High-speed vehicle forward jet wind tunnel test device and design method thereof

Abstract

The present application belongs to the technical field of high-speed wind tunnel test, and particularly relates to a high-speed aircraft forward jet flow wind tunnel test device and a design method thereof. The test device is provided with a thrust balance, a jet flow device and a ring balance device in a jet flow test model, and is connected with a gas supply pipeline and a support device outside the jet flow test model. The design method comprises the following steps: selecting simulation parameters; performing jet flow momentum similarity simulation; designing a jet flow test model; determining a jet flow test model support mode; designing a jet flow device; designing a jet flow thrust balance; performing ground jet flow debugging; and performing wind tunnel test verification. The test device and the design method thereof realize direct measurement of jet flow thrust and direct measurement of aerodynamic characteristics of the jet flow test model, realize direct measurement of jet flow thrust without increasing the internal space of the model, can accurately obtain jet flow thrust while obtaining model axial force, and further obtain the overall influence law of jet flow on model drag, and have engineering practical value.

Description

Technical Field

[0001] This invention belongs to the field of high-speed wind tunnel testing technology, specifically relating to a forward jet wind tunnel testing device for high-speed aircraft and its design method. Background Technology

[0002] With the development of high-speed aircraft, the types of forward jet wind tunnel tests are gradually increasing, such as forward jet drag reduction, forward jet deceleration, and forward jet heat protection technology verification for high-speed aircraft. When conducting forward jet wind tunnel tests on high-speed aircraft, in order to accurately obtain the overall response law of the jet to the model's drag, it is often necessary to obtain the jet thrust at the same time as obtaining the axial force of the model.

[0003] Typically, jet thrust is obtained using both theoretical calculations and experimental methods. Theoretical calculations, primarily based on Newton's momentum theorem, are mature but do not fully account for real-world conditions and require wind tunnel testing. Jet thrust measurement experiments are conducted before the actual test, without a model or flow. A thrust balance is typically used to measure the jet thrust independently, perpendicular to the jet direction. In the absence of flow, the jet thrust is converted into the balance's normal force (perpendicular to the balance axis), avoiding interference from lateral jet forces. This quasi-static method, where the lateral force interference is treated as the balance's axial force and subtracted during calibration, is relatively reliable. However, this method does not consider flow interference and does not simulate real-world thrust measurement. In actual flight, jet thrust is also directly affected by the incoming flow. Incoming flow interference significantly alters the environmental pressure at the jet exit, leading to increased jet thrust. Directly measuring jet thrust through wind tunnel testing is the best way to effectively obtain the overall aerodynamic characteristics, especially drag characteristics, of the model under incoming flow interference. When there is incoming flow interference, the jet and the incoming flow exhibit complex interference, forming a bow-shaped shock wave. Behind this shock wave, there is often a large environmental pressure, far exceeding the environmental pressure of conventional side or rear jets. Accurate consideration of the environmental pressure impact is necessary. However, the environmental pressure distribution exhibits spatial nonlinearity and cannot be directly given; therefore, jet thrust must be obtained in real-time through CFD calculations or wind tunnel testing.

[0004] Common jet flow tests design simulation parameters according to the N. Pindzola simulation criteria. The jet flow medium used in jet flow tests is mainly dry compressed air, requiring a separate air supply line for continuous air supply. The air supply line and the vertically supplied thrust balance must be placed inside or at the rear of the model, requiring a large amount of internal space. The internal space of the model generally has a smaller front and larger rear shape. Considering that the main model needs to measure forces simultaneously, the main balance generally occupies a larger space at the rear, while the thrust balance can only occupy a smaller space at the front. The small space at the front is difficult to simultaneously meet the space requirements of a conventional thrust balance and the air supply method. Furthermore, due to the limitations of wind tunnel space and model blockage, the geometrically scaled-down model cannot be too large, making it difficult to vertically arrange the ventilator balance in a conventional manner. While arranging the thrust balance along the axial direction (i.e., the balance axis aligns with the nozzle axis) is relatively easy, this type of axial thrust balance does not measure the direct thrust of the jet stream. It misses the product of the stagnation chamber pressure and the stagnation chamber cross-sectional area—the wall pressure integral. The wall pressure integral is substantial compared to the jet thrust, and it is not a fixed value; it exhibits a non-linear distribution influenced by wall flows such as eddies, making it difficult to accurately determine. Using flexible piping for vertical air supply might seem to solve the problems of insufficient space and the omission of the critical axial wall area integral. However, in practice, it is difficult to find piping that is both sufficiently flexible and capable of withstanding pressures in the MPa range. Generally, smaller piping sizes result in higher rigidity, and there are also issues with excessively large pipe diameters and joints, leading to decreased flexibility when filled with high-pressure gas.

[0005] Currently, there is an urgent need to develop a forward jet wind tunnel test device for high-speed aircraft and its design method. Summary of the Invention

[0006] One technical problem to be solved by the present invention is to provide a design method for a forward jet wind tunnel test device for high-speed aircraft. Another technical problem to be solved by the present invention is to provide a forward jet wind tunnel test device for high-speed aircraft to overcome the defects of the prior art.

[0007] The design method of the high-speed aircraft forward jet wind tunnel test device of the present invention includes the following steps:

[0008] S10. Select simulation parameters;

[0009] The jet medium used in the jet test was dry compressed air. Based on the theoretical analysis and experimental research results of the jet structure and characteristics by Pindzola N., under the condition that the jet test model is geometrically similar to the aircraft, the simulation parameters selected for the jet test include: incoming Mach number, jet momentum ratio, jet total pressure ratio, jet exit Mach number, and specific heat ratio. Among them, the jet momentum ratio and jet total pressure ratio reflect the direct effect, ejection effect, and volume effect of the jet. According to the mission requirements and wind tunnel testing capabilities, the total pressure ratio and jet exit Mach number are simulated. At the same time, the jet nozzle exit size, throat size, and expansion section semi-cone angle are all obtained by geometric scaling down the actual nozzle.

[0010] S20. Perform jet flow similarity simulation;

[0011] According to Pindzola's theory, to perform jet flow similarity simulations, the following must be satisfied:

[0012] ;

[0013] Among them, subscript fs Indicates actual flight conditions, subscript m Indicate the test conditions; P j This indicates the static pressure at the jet outlet. γ j The specific heat ratio at the jet outlet is shown. M j Indicates the Mach number at the jet exit. A j Indicates the area of ​​the jet outlet; P ∞ This indicates the static pressure of the incoming flow in the wind tunnel. r ∞ Indicates the specific heat ratio of the wind tunnel inflow. M ∞ This indicates the Mach number of the wind tunnel incoming flow. S Indicates the model reference area;

[0014] Under the conditions of simulating the Mach number at the jet outlet, the specific heat ratio at the jet outlet, the total pressure ratio of the jet, and the momentum ratio of the jet, equation (1) simplifies to:

[0015] ;

[0016] Under the condition of geometric similarity of the jet test model, equation (2) holds and satisfies:

[0017] ;

[0018] As can be seen from equation (3), in order to achieve similar simulation of jet flow, when designing the forward jet wind tunnel test device for high-speed aircraft, the jet nozzle outlet pressure is designed according to equation (3), thus achieving the goal of simulating the total pressure ratio, static pressure ratio and flow ratio of the jet flow on the basis of simulating the Mach number of the internal and external flow and the specific heat ratio of the jet outlet.

[0019] S30. Design a jet flow test model;

[0020] The jet test model adopts a segmented design, with the front segment made of alloy steel and the rear segment made of ultra-hard aluminum; the thrust balance is made of F141 high-strength alloy steel.

[0021] S40. Determine the support method for the jet test model;

[0022] The jet test model adopts a tail support method and is installed on the angle-of-attack mechanism of the wind tunnel through a tail support rod. During the test, the angle of attack of the jet test model is continuously changed through the angle-of-attack mechanism of the wind tunnel.

[0023] S50. Design of jet spray device;

[0024] The jetting device is located in the front section of the jetting test model. Compressed air is used as the jetting medium. The jetting nozzle is a Laval cold nozzle. The jetting momentum is simulated by adjusting the jetting pressure in the jetting nozzle chamber.

[0025] Compressed air enters the vent of the tail support rod through the air supply line, then enters the jet nozzle chamber through the jet thrust balance, and finally exits through the contraction and expansion section of the jet nozzle; the flow velocity of compressed air in the jet nozzle chamber is controlled to be 5m / s±0.1m / s, so that the compressed air is kept uniform and stable before entering the jet nozzle; the flow rate of the air supply line is adjusted by changing the jet air source pressure and valve opening, and the jet pressure in the jet nozzle chamber is controlled and adjusted; the parameters of the jet nozzle are calculated and determined by formula (3);

[0026] S60. Design a jet thrust balance and a model force balance;

[0027] To accurately evaluate the drag reduction effect of the jet, the jet thrust needs to be measured in real time during the jet process. The jet thrust is measured separately using a jet thrust balance located between the tail support and the jet nozzle. The model force balance is located in the inner cavity of the rear section of the jet test model to measure the aerodynamic force and aerodynamic torque of the jet test model.

[0028] S70. Conduct ground jet stream testing;

[0029] A dedicated pressure regulating device is designed for ground jet commissioning. It adjusts the pipeline flow rate by changing the jet gas source pressure and valve opening, thereby controlling and regulating the jet pressure in the nozzle chamber.

[0030] Compared to the jet test model, the jet nozzle has a smaller diameter. Since the internal space of the jet test model is characterized by being smaller at the front and larger at the back, a larger diameter nozzle chamber is set on the air supply pipeline at the rear of the jet test model. Measuring points are arranged on the nozzle chamber to measure the total jet pressure.

[0031] During ground jet commissioning, the jet pressure in the jet nozzle sump chamber is adjusted according to the wind tunnel test conditions to ensure that the jet sump chamber pressure and temperature reach the expected test values, and the repeatability accuracy of the total jet pressure commissioning results for 3 to 5 tests is provided.

[0032] S80. Conduct wind tunnel testing for verification;

[0033] Based on the wind tunnel test conditions, the wind tunnel is operated with given total incoming pressure and total temperature. The jet is started according to the total jet pressure during debugging. At the same time, data signals from the ring balance and thrust balance are collected. Based on the coefficient files and balance parameters and model parameters input from the ring balance and thrust balance, the aerodynamic force and jet thrust of the jet test model are calculated. The aerodynamic force coefficient and thrust coefficient of the jet test model are output.

[0034] The reliability of the forward jet wind tunnel test device for high-speed aircraft was verified through wind tunnel testing, and feedback iteration was carried out to improve the forward jet wind tunnel test device for high-speed aircraft until the design requirements were met.

[0035] The high-speed aircraft forward jet wind tunnel test device of the present invention includes an air supply pipeline and support device, a ring balance device, a jet test model and a thrust balance and jet device;

[0036] The jet test model is equipped with a thrust balance, a jet device, and a ring balance device. The jet test model is connected to an air supply pipeline and a support device.

[0037] Furthermore, the gas supply pipeline and support device include a tail support rod, a pipeline support rod end adapter rod, a support rod end connecting nut and a ball joint, a high-pressure hose, a hole wall end ball sealing joint, a hole wall end locking nut, a hole wall joint and a pressure measuring hole plug;

[0038] The tail support rod is used to connect and support the ring balance device, bearing the aerodynamic force and weight of the jet test model. A vent is also provided inside the tail support rod for supplying air to the jet. The front section of the tail support rod has an extension section, and the middle section has a tapered section. The rear end of the tail support rod is sequentially connected to a pipeline support rod adapter, a high-pressure hose, and a tunnel wall connector. The pipeline support rod adapter and the high-pressure hose are connected via a support rod end connecting nut and a ball joint. The high-pressure hose and the tunnel wall connector are connected via a tunnel wall end ball sealing connector and a tunnel wall end locking nut. Several pressure sensor test holes are provided on the tunnel wall connector. Pressure is monitored by pressure sensors installed in these test holes. Unused pressure sensor test holes are sealed with pressure hole plugs and copper gaskets.

[0039] Furthermore, the connecting rod at the end of the pipeline support is a steel pipe; the high-pressure hose is a thin-walled copper pipe, a high-pressure soft rubber hose, or a high-pressure steam hose; the ball joint is used for sealing the steel parts and the brass parts or the rubber hose, or the ball joint can be replaced with a copper gasket on the flat end face for connection and sealing; the high-pressure hose is used to withstand pressures above 10MPa or temperatures above 200℃; the length of the high-pressure hose is 1.5 times the connection distance, meeting the flexibility requirements of the wind tunnel mechanism within a ±30° range of motion angle.

[0040] Furthermore, the jet test model is a cone, including a front section of the model, a rear section of the model, model flange connecting screws, and a rear cover of the model; a thrust balance and a jet device are installed in the inner cavity of the front section of the model, and a ring balance device is installed in the inner cavity of the rear section of the model.

[0041] The front and rear sections of the model are assembled using cylindrical mating, screw connection, and pin positioning. A fixed end face is provided between the front and rear sections of the model. The rear cover of the model is fixed to the rear end face of the rear section of the model by screws evenly distributed along the circumference.

[0042] Furthermore, the ring balance device includes a ring balance, an outer heat insulation sleeve for the ring balance, an inner heat insulation sleeve for the ring balance, a rear locking screw for the ring balance, a rear positioning pin hole for the ring balance, and a front positioning pin hole for the ring balance.

[0043] The central axis of the ring balance coincides with the central axis of the jet test model; an outer heat insulation sleeve is fitted over the ring balance; an inner heat insulation sleeve is embedded in the inner cavity of the ring balance, and an isolation gap is provided between the inner cavity and the inner heat insulation sleeve; the front end face of the inner heat insulation sleeve is connected to the outer mating surface of the thrust balance and jet device's thrust balance connecting flange; the extended section of the front end of the tail support rod is inserted through the inner cavity of the inner heat insulation sleeve and connected to the thrust balance and jet device. The inner mating surface of the thrust balance connecting flange enables the connection of the air supply pipeline; the front conical surface of the ring balance is positioned through the positioning pin hole at the front end of the ring balance, and is inserted and fixed to the fixed end face between the front and rear sections of the model through a 1:5 conical surface fit; the rear section of the ring balance is provided with an inner conical surface, and the conical section of the middle section of the tail support rod is positioned through the positioning pin hole at the rear end of the ring balance, and is inserted into the rear section of the ring balance through a 1:10 conical surface fit, and is fixed to the rear section of the ring balance through the locking screw at the rear end of the ring balance.

[0044] Furthermore, the outer heat insulation sleeve and the inner heat insulation sleeve of the ring-shaped balance are made of fiberglass or high-silica resin.

[0045] Furthermore, the thrust balance and jet device include a thrust balance connecting flange, a thrust balance, a jet chamber transition section, a jet nozzle, a thrust balance rear end sealing gasket, a thrust balance front end sealing gasket, a pressure regulating sensor interface sealing gasket, a pressure regulating sensor interface plug, a thrust balance support rod positioning key, and a thrust balance flange positioning key.

[0046] The jet nozzle, jet chamber transition section, thrust balance, and thrust balance connecting flange are connected sequentially from front to back. The jet chamber transition section and the thrust balance are positioned by a positioning key and sealed by a front sealing gasket of the thrust balance. The thrust balance and the thrust balance connecting flange are positioned by a thrust balance flange positioning key and sealed by a rear sealing gasket of the thrust balance. The thrust balance connecting flange and the extended section of the tail support rod are positioned by a thrust balance support rod positioning key. The inner cavity of the jet chamber transition section is equipped with a jet chamber. The jet chamber transition section has a pressure regulating sensor interface, which is sealed by a pressure regulating sensor interface plug and a pressure regulating sensor interface sealing gasket.

[0047] Furthermore, the thrust balance is a three-component balance with axial, normal, and pitch components; the thrust balance includes a front end interface, a thrust balance main beam, and a rear end interface connected sequentially from front to back, and the central axis of the thrust balance main beam is perpendicular to the central axis of the jet test model.

[0048] The front-end interface connects to the jet chamber transition section, and the rear-end interface connects to the inner heat insulation sleeve of the ring balance; the inner cavities of both the front-end and rear-end interfaces are equipped with air supply pipelines coaxial with the central axis of the jet test model.

[0049] An air supply pipeline is installed on the central axis of the thrust balance main beam, and the midpoint is connected to the air supply pipeline of the front end interface. The midpoint is the centering point of the thrust balance. Air supply pipelines are installed on both the left and right ends of the thrust balance main beam. The air supply pipelines on the left and right ends are symmetrical and merge at the rear end, and are connected to the air supply pipeline of the rear end interface.

[0050] The inlet of the rear interface is the air inlet of the thrust balance; the compressed air entering from the air inlet of the thrust balance enters along the air supply pipeline of the rear interface, and then splits along the air supply pipelines at both ends of the thrust balance main beam, achieving symmetrical vertical air intake at both ends of the thrust balance main beam, and after converging at the midpoint, it flows into the jet chamber of the jet chamber transition section along the air supply pipeline of the front interface.

[0051] The symmetrical vertical air intake cancels out the pressure on the side walls of the air intake. The integral force of the air intake wall pressure is directly transmitted to the main beam of the thrust balance. The component of the wall pressure integral along the nozzle axis is the jet thrust, realizing the direct measurement of jet thrust.

[0052] The forward jet wind tunnel test device and its design method for high-speed aircraft of the present invention realize the direct measurement of jet thrust and the direct measurement of the aerodynamic characteristics of the jet test model. It solves the problem that the space required by conventional thrust balance and air supply methods is difficult to meet, and at the same time solves the problem of the underestimation of the contribution of the product of the stagnation chamber pressure and the stagnation chamber cross-sectional area caused by direct air supply. It realizes the direct measurement of jet thrust without increasing the internal space of the model. While obtaining the axial force of the model, it can accurately know the jet thrust, and then obtain the overall influence law of the jet on the drag of the model, which has practical engineering value. Attached Figure Description

[0053] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0054] Fig. la This is a front view of the high-speed aircraft forward jet wind tunnel test apparatus of the present invention;

[0055] Fig. lb This is a top view of the forward jet wind tunnel test apparatus for high-speed aircraft according to the present invention;

[0056] Fig. lc This is a front cross-sectional view (AA section view) of the high-speed aircraft forward jet wind tunnel test device of the present invention.

[0057] Fig. Id This is a top sectional view (BB section) of the forward jet wind tunnel test device for high-speed aircraft of the present invention.

[0058] Fig. 2a This is a schematic diagram of the air supply pipeline and support device of the high-speed aircraft forward jet wind tunnel test device of the present invention.

[0059] Fig. 2b This is a cross-sectional view (CC view) of the tail support rod in the air supply pipeline and support device of the forward jet wind tunnel test device for high-speed aircraft of the present invention.

[0060] Fig. 2c This is a perspective view of the wind tunnel connection end in the air supply pipeline and support device of the high-speed aircraft forward jet wind tunnel test device of the present invention.

[0061] Fig. 2d This is a cross-sectional view of the wind tunnel connection end in the air supply pipeline and support device of the high-speed aircraft forward jet wind tunnel test device of the present invention.

[0062] Fig. 3This is a schematic diagram of the jet test model structure of the forward jet wind tunnel test device for high-speed aircraft of the present invention;

[0063] Fig. 4a This is a three-dimensional view of the ring balance structure of the forward jet wind tunnel test device for high-speed aircraft of the present invention.

[0064] Fig. 4b This is a cross-sectional view of the annular balance structure of the high-speed aircraft forward jet wind tunnel test device of the present invention;

[0065] Fig. 5 This is an assembly diagram of the forward jet wind tunnel test device for high-speed aircraft of the present invention;

[0066] Fig. 6a This is a perspective view of the thrust balance and jet device of the forward jet wind tunnel test apparatus for high-speed aircraft of the present invention.

[0067] Fig. 6b This is a front cross-sectional view of the thrust balance and jet device of the forward jet wind tunnel test apparatus for high-speed aircraft of the present invention.

[0068] Fig. 6c This is a top-view cross-sectional view of the thrust balance and jet device of the high-speed aircraft forward jet wind tunnel test device of the present invention.

[0069] Fig. 7 This is a schematic diagram of the airflow direction of the thrust balance of the forward jet wind tunnel test device for high-speed aircraft according to the present invention.

[0070] In the diagram: 1. Gas supply pipeline and supporting device; 2. Ring balance device; 3. Jet test model; 4. Thrust balance and jet device;

[0071] 101. Tail support rod; 102. Pipeline support rod end adapter rod; 103. Support rod end connecting nut and ball joint; 104. High-pressure hose; 105. Tunnel wall end ball sealing joint; 106. Tunnel wall end lock nut; 107. Tunnel wall joint; 108. Pressure test hole plug;

[0072] 201. Ring balance; 202. Outer heat insulation sleeve of ring balance; 203. Inner heat insulation sleeve of ring balance; 204. Rear locking screw of ring balance; 205. Rear positioning pin hole of ring balance; 206. Front positioning pin hole of ring balance; 207. Front conical surface; 208. Inner conical surface;

[0073] 301. Rear section of the model; 302. Front section of the model; 303. Model flange connecting screws; 304. Model rear cover;

[0074] 401. Thrust balance connecting flange; 402. Thrust balance; 403. Jet chamber transition section; 404. Jet nozzle; 405. Thrust balance rear end sealing gasket; 406. Thrust balance front end sealing gasket; 407. Pressure sensor interface sealing gasket; 408. Pressure sensor interface plug; 409. Thrust balance support rod positioning key; 410. Thrust balance flange positioning key; 411. Pressure sensor interface. Detailed Implementation

[0075] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0076] Example: The design method of the high-speed aircraft forward jet wind tunnel test device in this example includes the following steps:

[0077] S10. Select simulation parameters;

[0078] The jet medium used in the jet test was dry compressed air. Based on the theoretical analysis and experimental research results of the jet structure and characteristics by Pindzola N., under the condition that the jet test model 3 is geometrically similar to the aircraft, the simulation parameters selected for the jet test include: incoming Mach number, jet momentum ratio, jet total pressure ratio, jet exit Mach number, and specific heat ratio. Among them, the jet momentum ratio and jet total pressure ratio reflect the direct effect, ejection effect, and volume effect of the jet. According to the mission requirements and wind tunnel testing capabilities, the total pressure ratio and jet exit Mach number are simulated. At the same time, the jet nozzle exit size, throat size, and expansion section semi-cone angle are all obtained by geometric scaling down the actual nozzle.

[0079] S20. Perform jet flow similarity simulation;

[0080] According to Pindzola's theory, to perform jet flow similarity simulations, the following must be satisfied:

[0081] ;

[0082] Among them, subscript fs Indicates actual flight conditions, subscript m Indicate the test conditions; P j This indicates the static pressure at the jet outlet. γ j The specific heat ratio at the jet outlet is shown. M j Indicates the Mach number at the jet exit. A j Indicates the area of ​​the jet outlet; P ∞ This indicates the static pressure of the incoming flow in the wind tunnel. r ∞ Indicates the specific heat ratio of the wind tunnel inflow.M ∞ This indicates the Mach number of the wind tunnel incoming flow. S Indicates the model reference area;

[0083] Under the conditions of simulating the Mach number at the jet outlet, the specific heat ratio at the jet outlet, the total pressure ratio of the jet, and the momentum ratio of the jet, equation (1) simplifies to:

[0084] ;

[0085] Under the condition of geometric similarity of jet test model 3, equation (2) holds and satisfies:

[0086] ;

[0087] As can be seen from equation (3), in order to achieve similar simulation of jet flow, when designing the forward jet wind tunnel test device for high-speed aircraft, the jet nozzle outlet pressure is designed according to equation (3), thus achieving the goal of simulating the total pressure ratio, static pressure ratio and flow ratio of the jet flow on the basis of simulating the Mach number of the internal and external flow and the specific heat ratio of the jet outlet.

[0088] S30. Design jet test model 3;

[0089] The jet test model 3 adopts a front and rear segment design, with the front segment made of alloy steel and the rear segment made of ultra-hard aluminum; the thrust balance is made of F141 high-strength alloy steel.

[0090] S40. Determine the support method for jet test model 3;

[0091] The jet test model 3 adopts a tail support method and is installed on the angle of attack mechanism of the wind tunnel through the tail support rod 101. During the test, the angle of attack of the jet test model 3 is continuously changed through the angle of attack mechanism of the wind tunnel.

[0092] S50. Design of jet spray device;

[0093] The jetting device is located in the front section of the jetting test model 3. The jetting device uses compressed air as the jetting medium. The jetting nozzle is a Laval cold nozzle. The jetting momentum similarity simulation is achieved by adjusting the jetting pressure in the jetting nozzle chamber.

[0094] Compressed air enters the vent of tail support rod 101 through the air supply pipeline, then enters the jet nozzle chamber through the jet thrust balance, and finally exits through the contraction and expansion section of the jet nozzle; the flow velocity of compressed air in the jet nozzle chamber is controlled to be 5m / s±0.1m / s, so that the compressed air is kept uniform and stable before entering the jet nozzle; the flow rate of the air supply pipeline is adjusted by changing the jet air source pressure and valve opening, and the jet pressure in the jet nozzle chamber is controlled and adjusted; the parameters of the jet nozzle are calculated and determined by formula (3);

[0095] In this embodiment, the air supply pipeline is a copper pipe or high-pressure hose with an diameter of F15×2×3000mm, and the inner diameter of the vent hole at the center of the tail support rod is F20mm; the ventilation area of ​​the jet nozzle chamber is 354mm². 2 .

[0096] S60. Design a jet thrust balance and a model force balance;

[0097] To accurately evaluate the drag reduction effect of the jet, the jet thrust needs to be measured in real time during the jet process. The jet thrust is measured separately using a jet thrust balance located between the tail support rod 101 and the jet nozzle. The model force balance is located in the inner cavity of the rear section of the jet test model 3 to measure the aerodynamic force and aerodynamic torque of the jet test model 3.

[0098] S70. Conduct ground jet stream testing;

[0099] A dedicated pressure regulating device is designed for ground jet commissioning. It adjusts the pipeline flow rate by changing the jet gas source pressure and valve opening, thereby controlling and regulating the jet pressure in the nozzle chamber.

[0100] Compared to the jet test model 3, the jet nozzle diameter is smaller. Since the internal space of the jet test model 3 is characterized by being smaller in the front and larger in the back, a nozzle chamber with a larger diameter is set on the air supply pipeline relatively at the rear of the jet test model 3. Measuring points are arranged on the nozzle chamber to measure the total jet pressure.

[0101] During ground jet commissioning, the jet pressure in the jet nozzle sump chamber is adjusted according to the wind tunnel test conditions to ensure that the jet sump chamber pressure and temperature reach the expected test values, and the repeatability accuracy of the total jet pressure commissioning results for 3 to 5 tests is provided.

[0102] S80. Conduct wind tunnel testing for verification;

[0103] Based on the wind tunnel test conditions, the wind tunnel is operated with given total incoming pressure and total temperature. The jet is started according to the total jet pressure during debugging. At the same time, data signals from the ring balance 201 and thrust balance 402 are collected. Based on the coefficient files and balance parameters and model parameters input from the ring balance 201 and thrust balance 402, the aerodynamic force and jet thrust of the jet test model 3 are calculated. The aerodynamic coefficient and thrust coefficient of the jet test model 3 are output.

[0104] The reliability of the forward jet wind tunnel test device for high-speed aircraft was verified through wind tunnel testing, and feedback iteration was carried out to improve the forward jet wind tunnel test device for high-speed aircraft until the design requirements were met.

[0105] like Fig. la~Fig. Id As shown, the high-speed aircraft forward jet wind tunnel test device of this embodiment includes an air supply pipeline and support device 1, a ring balance device 2, a jet test model 3, and a thrust balance and jet device 4.

[0106] The jet test model 3 is equipped with a thrust balance, a jet device 4, and a ring balance device 2. The jet test model 3 is externally connected to an air supply pipeline and a support device 1.

[0107] Furthermore, such as Fig. 2a~Fig. 2d As shown, the gas supply pipeline and support device 1 includes a tail support rod 101, a pipeline support rod end adapter rod 102, a support rod end connecting nut and a ball joint 103, a high-pressure hose 104, a hole wall end ball sealing joint 105, a hole wall end locking nut 106, a hole wall joint 107, and a pressure measuring hole plug 108.

[0108] The tail support rod 101 is used to connect and support the ring-type balance device 2, and bear the aerodynamic force and weight of the jet test model 3. At the same time, the tail support rod 101 has a vent hole inside for jet air supply. The front section of the tail support rod 101 is provided with an extension section, and the middle section of the tail support rod 101 is provided with a tapered section. The rear end of the tail support rod 101 is connected in sequence to the pipeline support rod end adapter rod 102, the high-pressure hose 104, and the cave wall joint 107. The pipeline support rod end adapter rod 102 and the high-pressure hose 104 are connected by the support rod end connecting nut and the ball joint 103. The high-pressure hose 104 and the cave wall joint 107 are connected by the cave wall end ball sealing joint 105 and the cave wall end locking nut 106. Several pressure sensor test holes are provided on the cave wall joint 107. Pressure is monitored by pressure sensors installed in the pressure sensor test holes. Unused pressure sensor test holes are sealed with pressure test hole plugs 108 and copper gaskets.

[0109] Furthermore, the pipeline support end adapter 102 is a steel pipe; the high-pressure hose 104 is a thin-walled copper pipe, a high-pressure soft rubber hose, or a high-pressure steam hose; the ball joint is used for sealing the steel parts and the brass parts or the rubber hose, or the ball joint can be replaced with a copper gasket on the flat end for connection and sealing; the high-pressure hose 104 is used to withstand pressures above 10MPa or temperatures above 200℃; the length of the high-pressure hose 104 is 1.5 times the connection distance, meeting the flexibility requirements of the wind tunnel mechanism's angle of attack within a range of ±30°.

[0110] Furthermore, such as Fig. 3 As shown, the jet test model 3 is a cone, including a front section 302, a rear section 301, a flange connecting screw 303, and a rear cover 304; a thrust balance and a jet device 4 are installed in the inner cavity of the front section 302, and a ring balance device 2 is installed in the inner cavity of the rear section 301.

[0111] The front section 302 and the rear section 301 of the model are combined by means of cylindrical mating, screw connection and pin positioning. A fixed end face is provided between the front section 302 and the rear section 301 of the model. The rear cover 304 of the model is fixed to the rear end face of the rear section 301 of the model by screws evenly distributed in the circumferential direction.

[0112] Furthermore, such as Fig. 4a , Fig. 4b , Fig. 5 As shown, the ring balance device 2 includes a ring balance 201, an outer heat insulation sleeve 202, an inner heat insulation sleeve 203, a rear locking screw 204, a rear positioning pin hole 205, and a front positioning pin hole 206.

[0113] The central axis of the ring balance 201 coincides with the central axis of the jet test model 3; an outer heat insulation sleeve 202 is fitted over the ring balance 201; an inner heat insulation sleeve 203 is embedded in the inner cavity of the ring balance 201, and an isolation gap is provided between the inner cavity of the ring balance 201 and the inner heat insulation sleeve 203; the front end face of the inner heat insulation sleeve 203 is connected to the outer mating surface of the thrust balance and jet device 4 thrust balance connecting flange 401; the extended section of the front end of the tail support rod 101 is inserted through the inner cavity of the inner heat insulation sleeve 203 and connected to the thrust balance and jet device 4 thrust balance. The inner mating surface of the force balance connecting flange 401 enables the connection of the gas supply pipeline; the front conical surface 207 of the ring balance 201 is positioned through the front positioning pin hole 206 of the ring balance, and is inserted and fixed to the fixed end face between the front section 302 and the rear section 301 of the model through a 1:5 conical surface fit; the rear section of the ring balance 201 is provided with an inner conical surface 208, and the conical section of the middle section of the tail support rod 101 is positioned through the rear positioning pin hole 205 of the ring balance, and is inserted into the rear section of the ring balance 201 through a 1:10 conical surface fit, and is fixed to the rear section of the ring balance 201 through the rear locking screw 204 of the ring balance.

[0114] Furthermore, the outer heat insulation sleeve 202 and the inner heat insulation sleeve 203 of the ring-shaped balance are made of fiberglass or high-silica resin.

[0115] Furthermore, such as Fig. 6a~Fig. 6c As shown, the thrust balance and jet device 4 includes a thrust balance connecting flange 401, a thrust balance 402, a jet chamber transition section 403, a jet nozzle 404, a thrust balance rear end sealing gasket 405, a thrust balance front end sealing gasket 406, a pressure regulating sensor interface sealing gasket 407, a pressure regulating sensor interface plug 408, a thrust balance support rod positioning key 409, and a thrust balance flange positioning key 410.

[0116] The jet nozzle 404, jet chamber transition section 403, thrust balance 402, and thrust balance connecting flange 401 are connected sequentially from front to back. The jet chamber transition section 403 and the thrust balance 402 are positioned by a positioning key and sealed by a front sealing gasket 406. The thrust balance 402 and the thrust balance connecting flange 401 are positioned by a thrust balance flange positioning key 410 and sealed by a rear sealing gasket 405. The thrust balance connecting flange 401 and the extended section of the tail support rod 101 are positioned by a thrust balance support rod positioning key 409. The inner cavity of the jet chamber transition section 403 is provided with a jet chamber. The jet chamber transition section 403 has a pressure regulating sensor interface, which is sealed by a pressure regulating sensor interface plug 408 and a pressure regulating sensor interface sealing gasket 407.

[0117] Furthermore, such as Fig. 7 As shown, the thrust balance 402 is a three-component balance with axial, normal and pitch components; the thrust balance 402 includes a front end interface, a thrust balance main beam and a rear end interface connected sequentially from front to back, and the central axis of the thrust balance main beam is perpendicular to the central axis of the jet test model 3.

[0118] The front end interface is connected to the jet chamber transition section 403, and the rear end interface is connected to the inner heat insulation sleeve 203 of the ring balance; the inner cavities of both the front end and the rear end interface are equipped with air supply pipelines coaxial with the central axis of the jet test model 3.

[0119] An air supply pipeline is installed on the central axis of the thrust balance main beam, and the midpoint is connected to the air supply pipeline of the front end interface. The midpoint is the centering point of the thrust balance. Air supply pipelines are installed on both the left and right ends of the thrust balance main beam. The air supply pipelines on the left and right ends are symmetrical and merge at the rear end, and are connected to the air supply pipeline of the rear end interface.

[0120] The inlet of the rear interface is the air inlet of the thrust balance; the compressed air entering from the air inlet of the thrust balance enters along the air supply pipeline of the rear interface, and then splits along the air supply pipelines at both ends of the thrust balance main beam, achieving symmetrical vertical air intake at both ends of the thrust balance main beam, and after converging at the midpoint, it flows into the jet chamber of the jet chamber transition section 403 along the air supply pipeline of the front interface.

[0121] The symmetrical vertical air intake cancels out the pressure on the side walls of the air intake. The integral force of the air intake wall pressure is directly transmitted to the main beam of the thrust balance. The component of the wall pressure integral along the nozzle axis is the jet thrust, realizing the direct measurement of jet thrust.

[0122] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A design method for a forward-flow wind tunnel test device for high-speed aircraft, characterized in that, The design method includes the following steps: S10. Select simulation parameters; The jet medium used in the jet test is dry compressed air. Based on the theoretical analysis and experimental research results of the jet structure and characteristics by Pindzola N., under the condition that the jet test model (3) is geometrically similar to the aircraft, the simulation parameters selected for the jet test include: incoming Mach number, jet momentum ratio, jet total pressure ratio, jet outlet Mach number, and specific heat ratio. Among them, the jet momentum ratio and jet total pressure ratio reflect the direct effect, ejection effect, and volume effect of the jet. According to the mission requirements and wind tunnel test capabilities, the total pressure ratio and jet outlet Mach number are simulated. At the same time, the jet nozzle outlet size, throat size, and expansion section semi-cone angle are all obtained by geometric scaling down the actual nozzle. S20. Perform jet flow similarity simulation; According to Pindzola's theory, to perform jet flow similarity simulations, the following must be satisfied: ； Among them, subscript fs Indicates actual flight conditions, subscript m Indicate the test conditions; P j This indicates the static pressure at the jet outlet. γ j The specific heat ratio at the jet outlet is shown. M j Indicates the Mach number at the jet exit. A j Indicates the area of ​​the jet outlet; P ∞ This indicates the static pressure of the incoming flow in the wind tunnel. r ∞ Indicates the specific heat ratio of the wind tunnel inflow. M ∞ This indicates the Mach number of the wind tunnel incoming flow. S Indicates the model reference area; Under the conditions of simulating the Mach number at the jet outlet, the specific heat ratio at the jet outlet, the total pressure ratio of the jet, and the momentum ratio of the jet, equation (1) simplifies to: ； Under the condition of geometric similarity of the jet test model (3), equation (2) holds and satisfies: ； As can be seen from equation (3), in order to achieve similar simulation of jet flow, when designing the forward jet wind tunnel test device for high-speed aircraft, the jet nozzle outlet pressure is designed according to equation (3), thus achieving the goal of simulating the total pressure ratio, static pressure ratio and flow ratio of the jet flow on the basis of simulating the Mach number of the internal and external flow and the specific heat ratio of the jet outlet. S30. Design a jet test model (3); The jet test model (3) adopts a front and rear segment design, with the front segment made of alloy steel and the rear segment made of ultra-hard aluminum; the thrust balance is made of F141 high-strength alloy steel. S40. Determine the support method for the jet test model (3); The jet test model (3) adopts a tail support method and is installed on the angle of attack mechanism of the wind tunnel through the tail support rod (101). During the test, the angle of attack of the jet test model (3) is continuously changed through the angle of attack mechanism of the wind tunnel. S50. Design of jet spray device; The jetting device is located in the front section of the jetting test model (3). Compressed air is used as the jetting medium in the jetting device. The jetting nozzle is a Laval cold nozzle. The jetting momentum similarity simulation is achieved by adjusting the jetting pressure in the jetting nozzle chamber. Compressed air enters the vent of the tail support rod (101) through the air supply line, then enters the jet nozzle chamber through the jet thrust balance, and finally exits through the contraction and expansion section of the jet nozzle; the flow velocity of compressed air in the jet nozzle chamber is controlled to be 5m / s±0.1m / s, so that the compressed air is kept uniform and stable before entering the jet nozzle; the flow rate of the air supply line is adjusted by changing the jet air source pressure and valve opening, and the jet pressure in the jet nozzle chamber is controlled and adjusted; the parameters of the jet nozzle are calculated and determined by formula (3); S60. Design a jet thrust balance and a model force balance; To accurately evaluate the drag reduction effect of the jet, the jet thrust needs to be measured in real time during the jet process. The jet thrust is measured separately using a jet thrust balance, which is located between the tail support rod (101) and the jet nozzle. The model force balance is located in the inner cavity of the rear section of the jet test model (3) to measure the aerodynamic force and aerodynamic torque of the jet test model (3). S70. Conduct ground jet stream testing; A dedicated pressure regulating device is designed for ground jet commissioning. It adjusts the pipeline flow rate by changing the jet gas source pressure and valve opening, thereby controlling and regulating the jet pressure in the nozzle chamber. Compared to the jet test model (3), the jet nozzle diameter is smaller. Since the internal space of the jet test model (3) is characterized by being smaller in the front and larger in the back, a nozzle chamber with a larger diameter is set on the air supply pipeline relatively at the back of the jet test model (3). Measuring points are arranged on the nozzle chamber to measure the total pressure of the jet. During ground jet commissioning, the jet pressure in the jet nozzle sump chamber is adjusted according to the wind tunnel test conditions to ensure that the jet sump chamber pressure and temperature reach the expected test values, and the repeatability accuracy of the total jet pressure commissioning results for 3 to 5 tests is provided. S80. Conduct wind tunnel testing for verification; According to the wind tunnel test status, the wind tunnel is operated with given total pressure and total temperature of incoming flow. The jet is turned on according to the total pressure of the jet flow during debugging. At the same time, data signals from the ring balance (201) and the thrust balance (402) are collected. Based on the coefficient files and balance parameters and model parameters input by the ring balance (201) and the thrust balance (402), the aerodynamic force and jet thrust of the jet test model (3) are calculated in reverse. At the same time, the aerodynamic coefficient and thrust coefficient of the jet test model (3) are output. The reliability of the forward jet wind tunnel test device for high-speed aircraft was verified through wind tunnel testing, and feedback iteration was carried out to improve the forward jet wind tunnel test device for high-speed aircraft until the design requirements were met.

2. A high-speed aircraft forward jet wind tunnel test device, designed using the design method of the high-speed aircraft forward jet wind tunnel test device as described in claim 1, characterized in that, The high-speed aircraft forward jet wind tunnel test device includes an air supply pipeline and support device (1), a ring balance device (2), a jet test model (3), and a thrust balance and jet device (4). The jet test model (3) is equipped with a thrust balance and a jet device (4) and a ring balance device (2). The jet test model (3) is connected to an air supply pipeline and a support device (1).

3. The high-speed aircraft forward jet wind tunnel test apparatus according to claim 2, characterized in that, The gas supply pipeline and support device (1) includes a tail support rod (101), a pipeline support rod end adapter rod (102), a support rod end connecting nut and a ball joint (103), a high-pressure hose (104), a hole wall end ball sealing joint (105), a hole wall end locking nut (106), a hole wall joint (107), and a pressure measuring hole plug (108). The tail support rod (101) is used to connect and support the ring-type balance device (2), bear the aerodynamic force and weight of the jet test model (3), and at the same time, a vent is opened inside the tail support rod (101) for jet air supply; the front section of the tail support rod (101) is provided with an extension section, and the middle section of the tail support rod (101) is provided with a tapered section; the rear end of the tail support rod (101) is connected in sequence to the pipeline support rod end adapter rod (102), the high-pressure hose (104) and the hole wall joint (107), and the pipeline support rod end adapter rod (102) is connected to the high-pressure hose (104) and the hole wall joint (107). The high-pressure hoses (104) are connected to each other by a support rod end connecting nut and a ball joint (103). The high-pressure hoses (104) and the tunnel wall joints (107) are connected by a tunnel wall end ball sealing joint (105) and a tunnel wall end locking nut (106). Several pressure sensor test holes are provided on the tunnel wall joints (107). Pressure is monitored by pressure sensors installed in the pressure sensor test holes. Unused pressure sensor test holes are sealed with pressure test hole plugs (108) and copper gaskets.

4. The high-speed aircraft forward jet wind tunnel test apparatus according to claim 3, characterized in that, The pipeline support end adapter (102) is a steel pipe; the high-pressure hose (104) is a thin-walled copper pipe, a high-pressure soft rubber hose, or a high-pressure steam hose; the ball joint is used for sealing the steel parts and the brass parts or the rubber hose, or the ball joint is replaced with a copper gasket on the flat end for connection and sealing; the high-pressure hose (104) is used to withstand pressure above 10MPa or temperature above 200℃; the length of the high-pressure hose (104) is 1.5 times the connection distance, which meets the flexibility requirements of the wind tunnel mechanism's angle of attack within a range of ±30°.

5. The high-speed aircraft forward jet wind tunnel test apparatus according to claim 3, characterized in that, The jet test model (3) is a cone, including a front section (302), a rear section (301), a flange connecting screw (303), and a rear cover (304); a thrust balance and a jet device (4) are installed in the inner cavity of the front section (302), and a ring balance device (2) is installed in the inner cavity of the rear section (301). The front section (302) and the rear section (301) of the model are combined by means of cylindrical mating, screw connection and pin positioning. A fixed end face is provided between the front section (302) and the rear section (301). The rear cover (304) of the model is fixed to the rear end face of the rear section (301) of the model by screws evenly distributed along the circumference.

6. The high-speed aircraft forward jet wind tunnel test apparatus according to claim 5, characterized in that, The ring balance device (2) includes a ring balance (201), an outer heat insulation sleeve (202) of the ring balance, an inner heat insulation sleeve (203) of the ring balance, a rear locking screw (204) of the ring balance, a rear positioning pin hole (205) of the ring balance, and a front positioning pin hole (206) of the ring balance. The central axis of the ring balance (201) coincides with the central axis of the jet test model (3); the ring balance (201) is fitted with an outer heat insulation sleeve (202); the inner cavity of the ring balance (201) is embedded with the inner heat insulation sleeve (203), and an isolation gap is provided between the inner cavity of the ring balance (201) and the inner heat insulation sleeve (203). The front end face of the inner heat insulation sleeve (203) is connected to the outer mating surface of the thrust balance connecting flange (401) of the thrust balance and jet device (4). The extended section of the front end of the tail support rod (101) is inserted through the inner cavity of the inner heat insulation sleeve (203) and connected to the thrust balance and jet device (4). The inner mating surface of the thrust balance connecting flange (401) enables the connection of the air supply pipeline; the front conical surface (207) of the ring balance (201) is positioned through the positioning pin hole (206) at the front end of the ring balance, and is inserted and fixed to the fixed end face between the front section (302) and the rear section (301) of the model through a 1:5 conical surface fit; the rear section of the ring balance (201) is provided with an inner conical surface (208), and the conical section of the middle section of the tail support rod (101) is positioned through the positioning pin hole (205) at the rear end of the ring balance, and is inserted into the rear section of the ring balance (201) through a 1:10 conical surface fit, and is fixed to the rear section of the ring balance (201) through the locking screw (204) at the rear end of the ring balance.

7. The high-speed aircraft forward jet wind tunnel test apparatus according to claim 6, characterized in that, The outer heat insulation sleeve (202) and the inner heat insulation sleeve (203) of the ring balance are made of fiberglass or high silica.

8. The high-speed aircraft forward jet wind tunnel test apparatus according to claim 6, characterized in that, The thrust balance and jet device (4) includes a thrust balance connecting flange (401), a thrust balance (402), a jet chamber transition section (403), a jet nozzle (404), a thrust balance rear end sealing gasket (405), a thrust balance front end sealing gasket (406), a pressure regulating sensor interface sealing gasket (407), a pressure regulating sensor interface plug (408), a thrust balance support rod positioning key (409), and a thrust balance flange positioning key (410). The jet nozzle (404), jet chamber transition section (403), thrust balance (402), and thrust balance connecting flange (401) are connected sequentially from front to back. The jet chamber transition section (403) and the thrust balance (402) are positioned by a positioning key and sealed by a front sealing gasket (406) of the thrust balance. The thrust balance (402) and the thrust balance connecting flange (401) are positioned by a thrust balance flange positioning key (410) and sealed by a thrust balance... The rear end sealing gasket (405) is sealed, and the extension section of the thrust balance connecting flange (401) and the tail support rod (101) is positioned by the thrust balance support rod positioning key (409); the inner cavity of the jet flow chamber transition section (403) is provided with a jet flow chamber, and the jet flow chamber transition section (403) has a pressure regulating sensor interface, which is sealed by the pressure regulating sensor interface plug (408) and sealed by the pressure regulating sensor interface sealing gasket (407).

9. The high-speed aircraft forward jet wind tunnel test apparatus according to claim 6, characterized in that, The thrust balance (402) is a three-component balance with axial, normal and pitch components; the thrust balance (402) includes a front end interface, a thrust balance main beam and a rear end interface connected sequentially from front to back, and the central axis of the thrust balance main beam is perpendicular to the central axis of the jet test model (3); The front end interface is connected to the jet chamber transition section (403), and the rear end interface is connected to the inner heat insulation sleeve (203) of the ring balance; the inner cavities of the front end interface and the rear end interface are both equipped with air supply pipelines coaxial with the central axis of the jet test model (3); An air supply pipeline is installed on the central axis of the thrust balance main beam, and the midpoint is connected to the air supply pipeline of the front end interface. The midpoint is the centering point of the thrust balance. Air supply pipelines are installed on both the left and right ends of the thrust balance main beam. The air supply pipelines on the left and right ends are symmetrical and merge at the rear end, and are connected to the air supply pipeline of the rear end interface. The inlet of the rear interface is the thrust balance air inlet; the compressed air entering from the thrust balance air inlet enters along the air supply pipeline of the rear interface, and then splits along the air supply pipelines at both ends of the thrust balance main beam, achieving symmetrical vertical air intake at both ends of the thrust balance main beam, and after converging at the midpoint, it flows into the jet chamber of the jet chamber transition section (403) along the air supply pipeline of the front interface. The symmetrical vertical air intake cancels out the pressure on the side walls of the air intake. The integral force of the air intake wall pressure is directly transmitted to the main beam of the thrust balance. The component of the wall pressure integral along the nozzle axis is the jet thrust, realizing the direct measurement of jet thrust.

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