A ventilation wind tunnel air flow temperature control device and design method

Abstract

The present invention discloses a ventilation wind tunnel airflow temperature control device and design method, which relates to the field of wind tunnel equipment design. The device comprises: a wind tunnel duct, wherein an air intake structure and an exhaust structure are respectively arranged on both sides of the wind tunnel duct; at least one pair of air intakes and exhaust ports are respectively arranged on the tunnel walls on both sides of the wind tunnel duct, wherein the air intake structure comprises an air intake valve with adjustable opening, which is correspondingly installed at the air intake port, and the exhaust structure comprises an exhaust valve with adjustable opening, which is correspondingly installed at the exhaust port. The present invention can provide a simple and low-cost airflow temperature control method for a reflow wind tunnel.

Description

Technical Field

[0001] The present invention relates to the field of wind tunnel equipment design, and in particular to a ventilation type wind tunnel airflow temperature control device and a design method. Background Art

[0002] When the recirculation wind tunnel is in operation, the airflow is always circulating in the tunnel. The energy required for the airflow to overcome the pipe resistance will be dissipated in the form of heat energy, causing the airflow temperature in the tunnel to rise rapidly, affecting the safety and reliability of the wind tunnel equipment operation and the accuracy of the test data collection. It is necessary to design an airflow temperature control system to keep the airflow temperature and the temperature rise rate within an acceptable range. The traditional method of wind tunnel airflow temperature control is to configure a cooling system with equivalent power according to the wind tunnel airflow driving power, and arrange a heat exchanger in the tunnel, pass a low-temperature medium inside, cool the airflow in the tunnel, and achieve a dynamic balance of driving energy dissipation-airflow heating-airflow cooling. In order to improve the heat exchange capacity and efficiency and achieve effective control of the airflow temperature, the contact area between the heat exchanger and the airflow should be large enough, and it is generally arranged at the largest cross-sectional area of ​​the wind tunnel, and even local area diffusion is required. Therefore, the traditional wind tunnel airflow temperature control method has problems such as complex system, high construction cost, and high operating energy consumption. In the design and construction process of some wind tunnels, due to the limitations of construction investment cost, power input, operation and maintenance capabilities, the design of the airflow temperature control system is directly cancelled, which seriously affects the equipment performance and continuous operation capability. Summary of the invention

[0003] The object of the present invention is to provide a simple and low-cost air flow temperature control method for a recirculation wind tunnel.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides a ventilation wind tunnel airflow temperature control device, the device comprising:

[0005] A wind tunnel duct, wherein an air intake structure and an exhaust structure are respectively arranged on both sides of the wind tunnel duct; at least one pair of air intake ports and exhaust ports are respectively arranged on the tunnel walls on both sides of the wind tunnel duct, wherein the air intake structure comprises an air intake valve with adjustable opening, and the air intake valve is correspondingly installed at the air intake port, and the exhaust structure comprises an exhaust valve with adjustable opening, and the exhaust valve is correspondingly installed at the exhaust port.

[0006] Among them, the principle of the present invention is: by opening an air inlet and an exhaust port in a recirculation wind tunnel, using the pressure difference between the inside and outside of the tunnel, part of the high-temperature airflow in the wind tunnel is forced to exchange with the low-temperature airflow in the environment, and the heat energy dissipation of the wind tunnel is quickly transferred to the surrounding environment, and the continuous rise of the airflow temperature in the tunnel body is suppressed, so as to achieve effective control of the airflow temperature of the wind tunnel. The present invention can effectively control the airflow temperature of the wind tunnel, and thus can ensure the performance and continuous operation capability of the wind tunnel equipment. Moreover, the device in the present invention only needs to open an air inlet and an exhaust port on the wind tunnel pipeline and match a simple air inlet structure and an exhaust structure. It is not necessary to configure a cooling system that needs to be driven and has equivalent power for the wind tunnel, nor is it necessary to arrange a heat exchanger that passes a low-temperature medium in the tunnel body. Therefore, the present device has the effect of complex structure, low cost for wind tunnel construction, and no additional energy consumption for operation, and achieves the effect of low cost and simple airflow temperature control for the recirculation wind tunnel.

[0007] For the reflow wind tunnel airflow temperature control, the present invention reduces the complexity and construction cost of the wind tunnel airflow temperature control system and equipment, enriches the wind tunnel airflow temperature control design method, and meets different design requirements.

[0008] In some embodiments, the air intake valve is connected to the wall of the wind tunnel duct via an air intake valve hinge, and the exhaust valve is connected to the wall of the wind tunnel duct via an exhaust valve hinge.

[0009] Among them, in some embodiments, the intake structure includes: an intake valve opening adjustment rod with adjustable length, and the two ends of the intake valve opening adjustment rod are respectively fixedly connected to the intake valve and the wall of the wind tunnel duct on the side of the intake valve; the exhaust structure includes: an exhaust valve opening adjustment rod with adjustable length, and the two ends of the exhaust valve opening adjustment rod are respectively fixedly connected to the exhaust valve and the wall of the wind tunnel duct on the side of the exhaust valve.

[0010] The intake valve opening adjustment rod and the exhaust valve opening adjustment rod are designed to be length-adjustable, so that the intake valve and exhaust valve openings can be adjusted by adjusting the length of the adjustment rod.

[0011] In some embodiments, each pair of the intake valve and the exhaust valve is symmetrically distributed on both sides of the wind tunnel duct. Such a design can avoid excessive flow in a local section of the wind tunnel circuit under the condition of high ventilation rate, and reduce the pressure and energy loss caused by ventilation.

[0012] Among them, in some embodiments, the intake valve hinge is located upstream of the intake valve along the airflow direction, and the exhaust valve hinge is located downstream of the exhaust valve along the airflow direction. The intake valve and exhaust valve hinges are respectively opened at the upstream front end and the downstream end. During ventilation, the intake valve opens toward the inside of the hole and the exhaust valve opens toward the outside of the hole. The flow area in the hole remains basically unchanged along the flow direction, so that the velocity change in the hole is small during ventilation and the downstream flow is more uniform.

[0013] Among them, in some embodiments, the air intake structure also includes an air intake duct, which is located outside the wind tunnel duct and is docked with the air inlet; the exhaust structure also includes an exhaust duct, which is located outside the wind tunnel duct and is docked with the exhaust port.

[0014] Among them, in some embodiments, the cross-sectional shape of the wind tunnel duct perpendicular to the airflow direction is rectangular, the cross-sectional shapes of the openings of the air inlet and the exhaust port are both rectangular, and the width dimensions of the air inlet and the exhaust port perpendicular to the airflow direction are the same as the width dimensions of the opening wall of the wind tunnel duct. This is to improve the uniformity of the flow field downstream of the wind tunnel duct under ventilation conditions. By ensuring that the width of the ventilation door is consistent (or close) to the width of the tunnel duct, the three-dimensional shear flow caused by the inconsistency between the air flow velocity in the tunnel and the ventilation air flow velocity at the corner between the ventilation door and the side wall of the tunnel duct perpendicular to the ventilation door is avoided (or suppressed), thereby improving the uniformity of the flow downstream of the ventilation device.

[0015] In some embodiments, the air intake structure includes a first rectifying plate, which is mounted on the air intake valve at the downstream end in the airflow direction, and is parallel to the airflow direction to suppress flow separation downstream of the air intake valve in the wind tunnel duct and improve flow stability and uniformity. The first rectifying plate is parallel to the airflow direction, which avoids flow separation in a large area on the leeward side of the air intake valve at a large angle of attack when the airflow flows around the air intake valve when there is no first rectifying plate, thereby avoiding flow-induced vibration and uneven flow.

[0016] The exhaust structure includes a second rectifying plate, which is mounted on the exhaust valve at the front end upstream in the airflow direction, and is parallel to the airflow direction to suppress flow separation downstream of the exhaust valve in the wind tunnel duct, thereby improving flow stability and uniformity. The second rectifying plate is parallel to the airflow direction, thereby avoiding flow-induced vibration and uneven flow caused by large-area flow separation on the leeward side of the intake valve when the airflow flows around the intake valve at a large angle of attack when the second rectifying plate is not present.

[0017] Among them, in some embodiments, the intake valve opening adjustment rod and the exhaust valve opening adjustment rod both include: a first ear seat, a second ear seat, a first screw rod, a second screw rod and a sleeve; the first ear seat in the intake valve opening adjustment rod is fixedly connected to the intake valve, the first ear seat in the exhaust valve opening adjustment rod is fixedly connected to the exhaust valve, and the second ear seat is fixedly connected to the wall of the wind tunnel duct; the first ear seat and one end of the first screw rod and the second ear seat and one end of the second screw rod are both connected by a latch; the other end of the first screw rod and the other end of the second screw rod are respectively provided with external threads of the same size and opposite directions, and the other end of the first screw rod and the other end of the second screw rod are respectively connected with the internal threads at both ends of the sleeve. The axial length of the intake valve opening adjustment rod (or the exhaust valve opening adjustment rod) is adjusted by rotating the sleeve forward and backward.

[0018] The present invention also provides a method for designing a ventilation wind tunnel airflow temperature control device, the method comprising:

[0019] Step 1: Calculate the temperature difference between the airflow inside and outside the wind tunnel ΔT Minimum value of ΔT min , calculated as:

[0020] ΔT min = T max －T a_max ;

[0021] in, T max is the maximum permissible value of the wind tunnel airflow temperature, T a_max is the maximum temperature of the ambient airflow around the wind tunnel;

[0022] Step 2: Calculate the wind tunnel ventilation rate or The maximum value of or max , calculated as:

[0023] or max = U max 2 / (2 E·Cp·ΔT min );

[0024] in, or is the wind tunnel ventilation rate, U max Airflow speed for wind tunnel runs U The maximum value of E is the wind tunnel energy ratio, Cpis the specific heat capacity of air;

[0025] Step 3: Determine the design positions of the air inlet and exhaust port according to the overall layout of the wind tunnel;

[0026] Step 4: Based on the maximum value or max As well as the design position of the air inlet and exhaust port, determine the size and shape of the air inlet and exhaust port.

[0027] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:

[0028] 1. Compared with the traditional temperature control method, the temperature control method corresponding to the device of the present invention does not need to arrange a heat exchanger in the cave loop, but only needs to design a ventilation port at a suitable position of the cave loop. The structure is simple, the layout of the wind tunnel loop is easy, and the system reliability is high.

[0029] 2. Compared with the traditional temperature control method, the temperature control method corresponding to the device of the present invention does not require the configuration of a high-power cooling system, which effectively saves the investment in wind tunnel construction and operating energy consumption, and reduces the difficulty of equipment maintenance.

[0030] 3. The temperature control method corresponding to the device of the present invention is that in a typical 4-meter-level low-speed wind tunnel at 60m / s, the wind tunnel airflow circulates once in the tunnel body in about 3 to 5 seconds, and the ventilation rate in each cycle is η*100%. If η=0.15, then after 30 to 50 seconds (10 cycles), the high-temperature airflow in the tunnel of 1-(1-η)^2=80% will be exchanged with the low-temperature airflow in the environment, achieving rapid ventilation and cooling (recovering to ambient temperature). This means that the exchange of the airflow in the tunnel body with the ambient airflow can be quickly achieved, and when the temperature in the tunnel body is high, the temperature of the airflow can be quickly reduced.

[0031] 4. The ventilation wind tunnel airflow temperature control device of the present invention can adjust the ventilation rate by adjusting the opening of the ventilation door (including the intake door and the exhaust door). The opening of the ventilation door can be achieved by adjusting the total length of the tie rod and sleeve of the fixing device. The adjustment method is simple and reliable, and the device is easy to maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation on the embodiments of the present invention;

[0033] Figure 1 It is an isometric schematic diagram of the structure of the device of the present invention;

[0034] Figure 2 It is an isometric cross-sectional schematic diagram of the structure of the device of the present invention;

[0035] Figure 3Schematic diagram of opening the ventilation port of the wind tunnel duct;

[0036] Figure 4 Schematic diagram of the opening adjustment rod structure;

[0037] Figure 5 It is a schematic diagram of the air intake duct structure;

[0038] Figure 6 It is a schematic diagram of the exhaust diffusion pipe structure;

[0039] Among them, 1 is a wind tunnel duct, 2 is an air inlet, 3 is an exhaust port, 4 is an air inlet valve, 5 is an air inlet valve hinge, 6 is an air inlet valve opening adjustment rod, 7 is an exhaust valve, 8 is an exhaust valve hinge, 9 is an exhaust valve opening adjustment rod, 10 is an air inlet duct, 11 is an exhaust duct, 401 is a first rectifying plate, 701 is a second rectifying plate, 061 is a first ear seat, 062 is a second ear seat, 063 is a first screw rod, 064 is a second screw rod, 065 is a sleeve, 101 is a lower wall of the air inlet duct, 102 is an upper wall of the air inlet duct, 103 is a left wall of the air inlet duct, 104 is a right wall of the air inlet duct, 112 is an outer wall of the exhaust duct, 113 is a left wall of the exhaust duct, and 114 is a right wall of the exhaust duct. DETAILED DESCRIPTION

[0040] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those within the scope of this description. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0042] Embodiment 1;

[0043] Please refer to Figure 1-Figure 6 The present invention provides a ventilation wind tunnel airflow temperature control device, the device comprising:

[0044] The invention comprises a wind tunnel duct 1, an air inlet 2, an exhaust port 3, an air inlet valve 4, an air inlet valve hinge 5, an air inlet valve opening adjustment rod 6, an exhaust valve 7, an exhaust valve hinge 8, an exhaust valve opening adjustment rod 9, an air inlet duct 10 and an exhaust duct 11; the air inlet and the exhaust port are located on the side wall of the wind tunnel duct, are symmetrically distributed, and are formed by openings on the side wall of the wind tunnel duct; the air inlet valve is installed on the air inlet, and is connected to the wind tunnel duct through the air inlet valve hinge; it is located upstream of the air inlet valve along the air flow direction; the two ends of the air inlet valve opening adjustment rod are respectively connected to the air inlet valve and the air inlet valve. The exhaust valve is installed at the exhaust port and connected to the wind tunnel duct through the intake valve hinge; it is located downstream of the exhaust valve along the air flow direction; the two ends of the exhaust valve opening adjustment rod are respectively fixed to the exhaust valve and the wind tunnel duct wall, and the exhaust valve opening angle can be adjusted by adjusting the axial length; the intake duct is installed at the air inlet, fixed to the wind tunnel duct, and located outside the wind tunnel duct; the exhaust duct is installed at the exhaust port, fixed to the wind tunnel duct, and located outside the wind tunnel duct.

[0045] Among them, after the ventilation port is opened in this device, a ventilation door for guiding flow is installed at the ventilation port. By setting the relative position of the exhaust door hinge and the direction of the door opening, the airflow in the hole is guided, and the airflow inertia is used to discharge the airflow in the hole to the outside of the hole. At the same time as the airflow in the hole is discharged, due to the reduction of the airflow quality in the hole, the pressure in the hole is lower than the ambient pressure. The existence of the pressure difference between them makes the ambient airflow enter the hole from the air inlet, realizing the dynamic balance of the airflow quality in the hole, that is, the intake flow is consistent with the exhaust flow.

[0046] In the embodiment of the present invention, the cross-sectional shape of the wind tunnel duct perpendicular to the airflow is rectangular, so as to facilitate the opening of the air inlet and the exhaust port, and the installation and adjustment of the air inlet valve and the exhaust valve.

[0047] Among them, in the embodiment of the present invention, the air inlet and the exhaust port have rectangular opening shapes, and the width direction dimension perpendicular to the airflow is the same as that of the wind tunnel duct, so as to improve the uniformity of the flow field downstream of the wind tunnel duct in the ventilation state.

[0048] Among them, the ventilation state is when the inlet and exhaust valves of the device are open. The valve opening is positively correlated with the ventilation rate, and the ventilation rate is positively correlated with the wind tunnel driving power-the heat dissipation power from the tunnel wall to the environment. Under the following conditions, the ventilation door opening can be reduced or closed: ① The test wind speed is low and the driving power is low; ② The test time is short. Due to the heat storage of the cave body and the air inside the cave, the air flow temperature rises but the amplitude is small and still within the allowable range; ③ The ambient temperature is low in winter, and the heat dissipation power from the tunnel wall to the environment is large.

[0049] In the embodiment of the present invention, the air inlet and the air outlet can be opened one each and located on opposite walls of the wind tunnel duct; or two each can be opened and located on the four walls of the wind tunnel duct.

[0050] In the embodiment of the present invention, the inlet valve and the exhaust valve are rectangular flat plates, and their sizes match the inlet and exhaust ports, respectively. The matching sizes enable the cavity pipe to be completely sealed when the ventilation valve is closed. The inlet valve and the exhaust valve need to be opened at the same time. Since the flow rate in the cavity remains unchanged, the inlet and exhaust flow rates should be suppressed, and the flow areas of the inlet valve and the exhaust valve are basically the same, and the corresponding air flow velocities are basically the same.

[0051] In the embodiment of the present invention, the air intake valve is provided with a first rectifying plate 401 at the downstream end of the air flow, and the first rectifying plate is parallel to the air flow direction to suppress the flow separation downstream of the air intake valve in the wind tunnel duct and improve the stability and uniformity of the flow.

[0052] Among them, in the embodiment of the present invention, a second rectifying plate 701 is provided at the front end of the exhaust valve located upstream of the airflow, and the second rectifying plate is parallel to the airflow direction to suppress the flow separation downstream of the exhaust valve in the wind tunnel duct and improve the stability and uniformity of the flow.

[0053] Among them, in the embodiment of the present invention, the intake valve opening adjustment rod and the exhaust valve opening adjustment rod both include: a first ear seat 061, a second ear seat 062, a first screw rod 063, a second screw rod 064 and a sleeve 065. The first ear seat is fixedly connected to the intake valve (or exhaust valve), and the second ear seat is fixedly connected to the wall of the wind tunnel duct; the first ear seat and the first screw rod, and the second ear seat and the second screw rod are respectively connected by a bolt; the other ends of the first screw rod and the second screw rod are provided with external threads with the same size and opposite directions, which are respectively matched and connected with the internal threads at both ends of the sleeve; the axial length of the intake valve opening adjustment rod (or the exhaust valve opening adjustment rod) is adjusted by rotating the sleeve forward and backward.

[0054] Among them, in the embodiment of the present invention, the air intake duct is connected by the lower wall 101 of the air intake duct, the upper wall 102 of the air intake duct, the left wall 103 of the air intake duct and the right wall 104 of the air intake duct. The lower wall of the air intake duct is composed of a circular arc plate and a flat plate, wherein the circular arc plate is tangent to the flat plate and the wall of the wind tunnel duct to improve the uniformity of the airflow entering the wind tunnel duct; the upper wall of the air intake duct, the left wall of the air intake duct, and the right wall of the air intake duct are all rectangular flat plates; the left wall of the air intake duct and the right wall of the air intake duct are perpendicular to the wall of the wind tunnel duct; the circular arc plate forms a trumpet-shaped air inlet, the purpose of which is to guide the ambient static airflow to uniformly accelerate and change direction during the process of entering the wind tunnel. One end of the circular arc plate is connected to the wall of the wind tunnel, and the other end is suspended or a flat plate is added.

[0055] Among them, in the embodiment of the present invention, the exhaust duct is composed of the exhaust duct inner wall, the exhaust duct outer wall 112, the exhaust duct left wall 113 and the exhaust duct right wall 114. The exhaust duct inner wall is consistent with the wind tunnel duct wall. The exhaust duct outer wall and the exhaust duct inner wall are at a certain expansion angle to achieve the exhaust duct diffusion along the flow direction and the flow rate reduction. In order to avoid flow separation, the expansion angle between the exhaust duct outer wall and the exhaust duct inner wall should not be greater than 5° to 8°, and a flow separation net is arranged in the middle or near the outlet.

[0056] Among them, in the embodiment of the present invention, an air intake protection net is set at the upstream inlet of the air intake duct to prevent various debris from entering the wind tunnel duct; an exhaust protection net is set at the downstream outlet of the exhaust duct to prevent various debris from entering the wind tunnel duct and suppress the possibility of separation and backflow of airflow in the exhaust duct. The air intake protection net and the exhaust protection net are metal screens.

[0057] Embodiment 2:

[0058] On the basis of the first embodiment, the second embodiment of the present invention further provides a design method for a ventilation wind tunnel airflow temperature control device, the method comprising:

[0059] Step 1: Determine the temperature difference between the airflow inside and outside the wind tunnel ΔT Minimum value of ΔT min Control requirements:

[0060] ΔT min = T max －T a_max ;

[0061] in, T max is the maximum permissible value of the wind tunnel airflow temperature, T a_max It is the maximum temperature of the ambient air flow around the wind tunnel.

[0062] Step 2: Determine the wind tunnel ventilation rate or The maximum value of or max Design requirements:

[0063] or max = U max 2 / (2 E·Cp·ΔT min );

[0064] in, orThe wind tunnel ventilation rate is defined as the air exchange mass between the inside and outside of the tunnel per unit time. m e (or volume) and the mass of the flow through the wind tunnel test section m (or volume) ratio.

[0065] in, U max Airflow speed for wind tunnel runs U The maximum value of E is the wind tunnel energy ratio, Cp is the specific heat capacity of air.

[0066] Step 3: Determine the design location of the ventilation port based on the overall layout of the wind tunnel.

[0067] The ventilation opening includes an air inlet through which air flows from the environment into the wind tunnel, and an air outlet through which air flows from the wind tunnel into the environment.

[0068] Preferably, the exhaust port should be located at the same position as or upstream of the air inlet to prevent the ambient cold air entering through the air inlet from being discharged from the exhaust port without being completely mixed with the airflow in the wind tunnel.

[0069] Preferably, the air inlet and the air outlet should be designed near the same position of the wind tunnel circuit to reduce the airflow driving energy loss caused by ventilation.

[0070] Preferably, the ventilation opening should be designed in a section with a lower air flow velocity in the wind tunnel to reduce the air flow driving energy loss caused by ventilation.

[0071] Preferably, the ventilation port should be designed in a section of the wind tunnel where the total airflow pressure is lower, so as to reduce the difference between the static pressure of the wind tunnel test section and the ambient pressure and lower the pressure-bearing and sealing requirements of the wind tunnel test section.

[0072] Preferably, the ventilation openings should be designed in straight sections, diffuser sections and other sections without wind tunnel internal components to avoid interference between the ventilation device structure and the wind tunnel internal components, while reducing the impact of the ventilation openings on the aerodynamic performance of the wind tunnel internal components.

[0073] Step 4: Determine the size and shape of the ventilation port based on the maximum ventilation rate requirement and the location of the ventilation port.

[0074] Preferably, the aerodynamic profile of the air inlet (or exhaust port) should be symmetrical to avoid causing asymmetry in the downstream flow in the wind tunnel and reduce the impact of the air inlet (or exhaust port) flow on the uniformity and stability of the wind tunnel flow field.

[0075] Preferably, an exhaust diffusion section is arranged at the exhaust port to reduce the speed of the airflow discharged into the surrounding environment, so as to reduce the airflow driving energy loss caused by ventilation, and at the same time improve the uniformity of the flow speed downstream of the air inlet.

[0076] Preferably, when the wind tunnel is operating normally, the angle between the intake valve, the exhaust valve and the axis of the wind tunnel duct should not exceed 15° to prevent large-area flow diversion downstream of the intake valve and the exhaust valve.

[0077] Preferably, the expansion half angle of the exhaust diffusion section should be no greater than 3° to 5° to avoid airflow separation and reduce airflow drive energy loss caused by ventilation.

[0078] Preferably, the cross-sectional area of ​​the air flow of the ventilation port is adjustable to achieve control of the ventilation rate within a range from zero to a maximum ventilation rate to meet different operating requirements of the wind tunnel.

[0079] Preferably, the cross-sectional area of ​​the air flow at the air inlet should be equivalent to the cross-sectional area of ​​the air flow at the air outlet, so as to reduce the influence of the ventilation port configuration on the uniformity and stability of the air flow in the wind tunnel.

[0080] Among them, the present invention opens an air inlet and an exhaust port in a recirculation wind tunnel, utilizes the pressure difference between inside and outside the tunnel, forces part of the high-temperature airflow in the wind tunnel to exchange with the low-temperature airflow in the environment, quickly transfers the heat energy dissipated in the wind tunnel to the surrounding environment, suppresses the continuous increase of the airflow temperature in the tunnel, and realizes effective control of the airflow temperature in the wind tunnel.

[0081] Wind tunnels can be divided into recirculation type and direct flow type according to the circulation of airflow in the tunnel. Among them, the recirculation type can be regarded as two extreme cases with a ventilation rate of 0% and the direct flow type can be regarded as two extreme cases with a ventilation rate of 100%. Because the direct flow type has a ventilation rate of 100%, the airflow temperature is completely consistent with the environment. Compared with the direct flow type, the main advantage of the recirculation type layout is that the operation is not affected by the environment (or the impact is very small), but because the airflow is always circulating in the tunnel, the temperature will continue to rise and require additional cooling treatment. There are a few studies abroad on the cooling of recirculation wind tunnels by ventilation, but no application has been made public in China. There are two studies abroad: one is the transformation of NASAAms full-scale wind tunnel. Due to the huge size of the wind tunnel (24mx36m), no heat exchange design was made during the initial construction. During the transformation, a scaled wind tunnel was established to carry out ventilation and cooling design research and experiments. The exhaust port is located downstream of the fan and the air inlet is located upstream of the fan. Finally, due to the pressure resistance performance of the test section structure, the ventilation rate is very low, only about 5%, and it has not been used in large wind tunnels. The second is the 5.5m x 7.5m subsonic wind tunnel design of Russia's TsAGI. Due to the large power and size of the heat exchanger and the high cost, a ventilation design was considered. The air intake was also upstream of the fan and the exhaust was downstream. The simulation calculated the ventilation rate to be about 20%, but no comprehensive evaluation was conducted and no final application was reported. There are two main problems: 1. The fan section flow = test section flow * (1 + ventilation rate), which greatly increases the power consumption of the wind tunnel operation and then converts it into heat energy. 2. The mainstream velocity in the tunnel at the air inlet is high, and the intake air flow velocity is low. The uniformity after confluence is poor, which is very easy to produce flow separation. In addition, there are many diffusion sections downstream to amplify the flow separation effect, which has a great impact on the flow stability of the wind tunnel.

[0082] At present, in recirculation wind tunnels, the ventilation type temperature control design is rarely used, which has the following problems and difficulties: (1) The intake valve and the exhaust valve are located at different positions, the structure is complex, and the operation and maintenance are difficult. (2) There are few studies on the flow and thermal energy mechanism related to ventilation temperature control, there is no specific theoretical guidance, and the position of the ventilation door is unreasonable. (3) The aerodynamic shape design of the ventilation door is unreasonable, which has a great impact on the stability and uniformity of the downstream flow in the wind tunnel, affecting the performance of the wind tunnel. (4) Compared with general ventilation devices, wind tunnels have greater power consumption (due to large size and high air flow velocity) and higher flow stability requirements (in order to achieve accurate simulation of the real flight environment of the model). Therefore, the influence of the ventilation door on the wind tunnel energy consumption, flow stability, etc. needs to be considered as the key points and difficulties (which are often not considered in general ventilation devices). The device and design method of the present invention can effectively solve this problem. (5) The device described in the present invention has a simple structure, but its layout and aerodynamic design method are highly innovative, especially solving key problems such as the opening position of the ventilation door and the aerodynamic shape of the ventilation door.

[0083] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0084] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A ventilation wind tunnel airflow temperature control device, It is characterized in that The device comprises: A wind tunnel duct, wherein an air intake structure and an exhaust structure are respectively provided on both sides of the wind tunnel duct; at least one pair of air intake ports and exhaust ports are respectively provided on the tunnel walls on both sides of the wind tunnel duct, the air intake structure comprises an air intake valve with adjustable opening, and the air intake valve is correspondingly installed at the air intake port, and the exhaust structure comprises an exhaust valve with adjustable opening, and the exhaust valve is correspondingly installed at the exhaust port; the air intake valve is connected to the tunnel wall of the wind tunnel duct through an air intake valve hinge, and the exhaust valve is connected to the tunnel wall of the wind tunnel duct through an exhaust valve hinge; the air intake structure comprises: an air intake valve opening adjustment rod with adjustable length, and the two ends of the air intake valve opening adjustment rod are respectively fixedly connected to the air intake valve and the tunnel wall of the wind tunnel duct on the side of the air intake valve; the exhaust structure comprises: an exhaust valve opening adjustment rod with adjustable length, and the two ends of the exhaust valve opening adjustment rod are respectively fixedly connected to the exhaust valve and the tunnel wall of the wind tunnel duct on the side of the exhaust valve; each pair of the air intake valve and the exhaust valve are symmetrically distributed on both sides of the wind tunnel duct; the air intake valve hinge is located upstream of the air intake valve along the air flow direction, and the exhaust valve hinge is located downstream of the exhaust valve along the air flow direction.

2. A ventilation wind tunnel airflow temperature control device according to claim 1, It is characterized in that The air intake structure also includes an air intake duct, which is located outside the wind tunnel duct and is docked with the air intake port; the exhaust structure also includes an exhaust duct, which is located outside the wind tunnel duct and is docked with the exhaust port.

3. The ventilation wind tunnel airflow temperature control device according to claim 1, It is characterized in that The cross-sectional shape of the wind tunnel duct perpendicular to the airflow direction is a rectangle, the cross-sectional shapes of the openings of the air inlet and the exhaust port are both rectangular, and the width dimensions of the air inlet and the exhaust port perpendicular to the airflow direction are the same as the width dimensions of the opening wall of the wind tunnel duct.

4. The ventilation wind tunnel airflow temperature control device according to claim 1, It is characterized in that The intake structure includes a first rectifying plate, which is installed on the intake valve at the downstream end in the airflow direction, and the first rectifying plate is parallel to the airflow direction; the exhaust structure includes a second rectifying plate, which is installed on the exhaust valve at the upstream front end in the airflow direction, and the second rectifying plate is parallel to the airflow direction.

5. The ventilation wind tunnel airflow temperature control device according to claim 1, It is characterized in that The intake valve opening adjustment rod and the exhaust valve opening adjustment rod both include: a first ear seat, a second ear seat, a first screw rod, a second screw rod and a sleeve; the first ear seat in the intake valve opening adjustment rod is fixedly connected to the intake valve, the first ear seat in the exhaust valve opening adjustment rod is fixedly connected to the exhaust valve, and the second ear seat is fixedly connected to the wall of the wind tunnel duct; the first ear seat and one end of the first screw rod and the second ear seat and one end of the second screw rod are both connected by means of a latch; the other end of the first screw rod and the other end of the second screw rod are respectively provided with external threads of the same size and opposite directions, and the other end of the first screw rod and the other end of the second screw rod are respectively connected with the internal threads at both ends of the sleeve.

6. A method for designing a ventilation wind tunnel airflow temperature control device according to any one of claims 1 to 5, It is characterized in that The method comprises: Step 1: Calculate the temperature difference between the airflow inside and outside the wind tunnel ΔT Minimum value of ΔT min , calculated as: ΔT min = T max －T a_max ； in, T max is the maximum permissible value of the wind tunnel airflow temperature, T a_max is the maximum temperature of the ambient airflow around the wind tunnel; Step 2: Calculate the wind tunnel ventilation rate η The maximum value of η max , calculated as: η max = U max 2 / (2 E·Cp·ΔT min )； in, η is the wind tunnel ventilation rate, U max Airflow speed for wind tunnel runs U The maximum value of E is the wind tunnel energy ratio, Cp is the specific heat capacity of air; Step 3: Determine the design positions of the air inlet and exhaust port according to the overall layout of the wind tunnel; Step 4: Based on the maximum value η max As well as the design positions of the air inlet and exhaust port, determine the size and shape of the air inlet and exhaust port; wherein, in the wind tunnel circuit, the exhaust port is located at the corresponding position of the air inlet or upstream; the exhaust port and the air inlet are both designed in the low-speed and low-total-pressure sections of the air flow in the wind tunnel; the exhaust port and the air inlet are both designed in the straight section and the diffuser section without wind tunnel internal components, and the aerodynamic profile of the air inlet or the exhaust port should be symmetrical; the exhaust port is arranged in the exhaust diffuser section, and when the wind tunnel is operating normally, the angle between the exhaust port and the air inlet and the axis of the wind tunnel duct does not exceed 15°, the exhaust diffuser section expansion half angle is not greater than 3°~5°, the air flow cross-sectional area of ​​the exhaust port and the air inlet is adjustable, and the air flow cross-sectional area of ​​the air inlet is the same as that of the exhaust port.

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