1 , resulting in an increased pressure and temperature of flow F 1  in combustion chamber  214 . Pressure within combustion chamber  214  forces flow F 1  into turbine section  216 , which is comprised of a plurality of turbine blades  218 . Turbine section  216  removes some energy from flow F 1  to power compressor section  210  and fan section  204 . Flow F 1  then passes into exhaust chamber  220  where it combines with the flow from bypass section  208 . An afterburner  222  can provide additional fuel that is ignited increase the energy of flow F 1 . Flow F 1  is then expelled from engine  200  through exit area  118  as an exhaust flow. 
     Air duct  134  collects high pressure air from flow F 1  at compressor section  210  to provide secondary fluid flow F 2  to injectors  102 . In alternative embodiments, air duct  134  can collect air from bypass section  208 , combustion chamber  214  or any other portion of engine  200  having high pressure air. In some embodiments, a separate compressor can provide high pressure air to air duct  134 . A controller  224  controls a valve (not shown) operationally coupled to air duct  134  to regulate secondary fluid flow F 2  to injectors  102 . One or more air ducts  134  can provide secondary fluid flow F 2  to one or more injectors  102 . 
     In operation, controller  224  can vary the amount of secondary fluid flow F 2  injected into nozzle  100  to achieve the desired amount of thrust vectoring. For example, pitch, roll, yaw, and airspeed commands can be provided to controller  224  to determine the amount of primary flow F 1  to divert to provide thrust vectoring. Gradual changes in pitch, roll, and yaw attitude typically will require less secondary fluid flow F 2  than rapid changes. Controller  224  can direct an appropriate amount of secondary fluid flow F 2  to achieve the commanded rate of change of pitch, roll, or yaw attitude. In one embodiment, a mechanical valve can provide a mechanism for controlling the amount of secondary fluid flow F 2  injected into nozzle  100 . In another embodiment, each injector  102  or group of injectors  102  can be controlled by its own associated controller  224 . Controller  224  can include processing hardware, firmware, and/or software with instructions for controlling engine operational parameters and thrust vectoring. In other embodiments, the function of controlling engine  200  and thrust vectoring via injection of secondary fluid flow F 2  can be accomplished with separate controllers. 
     Referring now to FIGS. 3A and 3B, FIG. 3A depicts a cross-sectional side view of an embodiment of nozzle  100  that includes two injectors  102 . As shown, no secondary fluid flow F 2  is being supplied through injectors  102  via air duct  134 . The only fluid within nozzle  100  is primary fluid flow F 1  passing through throat  120  of nozzle  100  toward the downstream end thereof, and the thrust field is substantially uniform and directed along thrust  114  of nozzle  100 . Accordingly, the exhaust stream of primary fluid flow F 1  is substantially symmetric about thrust axis  114 . 
     FIG. 3B depicts a side view of nozzle  100  of FIG. 3A showing secondary fluid flow F 2  injected into the exhaust stream through injectors  102  in a direction opposite to the direction of primary fluid flow F 1 . The force exerted by secondary fluid flow F 2  on primary fluid flow F 1  skews primary fluid flow F 1  away from side wall  106 . It should be clear, therefore, that by rendering injectors  102  operative, primary fluid flow F 1  is deflected at an angle to axis  114 , thereby creating a pitch, roll, or yaw moment about the center of gravity of the vehicle in which nozzle  100  is incorporated to influence the direction of the vehicle. It should also be obvious that the strength of, or power behind, the injected secondary fluid flow F 2  can also influence the deflection of primary fluid flow F 1 . 
     In general, the larger the angle at which secondary fluid flow  102  is injected against the direction of primary fluid flow F 1 , the greater the deflection of primary fluid flow F 1  with respect to thrust axis  114 . Thus, higher thrust vectoring forces are generated by increasing the angle a at which injectors  102  are oriented with respect to the surface of sidewall  106 ,  110 . Sidewalls  106 ,  108 ,  110 , and/or  112  can include any number of rows of injectors  102 , and any number of injectors per row. One consideration, however, is the amount of secondary fluid flow F 2  required to achieve the desired amount of thrust vectoring. In some configurations, a greater number of holes will diffuse the force per area of a given amount of secondary fluid flow F 2  on primary fluid flow F 1 . Additionally, injectors  102  positioned closer to exit area  118  typically generate more effective thrust vectoring force compared to injectors  102  positioned further upstream. In some embodiments, an auxiliary source of secondary fluid flow F 2 , such as a tank of compressed fluid (not shown), can be coupled to plenum  130  and controller  224  (FIG. 2) to augment secondary fluid flow F 2  from engine  200  (FIG.  2 ). 
     Referring to FIGS. 3B, and  4 A to  4 G, FIGS. 4A through 4G depict cross-sectional views of some examples of nozzle  100  adjacent exit area  118  in which secondary fluid injection can be utilized to provide thrust vectoring. FIGS. 4A through 4C show injectors  102  disposed in opposing side wall portions  106  and  110  to provide forces in two directions, however injectors  102  can also be disposed in side wall portions  108  and  112 , as shown in FIGS. 4D and 4E, to provide thrust vectoring forces in four directions. 
     The configurations shown in FIGS. 4A to  4 C are typically integrated in a vehicle to provide either nose up/nose down thrust vectoring or nose left/nose right thrust vectoring. The configurations shown in FIGS. 4D and 4E can be used to provide nose up, nose down, nose left, and nose right thrust vectoring capability. Further, secondary flow F 2  can be injected in adjacent sidewalls in the configurations shown in FIGS. 4D and 4E to cause simultaneous thrust vectoring forces in two directions, such as nose up/nose left, nose up/nose right, nose down/nose left, and nose down/nose right. 
     The configurations shown in FIGS. 4F and 4G show examples of configurations having three sidewalls  402 ,  404 ,  406 , and eight sidewalls  410 ,  412 ,  414 ,  416 ,  418 ,  420 ,  422 ,  424 , respectively. Note that injectors  102  can be provided in any number of sidewalls to provide maneuvering control in the desired directions. Further, secondary flow F 2  can be injected simultaneously in two or more sidewalls to effect maneuvering control in two or more directions, It should also be noted that the position of one or more of nozzle  100  on a vehicle can be selected with respect to the vehicle&#39;s center of gravity to increase or decrease the pitch, roll, and yaw moments that can be achieved with a given amount of thrust vectoring force. 
     In the configurations shown in FIGS. 4A to  4 C, exit area  118  has a high aspect ratio, e.g. greater than 2, compared to configurations shown in FIGS. 4D and 4G. For given amounts of primary fluid flow F 1  and secondary fluid flow F 2 , and length of sidewalls  108  and/or  112 , the configurations shown in FIGS. 4A to  4 C will exhibit greater deflection of primary fluid flow F 1 , when the injection occurs thru the shorter sidewall, than the configurations shown in FIGS. 4D through 4G. This is due to the fact that the same amount of secondary fluid flow F 2  is more concentrated in the shorter length of sidewall  106  or  110 , thus producing more deflection of the primary flow F 1  near the wall. This effect is then propagated across the duct along sidewalls  108  and  112 , thus deflecting the entire primary flow F 1 . 
     A variety of configurations other than those shown in FIGS. 1A through 4G can be utilized in various embodiments of nozzle  100 . Parameters that can be selected to achieve a desired amount of thrust vectoring include the angle at which secondary fluid flow F 2  is injected against the direction of primary fluid flow F 1 , the aspect ratio of exit area  118 , the amount of secondary fluid flow F 2  injected into primary fluid flow F 1 , the number of injectors  102 , the size of the injectors  102  and the position of injectors  102  relative to exit area  118 . 
     Experimental tests were conducted using a configuration of nozzle  100  having an aspect ratio of 4.5 at the nozzle exit  118 , with a secondary flow area of combined injectors  102  to throat area  120  ratio of 0.015. The holes were oriented in sidewall  106  to inject secondary fluid flow F 2  at an angle of 125 degrees with respect to the direction of primary fluid flow F 1  and located at approximately 90% of the length from throat  120  to exit area  118 . Injectors  102  in sidewall  106  had a cylindrical shape with a length to diameter ratio over 2. The test configuration nozzle  100  exhibited peak thrust vector angles of up to approximately twenty-two (22) degrees utilizing 6 percent of primary fluid flow F 1  to supply secondary fluid flow F 2  at a low NPR of 1.3. Twelve and one-half (12.5) degrees of vectoring were achieved at NPR 4 with 5 percent of F 2 /F 1 . Superior fluidic thrust vectoring capability of 2.5 degrees of thrust vector angle per percent of primary fluid flow F 1  utilized for thrust vectoring was achieved for NPR 4 and 3.6 degrees per percent F 1  at NPR 1.3. In contrast, known prior art devices are only capable of deflecting primary fluid flow F 1  approximately 1.6 degrees for every one percent of primary fluid flow F 1  utilized to supply secondary fluid flow F 2  for NPR 4. 
     Embodiments of nozzle  100  can be incorporated in a variety of devices where thrust vectoring can be utilized including devices that operate on the ground and/or in the air. Additionally, other embodiments of an apparatus for deflecting the flow of a primary fluid by injecting a secondary fluid against the direction of the primary fluid can be provided for uses in addition to thrust vectoring in vehicles. Applications can include devices in the medical, agricultural, entertainment, and transportation industries, for example. The primary and secondary fluids can be in gaseous, solid particle, or liquid form. 
     Those skilled in the art will appreciate that various adoptions and modifications of the invention as described above can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.