Grating type noise reduction ring gap type pressure regulating valve for wind tunnel

Abstract

The application discloses a grid type noise reduction ring gap type pressure regulating valve device for a wind tunnel and belongs to the technical field of fluid regulating equipment. The device comprises an outer conical cylinder, an inner conical cylinder, a grid type pressure regulating profile cone, a piston, a servo driving device, an inclined pull rod and a flow guide ring. The inner conical cylinder is arranged in the outer conical cylinder, and an airflow circulation area is formed between the outer conical cylinder and the inner conical cylinder. The grid type pressure regulating profile cone is used for adjusting the flow field pressure, and the two ends of the inclined pull rod are respectively hinged to the servo driving device and the piston. The piston is slidably connected to the inner conical cylinder through the servo driving device, so that the axial displacement of the piston and the grid type pressure regulating profile cone changes, the passage sectional area of the piston and the grid type pressure regulating profile cone changes, the adjustment of the flow field pressure is realized, and the noise can be effectively reduced, the gas leakage can be reduced, and the wind tunnel resonance can be avoided.

Description

Technical Field

[0001] This invention relates to a grid-type noise reduction annular slit pressure regulating valve for wind tunnels, belonging to the technical field of fluid control equipment. Background Technology

[0002] Wind tunnel testing, as an important aerodynamic testing method, is widely used in aerospace, automotive, and civil engineering fields. In wind tunnel testing, regulating the pressure of the airflow inside the tunnel is crucial. Conventional pressure regulating valve devices, while meeting accuracy and stability requirements, suffer from problems such as airflow turbulence, excessive noise, and structural vibration.

[0003] Currently, conventional industrial-grade pressure regulating valves have a flow regulation accuracy of only 1-5% and noise levels exceeding 170dB, making it difficult to meet the requirements for precise pressure regulation and low noise in wind tunnel experiments. Traditional wind tunnel pressure regulating valves mostly adopt annular slit-type pressure regulating structures, but they have drawbacks such as easy airflow separation, high valve noise, and easy sealing leakage, making it impossible to achieve precise flow field pressure regulation and low noise requirements. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a grid-type noise reduction annular slit pressure regulating valve for wind tunnels. Through the flow stabilization design of the grid-type pressure regulating cone, the pressure regulation design of the servo drive device, and the vibration reduction design of the damper, the flow field pressure in wind tunnel experiments can be accurately adjusted.

[0005] The technical solution of this invention is:

[0006] A grid-type noise reduction annular slot pressure regulating valve for wind tunnels includes an outer cone, an inner cone, a grid-type pressure regulating profile cone, a piston, a servo drive device, a horizontal damper, a vertical damper, a tie rod, and a flow guide ring.

[0007] The inner cone is disposed inside the outer cone, and an airflow area is formed between the outer cone and the inner cone;

[0008] The grid-type pressure-regulating cone inlet is connected to the outer cone cylinder, and the outlet is connected to the guide ring, which is used to regulate the flow field pressure;

[0009] The piston is located between the inner cone and the grid-type pressure-adjusting cone. The piston is integrally formed by a ring, longitudinal ribs and transverse ribs. Horizontal vibration dampers and vertical vibration dampers are respectively installed in the multiple concave cavities formed by the longitudinal ribs and transverse ribs. The horizontal vibration dampers are used to reduce the axial horizontal vibration of the piston, and the vertical vibration dampers are used to reduce the vertical vibration of the piston.

[0010] The servo drive device is fixed inside the inner cone cylinder;

[0011] The two ends of the diagonal tie rod are respectively hinged to the servo drive device and the piston;

[0012] The piston is slidably connected to the inner cone via a servo drive device, which causes a change in the axial displacement of the piston and the grid-type pressure-regulating cone, resulting in a change in the cross-sectional area of ​​the channel between the piston and the grid-type pressure-regulating cone, thereby achieving the regulation of the flow field pressure.

[0013] Furthermore, the servo drive device includes a servo hydraulic cylinder, a splined shaft, a splined sleeve, a support, and a displacement sensor;

[0014] The spline shaft is fixed to the front of the inner side of the inner cone by a support, and the spline shaft and the spline sleeve form a ball spline; one end of the diagonal tie rod is hinged to the outer wall of the spline sleeve, and the other end is connected to the piston;

[0015] The servo hydraulic cylinder is arranged in the middle of the inner side of the inner cone cylinder, and the end of the hydraulic rod of the servo hydraulic cylinder is fixedly connected to the spline sleeve; the servo hydraulic cylinder drives the spline sleeve to slide back and forth relative to the spline shaft, thereby driving the diagonal tie rod to drive the piston to move axially;

[0016] The displacement sensor is arranged in parallel with the servo hydraulic cylinder to monitor the piston's displacement.

[0017] Furthermore, the servo hydraulic cylinder is a double-acting servo hydraulic cylinder, which adopts a dual-closed-loop PID servo control strategy based on valve characteristics, with the outer loop representing the total pressure and the inner loop representing the valve position. The valve core opening and closing mechanism is optimized using a parabolic velocity curve method.

[0018] Furthermore, the piston end is provided with a main seal and a secondary seal, which are sealed by air inflation; the main seal is a double-layer structure with a valve core check valve check port, the outer layer is a T-shaped structure with draft angle, and the inner layer is an inflatable O-ring structure; the secondary seal is a multi-channel V-shaped structure.

[0019] Furthermore, the horizontal and vertical vibration dampers are permanent magnet adjustable magnetorheological dampers, or viscous fluid dampers, magnetorheological dampers, or viscous shear dampers.

[0020] Furthermore, the guide ring is connected to the grid-type pressure regulating cone outlet. The cross-section of the guide ring is a structure of arc and tangent. The outlet tangent angle is the same as the angle of the external large-angle diffuser section connected to the rear end, and the expansion angle is between 30 and 90°.

[0021] Furthermore, the grid of the grid-type pressure regulating cone has a circumferential spacing angle of less than 15°. The grid evenly divides the flow channel into small channels to avoid circumferential flow of air. The side of the grid that contacts the piston radially has a wear-resistant slider with graphite lubrication, which guides the piston.

[0022] Furthermore, the grid is composed of multiple layers of sintered metal mesh blocks with a mesh count ranging from 10 to 300 meshes; the noise reduction frequency of the sintered metal mesh block noise reduction arc plate is 0 to 40,000 Hz, and the air permeability is 30% to 100%.

[0023] Furthermore, the tie rod is a rod with spherical hinge lugs at both ends, and the thread direction of the spherical hinge lugs is opposite to that of the tie rod; one end is connected to the piston through a spherical hinge lug with a trapezoidal thread for self-locking, and the other end is hinged to a spline sleeve through a spherical hinge lug, which has the functions of self-locking and length adjustment.

[0024] Furthermore, the outer conical cylinder is designed as a cylinder-cone-cylinder structure, the cone angle of the outer conical cylinder is less than 30°, and the cone angle of the inner conical cylinder is less than 60°.

[0025] The advantages of this invention compared to the prior art are:

[0026] (1) Flow stabilization measures: The present invention sets a grid-type pressure regulating cone on the pressure regulating surface to reduce airflow pulsation and improve the uniformity of inlet airflow; there is no support at the outlet to avoid structural vibration caused by airflow separation.

[0027] (2) Precise pressure regulation: This invention employs a servo drive device consisting of a servo pump controlling a servo hydraulic cylinder, a hydraulic rod, and a displacement sensor, which drives the spline sleeve to drive the inclined tie rod and ultimately drive the piston to move axially. By changing the axial displacement of the piston and the pressure regulating cone, the cross-sectional area of ​​the channel is precisely adjusted, thereby achieving precise regulation of the flow field pressure.

[0028] (3) Vibration reduction design: The present invention designs horizontal and vertical vibration dampers for the piston to avoid axial and radial vibration of the piston and improve the stability of the pressure regulating valve.

[0029] (4) Bidirectional sealing structure: The present invention adopts a bidirectional sealing structure of V-type secondary seal and convex main seal, which uses pipeline gas for gas filling and sealing to avoid overpressure leakage, and at the same time achieves rapid pipeline opening and closing sealing.

[0030] (5) Servo hydraulic control: The servo pump and servo hydraulic valve designed in this invention perform coarse and fine control on the flow of the servo hydraulic cylinder. The dual closed-loop PID control strategy is adopted. The valve core opening and closing process is optimized by parabolic velocity curve to avoid the impact of the valve core on the valve structure and extend the service life. Attached Figure Description

[0031] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0032] Figure 1 This is a cross-sectional schematic diagram of the overall structure of the pressure regulating valve device according to an embodiment of the present invention;

[0033] Figure 2 This is a 3 / 4 schematic diagram of the overall structure of the pressure regulating valve device according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the piston and vibration damper structure according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the adjacent relationship structure of the grid-type pressure-adjusting cone according to an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the main sealing section of the inflatable sealing valve core according to an embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram showing the relative positional relationship between the tie rod and the hydraulic cylinder support in an embodiment of the present invention. Detailed Implementation

[0038] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0039] This invention proposes a grid-type noise reduction annular gap pressure regulating valve for wind tunnels, such as... Figure 1 , Figure 2 As shown, it includes an outer cone 1, an inner cone 17, a grid-type pressure regulating cone 3, a piston 8, a servo drive device, and a flow guide ring 4.

[0040] The outer cone 1 is composed of an inlet flange (standard gas pressure bearing flange structure), a circular ring, a conical ring, another circular ring, an arc ring, and an outlet flange (standard gas pressure bearing flange structure) arranged sequentially. The inlet and outlet flanges are determined based on the flow rate and pressure regulation characteristics of the sub-span super-wind tunnel, and preferably have similar diameters.

[0041] The inlet of the grid-type pressure regulating cone 3 is connected to the outlet flange of the outer cone 1, and the outlet is connected to the guide ring. The inner surface of the grid-type pressure regulating cone 3 and the arc ring of the outer cone 1 combine to form an arc and multi-segment exponential combined aerodynamic pressure regulating profile. The grid of the pressure regulating cone evenly divides the flow channel into small channels, avoiding circumferential flow of air.

[0042] The guide ring 4 is connected to the outlet of the grid-type pressure regulating cone 3. Its cross-section is a structure of circular arc and tangent, which utilizes the fluid's adhesion effect to reduce flow separation. The outlet tangent angle is the same as the angle of the external large-angle diffuser section connected to the rear end, and the expansion angle is between 30° and 90°, preferably 45°.

[0043] The inner cone 17 is located inside the outer cone 1. The outer cone 1 and the inner cone 17 form a flow area. The cone angle of the outer cone 1 is less than 30° to ensure smooth airflow in the channel. The outer cone 1 is connected to the inner cone 17 by an even number of support ribs 18 (6 in this case). The inner cone 17 has a conical-cylindrical annular structure, and the cone angle of the inner cone 10 is less than 60°. The combined flow channel area is comparable to the inlet area.

[0044] A piston 8 is provided at the inner end of the inner cone 17. The piston 8 is slidably connected to the inner cone 17 via a servo drive device. The piston 8 is positioned between the inner cone 17 and the grid-type pressure-regulating cone 3. By changing the axial displacement of the piston 8 and the grid-type pressure-regulating cone 3, the cross-sectional area of ​​the channels of the piston 8 and the grid-type pressure-regulating cone 3 changes, thereby achieving precise adjustment of the flow field pressure. The radial side of the grid that contacts the piston has a wear-resistant slider made of beryllium bronze with graphite lubrication to guide the piston. The sidewall of the grid is equipped with a microporous noise-absorbing structure with a diameter of less than 0.2 mm. The grid can be composed of multiple layers of sintered metal mesh blocks with a mesh size ranging from 10 to 300 mesh. The noise reduction frequency of the sintered metal mesh block noise-reducing arc plate is 0 to 40000 Hz, and the air permeability is 30% to 100%.

[0045] Specifically, the servo drive device includes a servo hydraulic cylinder 14 (containing a double-acting, double-output hydraulic rod), a splined sleeve 19, and a displacement sensor 11. The servo hydraulic cylinder 14 is fixed to the middle of the inner cone cylinder 17 via a hydraulic cylinder support 15. Figure 6 As shown, the hydraulic cylinder support 15 has guide grooves in the same number and position as the diagonal tie rods 16. Driven by the servo hydraulic cylinder 14, it drives the spline sleeve 19, diagonal tie rods 16, and piston 8 to reciprocate linearly. The hydraulic cylinder 14, connected in parallel with the displacement sensor 11, drives the anti-torsion assembly of the spline sleeve 19, and multiple sets of diagonal tie rods 16 drive the piston 8 to achieve linear pressure control through changes in the area of ​​the pressure regulating valve. By rationally utilizing three-dimensional space and staggering the arrangement of the hydraulic cylinder 14, displacement sensor 11, spline sleeve 19, diagonal tie rods 16, and piston 8, the axial distance of the pressure regulating valve is reduced, lowering construction costs. The conical ring of the hydraulic cylinder support 15 and the diagonal tie rods 16 form an X-shaped layout. The diagonal tie rods 16 can be of different shapes to match the hydraulic cylinder support 15.

[0046] In this embodiment, the grid-type pressure regulating cone 3 is used to adjust the flow field pressure, and the servo hydraulic cylinder 14 is used to drive the piston 8 for precise pressure adjustment. The hydraulic rod of the servo hydraulic cylinder 14 is a double-acting servo hydraulic cylinder, which uses dual servo hydraulic valves to achieve precise pressure adjustment and emergency shutdown functions through coarse and fine adjustment control of the flow rate. Based on the valve characteristics, a dual closed-loop PID servo control strategy is adopted, with the outer loop representing the total pressure and the inner loop representing the valve position. The valve core opening and closing is optimized using a parabolic velocity curve method. By adjusting the valve position through a precise PID control strategy, the valve core opening and closing process is optimized, avoiding rapid impact damage to the valve structure by the valve core. The servo hydraulic cylinder 14 and the displacement sensor 11 are arranged in parallel to form a servo drive device. One end of the hydraulic rod of the servo hydraulic cylinder 14 is connected to the spline sleeve 19, and one end of the displacement sensor 11 is fixed on the base of the servo hydraulic cylinder 14, while the other end is connected to the spline sleeve 19. The displacement sensor 11 and the servo hydraulic cylinder 14 are arranged in parallel. Preferably, the telescopic rod of the displacement sensor 11 is located inside the hydraulic cylinder sleeve to avoid airflow impact and to monitor the piston position in real time.

[0047] The inner cone cylinder 17 has a support 21 fixed at its air inlet front end. A splined shaft 20 is fixed on the support 21, and a splined sleeve 19 is slidably connected to the splined shaft 20. The splined sleeve 19 is fixedly connected to the end of the hydraulic rod of the servo hydraulic cylinder 14. The servo hydraulic cylinder 14 can drive the splined sleeve 19 to slide back and forth relative to the splined shaft 20. The inner cone cylinder 17 is also equipped with a metal protective pipe 22 for the hydraulic oil supply line of the hydraulic cylinder. The hydraulic rod protective covers 12 and 13 of the servo hydraulic cylinder 14 prevent airflow impact from damaging the hydraulic lines.

[0048] Several diagonal tie rods 16 are hinged to the outer wall of the splined sleeve 19. The other end of the diagonal tie rods 16 is hinged to the piston 8. A servo drive device consisting of a servo hydraulic cylinder 14 and a displacement sensor 11 drives the splined sleeve 19 axially, which in turn drives the diagonal tie rods 16, ultimately driving the piston 8 to move axially. The axial position of the piston 8 is fed back in real time by the displacement sensor 11.

[0049] In this embodiment, the diagonal tie rod 16 is a rod with spherical hinge lugs at both ends. The lugs are connected to the rod by trapezoidal threads. The spherical hinge lugs at both ends are opposite to the threads of the diagonal tie rod, and have self-locking and length adjustment functions. An even number of them are evenly distributed along the circumference (6 in this embodiment). One end is connected to the piston 8 through the diagonal tie rod support 23, and the other end is connected to the spline sleeve 19.

[0050] The servo hydraulic cylinder 14 drives the spline sleeve 19 to slide back and forth relative to the spline shaft via a hydraulic rod. The spline sleeve 19 drives the movement between the tie rod 16 and the piston 8. The position of the piston is precisely adjusted by the displacement sensor 11 with real-time feedback, thereby adjusting the cross-sectional area of ​​the channel of the pressure-adjusting cone and achieving precise control of the flow field pressure.

[0051] In this embodiment, the grid of the grid-type pressure regulating cone 3 has a circumferential spacing angle of 8° to stabilize the flow and reduce airflow pulsation. The absence of supports at the flow field outlet avoids structural vibrations caused by flow separation. The total cross-sectional area of ​​the grid of the grid-type pressure regulating cone 3 is approximately equal to the total cross-sectional area of ​​the support ribs 18.

[0052] In this embodiment, the spline sleeve 19 can prevent circumferential vibration of the piston 8. The piston 8 is preferably made of cast aluminum to reduce weight; it is integrally formed from a ring, longitudinal ribs, and transverse ribs. When the large structure exceeds the machining capacity of cast aluminum, it can be made of ordinary steel. The outlet end is connected to a valve core inflation ring 7 with evenly distributed unidirectional micro-pores, which clamps with the main sealing cover plate 6 to achieve valve core sealing of the main seal 5. The main seal 5 is a double-layer sealing structure consisting of an inflation ring and a convex structure with a draft angle. The outer layer is a T-shaped structure with a draft angle, and the inner layer is an inflation O-ring structure. Figure 5 As shown, it is equipped with a pressure monitoring device, a tire pressure gauge (similar to the structure of a car's pneumatic tire).

[0053] The spline sleeve 19 and the spline shaft 20 form a high-torque ball spline, which reduces the coefficient of friction by about an order of magnitude compared to sliding friction, improves the anti-torsional characteristics of the piston 8, and avoids circumferential vibration of the piston 8.

[0054] To reduce valve noise, especially at high flow rates, horizontal dampers 9 and vertical dampers 10 are installed in the concave cavities formed by the longitudinal and transverse ribs of piston 8, such as... Figure 3 As shown, multiple dampers are evenly distributed along the circumference. Horizontal dampers 9 are used to reduce the axial horizontal vibration of piston 8, and vertical dampers 10 are used to reduce the vertical vibration of piston 8. The horizontal dampers 9 and vertical dampers 10 are permanent magnet adjustable magnetorheological dampers, or viscous fluid dampers, magnetorheological dampers, or viscous shear dampers, which can effectively reduce the vibration and noise of the wind tunnel.

[0055] In this embodiment, the piston 8 is provided with a main seal 5 and a secondary seal 2 at its end. The main seal 5 and the secondary seal 2 of the piston 8 are sealed by inflation. High-pressure gas is used to enhance the sealing performance and prevent leakage.

[0056] like Figure 4 As shown, the secondary seal 2 has a V-shaped structure, and the main seal 5 has a convex structure with an inlet and a beveled surface. High-pressure gas passing through the inlet ensures a tighter fit between the secondary seal 2, the main seal 5, and the sealing surface, preventing overpressure leakage. In this embodiment, both the cover plate 6 of the secondary seal 2 and the cover plate of the main seal are detachable and replaceable in circumferentially segmented sections. This design can be used for quick on / off sealing of pipelines, and multiple arrangements of the main seal 5 and the secondary seal 2 can be used to improve sealing redundancy and safety.

[0057] The present invention avoids the vibration of the pressure regulating valve and achieves precise closed-loop control of the flow field pressure. Necessary mechanical limits are designed at both ends of the piston and both ends of the spline sleeve to ensure movement within the effective stroke.

[0058] The entire device is equipped with necessary supports and lifting lugs for easy installation and storage.

[0059] This invention addresses the problems of poor inlet airflow uniformity and large flow separation caused by valve core support at the outlet in existing wind tunnel pressure regulating valves, which lack flow stabilization measures at the inlet and have valve core support at the outlet. This invention features a grid-type pressure regulating cone 3 at the inlet for flow stabilization and no support separation at the outlet, ensuring a stable flow field.

[0060] This invention employs a servo hydraulic cylinder to drive a high-torque ball-spline servo drive device, which axially drives the spline sleeve to drive the diagonal tie rod, ultimately driving the piston axially. Rolling friction replaces sliding friction, simultaneously improving the piston's torsional resistance. A vibration damper prevents buckling deformation of the diagonal tie rod and achieves vibration reduction. A displacement sensor provides real-time feedback on the piston's axial position. Precise adjustment of the flow field pressure is achieved by changing the cross-sectional area of ​​the channels between the piston and the pressure-regulating cone due to variations in their axial displacement.

[0061] The piston auxiliary seal of this invention has a V-shaped structure, and the main seal has a convex structure with a beveled surface and an air inlet with a valve core. The air inlet ensures a tighter fit between the auxiliary and main seals on the sealing surface, preventing overpressure leakage. Multiple seals can be combined to form a bidirectional sealing structure, suitable for rapid on / off sealing of pipelines.

[0062] The pressure regulating valve driving device of this invention adopts a dual servo hydraulic valve with servo pump drive to achieve precise pressure regulation and emergency shutdown functions through coarse and fine adjustment control of flow. Based on the valve characteristics, a dual closed-loop PID servo control strategy with the outer loop as the total pressure and the inner loop as the valve position is adopted. The valve core opening and closing is optimized by using a parabolic velocity curve method, which avoids the valve core from rapidly impacting and damaging the valve structure.

[0063] The usage method of the large-diameter grille-type noise reduction annular slit pressure regulating valve for super wind tunnels includes:

[0064] The two ends of the grid-type pressure regulating cone 3 are connected to the outer cone 1 and the guide ring 4 respectively, and the inner cone 17 and the outer cone 1 form a fluid flow area;

[0065] The servo drive unit axially drives the spline sleeve 19 to drive the tie rod 16 and finally drives the piston 8 to move axially. The displacement sensor 11 is arranged in parallel with the hydraulic cylinder 14 to provide real-time feedback on the axial position of the piston 8. The change in the axial displacement of the piston 8 and the grid-type pressure regulating cone 3 causes the change in the cross-sectional area of ​​the channel of the piston 8 and the pressure regulating cone 3, thereby achieving precise adjustment of the flow field pressure.

[0066] The grid-type pressure regulating cone 3 stabilizes the flow and reduces airflow pulsation. The flow field outlet is unsupported to avoid structural vibration caused by flow separation. The spline sleeve 19 prevents circumferential vibration of the piston 8. The dampers 9 and 10 prevent radial and axial vibration of the piston and achieve vibration reduction. The piston main seal 5 and secondary seal 2 use air to achieve air-filled sealing and have tire pressure monitoring function.

[0067] This invention enables real-time adjustment of flow field pressure according to the needs of wind tunnel experiments. It possesses excellent hydrodynamic performance and structural durability, especially under high-frequency adjustment operations, maintaining precise control and stable operation. It can precisely adjust the pressure distribution of the flow field through simple adjustments and controls to meet different wind tunnel experimental requirements. During high-flow-rate adjustment, it effectively reduces mechanical impact and noise from valves. The vibration damping device, through coupling with the piston, mitigates vibrations caused by rapid piston movement and airflow impact, thereby ensuring the long-term stability and reliability of the equipment.

[0068] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A grid-type noise reduction annular slit pressure regulating valve for wind tunnels, characterized in that, It includes an outer cone, an inner cone, a grid-type pressure-adjusting cone, a piston, a servo drive unit, a horizontal damper, a vertical damper, a tie rod, and a flow guide ring; The inner cone is disposed inside the outer cone, and an airflow area is formed between the outer cone and the inner cone; The grid-type pressure-regulating cone inlet is connected to the outer cone cylinder, and the outlet is connected to the guide ring, which is used to regulate the flow field pressure; The piston is located between the inner cone and the grid-type pressure-adjusting cone. The piston is integrally formed by a ring, longitudinal ribs and transverse ribs. Horizontal vibration dampers and vertical vibration dampers are respectively installed in the multiple concave cavities formed by the longitudinal ribs and transverse ribs. The horizontal vibration dampers are used to reduce the axial horizontal vibration of the piston, and the vertical vibration dampers are used to reduce the vertical vibration of the piston. The servo drive device is fixed inside the inner cone cylinder; The two ends of the diagonal tie rod are respectively hinged to the servo drive device and the piston; The piston is slidably connected to the inner cone via a servo drive device, which causes a change in the axial displacement of the piston and the grid-type pressure-regulating cone, resulting in a change in the cross-sectional area of ​​the channel between the piston and the grid-type pressure-regulating cone, thereby achieving the regulation of the flow field pressure. The servo drive device includes a servo hydraulic cylinder, a splined shaft, a splined sleeve, a support, a hydraulic cylinder support, and a displacement sensor. The spline shaft is fixed to the front of the inner side of the inner cone by a support, and the spline shaft and the spline sleeve form a ball spline; one end of the diagonal tie rod is hinged to the outer wall of the spline sleeve, and the other end is connected to the piston; The servo hydraulic cylinder is fixed to the middle of the inner side of the inner cone cylinder by a hydraulic cylinder support. The end of the hydraulic rod of the servo hydraulic cylinder is fixedly connected to the spline sleeve. The hydraulic cylinder support has guide grooves with the same number and position as the tie rod. The servo hydraulic cylinder drives the spline sleeve to slide back and forth relative to the spline shaft, thereby driving the tie rod to drive the piston to move axially. The displacement sensor is arranged in parallel with the servo hydraulic cylinder to monitor the piston displacement. The piston end is provided with a main seal and a secondary seal, which are sealed by inflation. The main seal is a double-layer structure with a valve core check valve inlet. The outer layer is a T-shaped structure with a draft angle, and the inner layer is an inflation O-ring structure. The secondary seal is a multi-channel V-shaped structure. The piston outlet end is connected to a valve core inflation ring with evenly distributed one-way air holes, which clamps with the main seal cover to achieve valve core sealing.

2. The wind tunnel grid-type noise reduction annular slit pressure regulating valve according to claim 1, characterized in that, The servo hydraulic cylinder is a double-acting servo hydraulic cylinder, which adopts a dual-closed-loop PID servo control strategy based on valve characteristics, with the outer loop representing the total pressure and the inner loop representing the valve position. The valve core opening and closing mechanism is optimized using a parabolic velocity curve method.

3. The wind tunnel grid-type noise reduction annular slit pressure regulating valve according to claim 1, characterized in that, The horizontal and vertical vibration dampers are permanent magnet adjustable magnetorheological dampers, or viscous fluid dampers, magnetorheological dampers, or viscous shear dampers.

4. The wind tunnel grid-type noise reduction annular slit pressure regulating valve according to claim 1, characterized in that, The guide ring is connected to the grid-type pressure regulating cone outlet. The cross-section of the guide ring is a structure of arc and tangent. The outlet tangent angle is the same as the angle of the external large-angle diffuser section connected to the rear end, and the expansion angle is between 30 and 90°.

5. A grid-type noise reduction annular slit pressure regulating valve for wind tunnels according to claim 1, characterized in that, The grid of the grid-type pressure regulating cone has a circumferential spacing angle of less than 15°. The grid divides the flow channel into small channels evenly to prevent the airflow from moving around in the circumferential direction. The side of the grid that contacts the piston in the radial direction has a wear-resistant slider with graphite lubrication, which guides the piston.

6. A grid-type noise reduction annular slit pressure regulating valve for wind tunnels according to claim 5, characterized in that, The grid is composed of multiple layers of sintered metal mesh blocks with a mesh count ranging from 10 to 300 meshes; the noise reduction frequency of the sintered metal mesh block noise reduction arc plate is 0~40000Hz, and the air permeability is 30%-100%.

7. A grid-type noise reduction annular slit pressure regulating valve for wind tunnels according to claim 1, characterized in that, The tie rod is a rod with ball joint lugs at both ends. The thread direction of the ball joint lugs is opposite to that of the tie rod. One end is connected to the piston through a ball joint lug with trapezoidal thread self-locking, and the other end is hinged to the spline sleeve through a ball joint lug, which has self-locking and length adjustment functions.

8. A grid-type noise reduction annular slit pressure regulating valve for wind tunnels according to claim 1, characterized in that, The inner cone has a cone-cylindrical annular structure, and the outer cone has a cylinder-cone-cylindrical structure; the cone angle of the outer cone is less than 30°, and the cone angle of the inner cone is less than 60°.

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