Design method for forebody and inlet thermal experiment model of high-speed wind tunnel

Abstract

The present invention belongs to the technical field of hypersonic vehicle design, and discloses a design method for a forebody and inlet thermal experiment model of a high-speed wind tunnel. The design verification method comprises the following steps: determining the overall structure and design requirements; determining the heating structure; determining the pressure measurement points and temperature measurement points; determining the independent temperature control and regulation device; verifying the influence of the heat insulation groove on the temperature gradient distribution; verifying the heat insulation effect of the heat insulation measures; investigating the model structure deformation caused by temperature; obtaining the relationship curve between the heat flux density and the surface temperature; and studying the influence of the model structure deformation on the flow field. The design verification method proves that the forebody and inlet thermal experiment model of the high-speed wind tunnel has precise temperature control and heat insulation protection capabilities, and verifies the significant influence of the wall temperature change on the flow field structure; can effectively reproduce the aerodynamic heat coupling effect, establishes a hypersonic inlet heat-flow coupling experiment platform, and has engineering practical value.

Description

Technical Field

[0001] The present invention belongs to the technical field of hypersonic vehicle design, and particularly relates to a design method for a forebody and an inlet thermal experiment model of a high-speed wind tunnel. Background Art

[0002] When a hypersonic vehicle changes from the cruise state to the return state, its speed will decrease from hypersonic (Ma > 5) to supersonic (1.2 < Ma < 5). In the supersonic stage, the flight speed of the hypersonic vehicle is lower than the cruise speed, and no obvious aerodynamic heating phenomenon will occur. However, during the cruise stage, the heat accumulated on the wall of the hypersonic vehicle has not been radiated out in time. The wall heat still has a significant impact on key flow phenomena such as aerodynamic heat transfer, flow separation, and shock wave / boundary layer interference. Therefore, studying the wall heat in the supersonic stage is crucial for optimizing the aerodynamic performance of the vehicle and reducing load design.

[0003] In 2011, Hirschel E H et al. published "Design of hypersonic flight vehicles: some lessons from the past and future challenges", which proposed a thermal experiment technique (Hot Experimental Technique, HET). The thermal experiment technique is a method of heating the model to a high temperature (about 1000K) similar to hypersonic conditions before the wind tunnel starts running. The thermal experiment technique can reproduce the model temperature representing hypersonic flight conditions, so as to achieve the wall-to-total temperature ratio of the real vehicle wall in a high-speed wind tunnel; it can also conduct experimental research on the influence of the wall heat environment generated in the hypersonic stage on the flow phenomena in the supersonic stage.

[0004] Common heating methods in thermal experiment techniques include external radiation heating, embedded resistance element heating, and variable cross-section carbon-carbon (C / C) heating element heating, etc. In 2013, "Hot-wall reentry testing in hypersonic impulse facilities" published by Zander et al. used a carbon-carbon (C / C) element sandwiched between two copper electrodes to generate a surface temperature of approximately 2000K. The heat conduction loss at the electrodes in this heating method cannot be ignored, which will lead to uneven temperature distribution. Resistance Joule heating is a representative method to achieve the temperature of the aircraft wall surface during simulated high-speed flight. In 2004, "Investigation of an intake injected hot wall scramje" published by Kovachevich et al. heated the intake wall surface to 500K by using an internal resistance wire to explore the influence of the intake wall surface temperature on ignition, and proved that heating the wall surface will significantly increase the temperature of the boundary layer within 1.4mm near the wall surface. In 2014, "A new method for prescribing non-uniform wall temperatures on wind tunnel models" published by Neely et al. formed a controllable temperature distribution on the element surface by changing the thickness of the reinforced carbon-carbon (RCC) material, and no significant deformation or stress occurred in the element. In 2021, "Hypersonic transition over a heated wall" published by Zhu et al. heated a cone model with a heating rod, and the highest temperature on the model surface was heated to 800K, with a surface temperature difference of 5K, and studied the transition process of the boundary layer on the heated wall surface; during the experiment, the wall surface temperature of the model was higher than T w / T 0 (where T w and T 0(which are the wall temperature and the total temperature respectively) can be controlled to vary between 0.66 and 1.77. In 2020, "Hopkins K J, etal. Electrically-heated flat plate testing in a free-piston driven shock tunnel" published by Chang et al. heated a rectangular graphite plate to a temperature above 800K and observed that the heated wall conditions had a significant impact on the growth of the boundary layer. In 2017, "Reproducing non-uniform surface temperature profiles on hypersonic cruise vehicles in impulsive wind tunnels" published by Vennik et al. conducted heated flat plate experiments in a wind tunnel and compared the boundary layer thicknesses under different temperature conditions of the unheated surface (290K), the uniformly heated surface (1025K), and the non-uniformly heated surface (675K to 1130K); the results showed that there were significant differences in the boundary layer thickness between the unheated and heated models. However, the differences between the uniformly and non-uniformly heated cases were difficult to distinguish and further exploration was needed; the study of the flat plate / compression ramp model showed that as the wall temperature decreased, the size of the separated bubble decreased significantly. In 2024, "Development of force measurement technique for preheated model in hypersonic combined test facility" published by Yang et al. heated a cone model to 435K in a hypersonic combined experimental facility integrating an arc jet and a shock tunnel and analyzed the different effects of ablation-induced shape changes and surface temperature on the drag coefficient.

[0005] It can be clearly seen from the above literature that the Joule heating model provides an effective means for simulating hypersonic wall temperature conditions in ground wind tunnel experiments. The Joule heating model has three characteristics: ① heating elements with high resistivity, such as ceramics, such as C / C, graphite, or C / SiC; ② flat plate model or flat plate / compression ramp model; ③ achieving uniform surface temperature or gradient temperature changes while maintaining a reasonable structure. However, in the current literature on the Joule heating model, there is a lack of detailed descriptions of the structural state of the Joule heating model under thermal loads (whether transient or steady-state conditions). Since it is necessary to ensure the reliability of the model, improve the fluid-thermal-structure interaction, and understand more details about the thermal stress generated by heating the model, the structural state is crucial for the design of the Joule heating model.

[0006] Currently, there is an urgent need to develop a design method for the thermal experiment model of the forebody and inlet of a high-speed wind tunnel. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a design method for the forebody and inlet duct thermal experiment model of a high-speed wind tunnel to overcome the defects of the prior art.

[0008] The design method for the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention includes the following steps:

[0009] S10. Determine the overall structure and design requirements;

[0010] S20. Determine the heating structure;

[0011] S30. Determine the pressure measurement points and temperature measurement points;

[0012] S40. Determine the independent temperature control and regulation device;

[0013] S50. Verify the influence of the heat insulation groove on the temperature gradient distribution;

[0014] S60. Verify the heat insulation effect of the heat insulation measures;

[0015] S70. Examine the model structure deformation caused by temperature;

[0016] S80. Obtain the relationship curve between the heat flux density and the surface temperature;

[0017] S90. Study the influence of the model structure deformation on the flow field.

[0018] Further, the determination of the overall structure and design requirements in S10 includes the following content;

[0019] The forebody and inlet duct thermal experiment model of the high-speed wind tunnel is based on the forebody and inlet duct coupling model. An internal flow channel is arranged inside the forebody of the forebody and inlet duct coupling model, and the lip is the inlet of the internal flow channel; heating structures are arranged on the wall surfaces at the sharp leading edge, compression surface and shoulder positions of the forebody to form the forebody and inlet duct thermal experiment model of the high-speed wind tunnel;

[0020] It is required that the heating structure realizes uniform temperature distribution or temperature gradient distribution, the electrical connection is safe and effective, and has a thermal expansion margin.

[0021] Further, the determination of the heating structure in S20 includes the following content;

[0022] The compression surface and the wall surface of the shoulder are sequentially divided into a primary compression surface, a secondary compression surface, and a shoulder from front to back along the oncoming flow direction; two heating rods perpendicular to the oncoming flow direction and symmetric about the left and right are arranged inside the sharp leading edge; three heating plates arranged in sequence along the oncoming flow direction are covered on the inner wall surface of the primary compression surface, and heat insulation grooves are provided between the heating plates; two groups of heating plates symmetric about the left and right are covered on the inner wall surface of the secondary compression surface and the shoulder along the oncoming flow direction, and heat insulation grooves are provided between the heating plates in each group; a local heat flux barrier network is formed through five heat insulation grooves, dividing six heating regions, increasing the x-direction equivalent thermal resistance value by 60% - 80%, and forcing the heat flux vector to conduct along the z-direction; a composite working condition of coordinated control of longitudinal heat conduction and transverse heat insulation is achieved, which is used to form a linear temperature gradient field;

[0023] Thermal conductive silicone grease is applied to the contact surfaces of the heating rods and each heating plate with the forebody to reduce the contact thermal resistance; far-infrared heating plates are selected for the heating plates.

[0024] Further, the determination of the pressure measurement points and temperature measurement points in S30 includes the following content;

[0025] A number of pressure sensors along the oncoming flow direction are arranged on the center lines of the secondary compression surface and the shoulder, and heat insulation ceramic tubes are sleeved outside the pressure sensors for heat insulation;

[0026] A temperature measurement point is set at the midpoint of the two heating rods; several temperature measurement points are arranged in the wall surfaces of the compression surface and the shoulder corresponding to each heating plate; a set of thermocouples are respectively installed on each temperature measurement point, and the thermocouple wires of each thermocouple are arranged on the inner wall surface of the forebody; the embedding depths of the thermocouple probes of each group of thermocouples are different, realizing temperature measurement over the entire area and entire depth of the wall surfaces of the compression surface and the shoulder.

[0027] Further, the determination of the independent temperature control and regulation device in S40 includes the following content;

[0028] Independent temperature regulation devices with independent control are respectively arranged on the sharp leading edge and each heating plate; the independent temperature control and regulation device includes a set of thermocouples, a data acquisition system, a computer, and a temperature controller;

[0029] The data acquisition system and the temperature controller are respectively connected to the computer; the temperature controller is connected to the heating plate; each set of thermocouples includes 4 thermocouples, among which, 3 thermocouples are measurement thermocouples, which are respectively connected to the data acquisition system to respectively obtain the measurement signals at three different depths of the wall surfaces of the compression surface and the shoulder; 1 thermocouple is a feedback thermocouple, and the feedback thermocouple is close to the heating plate and is connected to the temperature controller;

[0030] The measuring thermocouple transmits the measurement signal to the data acquisition system to convert it into the measured point temperature value. The computer displays the measured point temperature value. The staff sets the target temperature value on the computer and sends the target temperature value to the temperature controller. The temperature controller performs PID control through the feedback thermocouple until the feedback thermocouple heats up to the target temperature value.

[0031] Further, the verification of the influence of the heat insulation groove in S50 on the temperature gradient distribution includes the following contents;

[0032] Set temperatures of 600K, 600K, 550K, 500K, 450K, and 400K on the 6 heating areas of the heating rods and heating plates corresponding to the sharp leading edge, the first compression surface, the second compression surface, and the shoulder respectively; through numerical simulation, obtain the temperature distribution comparison curves with and without the heat insulation groove. The comparison curves show that the temperature curve with the heat insulation groove is closer to the temperature gradient distribution in the ideal state, proving that the heat insulation groove realizes the temperature gradient distribution.

[0033] Further, the verification of the heat insulation effect of the heat insulation measures in S60 includes the following contents;

[0034] The heat insulation measures include a heat insulation groove and a heat insulation ceramic tube; perform constant temperature heating at 500K and 600K on the second compression surface and the shoulder respectively. The surface temperature of the model without the heat insulation groove reaches equilibrium at 32s, and the surface temperature of the model with the heat insulation groove reaches equilibrium at 97s. By comparison, it is found that the heat insulation groove reduces the temperature rise rate of the model surface by 67%; when performing constant temperature heating at 500K on the second compression surface and the shoulder, the temperature contour map on the cross-section where the pressure sensor is installed shows that after applying the heat insulation ceramic tube, the temperature of the pressure sensor is lower than the temperature of the surrounding wall surface, proving that the heat insulation ceramic tube provides the required thermal protection for the pressure sensor; perform constant temperature heating at 500K, 600K, and 650K on the second compression surface and the shoulder respectively. Under the uniform heating condition of 600K, at 63.5s, the surface temperature of the pressure sensor is 480K, reaching the working temperature limit of the pressure sensor, and the surface temperature of the model is 586.04K, and the change curve of the model surface temperature is gentle. Subsequently, the change of the model surface temperature is within the pre-specified stable interval range. In order to save the wind tunnel experiment time, it is determined that the wind tunnel startup time is before 63.5s; under the uniform heating condition of 500K, according to the working temperature limit of the pressure sensor being 480K, the estimated wind tunnel experiment time is 50s, meeting the requirements of the dynamic load wind tunnel experiment.

[0035] Further, the investigation of the model structure deformation caused by temperature in S70 includes the following contents;

[0036] The heating methods of the forebody of the high-speed wind tunnel and the hot experiment model of the intake duct include uniform heating and non-uniform gradient heating;

[0037] The heating temperatures for uniform heating include low-temperature heating and high-temperature heating. The heating temperatures for low-temperature heating are 300K, 350K, 400K, 450K, 500K, and 550K. The corresponding thermal experiment models for the forebody and inlet of the high-speed wind tunnel are low-temperature heating models. The heating temperatures for high-temperature heating are 600K, 700K, 800K, 900K, and 1000K. The corresponding thermal experiment models for the forebody and inlet of the high-speed wind tunnel are high-temperature heating models. Pressure sensors are not installed on the high-temperature heating models.

[0038] For the low-temperature heating model, affected by the positions of the heating rods and heating plates and the model thickness, the temperature at the sharp leading edge is the highest, the temperature around the pressure sensor is the lowest, and the thermal strain is concentrated at the shoulder position on the center line. When uniformly heated at 550K, the temperature difference on the center line is the largest, which is 8.2K. At the same time, the maximum deformation in the Y direction at the shoulder is 0.183mm.

[0039] For the high-temperature heating model, the part with the highest temperature is at the sharp leading edge, and the thermal strain is concentrated at the leading edge and shoulder positions of the model on the center line. When uniformly heated at 1000K, the temperature difference on the center line is the largest, which is 26.31K. At the same time, the maximum deformation in the Y direction at the shoulder is 0.195mm.

[0040] The temperature distribution on the center line of the low-temperature heating model and the high-temperature heating model is uniform. As the heating temperature increases, the temperature fluctuation on the center line becomes larger. The surface temperature difference increases with the increase of the heating temperature, and the ratio of the surface temperature difference to the heating temperature is within 3%. The deformation of the low-temperature heating model and the high-temperature heating model increases with the increase of the heating temperature. The maximum deformation of the low-temperature heating model occurs at the shoulder position, and the maximum deformation of the high-heating model occurs at the sharp leading edge and shoulder positions. The ratio of the deformation to the inlet height is within 2%.

[0041] There are 2 working conditions for non-uniform gradient heating. In working condition 1, according to the directions of the sharp leading edge, the first-stage compression surface, the second-stage compression surface, and the shoulder, the heating temperatures of the 6 heating regions are 600K, 600K, 550K, 500K, 450K, and 400K in sequence, realizing a gradual decrease in the wall temperature along the oncoming flow direction. The maximum deformation occurs at the first-stage compression surface, which is 0.169mm. In working condition 2, according to the directions of the sharp leading edge, the first-stage compression surface, the second-stage compression surface, and the shoulder, the heating temperatures are 600K, 600K, 600K, not heated, 400K, and 400K in sequence, realizing a step change in the wall temperature along the oncoming flow direction. The maximum deformation occurs at the first-stage compression surface, which is 0.181mm.

[0042] It is proved that a uniform temperature distribution and a gradient-varying temperature distribution are achieved on the surface of the thermal experiment models for the forebody and inlet of the high-speed wind tunnel, and it is feasible to simulate the surface temperature distribution of real aerodynamic heating using the built-in heating rods and heating plates.

[0043] Further, obtaining the relationship curve between heat flux density and surface temperature of S80 includes the following content;

[0044] The temperature control of the heating plate by the independent temperature control adjustment device is achieved by changing the heat flux density of the heating plate. It is necessary to obtain the relationship curve between heat flux density and surface temperature for controlling non-uniform gradient heating and providing data support for realizing the gradient change temperature distribution;

[0045] The heat flux density of the heating plate of the low-temperature heating model is less than that of the heating plate of the high-temperature heating model; the heat flux density range of the heating plate of the low-temperature heating model is 0 - 0.12 kW / m 2 , obtaining the fitting curve of heat flux density and temperature of the center line of the low-temperature heating model; the heat flux density range of the heating plate of the high-temperature heating model is 0.15 - 1.2 kW / m 2 , obtaining the fitting curve of heat flux density and temperature of the center line of the high-temperature heating model.

[0046] Further, studying the influence of the structural deformation of the research model on the flow field of S90 includes the following content;

[0047] Design a wind tunnel experiment model to study the influence of the model structural deformation generated by temperature on the aerodynamic load, and provide data support for determining the materials and wall thicknesses of the forebody and inlet duct thermal experiment models of the high-speed wind tunnel.

[0048] The design method of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention realizes the precise regulation of the uniform or gradient temperature distribution on the model surface in the range of 350K - 1000K by embedding multiple groups of heating units in the wall surfaces at the sharp leading edge, compression surface and shoulder positions to simulate the wall thermal environment of hypersonic aircraft; it proves that the forebody and inlet duct thermal experiment model of the high-speed wind tunnel has precise temperature control and heat insulation protection capabilities, and verifies the significant influence of wall temperature change on the flow field structure; at the same time, it proves that the forebody and inlet duct thermal experiment model of the high-speed wind tunnel can effectively reproduce the aerodynamic heat coupling effect; a hypersonic inlet duct thermal-fluid coupling experimental platform is established, which has engineering practical value. Brief Description of the Drawings

[0049] Figure 1 is the flow chart of the design method of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention;

[0050] Figure 2 is the structural schematic diagram of the forebody and inlet duct coupling model;

[0051] Figure 3 is the structural schematic diagram of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention;

[0052] Figure 4Schematic cross-sectional view of the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0053] Figure 5 Pressure sensor distribution in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0054] Figure 6 Layout diagram of temperature measurement points in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0055] Figure 7a Schematic diagram of thermocouple installation (front view) in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0056] Figure 7b Schematic diagram of thermocouple installation (top view) in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0057] Figure 8 Schematic diagram of the independent temperature control and regulation device in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0058] Figure 9 Schematic diagram of the temperature distribution in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0059] Figure 10 Comparison curve of the temperature distribution (with or without heat insulation groove) in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0060] Figure 11 Curve of the model surface temperature varying with time (with or without heat insulation groove, 500K, 600K) in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0061] Figure 12 Steady-state temperature distribution diagram of the cross-section where the pressure sensor is installed (with heat insulation measures, 500K) in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0062] Figure 13 Curve of the model surface and the pressure sensor surface varying with time (with heat insulation measures, 500K, 600K and 650K) in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0063] Figure 14a Temperature distribution nephogram of the low-temperature heating model (550K) in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0064] Figure 14b Y-direction deformation nephogram of the low-temperature heating model (550K) in the forebody and inlet thermal experiment model of the high-speed wind tunnel of the present invention;

[0065] Figure 14c This is the steady-state temperature distribution diagram of the centerline of the low-temperature heating model of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention;

[0066] Figure 14d This is the deformation diagram in the Y direction of the centerline of the low-temperature heating model of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention;

[0067] Figure 15a This is the temperature distribution nephogram (1000K) of the high-temperature heating model of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention;

[0068] Figure 15b This is the deformation nephogram in the Y direction (1000K) of the high-temperature heating model of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention;

[0069] Figure 15c This is the steady-state temperature distribution diagram of the centerline of the high-temperature heating model of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention;

[0070] Figure 15d This is the deformation diagram in the Y direction of the centerline of the high-temperature heating model of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention;

[0071] Figure 16a This is the uniform temperature distribution diagram of the centerline of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention (operating condition 1);

[0072] Figure 16b This is the gradient-varying temperature distribution of the centerline of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention (operating condition 2);

[0073] Figure 17a This is the fitting curve of heat flux density and temperature of the centerline of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention (low-temperature heating model);

[0074] Figure 17b This is the fitting curve of heat flux density and temperature of the centerline of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel of the present invention (high-temperature heating model).

[0075] In the figure, 1. Forebody; 2. Inner flow path; 3. Lip; 4. Sharp leading edge; 5. Compression surface and shoulder position wall surface; 6. Heating rod; 7. Heat insulation groove; 8. Heating plate; 9. Heat insulation ceramic tube; 10. Pressure sensor; 11. Temperature measurement point; 12. Thermocouple; 13. Thermocouple probe; 14. Thermocouple wire; 15. Data acquisition system; 16. Computer; 17. Temperature controller; 18. Feedback thermocouple;

[0076] 501. Shoulder; 502. Secondary compression surface; 503. Primary compression surface. Detailed implementation mode

[0077] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0078] Embodiment: The material of the precursor 1 in this embodiment is FS-136 stainless steel, and the wall thickness is 10 mm; each heating rod 6 has a diameter of 8 mm and a length of 70 mm. The heating plate 8 is fixed by a cover plate and bolts. The sizes of the 3 heating plates 8 on the primary compression surface 503 are 26×130×4 mm, and the sizes of the 4 heating plates 8 on the secondary compression surface 502 and the shoulder 501 are 38×60×4 mm; the base material of the heating plate 8 is glass-ceramics, which can withstand a maximum temperature of 800 °C, and the heating power is 0.134 kW / m 2 . The temperature controller 17 is E5CN-Q2MT-500 of OMRON, which can provide high-precision temperature measurement and control for the heating plate 8, effectively reduce temperature fluctuations, and enable the model wall surface to reach and stabilize at the set temperature faster. The data acquisition system 15 is GM10 of Yokogawa Electric, with a collection accuracy of ±0.2 °C and a scanning interval of 100 ms. Measurement signals at depths of 2 mm, 5.5 mm, and 9 mm on the wall surfaces at the compression surface and the shoulder positions 5 are obtained respectively, and the surface temperature of the model and the heat flux density in the wall thickness direction are calculated according to Fourier's law of heat conduction.

[0079] There are 29 temperature measurement points 11. One, 20, 4, and 4 temperature measurement points are arranged on the sharp leading edge 4, the primary compression surface 503, the secondary compression surface 502, and the shoulder 501 respectively. Each temperature measurement point 11 consists of three thermocouples 12. The thermocouple 12 is GG-K-36 of OMEGA, and the temperature measurement range is -73 °C to 482 °C, and the temperature measurement accuracy is: ±1.1 °C. The three thermocouples 12 measure the temperatures at depths of 1 mm, 5.5 mm, and 9 mm respectively.

[0080] As Figure 1 shown, the design method of the precursor and intake duct thermal experiment model of the high-speed wind tunnel in this embodiment includes the following steps:

[0081] S10. Determine the overall structure and design requirements;

[0082] S20. Determine the heating structure;

[0083] S30. Determine the pressure measurement points and temperature measurement points 11;

[0084] S40. Determine the independent temperature control and adjustment device;

[0085] S50. Verify the influence of the heat insulation groove 7 on the temperature gradient distribution;

[0086] S60. Verify the heat insulation effect of the heat insulation measures;

[0087] S70. Examine the model structure deformation caused by temperature;

[0088] S80. Obtain the curve of the relationship between heat flux density and surface temperature;

[0089] S90. Study the influence of model structure deformation on the flow field.

[0090] Furthermore, the determination of the overall structure and design requirements in S10 includes the following;

[0091] The forebody and inlet duct thermal experiment model of the high-speed wind tunnel is based on the forebody and inlet duct coupling model as shown in Figure 2 An internal flow channel 2 is provided in the forebody 1 of the forebody and inlet duct coupling model, and the lip 3 is the inlet of the internal flow channel 2; heating structures are arranged on the sharp leading edge 4, compression surface and shoulder position wall surface 5 of the forebody 1 to form the forebody and inlet duct thermal experiment model of the high-speed wind tunnel as shown in Figure 3 , Figure 4 shown;

[0092] It is required that the heating structure realizes uniform temperature distribution or temperature gradient distribution, the electrical connection is safe and effective, and has a thermal expansion margin.

[0093] Furthermore, the determination of the heating structure in S20 includes the following;

[0094] The wall surface 5 of the compression surface and shoulder position is divided into a primary compression surface 503, a secondary compression surface 502 and a shoulder 501 in sequence from front to back along the oncoming flow direction; 2 heating rods 6 perpendicular to the oncoming flow direction and symmetric about the left and right are arranged in the sharp leading edge 4; 3 sequentially arranged heating plates 8 are covered on the inner wall surface of the primary compression surface 503 along the oncoming flow direction, and heat insulation grooves 7 are arranged between the heating plates 8; 2 groups of heating plates 8 symmetric about the left and right are covered on the inner wall surfaces of the secondary compression surface 502 and the shoulder 501 along the oncoming flow direction, and heat insulation grooves 7 are arranged between the heating plates 8; a local heat flux barrier network is formed through 5 heat insulation grooves 7, dividing 6 heating regions, increasing the x-direction equivalent thermal resistance value by 60% - 80%, forcing the heat flux vector to conduct along the z-direction; realizing the composite working condition of coordinated control of longitudinal heat conduction and transverse heat insulation, and used to form a linear temperature gradient field;

[0095] Thermal conductive silicone grease is applied on the contact surfaces of the heating rods 6 and each heating plate 8 with the forebody 1 to reduce the contact thermal resistance; the heating plate 8 is selected as a far-infrared heating plate.

[0096] Furthermore, the determination of the pressure measurement points and temperature measurement points 11 in S30 includes the following;

[0097] On the center lines of the secondary compression surface 502 and the shoulder 501, set as shown in Figure 5A number of pressure sensors 10 along the oncoming flow direction as shown are insulated by sleeving heat-insulating ceramic tubes 9 on the pressure sensors 10.

[0098] A temperature measurement point 11 is set at the midpoint of the 2 heating rods 6; several temperature measurement points 11 are arranged in the wall surface 5 at the corresponding compression surfaces and shoulder positions of each heating plate 8; the distribution of each temperature measurement point 11 is shown in Figure 6 ; A set of thermocouples 12 are respectively installed on each temperature measurement point 11, and the thermocouple wires 14 of each thermocouple 12 are arranged on the inner wall surface of the forebody 1; as Figure 7a 、 Figure 7b shown, the embedding depths of the thermocouple probes 13 of each set of thermocouples 12 are different, realizing temperature measurement over the entire area and entire depth of the wall surface 5 at the compression surface and shoulder positions.

[0099] Furthermore, the determination of the independent temperature control and regulation device in S40 includes the following;

[0100] Independent temperature regulation devices under independent control are respectively set on the sharp leading edge 4 and each heating plate 8; the independent temperature control and regulation device includes a set of thermocouples 12, a data acquisition system 15, a computer 16 and a temperature controller 17;

[0101] The data acquisition system 15 and the temperature controller 17 are respectively connected to the computer 16; the temperature controller 17 is connected to the heating plate 8; each set of thermocouples 12 includes 4 thermocouples 12, among which, 3 thermocouples 12 are measurement thermocouples, which are respectively connected to the data acquisition system 15 to respectively obtain the measurement signals at 3 different depths of the wall surface 5 at the compression surface and shoulder positions; 1 thermocouple 12 is a feedback thermocouple 18, and the feedback thermocouple 18 is close to the heating plate 8 and is connected to the temperature controller 17;

[0102] As Figure 8 shown, the measurement thermocouples transmit the measurement signals to the data acquisition system 15 to convert them into the measured point temperature values, the computer 16 displays the measured point temperature values, the staff sets the target temperature value on the computer 16 and sends the target temperature value to the temperature controller 17, and the temperature controller 17 performs PID control through the feedback thermocouple 18 until the feedback thermocouple 18 rises to the target temperature value.

[0103] Furthermore, the verification in S50 of the influence of the heat insulation groove 7 on the temperature gradient distribution includes the following;

[0104] As Figure 9 shown, temperatures of 600K, 600K, 550K, 500K, 450K and 400K are respectively set on the 6 heating areas of the heating rods 6 and heating plates 8 corresponding to the sharp leading edge 4, the primary compression surface 503, the secondary compression surface 502 and the shoulder 501; through numerical simulation, the results as shown in Figure 10The temperature distribution comparison curves with and without the heat insulation groove 7 are shown. The comparison curves show that the temperature curve with the heat insulation groove 7 is closer to the temperature gradient distribution in the ideal state, proving that the heat insulation groove 7 has achieved the temperature gradient distribution.

[0105] Further, the heat insulation effect of the heat insulation measures verified in S60 includes the following content;

[0106] The heat insulation measures include the heat insulation groove 7 and the heat insulation ceramic tube 9; the secondary compression surface 502 and the shoulder 501 are respectively heated at a constant temperature of 500K and 600K, as Figure 11 shown. The surface temperature of the model without the heat insulation groove 7 reaches equilibrium at 32s, and the surface temperature of the model with the heat insulation groove 7 reaches equilibrium at 97s. By comparison, it is found that the heat insulation groove 7 reduces the temperature rise rate of the model surface by 67%; when the secondary compression surface 502 and the shoulder 501 are heated at a constant temperature of 500K, as Figure 12 shown in the temperature contour map of the cross-section where the pressure sensor 10 is installed, after applying the heat insulation ceramic tube 9, the temperature of the pressure sensor 10 is lower than the temperature of the surrounding wall surface, proving that the heat insulation ceramic tube 9 provides the required thermal protection for the pressure sensor 10; as Figure 13 shown, when the secondary compression surface 502 and the shoulder 501 are respectively heated at a constant temperature of 500K, 600K, and 650K, under the uniform heating condition of 600K, at 63.5s, the surface temperature of the pressure sensor 10 is 480K, reaching the working temperature limit of the pressure sensor 10, and the surface temperature of the model is 586.04K, and the change curve of the model surface temperature is gentle. Subsequently, the change of the model surface temperature is within the pre-specified stable range. In order to save the wind tunnel experiment time, it is determined that the wind tunnel start time is before 63.5s; under the uniform heating condition of 500K, according to the working temperature limit of the pressure sensor 10 being 480K, the estimated wind tunnel experiment time is 50s, meeting the requirements of the dynamic load wind tunnel experiment.

[0107] Further, the investigation of the model structure deformation caused by temperature in S70 includes the following content;

[0108] The heating methods of the forebody and intake duct thermal experiment models of the high-speed wind tunnel include uniform heating and non-uniform gradient heating;

[0109] The heating temperatures of the uniform heating include low-temperature heating and high-temperature heating. The heating temperatures of the low-temperature heating are 300K, 350K, 400K, 450K, 500K, 550K, and the corresponding forebody and intake duct thermal experiment models of the high-speed wind tunnel are low-temperature heating models. The heating temperatures of the high-temperature heating are 600K, 700K, 800K, 900K, 1000K, and the corresponding forebody and intake duct thermal experiment models of the high-speed wind tunnel are high-temperature heating models. The pressure sensor 10 is not installed on the high-temperature heating model;

[0110] As shown Figure 14a - 14d in the figure, for the low-temperature heating model, affected by the positions of the heating rods 6 and the heating plates 8 and the model thickness, the temperature of the sharp leading edge 4 is the highest, the temperature around the pressure sensor 10 is the lowest, and the thermal strain is concentrated at the shoulder 501 position on the center line. When heated uniformly at 550K, the temperature difference on the center line is the largest, which is 8.2K. At the same time, the maximum deformation in the Y direction of the shoulder 501 is 0.183mm;

[0111] As shown Figure 15a - 15d in the figure, for the high-temperature heating model, the part with the highest temperature is at the sharp leading edge 4, and the thermal strain is concentrated at the model leading edge and the shoulder 501 position on the center line. When heated uniformly at 1000K, the temperature difference on the center line is the largest, which is 26.31K. At the same time, the maximum deformation in the Y direction of the shoulder 501 is 0.195mm;

[0112] The temperature distribution on the center line of the low-temperature heating model and the high-temperature heating model is uniform. As the heating temperature increases, the temperature fluctuation on the center line becomes larger. The surface temperature difference increases with the increase of the heating temperature, and the ratio of the surface temperature difference to the heating temperature is within 3%. The deformation of the low-temperature heating model and the high-temperature heating model increases with the increase of the heating temperature. The maximum deformation of the low-temperature heating model occurs at the shoulder 501 position, and the maximum deformation of the high-temperature heating model occurs at the sharp leading edge 4 and the shoulder 501 position. The ratio of the deformation to the inlet duct height is within 2%;

[0113] There are 2 working conditions for non-uniform gradient heating; in working condition 1, as shown Figure 16a in the figure, in the direction of the sharp leading edge 4, the first-stage compression surface 503, the second-stage compression surface 502 and the shoulder 501, the heating temperatures of the 6 heating regions are 600K, 600K, 550K, 500K, 450K, 400K in sequence, realizing that the wall temperature gradually decreases along the oncoming flow direction. The maximum deformation occurs at the first-stage compression surface 503, which is 0.169mm; in working condition 2, as shown Figure 16b in the figure, in the direction of the sharp leading edge 4, the first-stage compression surface 503, the second-stage compression surface 502 and the shoulder 501, the heating temperatures are 600K, 600K, 600K, not heated, 400K, 400K in sequence, realizing a step change in the wall temperature along the oncoming flow direction. The maximum deformation occurs at the first-stage compression surface 503, which is 0.181mm;

[0114] It is proved that a uniform temperature distribution and a gradient-varying temperature distribution are achieved on the surface of the forebody and inlet duct thermal experiment model of the high-speed wind tunnel, and it is feasible to use the built-in heating rods 6 and heating plates 8 to simulate the surface temperature distribution of real aerodynamic heating.

[0115] Furthermore, obtaining the relationship curve between the heat flux density and the surface temperature of the S80 includes the following content;

[0116] The temperature control of the heating plate 8 by the independent temperature control device is achieved by changing the heat flux density of the heating plate 8. It is necessary to obtain the relationship curve between the heat flux density and the surface temperature, which is used to control the non-uniform gradient heating and provide data support for realizing the gradient-varying temperature distribution.

[0117] The heat flux density of the heating plate 8 in the low-temperature heating model is less than that of the heating plate 8 in the high-temperature heating model; the heat flux density range of the heating plate 8 in the low-temperature heating model is 0 - 0.12 kW / m 2 , and obtain the Figure 17a fitting curve of the heat flux density and temperature of the center line of the low-temperature heating model as shown; the heat flux density range of the heating plate 8 in the high-temperature heating model is 0.15 - 1.2 kW / m 2 , and obtain the Figure 17b fitting curve of the heat flux density and temperature of the center line of the high-temperature heating model as shown.

[0118] Furthermore, the influence of the structural deformation of the research model of S90 on the flow field includes the following content;

[0119] Design a wind tunnel experiment model to study the influence of the structural deformation of the model generated by temperature on the aerodynamic load, and provide data support for determining the materials and wall thicknesses of the forebody and intake duct thermal experiment models of the high-speed wind tunnel.

[0120] Although the implementation schemes of the present invention have been disclosed as above, they are not limited to the applications listed in the description and implementation manners. For those skilled in the art, without departing from the principle of the present invention, all the features disclosed in the present invention, or all the steps in the disclosed methods or processes, except for the mutually exclusive features and / or steps, can be combined in any way. The present invention is not limited to the specific details and the illustrated examples here.

Claims

1. A design method for the forebody and inlet thermal experiment model of a high-speed wind tunnel, characterized in that Including the following steps: S10. Determine the overall structure and design requirements; The forebody and inlet duct thermal experiment model of the high-speed wind tunnel is based on the forebody and inlet duct coupling model. An internal flow channel (2) is arranged inside the forebody (1) of the forebody and inlet duct coupling model, and the lip (3) is the inlet of the internal flow channel (2); heating structures are arranged on the sharp leading edge (4), compression surface and shoulder position wall surface (5) of the forebody (1) to form the forebody and inlet duct thermal experiment model of the high-speed wind tunnel; It is required that the heating structure realizes uniform temperature distribution or temperature gradient distribution, the electrical connection is safe and effective, and has a thermal expansion margin; S20. Determine the heating structure; The compression surface and shoulder position wall surface (5) are sequentially divided into a primary compression surface (503), a secondary compression surface (502) and a shoulder (501) from front to back according to the oncoming flow direction; 2 heating rods (6) perpendicular to the oncoming flow direction and symmetric about the left and right are arranged inside the sharp leading edge (4); 3 heating plates (8) arranged in sequence are covered on the inner wall surface of the primary compression surface (503) along the oncoming flow direction, and heat insulation grooves (7) are arranged between the heating plates (8); 2 groups of heating plates (8) symmetric about the left and right are covered on the inner wall surfaces of the secondary compression surface (502) and the shoulder (501) along the oncoming flow direction, and heat insulation grooves (7) are arranged between the heating plates (8) in each group; a local heat flux barrier network is formed through 5 heat insulation grooves (7), dividing 6 heating regions, increasing the x-direction equivalent thermal resistance value by 60% - 80%, forcing the heat flux vector to conduct along the z-direction; realizing the composite working condition of coordinated control of longitudinal heat conduction and transverse heat insulation, and used to form a linear temperature gradient field; Thermal conductive silicone grease is applied on the contact surfaces of the heating rods (6) and each heating plate (8) with the forebody (1) to reduce the contact thermal resistance; the heating plate (8) is selected as a far-infrared heating plate; S30. Determine the pressure measurement points and temperature measurement points (11); A number of pressure sensors (10) along the oncoming flow direction are arranged on the center lines of the secondary compression surface (502) and the shoulder (501), and heat insulation ceramic tubes (9) are sleeved outside the pressure sensors (10) for heat insulation; A temperature measurement point (11) is arranged at the midpoint of the 2 heating rods (6); inside the compression surface and shoulder position wall surface (5) corresponding to each heating plate (8), a number of temperature measurement points (11) are arranged; a set of thermocouples (12) are respectively installed on each temperature measurement point (11), and the thermocouple wires (14) of each thermocouple (12) are arranged on the inner wall surface of the forebody (1); the embedding depths of the thermocouple probes (13) of each group of thermocouples (12) are different, realizing the temperature measurement of the entire area and entire depth along the compression surface and shoulder position wall surface (5); S40. Determine the independent temperature control and adjustment device; Independent temperature adjustment devices with independent control are respectively arranged on the sharp leading edge (4) and each heating plate (8); the independent temperature control and adjustment device includes a set of thermocouples (12), a data acquisition system (15), a computer (16) and a temperature controller (17); The data acquisition system (15) and the temperature controller (17) are respectively connected to the computer (16); the temperature controller (17) is connected to the heating plate (8); each group of thermocouples (12) includes 4 thermocouples (12), among which, 3 thermocouples (12) are measurement thermocouples, which are respectively connected to the data acquisition system (15) to respectively obtain the measurement signals of the wall surface (5) at the compression surface and the shoulder position at 3 different depths; 1 thermocouple (12) is a feedback thermocouple (18), the feedback thermocouple (18) is close to the heating plate (8) and is connected to the temperature controller (17); The measurement thermocouple transmits the measurement signal to the data acquisition system (15) to convert it into the measured point temperature value. The computer (16) displays the measured point temperature value. The staff sets the target temperature value on the computer (16) and sends the target temperature value to the temperature controller (17). The temperature controller (17) performs PID control through the feedback thermocouple (18) until the feedback thermocouple (18) heats up to the target temperature value; S50. Verify the influence of the heat insulation groove (7) on the temperature gradient distribution; Set temperatures of 600K, 600K, 550K, 500K, 450K and 400K on the 6 heating areas of the heating rods (6) and the heating plate (8) corresponding to the sharp leading edge (4), the primary compression surface (503), the secondary compression surface (502) and the shoulder (501) respectively; through numerical simulation, obtain the temperature distribution comparison curves with and without the heat insulation groove (7). The comparison curves show that the temperature curve with the heat insulation groove (7) is closer to the temperature gradient distribution in the ideal state, proving that the heat insulation groove (7) realizes the temperature gradient distribution; S60. Verify the heat insulation effect of the heat insulation measures; The heat insulation measures include a heat insulation groove (7) and a heat insulation ceramic tube (9); isothermal heating at 500K and 600K is respectively adopted on the secondary compression surface (502) and the shoulder (501). For the model without the heat insulation groove (7), the surface temperature reaches equilibrium at 32s, while for the model with the heat insulation groove (7), the surface temperature reaches equilibrium at 97s. By comparison, it is found that the heat insulation groove (7) reduces the temperature rise rate of the model surface by 67%; when isothermal heating at 500K is adopted on the secondary compression surface (502) and the shoulder (501), the temperature contour map on the installation section of the pressure sensor (10) shows that after applying the heat insulation ceramic tube (9), the temperature of the pressure sensor (10) is lower than the temperature of the surrounding wall surface, proving that the heat insulation ceramic tube (9) provides the required thermal protection for the pressure sensor (10); when isothermal heating at 500K, 600K, and 650K is respectively adopted on the secondary compression surface (502) and the shoulder (501), under the uniform heating condition of 600K, at 63.5s, the surface temperature of the pressure sensor (10) is 480K, reaching the working temperature limit of the pressure sensor (10), and the surface temperature of the model is 586.04K, and the change curve of the model surface temperature is gentle. Subsequently, the change of the model surface temperature is within the pre-specified stable interval range. In order to save the wind tunnel experiment time, it is determined that the wind tunnel startup time is before 63.5s; under the uniform heating condition of 500K, according to the working temperature limit of the pressure sensor (10) being 480K, the estimated wind tunnel experiment time is 50s, meeting the requirements of the dynamic load wind tunnel experiment; S70. Examine the model structure deformation caused by temperature; The heating methods of the forebody and intake duct thermal experiment models of the high-speed wind tunnel include uniform heating and non-uniform gradient heating; The heating temperatures of uniform heating include low-temperature heating and high-temperature heating. The heating temperatures of low-temperature heating are 300K, 350K, 400K, 450K, 500K, 550K, and the corresponding forebody and intake duct thermal experiment models of the high-speed wind tunnel are low-temperature heating models. The heating temperatures of high-temperature heating are 600K, 700K, 800K, 900K, 1000K, and the corresponding forebody and intake duct thermal experiment models of the high-speed wind tunnel are high-temperature heating models. The pressure sensor (10) is not installed on the high-temperature heating model; For the low-temperature heating model, affected by the positions of the heating rod (6) and the heating plate (8) and the model thickness, the temperature of the sharp leading edge (4) is the highest, and the temperature around the pressure sensor (10) is the lowest. The thermal strain is concentrated at the shoulder (501) position on the center line; when uniformly heated at 550K, the temperature difference on the center line is the largest, being 8.2K. At the same time, the maximum deformation in the Y direction of the shoulder (501) is 0.183mm; For the high-temperature heating model, the part with the highest temperature is at the sharp leading edge (4). The thermal strain is concentrated at the model leading edge and the shoulder (501) position on the center line. When uniformly heated at 1000K, the temperature difference on the center line is the largest, being 26.31K; at the same time, the maximum deformation in the Y direction of the shoulder (501) is 0.195mm; The temperature distribution on the centerline of the low-temperature heating model and the high-temperature heating model is uniform. As the heating temperature increases, the temperature fluctuation on the centerline becomes larger. The surface temperature difference increases with the increase of the heating temperature, and the ratio of the surface temperature difference to the heating temperature is within 3%. The deformation of the low-temperature heating model and the high-temperature heating model increases with the increase of the heating temperature. The maximum deformation of the low-temperature heating model occurs at the shoulder (501) position, and the maximum deformation of the high-heating model occurs at the sharp leading edge (4) and the shoulder (501) position. The ratio of the deformation to the intake duct height is within 2%. There are 2 working conditions for non-uniform gradient heating. In working condition 1, according to the direction of the sharp leading edge (4), the first-stage compression surface (503), the second-stage compression surface (502) and the shoulder (501), the heating temperatures of the 6 heating regions are 600K, 600K, 550K, 500K, 450K, 400K in turn, realizing that the wall temperature gradually decreases along the oncoming flow direction. The maximum deformation occurs at the first-stage compression surface (503), which is 0.169mm. In working condition 2, according to the direction of the sharp leading edge (4), the first-stage compression surface (503), the second-stage compression surface (502) and the shoulder (501), the heating temperatures are 600K, 600K, 600K, not heated, 400K, 400K in turn, realizing a step change in the wall temperature along the oncoming flow direction. The maximum deformation occurs at the first-stage compression surface (503), which is 0.181mm. It is proved that a uniform temperature distribution and a gradient-varying temperature distribution are achieved on the surface of the forebody and intake duct thermal experiment model of the high-speed wind tunnel. It is feasible to simulate the surface temperature distribution of real aerodynamic heating by using the built-in heating rods (6) and heating plates (8). S80. Obtain the relationship curve between the heat flux density and the surface temperature; The temperature control of the heating plate (8) by the independent temperature control adjustment device is achieved by changing the heat flux density of the heating plate (8). It is necessary to obtain the relationship curve between the heat flux density and the surface temperature for controlling non-uniform gradient heating and providing data support for realizing the gradient-varying temperature distribution; The heat flux density of the heating plate (8) of the low-temperature heating model is less than that of the heating plate (8) of the high-temperature heating model; the heat flux density range of the heating plate (8) of the low-temperature heating model is 0 - 0.12 kW / m 2 , and the heat flux density-temperature fitting curve of the center line of the low-temperature heating model is obtained; the heat flux density range of the heating plate (8) of the high-temperature heating model is 0.15 - 1.2 kW / m 2 , and the heat flux density-temperature fitting curve of the center line of the high-temperature heating model is obtained; S90. Study the influence of the model structure deformation on the flow field; Design the wind tunnel experiment model to study the influence of the model structure deformation caused by temperature on the aerodynamic load, and provide data support for determining the materials and wall thicknesses of the forebody and intake duct thermal experiment models of the high-speed wind tunnel.

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