A test apparatus and method for cold flow of a large expansion ratio nozzle based on a central plug cone.

Abstract

This invention discloses a cold flow testing device and method based on a central plug cone. The device includes a nozzle test body, a central plug cone, an inlet connection section, and a support structure. The inlet connection section includes an inlet section shell, an inlet connection section insulation layer, and a front positioning and fixing assembly. The inlet connection section insulation layer is bonded to the inner wall of the inlet section shell with high-temperature structural adhesive. The outer ring of the front positioning and fixing assembly is screwed onto the inlet section shell. The central plug cone is coaxially supported and fixed in the inner flow channel of the nozzle test body to define an annular flow channel. The support structure includes a front-end support assembly and a rear-end anchoring assembly with an installation slot. This invention modifies the effective internal flow space through the central plug cone, making it easier for nozzles with a large expansion ratio to establish a stable internal flow field under low flow conditions, reducing testing costs and improving versatility.

Description

Technical Field

[0001] This invention belongs to the field of aerospace experimental technology, specifically relating to a cold flow test device and method for a large expansion ratio nozzle based on a central plug cone. Background Technology

[0002] The nozzle is a core component of rocket engines, scramjet engines, and related aerodynamic test systems. Its main function is to efficiently convert the thermal energy of high-temperature, high-pressure gases into kinetic energy, thereby generating thrust or creating a specific flow field. To study the internal flow characteristics of the nozzle under different operating conditions and verify the rationality of its structural design, cold flow tests are usually conducted to obtain parameters such as pressure, temperature, and flow state, providing data support for nozzle performance analysis and structural optimization.

[0003] In existing nozzle cold flow testing equipment, the test nozzle typically employs a fixed geometry, with its throat dimensions, expansion section profile, and exit cross-sectional area remaining unchanged after machining. However, for nozzles with a large expansion ratio, during cold flow testing, if the gas supply system has a low flow rate or limited capacity, directly using the original nozzle internal profile often fails to establish a stable flow state within the nozzle that meets the testing requirements. This results in parameters such as velocity, pressure, or Mach number at the measuring points failing to reach the predetermined range, severely impacting the validity and accuracy of the test results.

[0004] With limited gas supply capacity, the original high-expansion-ratio nozzle profile often struggles to simultaneously meet the flow field establishment process and the matching requirements of the target test parameters. To address testing issues under low-flow-rate conditions, existing technologies typically improve the gas supply system capacity or redesign and manufacture dedicated nozzles. However, upgrading the gas source equipment to increase the gas flow rate increases filling and testing costs and adds complexity to the test bench system. Furthermore, remanufacturing a scaled-down test nozzle for specific low-flow-rate conditions suffers from long processing times, poor versatility, and significantly increases the workload of test preparation, making it particularly unsuitable for conducting multiple comparative tests on the same test platform.

[0005] In the existing technology, there is a lack of a structural solution that can easily modify the effective flow space inside the nozzle without significantly altering the main structure of the test rig. Therefore, under the existing test platform conditions and limited air supply capacity, how to ensure that a nozzle with a large expansion ratio can still obtain an internal flow field state that meets the test requirements, thereby improving the adaptability of the cold flow test device to specific operating conditions, has become a technical problem that engineers in this field urgently need to solve. Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a cold flow testing device based on a central blocking cone that is highly adaptable, has low testing costs, and good versatility. The specific solution is as follows: A cold flow test device based on a central plug cone includes a nozzle test body, a central plug cone, an inlet connecting section, and a support structure. The nozzle test body has a through-flow inner channel, which serves as the outer boundary of the test airflow channel. The inlet connecting section is connected to the upstream end of the nozzle test body and has an internal channel for airflow to enter, which communicates with the inner flow channel of the nozzle test body. The central plug cone is coaxially disposed in the inner flow channel of the nozzle test body, and the outer peripheral wall of the central plug cone and the inner wall of the nozzle test body define an annular flow channel for the expansion and acceleration of the test airflow. The support structure is connected to the inlet connecting section and the central plug cone respectively, for positioning and supporting the central plug cone on the central axis of the nozzle test body.

[0007] Furthermore, the nozzle test body comprises, in sequence along the airflow direction, a converging section shell and an expanding section shell connected together; a converging section insulation layer is fixed to the inner wall of the converging section shell; a throat liner defining the narrowest flow cross section of the nozzle is clamped at the inner side of the joint between the converging section shell and the expanding section shell; a composite material nozzle expanding section is nested and fixed to the inner wall of the expanding section shell; the downstream end face of the converging section insulation layer, the inner wall face of the throat liner, and the upstream end face of the composite material nozzle expanding section are smoothly connected sequentially along the airflow direction.

[0008] Furthermore, the central plug cone includes a front support rod, a plug cone throat, a plug cone expansion section, and a rear adapter, which are sequentially spliced ​​along the airflow direction; the front support rod is supported and fixed within the air intake connection section; the rear adapter extends axially from the downstream end of the nozzle test body and is fixedly connected to the support structure.

[0009] Furthermore, the throat of the plug cone has an axially extending stepped hole inside, and the downstream end of the front support rod is inserted into the stepped hole and fixed inside the stepped hole by a first fastener; the upstream end face of the plug cone throat has a sealing ring groove, and a sealing ring is provided in the sealing ring groove, and the end face of the front support rod is pressed against the sealing ring; the downstream end face of the plug cone throat and the upstream end face of the plug cone expansion section are connected and fixed by a second fastener, and the outer surfaces of the plug cone throat and the plug cone expansion section are flush with each other at the connection gap; the downstream end face of the plug cone expansion section has a boss, and the upstream end face of the rear adapter has a groove that mates with the boss; the plug cone expansion section and the rear adapter are connected and fixed by a third fastener, and the end face of the third fastener after installation is flush with the outer surface of the rear adapter.

[0010] Furthermore, the intake connection section includes an intake section housing, an intake connection section insulation layer that fits against the inner wall of the intake section housing, and a front positioning and fixing assembly fixed inside; the front positioning and fixing assembly includes an outer ring and an inner ring arranged coaxially, and four rectifier support columns evenly connected circumferentially between the outer ring and the inner ring; the surface of the intake connection section insulation layer is coated with high-temperature structural adhesive to bond and fix it to the inner wall of the intake section housing; the outer surface of the outer ring is provided with external threads and is fixed to the inner wall of the intake section housing by thread engagement, and the inner ring is sleeved on the front support column; the cross-section of the rectifier support column is streamlined and has an arc-shaped transition structure.

[0011] Furthermore, the support structure includes a front support assembly located at the front end of the device and a rear anchoring assembly located at the rear end of the device; the rear anchoring assembly includes a mounting base for fixing to an external test bench base, and a mounting flange located above it and fixed to the rear adapter; a thrust support plate is vertically arranged between the mounting base and the mounting flange; a reinforcing support member is connected between the mounting flange and the thrust support plate; the mounting base has an installation slot extending along the airflow direction for passing through fixing bolts.

[0012] Furthermore, the intake connection section has an intake pressure measuring hole and a temperature measuring hole that penetrate the internal channel on its pipe wall. The pipe wall is integrally formed with a pressure measuring boss corresponding to the intake pressure measuring hole and a temperature measuring connector corresponding to the temperature measuring hole. The outer surface of the intake connection section is partially provided with a flat surface, and a total pressure measuring hole that penetrates the pipe wall and connects to the total pressure measuring interface is provided at the flat surface. The expansion section shell and the composite material nozzle expansion section are provided with sensor mounting holes that penetrate both side walls at the fitting position.

[0013] Furthermore, a radially penetrating flow field pressure measurement hole is provided on the side wall of the expansion section of the plug cone, and a plug cone flow field pressure measurement connector is installed on the flow field pressure measurement hole.

[0014] Furthermore, the expansion section of the composite nozzle is made of carbon fiber braided material, the throat liner is made of graphite, and the insulation layer of the convergent section and the insulation layer of the air intake connection section are both made of bakelite; the load-bearing shell of the nozzle test body, the shell of the air intake connection section and the supporting structure are made of stainless steel.

[0015] This invention also provides a method for conducting cold flow tests on large expansion ratio nozzles using the aforementioned cold flow test device, comprising the following steps: Step 1: Coaxially fixing the central plug cone in the inner flow channel of the nozzle test body, using the central plug cone to occupy part of the inner flow channel volume to reduce the effective flow area inside the original large expansion ratio nozzle, thereby correcting the flow space distribution in the throat and post-throat expansion section, and defining an annular flow channel for airflow expansion; Step 2: Installing sensors at corresponding measuring points on the inlet connection section, the nozzle test body, and the central plug cone to construct a double boundary covering the inner and outer sides of the annular flow channel. The joint testing system is used, and a laser displacement sensor is arranged externally to be aligned with the wall surface to be tested; Step 3: Under the condition of limited air supply flow, the pneumatic valve is opened to introduce high-pressure gas into the internal channel; After the high-pressure gas enters the annular flow channel, it undergoes full expansion acceleration within the effective flow area corrected in Step 1 to establish an internal flow state that meets the predetermined Mach number and pressure requirements; Step 4: After the internal flow state stabilizes, the total intake pressure, the static pressure at the outer boundary of the flow channel, the static pressure at the inner boundary of the flow channel, and the wall vibration displacement data are collected simultaneously using a data acquisition device to comprehensively analyze the internal flow characteristics and structural performance of the large expansion ratio nozzle.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention is a cold flow test device based on a central plug cone. By coaxially setting a central plug cone inside the nozzle test body, the device addresses the testing requirements of nozzles with large expansion ratios under low flow conditions. The central plug cone occupies part of the internal space to reduce the effective flow area, thereby correcting the distribution of the effective flow space in the throat and the expansion section after the throat. This allows the nozzle with a large expansion ratio to quickly establish a stable flow field state that meets the predetermined test parameters (such as Mach number, pressure, etc.) even with limited air supply capacity.

[0017] 2. The device of the present invention can be put into testing directly without changing the main structure of the test bench and the original nozzle shape. Compared with the traditional solution of improving the gas supply system or redesigning and processing special nozzles, the present invention can meet the need to carry out multiple sets of large expansion ratio nozzle comparison tests efficiently on the same test platform, avoid the lengthy processing cycle, and improve the compatibility and versatility of the test device.

[0018] 3. The intake connection section of this invention is equipped with a streamlined cross-section flow-rectifying support column, and the support structure includes a rear anchoring assembly and a thrust support plate. Through the scientific combination of front and rear double-end support and flow guidance, the interference with the intake airflow field and airflow resistance are effectively reduced, while the central blocking cone is stably supported when subjected to the huge axial thrust of high-pressure airflow, ensuring the safety and stability of the test process.

[0019] 4. The central plug cone of this invention has a radially penetrating flow field pressure measurement hole on its sidewall. Combined with conventional test holes on the inlet connection section and the nozzle test body, it is possible to achieve comprehensive joint measurement of the flow field parameters at the inner and outer boundaries of the annular flow channel, providing more detailed and three-dimensional data support for flow field diagnosis and nozzle performance optimization. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the cold flow test device based on the central blocking cone according to an embodiment of the present invention; Figure 2 This is an axial sectional view of the cold flow testing device according to an embodiment of the present invention; Figure 3 This is a half-sectional view of the air intake connection section and the front positioning and fixing component according to an embodiment of the present invention; Figure 4 This is an axial half-sectional view of the central plug cone in an embodiment of the present invention; Figure 5 This is a three-dimensional structural schematic diagram of the back-end anchoring component according to an embodiment of the present invention; The figure shows: 1. Nozzle test body; 11. Converging section shell; 12. Expanding section shell; 13. Converging section insulation layer; 14. Throat liner; 15. Composite material nozzle expanding section; 16. Expanding section pressure sensor connector; 2. Central plug cone; 21. Front support rod; 211. Front threaded connection; 212. Rear insertion connection; 22. Plug cone throat; 221. Cylindrical connecting part; 222. Sealing ring groove; 23. Plug cone expanding section; 231. Upstream mating end face; 232. Boss connecting part; 24. Rear adapter; 241. Installation opening; 25. Plug cone flow. 3. Intake connection section; 31. Intake section housing; 32. Intake connection section insulation layer; 33. Front positioning and fixing assembly; 331. Outer ring; 332. Rectifier support column; 333. Inner ring; 34. Total pressure test interface; 35. Pressure test boss; 36. First intake pressure test connector; 37. Temperature test connector; 38. Second intake pressure test connector; 4. Support structure; 41. Front support assembly; 42. Rear anchoring assembly; 421. Mounting base; 422. Mounting flange; 423. Thrust support plate; 424. Reinforcing support component; 425. Mounting slot. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] See Figures 1 to 5 The cold flow test device based on the central plug cone in this embodiment of the invention includes a nozzle test body 1, a central plug cone 2, an air intake connection section 3, and a support structure 4.

[0023] The nozzle test body 1 has a through internal flow channel. The air inlet connection section 3 is connected to the upstream end of the nozzle test body 1. The air inlet connection section 3 has an internal channel for high-pressure airflow to enter. The internal channel communicates with the internal flow channel of the nozzle test body 1 so that the high-pressure airflow provided by the air supply system can be smoothly introduced into the test area. The central blocking cone 2 is coaxially arranged in the internal flow channel of the nozzle test body 1. The outer peripheral wall of the central blocking cone 2 and the inner wall of the nozzle test body 1 define an annular flow channel for the expansion and acceleration of the test airflow. The support structure 4 has support members that are respectively connected to the air inlet connection section 3 and the central blocking cone 2, so as to firmly position and support the central blocking cone 2 on the central axis of the nozzle test body 1, ensuring the axial symmetry of the annular flow channel.

[0024] After the central plug cone 2 is coaxially placed inside the nozzle test body 1, it reduces the effective flow area by occupying part of the volume of the inner flow channel, thus correcting the effective flow space distribution in the throat and post-throat expansion section of the original nozzle. Under conditions where the cold flow test air supply flow rate is small or the air supply capacity is limited, when the high-pressure airflow flows through the annular flow channel jointly defined by the central plug cone 2 and the nozzle test body 1, the reduction in the flow channel cross-sectional area makes the airflow easier to expand and accelerate, thereby quickly establishing a stable internal flow state at each test point that meets the predetermined Mach number, pressure, or velocity requirements, ensuring the effectiveness and accuracy of the cold flow test results under low flow conditions.

[0025] The following describes some specific embodiments of the cold flow test apparatus based on a central plug cone according to the present invention.

[0026] like Figure 1 and Figure 2 As shown, the cold flow test device based on the central plug cone in this embodiment of the invention includes a nozzle test body 1, a central plug cone 2, an air intake connection section 3, and a support structure 4.

[0027] Specifically, the nozzle test body 1 includes a converging section shell 11 and an expanding section shell 12 connected sequentially along the airflow direction. A converging section insulation layer 13 is fixed to the inner wall of the converging section shell 11 to provide heat insulation and protection for the metal shell under high-temperature or high-pressure airflow conditions. A throat liner 14, defining the narrowest flow cross-section of the nozzle, is sandwiched between the converging section shell 11 and the expanding section shell 12. The profile of the throat liner 14 determines the critical cross-sectional state of the flow field. A composite material nozzle expanding section 15 is nested and fixed to the inner wall of the expanding section shell 12. The downstream end face of the converging section insulation layer 13, the inner wall face of the throat liner 14, and the upstream end face of the composite material nozzle expanding section 15 are smoothly connected sequentially along the airflow direction, thus forming a continuous transition surface without step gaps on the inner wall of the nozzle test body 1. This avoids steps disturbing the high-speed airflow or causing boundary layer separation, ensuring the hydrodynamic quality of the flow channel.

[0028] like Figure 2 , Figure 3 and Figure 4 As shown, the central plug cone 2 includes a front support rod 21, a plug cone throat 22, a plug cone expansion section 23, and a rear adapter 24, which are sequentially assembled along the airflow direction. Specifically, the front support rod 21 includes a large end 211 and a small end 212 of a front fixing rod. The large end 211 of the front fixing rod is fixed to the air intake connection section by a threaded connection. The upstream end of the plug cone throat 22 has a cylindrical connecting part 221 as an installation cavity. The small end 212 of the front fixing rod is inserted into the cylindrical connecting part 221, which serves as the positioning and support function of the front end.

[0029] At the axial joints of each segment, the upstream end face of the expanding section 23 of the plug cone is an upstream mating end face 231, which mates with the downstream end face of the throat 22 of the plug cone and is fixed by a second fastener such as a connecting screw, so as to achieve a flush transition of the outer surfaces of the two. The downstream end face of the expanding section 23 of the plug cone forms a boss connecting part 232, and the upstream end face of the rear adapter 24 is provided with a groove that mates with the boss connecting part 232. The two are fixed by a third fastener such as a countersunk screw, and the end face of the countersunk screw is recessed into the groove to maintain a flush position. In addition, the rear end of the rear adapter 24 is provided with a mounting opening 241, and a plurality of screw holes are provided circumferentially around the mounting opening 241 for the installation and assembly of internal parts.

[0030] To ensure the reliability of the internal assembly of the central plug cone 2 and the streamlined features of its outer surface, a stepped hole extending axially is provided inside the throat 22 of the plug cone. The downstream end of the front support rod 21 is inserted into the stepped hole and is axially pressed and locked inside the stepped hole by a connecting screw, which serves as the first fastener. To prevent high-pressure airflow from leaking into the plug cone during testing, a circumferential sealing ring groove 222 is provided on the upstream end face of the throat 22 of the plug cone, and a sealing ring is provided in the sealing ring groove 222. In actual assembly, the sealing ring can be pre-fixed in the sealing ring groove 222 with petroleum jelly, and then pressed against the end face of the front support rod 21 to achieve axial end face sealing. The downstream end face of the throat 22 of the plug cone is connected and fixed to the upstream end face of the expansion section 23 of the plug cone by a connecting screw, which serves as the second fastener. Here, to eliminate surface discontinuities that may be caused by bolted connections, the outer surfaces of the plugging cone throat 22 and the plugging cone expansion section 23 are flush-transitioned at the connection gap; the expansion angle of the outer wall of the plugging cone expansion section 23 is the same as the expansion angle of the downstream side of the left end of the plugging cone throat 22, thereby forming a continuous conical expansion surface in the middle of the plugging cone; a boss is formed on the downstream end face of the plugging cone expansion section 23, and a groove that mates with the boss is provided on the upstream end face of the rear adapter 24; the plugging cone expansion section 23 and the rear adapter 24 are fixed by inserting a countersunk screw as a third fastener, and the end face of the countersunk screw after installation is sunk into the countersunk hole in the groove, keeping it flush with the outer surface of the rear adapter 24, thus avoiding the aerodynamic interference of the boundary layer caused by the protruding head of the fastener.

[0031] like Figure 2 and Figure 3As shown, the intake connection section 3 includes an intake section housing 31, an intake connection section insulation layer 32 that fits against the inner wall of the intake section housing 31, and a front positioning and fixing component 33 fixed inside. In order to ensure the radial stability of the front support rod 21 under the impact of high-speed airflow, the front positioning and fixing component 33 is used to support the front support rod 21. Specifically, the pre-positioning and fixing assembly 33 includes an outer ring 331 and an inner ring 333 coaxially arranged, and four rectifier support columns 332 circumferentially and uniformly connected between the outer ring 331 and the inner ring 333. The outer ring 331 has external threads and is fixed to the inner wall of the intake section housing 31 by threaded connection. During assembly, high-temperature structural adhesive can be applied to the outer surface of the insulation layer 32 of the intake connection section, and the entire assembly can be pushed in and bonded to the intake section housing 31. The inner ring 333 is sleeved and fixed on the pre-support rod 21, thereby achieving precise coaxial positioning of the front end of the central blocking cone. Considering that the high-pressure airflow needs to maintain good hydrodynamic quality before entering the nozzle, the cross-section of the rectifier support column 332 is streamlined, and its windward and leeward sides have arc-shaped transition structures. This design can effectively rectify the incoming flow and significantly reduce airflow resistance, avoid turbulence or boundary layer separation upstream of the central blocking cone, thereby improving the airflow quality entering the nozzle channel.

[0032] like Figure 2 and Figure 5 As shown, considering that the expansion of high-pressure gas in the annular flow channel will generate a huge axial thrust on the central plug cone 2, the support structure 4 includes a front support component 41 located at the front end of the device and a rear anchoring component 42 located at the rear end of the device to ensure the mechanical stability of the entire system. The rear anchoring assembly 42 includes a mounting base 421 for fixing to the external test bench base, and a mounting flange 422 located above the mounting base 421 and fixed to the rear adapter 24. To further improve the thrust resistance stiffness, a thrust-bearing support plate 423 for bearing thrust is vertically arranged between the mounting base 421 and the mounting flange 422. The mounting flange 422 is connected to the thrust-bearing support plates 423 on the left and right sides by welding reinforced support members 424, thereby forming a high-strength overall support frame together with the middle support plate. In addition, in order to prevent the test device from undergoing slight displacement due to axial thrust, the mounting base 421 is provided with a long mounting groove 425 extending along the airflow direction for passing through fixing bolts to lock the base. The edge of the thrust-bearing support plate 423 facing the airflow outlet direction has an arc-shaped transition edge to avoid stress concentration caused by structural abrupt changes.

[0033] like Figures 2 to 4As shown, in order to comprehensively acquire internal flow field data under different operating conditions, this embodiment of the invention arranges a combined pressure measurement system. On one hand, the intake section housing 31 of the intake connection section 3 has an intake pressure measurement hole and a temperature measurement hole extending into the internal channel on its pipe wall. Furthermore, a pressure measurement boss 35 is integrally formed on the outside of the pipe wall at a position corresponding to the intake pressure measurement hole, for mounting a pressure sensor to measure the total intake pressure. Further, on a small flat surface cut into the outer wall of the intake section housing 31, a total pressure measurement interface 34, a first intake pressure measurement connector 36, a temperature measurement connector 37, and a second intake pressure measurement connector 38 are respectively connected by threads. On the other hand... For static pressure measurement at the outer boundary of the flow channel, the expansion section shell 12 and the composite material nozzle expansion section share a sensor mounting hole penetrating both side walls at their contact points. An expansion section pressure sensor connector 16 is mounted outside this mounting hole to facilitate reliable connection and fixation of the external pressure sensor. To obtain core data of the inner boundary of the flow channel, a radially penetrating flow field pressure measurement hole is provided on the side wall of the plug cone expansion section 23, and a plug cone flow field pressure measurement connector 25 is installed on this flow field pressure measurement hole. Through the cooperation of the expansion section pressure sensor connector 16 and the plug cone flow field pressure measurement connector 25, the true flow field distribution of the inner and outer boundaries of the annular flow channel's internal cross-section can be obtained simultaneously, providing accurate experimental data for evaluating the performance of nozzles with a large expansion ratio.

[0034] In terms of the selection of temperature and pressure resistant materials, in order to meet the working conditions required in the test, the expansion section 15 of the composite material nozzle is made of carbon fiber braided parts, the throat liner 14 is made of graphite, and the insulation layer 13 of the convergence section and the insulation layer 32 of the air inlet connection section are both made of bakelite. The combined application of the above-mentioned non-metallic special materials can effectively meet the requirements of ablation resistance and heat insulation of the throat and expansion section. At the same time, the main load-bearing shell of the nozzle test body 1, the air inlet section shell 31 of the air inlet connection section 3, and the support structure 4 are all made of stainless steel to ensure that the device as a whole has sufficient structural rigidity and high pressure resistance.

[0035] The above materials are all commonly used in this field and can meet the requirements for structural strength, heat insulation and testing of the device.

[0036] This invention also provides a method for conducting cold flow tests on nozzles with large expansion ratios using the aforementioned device. This method combines physical structure modification with fluid dynamics testing techniques, enabling nozzles with large expansion ratios to be adapted for testing under low flow conditions. Specifically, it includes the following operational steps: S1. The central plug cone 2 is coaxially installed and fixed in the inner flow channel of the nozzle test body 1. When connecting the central plug cone 2 to the front support rod 21, the sealing ring is pre-fixed in the sealing ring groove 222 on the upstream end face of the throat 22 of the plug cone using petroleum jelly, and axially pressed and locked to achieve end face sealing; at the same time, the rear anchoring component 42 at the tail of the device is fixed on the external test bench base to resist axial thrust; after assembly, the central plug cone 2 reduces the effective flow area inside the original large expansion ratio nozzle to correct the flow space distribution in the throat and the expansion section after the throat.

[0037] S2. Pressure sensors and temperature sensors are installed at the pressure measuring boss 35 and each pressure / temperature measuring interface of the air intake connection section 3, the sensor mounting holes on the outer wall of the nozzle test body 1, and the flow field pressure measuring holes on the side wall of the central plug cone 2, respectively, to construct a flow field testing system covering the inner and outer boundaries of the annular flow channel; at the same time, a laser displacement sensor is arranged on the outside of the nozzle test body 1, and its position and measurement direction are adjusted so that its measurement axis is aligned with the wall surface to be tested, and all sensors are connected to the data acquisition device.

[0038] S3. Turn on the external vacuum pump and adjust the pressure of the flow channel inside the nozzle test body 1 to the preset cavity pressure by evacuating air. Open the pneumatic valve of the gas supply system and introduce high-pressure gas at a set flow rate into the internal channel; after the high-pressure gas enters the annular flow channel, it expands and accelerates within the effective flow area corrected in step S1 to establish an internal flow state that meets the predetermined Mach number and pressure parameters.

[0039] S4. After the internal flow state stabilizes, the data acquisition device and the laser displacement sensor are used to simultaneously collect data on the total intake pressure, static pressure at the outer boundary of the flow channel, static pressure at the inner boundary of the flow channel, total temperature, and vibration displacement of the wall. After the predetermined test acquisition time is reached, the pneumatic valve is closed and the data acquisition is stopped. The collected flow field and mechanical data are calculated and analyzed to evaluate the flow dynamics characteristics of the large expansion ratio nozzle under the current test conditions.

[0040] In the description of this invention, it should be understood that the terms "upstream", "downstream", "front end", "rear end", "radial", "axial", etc., indicate the orientation or positional relationship based on the direction of fluid flow and the relative positional relationship shown in the accompanying drawings. They are only for the purpose of objectively describing the structural features of this invention, and do not indicate or imply that the device or element referred to must have a specific orientation. Therefore, they should not be construed as limiting this invention.

[0041] Although specific embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art, within the scope of the present invention, can make conventional changes, modifications, substitutions, and variations to the structural dimensions of the above embodiments without departing from the principles of the present invention.

Claims

1. A cold flow testing device based on a central blocking cone, characterized in that, It includes the main body of the nozzle test (1), the central plug cone (2), the air intake connection section (3) and the support structure (4); The nozzle test body (1) has a through internal flow channel, which serves as the outer boundary of the test airflow channel; The air intake connection section (3) is connected to the upstream end of the nozzle test body (1). The air intake connection section (3) has an internal channel for airflow to enter. The internal channel is connected to the internal flow channel of the nozzle test body (1). The central plug cone (2) is coaxially disposed in the inner flow channel of the nozzle test body (1), and the outer peripheral wall of the central plug cone (2) and the inner wall of the nozzle test body (1) define an annular flow channel for the test airflow to expand and accelerate. The support structure (4) is connected to the air intake connection section (3) and the central plug cone (2) respectively, so as to position and support the central plug cone (2) on the central axis of the nozzle test body (1).

2. The cold flow testing apparatus according to claim 1, characterized in that, The nozzle test body (1) includes a converging section shell (11) and an expanding section shell (12) connected in sequence along the airflow direction; the inner wall of the converging section shell (11) is fixed with a converging section insulation layer (13); the inner side of the joint between the converging section shell (11) and the expanding section shell (12) is clamped with a throat liner (14) that defines the narrowest flow section of the nozzle; the inner wall of the expanding section shell (12) is nested and fixed with a composite material nozzle expanding section (15); the downstream end face of the converging section insulation layer (13), the inner wall face of the throat liner (14) and the upstream end face of the composite material nozzle expanding section (15) are smoothly connected in sequence along the airflow direction.

3. The cold flow testing apparatus according to claim 1, characterized in that, The central plug cone (2) includes a front support rod (21), a plug cone throat (22), a plug cone expansion section (23), and a rear adapter (24) that are sequentially spliced ​​along the airflow direction; the front support rod (21) is supported and fixed in the air intake connection section (3); the rear adapter (24) extends axially from the downstream end of the nozzle test body (1) and is fixedly connected to the support structure (4).

4. The cold flow testing apparatus according to claim 3, characterized in that, The throat (22) of the plug cone has an axially extending stepped hole inside. The downstream end of the front support rod (21) is inserted into the stepped hole and fixed inside the stepped hole by a first fastener. The upstream end face of the plug cone throat (22) has a sealing ring groove (222), and a sealing ring is provided in the sealing ring groove (222). The end face of the front support rod (21) is pressed against the sealing ring. The downstream end face of the plug cone throat (22) is connected to the upstream end face of the plug cone expansion section (23). The end face is connected and fixed by a second fastener, and the throat (22) of the plug cone and the outer surface of the expansion section (23) of the plug cone are flush with each other at the connection gap; a boss is formed on the downstream end face of the expansion section (23), and a groove is provided on the upstream end face of the rear adapter (24) to cooperate with the boss. The expansion section (23) of the plug cone and the rear adapter (24) are fixed by a third fastener, and the end face of the third fastener after installation is flush with the outer surface of the rear adapter (24).

5. The cold flow test apparatus according to claim 3, characterized in that, The air intake connection section (3) includes an air intake section housing (31), an air intake connection section insulation layer (32) that is attached to the inner wall of the air intake section housing, and a front positioning and fixing component (33) that is fixed inside. The front positioning and fixing assembly (33) includes an outer ring (331) and an inner ring (333) arranged coaxially, and four rectifier support columns (332) circumferentially connected between the outer ring and the inner ring; the surface of the air intake connection section insulation layer (32) is coated with high-temperature structural adhesive to bond and fix it to the inner wall of the air intake section housing (31); the outer surface of the outer ring (331) is provided with external threads and is fixed to the inner wall of the air intake section housing (31) by thread engagement; the inner ring (333) is sleeved on the front support rod (21); the cross section of the rectifier support column (332) is streamlined and has an arc-shaped transition structure.

6. The cold flow testing apparatus according to claim 3, characterized in that, The support structure (4) includes a front support assembly (41) located at the front end of the device and a rear anchoring assembly (42) located at the rear end of the device. The rear anchoring assembly (42) includes a mounting base (421) for fixing to an external test bench base, and a mounting flange (422) located above it and fixed to the rear adapter (24); a thrust support plate (423) is vertically arranged between the mounting base (421) and the mounting flange (422); a reinforcing support member (424) is connected between the mounting flange (422) and the thrust support plate (423); and a mounting groove (425) extending along the airflow direction is provided on the mounting base (421) for passing through fixing bolts.

7. The cold flow testing apparatus according to claim 2, characterized in that, The air intake connection section (3) has an air intake pressure measuring hole and a temperature measuring hole that penetrate the internal channel on its pipe wall. The pipe wall is integrally formed with a pressure measuring boss (35) corresponding to the air intake pressure measuring hole and a temperature measuring connector (37) corresponding to the temperature measuring hole. The outer surface of the air intake connection section (3) is partially provided with a plane, and a total pressure measuring hole that penetrates the pipe wall and connects to the total pressure measuring interface (34) is provided at the plane. The expansion section housing (12) and the composite material nozzle expansion section (15) are provided with sensor mounting holes that penetrate both side walls at the fitting position.

8. The cold flow testing apparatus according to claim 3, characterized in that, The side wall of the expansion section (23) of the plug cone is provided with a radially penetrating flow field pressure measuring hole, and the flow field pressure measuring hole is equipped with a plug cone flow field pressure measuring connector (25).

9. The cold flow testing apparatus according to claim 2, characterized in that, The expansion section (15) of the composite nozzle is made of carbon fiber braided material, the throat liner (14) is made of graphite, and the insulation layer (13) of the convergence section and the insulation layer (32) of the air intake connection section are both made of bakelite. The load-bearing shell of the nozzle test body (1), the shell of the air intake connection section (3) and the support structure (4) are made of stainless steel.

10. A method for conducting a large expansion ratio nozzle cold flow test using the cold flow test apparatus of claim 1, characterized in that, Includes the following steps: Step 1: Fix the central plug cone (2) coaxially in the inner flow channel of the nozzle test body (1). Use the central plug cone (2) to occupy part of the inner flow channel volume to reduce the effective flow area inside the original large expansion ratio nozzle, thereby correcting the flow space distribution in the throat and the expansion section after the throat, and defining the annular flow channel for airflow expansion. Step 2: Install sensors at the corresponding measuring points of the air intake connection section (3), the nozzle test body (1), and the central plug cone (2) to construct a joint test system covering the inner and outer boundaries of the annular flow channel, and arrange laser displacement sensors aligned with the test wall on the outside. Step 3: Under limited gas supply flow conditions, open the pneumatic valve to introduce high-pressure gas into the internal channel; after the high-pressure gas enters the annular flow channel, it undergoes full expansion acceleration within the effective flow area corrected in Step 1, establishing an internal flow state that meets the predetermined Mach number and pressure requirements. Step 4: After the internal flow state stabilizes, use a data acquisition device to simultaneously collect data on the total intake pressure, static pressure at the outer boundary of the flow channel, static pressure at the inner boundary of the flow channel, and wall vibration displacement, and conduct a comprehensive analysis of the internal flow characteristics and structural performance of the large expansion ratio nozzle.

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