High-vacuum long-period large-flow wind tunnel vacuum exhaust system

Abstract

The utility model discloses a high-vacuum long-period large-flow wind tunnel vacuum exhaust system which comprises a first switching valve, a vacuum spherical tank, a centrifugal vacuum pump unit, a positive displacement vacuum pump unit, a first exhaust silencer and a pressure detection device connected to the vacuum spherical tank, wherein the first switching valve, the vacuum spherical tank, the centrifugal vacuum pump unit, the positive displacement vacuum pump unit and the first exhaust silencer are sequentially connected through a main pipeline. The air inlet branch is connected to an inlet of the centrifugal vacuum pump unit, the first adjusting valve is arranged on the air inlet branch, the adjusting bypass is connected between the inlet and an outlet of the centrifugal vacuum pump unit, the second adjusting valve is arranged on the adjusting bypass, and the exhaust branch is connected to an inlet of the positive displacement vacuum pump unit. The second switching valve and the second exhaust silencer are sequentially arranged on the exhaust branch. According to the utility model, high vacuum degree can be matched with wind tunnel starting, long-time continuous operation of the wind tunnel is maintained under coarse vacuum degree, the air flow pressure of the flow field of the wind tunnel test section is controlled to be stable, a large-flow exhaust test can be carried out according to the wind tunnel test requirement, and the wind tunnel test efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of wind tunnel experiment vacuum exhaust systems, and specifically, to a wind tunnel vacuum exhaust system with high vacuum, long cycle and large flow rate. Background Technique

[0002] A wind tunnel, namely a wind tunnel laboratory, is a tubular experimental device that artificially generates and controls airflows to simulate the airflow around an aircraft or an entity, and can measure the effect of the airflow on the entity and observe physical phenomena. It is one of the most commonly used and effective tools for aerodynamic experiments. A wind tunnel mainly consists of an air source system, a heater, a nozzle, a test section, a diffuser, a vacuum valve, a vacuum exhaust system, etc.

[0003] Wind tunnel experiments are an indispensable part of aircraft development work. It not only plays an important role in the research and development of aviation and aerospace engineering, but also is indispensable in the fields of transportation, building construction, wind energy utilization, etc. with the development of industrial aerodynamics. With the development of aircraft technology in aviation and aerospace, the requirements for wind tunnel tests are also constantly increasing. Wind tunnel tests are changing from small model and short-time simulation model tests to large model or even full-scale real aircraft and long-time simulation flight test tests, thus increasing the specifications and dimensions of test wind tunnels. Currently, there are large-scale wind tunnel experiments, and the vacuum exhaust flow rate can reach 800 kg / s; in addition to large-flow exhaust, wind tunnel tests also have requirements for vacuum degree and duration. Generally, wind tunnel experiments are divided into two stages: wind tunnel startup and wind tunnel operation. And wind tunnel startup is further divided into two steps: wind tunnel cold blowing and wind tunnel ignition. In the first step, wind tunnel cold blowing is to spray cold gas, fuel, etc. into the test chamber in advance, with a duration of about 10 s. In the second step, wind tunnel ignition is to ignite the pre-sprayed fuel with an ignition device, with a very short duration (1 s - 2 s). Whether it is wind tunnel cold blowing or ignition, a relatively high vacuum degree (1 - 3 kpa.A) is required; finally, the way to maintain such a combustion flame in the test chamber is wind tunnel operation. Wind tunnel operation pays more attention to a continuous and stable time period (10 s - 7200 s), and the vacuum degree requirement generally reaches 10 kpa.A. The vacuum exhaust system is a key part for wind tunnel experiments to meet the required vacuum degree and other requirements.

[0004] The following are several common existing vacuum exhaust systems:

[0005] 1. Ejector vacuum exhaust system

[0006] The ejector vacuum exhaust system refers to an air ejector exhaust method, and its principle is shown in Figure 1As shown, it is difficult to improve the single-stage pressure ratio by air injection. Therefore, it is necessary to build a huge medium-high pressure air storage tank to provide a large flow of injection working medium. So, this type of exhaust method has deficiencies such as low injection efficiency and high operating costs, and the operation cycle of the wind tunnel is limited by the scale and gas volume of the medium-high pressure air storage tank.

[0007] 2. Pre-vacuum system

[0008] A wind tunnel body vacuuming system is disclosed in Chinese Patent ZL 201510770981.2. The above vacuum system consists of a spherical tank and a pre-vacuum exhaust system formed by connecting multiple multi-stage Roots pumps with different powers in series. Figure 2 As shown, this system can maintain the entire wind tunnel test section at a high vacuum state before the wind tunnel starts, enabling the wind tunnel to start smoothly. However, the operation time of the wind tunnel is limited by the volume of the spherical tank (currently up to 20000 m 3 ), and the gas extraction volume of the Roots pump group is much smaller at high vacuum (1 kPa.A) than under normal pressure conditions. This system cannot ensure continuous long-cycle large-flow operation of the wind tunnel.

[0009] 3. Vacuum combined exhaust system

[0010] (1) The first type of vacuum combined exhaust system retains the ejector-type vacuum exhaust system and adds another exhaust pipe on its exhaust main pipeline. This exhaust pipe consists of a spherical tank, a switching valve, and a centrifugal pump with a large extraction volume and a rough vacuum degree (higher than 10 kPa.A). Figure 3 As shown.

[0011] (2) The second type of vacuum combined exhaust system retains the original pre-vacuum system and adds a new exhaust pipe at the rear end of the original spherical tank. This exhaust pipe consists of a switching valve and a centrifugal pump with a large extraction volume and a rough vacuum degree (10 kPa.A). Figure 4 As shown.

[0012] The principles of these two types of vacuum combined exhaust systems are the same: when the wind tunnel is started by the ejector-type vacuum exhaust system or the pre-vacuum system, by opening the switching valve, the large air flow generated by the wind tunnel system can be sucked and discharged by the centrifugal pump. The combined exhaust system using "ejector or pre-pumping system + air extraction pump" can achieve long-term continuous operation of the wind tunnel. Its deficiencies are as follows: First, it still needs to rely on a separate ejector or pre-pumping system to start the wind tunnel, and the vacuum extraction ability of the centrifugal pump (10 kPa.A) can only ensure the operation of the wind tunnel; Second, the vacuum combined exhaust system has a complex composition, many operation links, high cost, large floor area, and too low efficiency. Utility model content

[0013] In view of the technical problems existing in the vacuum combination exhaust system in the prior art, the utility model provides a wind tunnel vacuum exhaust system with high vacuum, long cycle and large flow rate, achieving the effects of high vacuum degree (1 - 3 kpa.A), large exhaust flow rate and long continuous operation time. Through this wind tunnel vacuum exhaust system, the wind tunnel can be directly started, and continuous long-cycle and large-flow operation of the wind tunnel can be ensured.

[0014] In order to achieve the above object, the technical solution adopted by the utility model is as follows:

[0015] A wind tunnel vacuum exhaust system with high vacuum, long cycle and large flow rate, comprising a first switching valve, a vacuum spherical tank, a centrifugal vacuum pump unit, a positive displacement vacuum pump unit and a first exhaust silencer connected in sequence through a main pipeline, a pressure detection device connected to the vacuum spherical tank, an intake branch connected to the inlet of the centrifugal vacuum pump unit and communicating with the atmosphere, a first regulating valve arranged on the intake branch, a regulating bypass connected between the inlet and the outlet of the centrifugal vacuum pump unit, a second regulating valve arranged on the regulating bypass, an exhaust branch connected to the inlet of the positive displacement vacuum pump unit, a second switching valve and a second exhaust silencer arranged in sequence on the exhaust branch, and a control unit for controlling the operation of the system. The control unit is electrically connected to the centrifugal vacuum pump unit, the positive displacement vacuum pump unit, the first switching valve, the second switching valve, the pressure detection device, the first regulating valve and the second regulating valve. The head end of the main pipeline is connected to the oncoming flow of the wind tunnel test chamber.

[0016] Specifically, the centrifugal vacuum pump unit is a series connection of multiple-stage centrifugal vacuum pump units, with one-stage, two-stage or more than two-stage centrifugal vacuum pump units in series.

[0017] Specifically, the centrifugal vacuum pump unit is a parallel connection of multiple centrifugal vacuum pump units.

[0018] Specifically, the centrifugal vacuum pump unit is speed-controlled by a variable-frequency motor of a frequency converter.

[0019] Specifically, the drivers of the first switching valve and the second switching valve are hydraulic, pneumatic or electric, and the switching speed is 0.5 s - 10 s.

[0020] Specifically, the drivers of the first regulating valve and the second regulating valve are hydraulic, pneumatic or electric.

[0021] Specifically, the compression ratio of the centrifugal vacuum pump unit is 1.2 - 12.

[0022] Specifically, the positive displacement vacuum pump unit is a water ring vacuum pump or a roots vacuum pump.

[0023] Specifically, the highest vacuum degree achieved by the wind tunnel vacuum exhaust system is 1 kpa.A - 3 kpa.A.

[0024] Specifically, the maximum exhaust flow rate achieved by the wind tunnel vacuum exhaust system is 800 kg / s.

[0025] Compared with the prior art, the present utility model has the following beneficial effects:

[0026] By ingeniously designing the system structure, the present utility model integrates the wind tunnel startup and the wind tunnel operation into one. It can achieve a high vacuum degree to cooperate with the wind tunnel startup, and maintain a rough vacuum state after the wind tunnel startup to ensure long-term continuous operation. It controls the air flow pressure in the test section of the wind tunnel to be stable, provides a reliable guarantee for the wind tunnel operation, and can conduct large-flow exhaust tests according to the requirements of wind tunnel tests, improving the efficiency of wind tunnel tests. Moreover, under the condition of meeting the same existing operation requirements, the present utility model is superior in terms of the motor installed capacity, floor area, investment cost, etc. of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a schematic structural diagram of an ejector vacuum exhaust system in the prior art.

[0028] Figure 2 FIG. is a schematic structural diagram of a pre-pumping vacuum exhaust system in the prior art.

[0029] Figure 3 FIG. is a schematic structural diagram of a first type of vacuum combined exhaust system in the prior art.

[0030] Figure 4 FIG. is a schematic structural diagram of a second type of vacuum combined exhaust system in the prior art.

[0031] Figure 5 FIG. is a schematic structural diagram of an embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present utility model will be further described below with reference to the drawings and embodiments. The embodiments of the present utility model include but are not limited to the following embodiments.

[0033] Embodiment

[0034] As Figure 5As shown in the figure, the vacuum exhaust system of the high-vacuum long-period large-flow wind tunnel includes a first switching valve 5, a vacuum spherical tank 1, a centrifugal vacuum pump unit 2, a positive-displacement vacuum pump unit 3, and a first exhaust silencer 6 that are sequentially connected through a main pipeline, a pressure detection device 4 connected to the vacuum spherical tank, an intake branch connected to the inlet of the centrifugal vacuum pump unit and communicating with the atmosphere, a first regulating valve 7 provided on the intake branch, a regulating bypass connected between the inlet and the outlet of the centrifugal vacuum pump unit, a second regulating valve 8 provided on the regulating bypass, an exhaust branch connected to the inlet of the positive-displacement vacuum pump unit, a second switching valve 9 and a second exhaust silencer 10 sequentially provided on the exhaust branch, and a control unit 11 for controlling the operation of the system. The control unit is electrically connected to the centrifugal vacuum pump unit, the positive-displacement vacuum pump unit, the first switching valve, the second switching valve, the pressure detection device, the first regulating valve, and the second regulating valve. The head end of the main pipeline is connected to the oncoming flow of the wind tunnel test chamber. The wind tunnel vacuum exhaust system composed of the series connection of the centrifugal vacuum pump unit and the positive-displacement vacuum pump unit can, through the switching of valves, not only ensure the high-vacuum state (maximum vacuum degree 1 kPa.A) required for the wind tunnel startup condition but also maintain the large-flow exhaust state (maximum exhaust volume 800 kg / s) of the wind tunnel operation condition.

[0035] Specifically, the compression ratio of the centrifugal vacuum pump unit is 1.2 to 12. It can be a series connection of multiple-stage centrifugal vacuum pump units, a series connection of one-stage, two-stage or more than two-stage centrifugal vacuum pump units, or a parallel connection of multiple centrifugal vacuum pump units. The centrifugal vacuum pump in the centrifugal vacuum pump unit is speed-controlled by a variable-frequency motor of a frequency converter.

[0036] Specifically, the drivers of the first switching valve and the second switching valve are hydraulic, pneumatic or electric, and the switching speed is 0.5 s to 10 s. The drivers of the first regulating valve and the second regulating valve are hydraulic, pneumatic or electric.

[0037] Specifically, the positive-displacement vacuum pump unit is a water-ring vacuum pump or a Roots vacuum pump.

[0038] More specifically, the process of the control unit controlling the wind tunnel vacuum exhaust system includes the following steps:

[0039] S1. The control unit closes both the first switching valve and the second switching valve through the driver, and keeps both the first regulating valve and the second regulating valve at a certain opening degree, for example, an opening degree of 60% to 70%.

[0040] S2. According to the requirements of different test states of the wind tunnel, set the wind tunnel startup pressure value in the control unit, generally 1 kPa.A to 3 kPa.A.

[0041] S3. The control unit starts the positive-displacement vacuum pump unit and the centrifugal vacuum pump unit in sequence.

[0042] S4. The control unit jointly adjusts the rotational speed of the centrifugal vacuum pump unit (6000 rpm - 10000 rpm), the opening degree of the first regulating valve (35% - 50%), and the opening degree of the second regulating valve (20% - 50%) to adjust the inlet pressure of the main pipeline of the wind tunnel vacuum exhaust system to the set wind tunnel startup pressure value. Then, it sucks in the atmosphere through the first and second regulating valves for stable pre - operation, and the wind tunnel vacuum exhaust system enters the waiting - for - test state.

[0043] S5. When the control unit receives the wind tunnel startup instruction, it opens the first switching valve through the driver. The cold - blowing air flow of the wind tunnel enters the vacuum spherical tank from the wind tunnel test chamber through the first switching valve. At the same time, it controls the first regulating valve to slowly close to zero. The wind tunnel test chamber still maintains the high - vacuum state required for wind tunnel startup, and the high - vacuum state value is 1 kPa.A - 3 kPa.A.

[0044] S6. When the control unit receives the wind tunnel ignition instruction, it opens the second switching valve and closes the second regulating valve through the driver. The wind tunnel vacuum exhaust system changes to the rough - vacuum large - air - flow exhaust mode. The positive - displacement vacuum pump unit is cut out of the system and stops operating. The centrifugal vacuum pump unit sucks the air flow discharged during wind tunnel ignition in the vacuum spherical tank and discharges it to the atmosphere through the exhaust silencer. The wind tunnel vacuum exhaust system enters the stable - operation state, where the rough - vacuum state value is 10 kPa.A.

[0045] The wind tunnel vacuum exhaust system can maintain the rough - vacuum state for a long time in the stable - operation state to ensure the operation of the wind tunnel. According to the exhaust - flow demand during wind tunnel operation, the control unit adjusts the speed of the centrifugal vacuum pump unit to achieve exhaust tests with different flow rates, especially large - flow exhaust tests.

[0046] S7. When the wind tunnel test ends, the control unit closes the first switching valve at the inlet of the vacuum spherical tank, and the wind tunnel exhaust stops. At the same time, the control unit controls the driver to open the first regulating valve (opening degree 35% - 50%), and the wind tunnel vacuum exhaust system enters the standby state.

[0047] S8. The control unit stops the centrifugal vacuum pump unit and the positive - displacement vacuum pump unit, and the system shuts down.

[0048] Through the above - mentioned implementation method of the wind tunnel vacuum exhaust system and the control unit, the utility model can adapt to the entire process of wind tunnel startup and wind tunnel operation with the same set of systems, without relying on an independent ejector or pre - pumping system to start the wind tunnel. It optimizes the structure of the entire wind tunnel vacuum exhaust system and can achieve an operation effect no less than that of the existing technology. As shown in Table 1, the utility model is superior in terms of the motor installed capacity, floor area, investment cost, etc. of the system.

[0049]

[0050] Table 1 Comparison between the present system and the existing combined exhaust system

[0051] The above embodiments are only the preferred embodiments of the present utility model, and do not limit the protection scope of the present utility model. Any changes made by adopting the design principle of the present utility model and non-creative labor on this basis shall fall within the protection scope of the present utility model.

Claims

1. A high vacuum, long cycle, large flow wind tunnel vacuum exhaust system, characterized in that: The system comprises a first switching valve, a vacuum spherical tank, a centrifugal vacuum pump unit, a volumetric vacuum pump unit and a first exhaust muffler which are sequentially connected through a main pipeline, a pressure detection device connected to the vacuum spherical tank, an intake branch connected to the inlet of the centrifugal vacuum pump unit and communicating with the atmosphere, a first regulating valve arranged on the intake branch, a regulating bypass connected between the inlet and outlet of the centrifugal vacuum pump unit, a second regulating valve arranged on the regulating bypass, an exhaust branch connected to the inlet of the volumetric vacuum pump unit, a second switching valve and a second exhaust muffler sequentially arranged on the exhaust branch, and a control unit for controlling the operation of the system, wherein the control unit is electrically connected to the centrifugal vacuum pump unit, the volumetric vacuum pump unit, the first switching valve, the second switching valve, the pressure detection device, the first regulating valve and the second regulating valve, and the head end of the main pipeline is connected to the inflow of the wind tunnel test chamber.

2. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1 is characterized in that: The centrifugal vacuum pump unit is a multi-stage centrifugal vacuum pump unit connected in series, wherein one-stage, two-stage or more-stage centrifugal vacuum pump units are connected in series.

3. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1, characterized in that: The centrifugal vacuum pump unit is a plurality of centrifugal vacuum pump units connected in parallel.

4. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1, characterized in that: The centrifugal vacuum pump unit is speed-regulated by a frequency converter variable frequency motor.

5. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1 is characterized in that: The drivers of the first switching valve and the second switching valve are hydraulic, pneumatic or electric, and the switching speed is 0.5s to 10s.

6. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1 is characterized in that: The drivers of the first regulating valve and the second regulating valve are hydraulic, pneumatic or electric.

7. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1, characterized in that: The compression ratio of the centrifugal vacuum pump unit is 1.2-12.

8. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1, characterized in that: The positive displacement vacuum pump unit is a water ring vacuum pump or a Roots vacuum pump.

9. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1, characterized in that: The maximum vacuum degree reached by the wind tunnel vacuum exhaust system is 1 kpa.A to 3 kpa.A.

10. The high vacuum, long period, large flow rate wind tunnel vacuum exhaust system according to claim 1, characterized in that: The maximum exhaust flow rate achieved by the wind tunnel vacuum exhaust system is 800kg / s.

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