Pneumatic design method for high-precision low-noise pressure regulating valve of temporary impulse type wind tunnel

Abstract

The invention discloses a pneumatic design method for a high-precision low-noise pressure regulating valve of a temporary-flushing type wind tunnel, and belongs to the technical field of pneumatic design of pressure regulating valves. In order to improve low Mach number control precision and noise in design of the annular gap pressure regulating valve, the method comprises the following steps: carrying out pressure regulating valve profile design based on a pressure regulating valve index characteristic curve and a pressure regulating valve linear characteristic curve; based on the pressure regulating valve index characteristic curve and the pressure regulating valve linear characteristic curve, a pressure regulating valve profile curve is designed; downstream flow channel expanding design is carried out on the downstream of the pressure regulating valve profile; two annular section pore plates with uniform flow fields are arranged at an outlet of a flow channel of the pressure regulating valve, and a spherical pore plate or a sintered silk screen is arranged at the downstream of a central body of the pressure regulating valve; and calculating the air source pressure of the wind tunnel and the aerodynamic characteristics of the pressure regulating valve. The flow adjusting range is wide, the air source working pressure requirement is low, and the wind tunnel total pressure control precision is high.

Description

Technical Field

[0001] The invention belongs to the technical field of pneumatic design of pressure regulating valves, and in particular relates to a pneumatic design method of a high-precision and low-noise pressure regulating valve for a temporary wind tunnel. Background Art

[0002] In a down-blowing transonic wind tunnel, the function of the pressure regulating valve is to control the airflow pressure in the stable section of the wind tunnel. During the operation of the wind tunnel, as the air source pressure decreases, the opening of the pressure regulating valve is adjusted through the control system to ensure that the airflow pressure in the stable section is stable at a certain operating pressure value to maintain the normal operation of the wind tunnel. Therefore, the pressure regulating valve should have good pressure regulation characteristics to achieve rapid and accurate control of the pressure after the valve.

[0003] Reducing the noise of the wind tunnel can improve the quality of the flow field of the wind tunnel, which is meaningful for the accuracy of the measurement data, especially for dynamic tests. The pressure regulating valve is one of the main noise sources of the transient wind tunnel. On the one hand, appropriate noise reduction measures can be taken downstream of the pressure regulating valve to absorb the noise, such as the stable section muffler. On the other hand, the noise level should be actively reduced from the perspective of the design of the pressure regulating valve.

[0004] The commonly used pressure regulating valves in wind tunnels include window-type sleeve valves, cone-shaped pressure regulating valves, and annular gap pressure regulating valves. The advantages of the window-type sleeve valve are that the airflow after the valve is well symmetrical, the noise level is low, and the adjustment characteristics can also meet the requirements of wind tunnel operation pressure control, but there are disadvantages such as a narrow pressure adjustment range, uneven resistance changes during sleeve movement, and large resistance at the fully open position. Another type is the cone-shaped pressure regulating valve, which has a wide adjustment range but large operating inertia. The third type is the annular gap pressure regulating valve, which has the advantages of obtaining linear or nearly linear adjustment characteristics under the main working state, good airflow symmetry, low noise level, wide adjustment range, uniform resistance changes during sleeve movement, small resistance at the fully open position, flexible movement of the control component, and most importantly, the theoretical prediction of the valve characteristics is very consistent with the experimental results. However, the existing annular gap pressure regulating valve still has room for improvement in Mach number control accuracy and noise. Summary of the invention

[0005] The problem to be solved by the present invention is to improve the defects of low Mach number control accuracy and high noise in the design of an annular gap pressure regulating valve, and to propose a pneumatic design method for a temporary wind tunnel high-precision and low-noise pressure regulating valve.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions: A pneumatic design method for a high-precision, low-noise pressure regulating valve for a temporary wind tunnel comprises the following steps: S1. Design the profile of the pressure regulating valve based on the exponential characteristic curve and the linear characteristic curve of the pressure regulating valve; S2. Based on the pressure regulating valve exponential characteristic curve and the pressure regulating valve linear characteristic curve obtained in step S1, the pressure regulating valve profile curve is designed; S3. Design the downstream flow channel expansion downstream of the pressure regulating valve profile; S4. Two annular cross-section orifice plates with uniform flow fields are provided at the outlet of the pressure regulating valve flow channel, and a spherical orifice plate or sintered wire mesh is provided downstream of the center body of the pressure regulating valve; S5. Based on the design of the pressure regulating valve in steps S1 to S4, the wind tunnel air source pressure and the aerodynamic characteristics of the pressure regulating valve are calculated.

[0007] Furthermore, the specific implementation method of step S1 includes the following steps: S1.1. Design the exponential characteristic curve of the pressure regulating valve, expressed as: ; in, is the relative opening of the pressure regulating valve, is the minimum opening of the pressure regulating valve, is the maximum opening of the pressure regulating valve, is the relative stroke of the valve core of the pressure regulating valve; S1.2. For the profile whose profile coordinates cannot be solved by the exponential characteristic curve of the pressure regulating valve, design the linear characteristic curve of the pressure regulating valve, and the expression is: ; in, is the constant term of a linear function, is the slope of a linear function; ; ; in, For the tangent point t The relative opening of the pressure regulating valve at For the tangent point t The relative travel of the pressure regulating valve core at For the tangent point t The maximum opening of the pressure regulating valve at For the tangent point t The minimum opening of the pressure regulating valve at the S1.3. Calculate the surface coordinates ( X , Y ), the expression is: ; Where D is the outer diameter of the valve core.

[0008] Furthermore, the specific implementation method of step S2 includes the following steps: S2.1. Design the equation of the quintic curve, which is expressed as:

[0009] in, , , , , , They are the 0th coefficient to be determined, the 1st coefficient to be determined, the 2nd coefficient to be determined, the 3rd coefficient to be determined, the 4th coefficient to be determined, and the 5th coefficient to be determined; S2.2. Choose between exponential characteristic curve and linear characteristic curve , , The relative opening and the derivative of the relative opening and the relative stroke are used as known parameters to solve the coefficients in the quintic curve equation.

[0010] Furthermore, the specific implementation method of step S3 is to design the cross section of the downstream flow channel of the pressure regulating valve to be a circular cross section, based on the equivalent radius of the inlet cross section of the downstream flow channel of the pressure regulating valve R 1. Equivalent radius of the outlet section of the downstream flow channel of the pressure regulating valve R 2. Calculate the equivalent radius of the middle section of the pressure regulating valve according to the following linear formula: R , the expression is: ; in, x is the axial position of the middle section of the pressure regulating valve relative to the inlet, L is the axial length of the straight section of the center body of the pressure regulating valve; design R 2 and L The equivalent diffusion half angle of the flow channel is ensured to be less than 25° by artificial setting, and the design L Cover the jet area.

[0011] Further, the specific implementation method of step S4 is to set two annular cross-section orifice plates with uniform flow fields at the outlet of the downstream flow channel of the pressure regulating valve, the opening rate of the annular cross-section orifice plate of the first uniform flow field is 20%~30%, the opening rate of the annular cross-section orifice plate of the second uniform flow field is 30%~40%, and the wall plate thickness is 2~3 times the aperture diameter; A spherical orifice plate or sintered wire mesh is arranged downstream of the center body of the pressure regulating valve. The opening rate of the spherical orifice plate or sintered wire mesh is 40%-50%, and the thickness of the spherical orifice plate or sintered wire mesh is 1-3 times the aperture diameter.

[0012] Beneficial effects of the present invention: The pneumatic design method of a high-precision and low-noise pressure regulating valve for a temporary wind tunnel described in the present invention has the following advantages: 1) The pressure regulating valve designed by this method can obtain linear or nearly linear regulation characteristics; 2) The airflow has good symmetry, the airflow near the pressure regulating valve surface is not easy to separate, and the jet noise level is low; 3) Wide flow adjustment range, low gas source working pressure requirement, and high wind tunnel total pressure control accuracy; 4) The running time is long and the resistance during the movement of the sleeve is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a flow chart of the pneumatic design method for a high-precision, low-noise pressure regulating valve for a temporary wind tunnel described in the present invention. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the specific embodiments described are only part of the embodiments of the present invention, rather than all of the specific embodiments. The components of the specific embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0015] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected specific embodiments of the present invention. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0016] In order to further understand the content, features and effects of the present invention, the following specific implementation methods are given as examples, and the attached Figure 1 The detailed instructions are as follows:

[0017] Embodiment 1: A pneumatic design method for a high-precision, low-noise pressure regulating valve for a temporary wind tunnel comprises the following steps: S1. Design the profile of the pressure regulating valve based on the exponential characteristic curve and the linear characteristic curve of the pressure regulating valve; Furthermore, the specific implementation method of step S1 includes the following steps: S1.1. Design the exponential characteristic curve of the pressure regulating valve, expressed as: ; in, is the relative opening of the pressure regulating valve, is the minimum opening of the pressure regulating valve, is the maximum opening of the pressure regulating valve, is the relative stroke of the valve core of the pressure regulating valve; S1.2. For the profile whose profile coordinates cannot be solved by the exponential characteristic curve of the pressure regulating valve, design the linear characteristic curve of the pressure regulating valve, and the expression is: ; in, is the constant term of a linear function, is the slope of a linear function; ; ; in, For the tangent point t The relative opening of the pressure regulating valve at For the tangent point t The relative travel of the pressure regulating valve core at For the tangent point t The maximum opening of the pressure regulating valve at For the tangent point t The minimum opening of the pressure regulating valve at the S1.3. Calculate the surface coordinates ( X , Y ), the expression is: ; Where D is the outer diameter of the valve core.

[0018] S2. Based on the pressure regulating valve exponential characteristic curve and the pressure regulating valve linear characteristic curve obtained in step S1, the pressure regulating valve profile curve is designed; Furthermore, the specific implementation method of step S2 includes the following steps: S2.1. Design the equation of the quintic curve, which is expressed as:

[0019] in, , , , , , They are the 0th coefficient to be determined, the 1st coefficient to be determined, the 2nd coefficient to be determined, the 3rd coefficient to be determined, the 4th coefficient to be determined, and the 5th coefficient to be determined; S2.2. Choose between exponential characteristic curve and linear characteristic curve , , The relative opening and the derivative of the relative opening and the relative stroke are used as known parameters to solve the coefficients in the quintic curve equation.

[0020] S3. Design the downstream flow channel expansion downstream of the pressure regulating valve profile; Furthermore, the specific implementation method of step S3 is to design the cross section of the downstream flow channel of the pressure regulating valve to be a circular cross section, based on the equivalent radius of the inlet cross section of the downstream flow channel of the pressure regulating valve R 1. Equivalent radius of the outlet section of the downstream flow channel of the pressure regulating valve R 2. Calculate the equivalent radius of the middle section of the pressure regulating valve according to the following linear formula: R , the expression is: ; in, x is the axial position of the middle section of the pressure regulating valve relative to the inlet, L is the axial length of the straight section of the center body of the pressure regulating valve; design R 2 and L The equivalent diffusion half angle of the flow channel is ensured to be less than 25° by artificial setting, and the design L Covering the jet area; S4. Two annular cross-section orifice plates with uniform flow fields are provided at the outlet of the pressure regulating valve flow channel, and a spherical orifice plate or sintered wire mesh is provided downstream of the center body of the pressure regulating valve; Further, the specific implementation method of step S4 is to set two annular cross-section orifice plates with uniform flow fields at the outlet of the downstream flow channel of the pressure regulating valve, the opening rate of the annular cross-section orifice plate of the first uniform flow field is 20%~30%, the opening rate of the annular cross-section orifice plate of the second uniform flow field is 30%~40%, and the wall plate thickness is 2~3 times the aperture diameter; A spherical orifice plate or sintered wire mesh is arranged downstream of the central body of the pressure regulating valve, wherein the opening rate of the spherical orifice plate or sintered wire mesh is 40% to 50%, and the thickness of the spherical orifice plate or sintered wire mesh is 1 to 3 times the diameter of the aperture; S5. Based on the design of the pressure regulating valve in steps S1 to S4, the wind tunnel air source pressure and the aerodynamic characteristics of the pressure regulating valve are calculated.

[0021] Furthermore, the specific implementation method of step S5 includes the following steps: S5.1. The derivative of the gas source pressure with respect to time and the gas source operating time are calculated as follows: Air source pressure The derivative with respect to time t Calculate as follows: ; in, C 0 is the flow ratio between the bypass valve and the main valve in the double valve structure. P 3 is the total pressure of the test section, n is the polytropic specific heat ratio, A ts is the cross-sectional area of ​​the test section,V is the gas source volume, c is the specific heat ratio, R is the gas constant 287, T 0i is the initial total temperature of the gas source, , n is the polytropic specific heat ratio, m is a function of n, P 0i is the maximum initial pressure of the gas source; The gas source working time is calculated as follows: ; S5.2. Calculation of aerodynamic characteristics of pressure regulating valve; Calculation of the derivative of the valve pressure recovery coefficient with respect to the relative stroke by numerical iteration method .

[0022] The derivative of the pressure before the valve with respect to time is calculated as follows: ; Among them, P1 is the gas source pressure; The speed characteristic of the pressure regulating valve is calculated as follows: ; ; Among them, v is the pressure recovery coefficient of the pressure regulating valve, ; The acceleration characteristics of the pressure regulating valve are calculated as follows: ; The control accuracy of the downstream pressure of the pressure regulating valve relative to the relative stroke Calculate as follows: ; in, P 2 is the pressure after the valve, l th is the air velocity coefficient at the valve throttling channel, l 2 is the pipeline velocity after the valve; The control accuracy of the downstream pressure of the pressure regulating valve relative to time Calculate as follows: ; Furthermore, for the improved pressure regulating valve, since the flow space behind the valve annular gap is compressed, the development of the jet is restricted and the influence range of the jet is weakened, thereby achieving the effect of reducing valve noise.

[0023] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0024] Although the present application has been described above with reference to specific embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various features in the specific embodiments disclosed in the present application may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A pneumatic design method for a high-precision, low-noise pressure regulating valve for a temporary wind tunnel, characterized in that: The steps include: S1. Design the profile of the pressure regulating valve based on the exponential characteristic curve and the linear characteristic curve of the pressure regulating valve; S2. Based on the pressure regulating valve exponential characteristic curve and the pressure regulating valve linear characteristic curve obtained in step S1, the pressure regulating valve profile curve is designed; S3. Design the downstream flow channel expansion downstream of the pressure regulating valve profile; S4. Two annular cross-section orifice plates with uniform flow fields are provided at the outlet of the pressure regulating valve flow channel, and a spherical orifice plate or sintered wire mesh is provided downstream of the center body of the pressure regulating valve; S5. Based on the design of the pressure regulating valve in steps S1 to S4, the wind tunnel air source pressure and the aerodynamic characteristics of the pressure regulating valve are calculated.

2. The pneumatic design method for a high-precision, low-noise pressure regulating valve for a temporary wind tunnel according to claim 1 is characterized in that: The specific implementation method of step S1 includes the following steps: S1.

1. Design the exponential characteristic curve of the pressure regulating valve, expressed as: ； in, is the relative opening of the pressure regulating valve, is the minimum opening of the pressure regulating valve, is the maximum opening of the pressure regulating valve, is the relative stroke of the valve core of the pressure regulating valve; S1.

2. For the profile whose profile coordinates cannot be solved by the exponential characteristic curve of the pressure regulating valve, design the linear characteristic curve of the pressure regulating valve, and the expression is: ； in, is the constant term of a linear function, is the slope of a linear function; ； ； in, For the tangent point t The relative opening of the pressure regulating valve at For the tangent point t The relative travel of the pressure regulating valve core at For the tangent point t The maximum opening of the pressure regulating valve at For the tangent point t The minimum opening of the pressure regulating valve at the S1.

3. Calculate the surface coordinates ( X , Y ), the expression is: ； Where D is the outer diameter of the valve core.

3. The pneumatic design method for a high-precision, low-noise pressure regulating valve for a temporary wind tunnel according to claim 2 is characterized in that: The specific implementation method of step S2 includes the following steps: S2.

1. Design the equation of the quintic curve, which is expressed as: ； in, , , , , , They are the 0th coefficient to be determined, the 1st coefficient to be determined, the 2nd coefficient to be determined, the 3rd coefficient to be determined, the 4th coefficient to be determined, and the 5th coefficient to be determined; S2.

2. Choose between exponential characteristic curve and linear characteristic curve , , The relative opening and the derivative of the relative opening and the relative stroke are used as known parameters to solve the coefficients in the quintic curve equation.

4. The pneumatic design method for a high-precision, low-noise pressure regulating valve for a temporary wind tunnel according to claim 3 is characterized in that: The specific implementation method of step S3 is to design the cross section of the downstream flow channel of the pressure regulating valve to be a circular cross section, based on the equivalent radius of the inlet cross section of the downstream flow channel of the pressure regulating valve R 1. Equivalent radius of the outlet section of the downstream flow channel of the pressure regulating valve R 2. Calculate the equivalent radius of the middle section of the pressure regulating valve according to the following linear formula: R , the expression is: ； in, x is the axial position of the middle section of the pressure regulating valve relative to the inlet, L is the axial length of the straight section of the center body of the pressure regulating valve; design R 2 and L The equivalent diffusion half angle of the flow channel is ensured to be less than 25° by artificial setting, and the design L Cover the jet area.

5. The pneumatic design method for a high-precision, low-noise pressure regulating valve for a temporary wind tunnel according to claim 4 is characterized in that: The specific implementation method of step S4 is to set two annular cross-section orifice plates with uniform flow fields at the outlet of the downstream flow channel of the pressure regulating valve, the opening rate of the annular cross-section orifice plate of the first uniform flow field is 20%~30%, the opening rate of the annular cross-section orifice plate of the second uniform flow field is 30%~40%, and the wall plate thickness is 2~3 times the aperture diameter; A spherical orifice plate or sintered wire mesh is arranged downstream of the center body of the pressure regulating valve. The opening rate of the spherical orifice plate or sintered wire mesh is 40%-50%, and the thickness of the spherical orifice plate or sintered wire mesh is 1-3 times the aperture diameter.

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