An air inlet experimental device and experimental method for simulating and sensing a sand-dust environment

Abstract

The application discloses an air inlet experimental device and experimental method for simulating and sensing a sand dust environment, and the experimental device comprises a straightening contraction section, an expansion section and a duct fan, the straightening contraction section comprises a large inner diameter section and a small inner diameter section, the large inner diameter section and the small inner diameter section are smoothly connected through a curved surface, and the straightening contraction section is provided with a static pressure hole for measuring static pressure and a total pressure hole for measuring total pressure; a plurality of sand dust concentration measuring probes are arranged on the straightening contraction section; the expansion section also comprises a large inner diameter section and a small inner diameter section, the large inner diameter section and the small inner diameter section are smoothly connected through a curved surface, the small inner diameter section of the expansion section is connected with the small inner diameter section of the straightening contraction section, and the duct fan is installed at the connection position of the straightening contraction section and the expansion section. The straightening contraction section, the duct fan and the expansion section are matched, the working state of the engine air inlet can be simulated without an additional air source, the experimental device can be used for simulating the sand dust environment, and the risk of damaging the low-pressure air tank due to the suction of sand dust into the low-pressure air tank is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air intake environmental adaptability, and particularly relates to an air intake experimental device for measuring sand dust concentration and an experimental method. BACKGROUND

[0002] The air intake is called the "throat" of the engine, and is mainly responsible for capturing, compressing and regulating the free flow to provide sufficient flow, pressure and uniformity of airflow for the engine, and the particle separator of the helicopter turboshaft engine also shoulders the function of discharging foreign matters (such as sand dust). The flight performance characteristics of the helicopter determine that the helicopter often needs to fly in low-altitude and low-speed mode, and needs to take off and land in simple sites or even random outdoor sites. When used in a desert, a desert and a dry environment with bare soil, the sand dust particles on the ground will be blown up and suspended in the air to a certain extent due to the effect of the downwash of the rotor, and a high-concentration sand dust cloud will cover the helicopter in a short time, forming a "sand blind" or "sand cloud", and a large amount of sand dust will be sucked into the engine. If the turboshaft engine is not protected, its performance will rapidly deteriorate due to sand dust erosion, corrosion and blockage of air holes, greatly shortening the service life of the engine.

[0003] The common helicopter sand dust protection devices at present include a scroll tube separator, an air intake blocking filter and a whole inertial particle separator. The whole inertial particle separator has the advantages of high separation efficiency, simple structure and light weight, and has attracted wide attention of scholars at home and abroad. However, due to its fixed structure, it cannot simultaneously meet the requirements of high aerodynamic performance and high sand separation performance, and can only be selected according to actual needs, and when flying at high speed, the total pressure loss will also increase due to the excessive curvature of the flow passage. Therefore, a concept of a surface self-adaptive variable-geometry particle separator with intelligent sand dust environment perception is proposed, and the sand dust environment perception technology is the premise of the research on the environment-adaptive particle separator. The traditional air intake suction test bench needs to be connected with a low-pressure gas source at the rear end of the air intake, and if the sand injection experiment of the air intake is carried out on the traditional air intake test bench, the sand dust will be sucked into the gas storage tank and be difficult to be discharged, and the sand dust suction amount is too large to damage the vacuum pump, which is very dangerous. SUMMARY

[0004] The present application provides an air intake experimental device and an experimental method for simulating and perceiving a sand dust environment, which can be used for simulating a sand dust environment and perceiving and measuring the sand dust concentration at the inlet of the air intake.

[0005] Technical solution: To solve the above problems, the present application adopts a kind of air inlet experimental device for simulating and sensing sand dust environment, including rectification contraction section, expansion section, duct fan, the rectification contraction section includes large inner diameter section and small inner diameter section, and the large inner diameter section is smoothly connected with the small inner diameter section by curved surface, and the rectification contraction section is provided with static pressure hole for static pressure probe to enter to measure static pressure and total pressure hole for total pressure probe to enter to measure total pressure;Rectification contraction section is provided with multiple sand dust concentration measuring probes;The expansion section also includes large inner diameter section and small inner diameter section, and the large inner diameter section is smoothly connected with the small inner diameter section by curved surface, and the small inner diameter section of the expansion section is connected with the small inner diameter section of the rectification contraction section, and the duct fan is installed at the connection of the rectification contraction section and the expansion section.

[0006] Further, the sand dust concentration measuring probe includes a plurality of first sand dust concentration measuring probes uniformly distributed on the wall surface of the large inner diameter section of the rectification contraction section and a plurality of second sand dust concentration measuring probes arranged on the wall surface of the small inner diameter section of the rectification contraction section.

[0007] Further, the probe depth of the sand dust concentration measuring probe measuring end is 50%-90% of the inner diameter of the position where the probe is located.

[0008] Further, the cross-sectional shape of the rectification contraction section and the expansion section is the same, the diameter of the large inner diameter section of the rectification contraction section is equal to the diameter of the large inner diameter section of the expansion section, and the diameter of the small inner diameter section of the rectification contraction section is equal to the diameter of the small inner diameter section of the expansion section.

[0009] Further, the inlet of the large inner diameter section of the rectification contraction section is provided with a blunt flow lip with a double-curve cross section.

[0010] Further, the end of the rectification contraction section and the small inner diameter section of the expansion section is provided with a duct fan fixing plate, and the duct fan is provided with a mounting ring, and the mounting ring is fixedly connected with the duct fan fixing plate.

[0011] Further, it further includes a sand throwing device, and the sand throwing device is used for throwing sand dust into the rectification contraction section.

[0012] Further, it further includes a filtering device, and the filtering device is connected to the tail end of the expansion section for filtering sand dust in the airflow, and the filtering device includes a sand dust filtering cylinder and a filter element installed in the sand dust filtering cylinder.

[0013] Further, the filtering device is connected with the expansion section through an adapter pipe, and the bending angle of the adapter pipe is ≤90°.

[0014] The present application also provides an experimental method of the air inlet experimental device, and provides a sand throwing device, a static pressure probe, a total pressure probe and a scanning valve, which includes the following steps:

[0015] Step 1, install the rectification contraction section, the expansion section and the ducted fan vertically to the ground; insert the static pressure probe and the total pressure probe into the static pressure hole and the total pressure hole respectively;

[0016] Step 2, start the ducted fan to make the rectification contraction section intake, obtain the static pressure and the total pressure measured by the static pressure probe and the total pressure probe through the scanning valve, and calculate the inlet flow rate; adjust the rotation speed of the ducted fan to obtain the preset inlet flow rate;

[0017] Step 3, after the flow field is stable, start the sand throwing device to throw sand to simulate the sand dust environment, the sand dust concentration measuring probe measures the sand dust concentration in the rectification contraction section, and the exhaust gas is discharged from the expansion section.

[0018] Advantages: compared with the prior art, the present application has the following advantages: (1) by the cooperation of the rectification contraction section, the ducted fan and the expansion section, the working state of the engine intake duct can be simulated without additional air source, so that the experimental device can be used to simulate the sand dust environment, and there is no risk of damaging the air tank by sucking sand dust into the low-pressure air tank; (2) the sand dust concentration and the inlet flow rate can be flexibly adjusted, which is suitable for simulating sand dust environments under various working conditions, and has a wide application range; (3) in addition, the experimental bench device has simple structure, small size, low maintenance and experimental cost, and low requirements for experimental site and air source, which provides a practical experimental device for the research on the sand dust movement mechanism in the inlet duct of the turboshaft engine and the sand dust environment sensing principle. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the inlet duct experimental device of the present application;

[0020] Figure 2 It is a schematic diagram of the experimental measurement device structure of the present application;

[0021] Figure 3 It is a schematic diagram of the rectification contraction section structure of the present application;

[0022] Figure 4 It is a schematic diagram of the ducted fan structure of the present application;

[0023] Figure 5 It is a schematic diagram of the filter device structure of the present application;

[0024] Figure 6 It is a total pressure profile of the total pressure probe at the inlet velocity of 45 m / s of the rectification contraction section. DETAILED DESCRIPTION

[0025] As Figures 1 to 5As shown, the air inlet experimental device for simulating and sensing sand dust environment in the embodiment comprises a sand throwing device, an experimental measurement device and a filtering device. The sand throwing device in the embodiment is an electric screen sand throwing device 1. The experimental measurement device comprises a rectifying contraction section 2, an expansion section 5 and a ducted fan 10, wherein the ducted fan 10 is installed between the rectifying contraction section 2 and the expansion section 5. The rectifying contraction section 2 comprises a large-diameter section and a small-diameter section, and the large-diameter section and the small-diameter section are smoothly connected through a curved surface. In the embodiment, the diameter of the large-diameter section is 142 mm, and the diameter of the small-diameter section is 100 mm. A blunt rectifying lip 23 with a double-clothoid cross section is arranged at the inlet of the large-diameter section of the rectifying contraction section 2 to avoid flow separation at the inlet when the flow rate is high. A static pressure hole 21 is arranged at a position 45 mm away from the inlet of the rectifying contraction section 2, and a total pressure hole 22 is arranged at a position 65 mm away from the inlet. During the experiment, a static pressure probe and a total pressure probe are respectively inserted into the static pressure hole and the total pressure hole to measure the static pressure and the total pressure of the air inlet. The measurement end of the static pressure probe is flush with the inner wall of the rectifying contraction section 2, and the total pressure probe needs to be inserted into the rectifying contraction section 2. Figure 6 It can be known that the flow field is stable at a position 40 mm away from the inlet, and the total pressure is basically stable at a position about 25 mm away from the pipe wall according to the total pressure profile curve. Therefore, the length of the total pressure probe inserted into the flow field should be greater than or equal to 25 mm to accurately measure the total pressure.

[0026] The rectifying contraction section 2 is further provided with first probe mounting seats (9 / 9’ / 9”’ / 9””) uniformly distributed on the wall surface of the large-diameter section thereof and a second probe mounting seat 9” arranged on the wall surface of the small-diameter section of the rectifying contraction section 2. A first sand dust concentration measuring probe 31 and a second sand dust concentration measuring probe 32 are respectively installed in the corresponding probe mounting seats. The first sand dust concentration measuring probe 31 is used to measure the sand dust concentration at the inlet of the air inlet, and the second sand dust concentration probe 32 is used to measure the sand dust concentration at the inlet of the fan. A plurality of probes are arranged to cover the entire cross section of the large-diameter section and the small-diameter section of the air inlet, so that the measurement result is more accurate. The sand dust concentration measuring probe in the embodiment adopts the principle of friction electricity generation. Electrostaticity is generated by the collision and friction between sand dust and the sand dust concentration measuring probe. The purpose of measuring the sand dust concentration is achieved by converting the electrostatic signal into a concentration signal. The insertion depth of the measurement end of each sand dust concentration measuring probe is 50%-90% of the inner diameter of the position where the probe is located, so as to ensure that the measurement end of each sand dust concentration measuring probe is fully inserted into the air inlet, and the measurement ends of the probes are separated by a certain distance, so that the measurement results are not affected by the interference between the probes.

[0027] The expansion section 5 has the same cross-sectional shape as the rectifying contraction section 2, and in the embodiment, the large-diameter section of the expansion section 5 has a diameter of 142 mm, and the small-diameter section has a diameter of 100 mm. The rectifying contraction section 2 and the end of the small-diameter section of the expansion section 5 are provided with a duct fan fixing plate 24, and the duct fan 10 is provided with a mounting ring 4, which is connected with the duct fan fixing plate to fix the duct fan 10 between the rectifying contraction section 2 and the expansion section 5. Through this mounting mode, the installation of the duct fan 10 can be stable, and the displacement in the flow direction and the radial direction caused by excessive thrust and fan rotation can be reduced. The thrust of the duct fan 10 should be greater than or equal to 3 kg to simulate the working state of the inlet flow passage at different flow rates.

[0028] The filtering device includes a sand dust filtering cylinder 7 and a filter core 8 mounted in the sand dust filtering cylinder 7, and is connected with the expansion section 5 through a adapter pipe 6. The adapter pipe 6 is made of PVC, and the total length of the adapter pipe 6 should be greater than 1000 mm, and the bending angle of the adapter pipe 6 is less than or equal to 90° to avoid excessive curvature of the outlet flow passage to affect the upstream flow. The filtering efficiency of the filtering device for sand dust can reach more than 99%, and the airflow filtered by the filtering system is basically clean airflow. The rectifying contraction section 2, the duct fan fixing ring 4, the expansion section 5 and the filtering cylinder 7 are processed by additive manufacturing to reduce the overall weight of the experimental piece, the number of connecting pieces, the experimental cost and the processing difficulty.

[0029] The specific experimental method of the application is as follows: the experimental measurement device is installed vertically to the ground to avoid the influence of gravity on the trajectory of the sand dust, and the static pressure probe and the total pressure probe are respectively inserted into the static pressure hole 21 and the total pressure hole 22. The duct fan 10 is started to make the experimental measurement device start to intake air. The static pressure and the total pressure measured by the static pressure probe and the total pressure probe are obtained through the scanning valve, the inlet flow rate is calculated, and different inlet flow rates required by the experiment are obtained by adjusting the rotating speed of the duct fan 10. After the flow field is stable, the electric sieve sand thrower 1 is started to simulate the working state of the inlet flow passage in the sand dust environment. The height of the electric sieve sand thrower 1 from the inlet face of the rectifying contraction section 2 should be greater than or equal to 500 mm to avoid the hindering effect of the electric sieve sand thrower 1 on the inlet flow field. The sand dust concentration measuring probes measure the sand dust concentration in the inlet flow passage, and the sand dust enters the filtering device through the expansion section 5 and is finally discharged. The experimental device of the embodiment can be used for various working conditions with an inlet flow rate of 5 m / s to 80 m / s, sand dust diameter of 1-200 μm, and sand dust concentration of 1-2000 mg / m 3 .

[0030] The application can simulate the working state of the engine air inlet channel by the cooperation of the rectifying contraction section, the ducted fan and the expansion section without additional air source, so that the experimental device can be used to simulate the sand dust environment, and there is no risk of damaging the low-pressure air tank by sucking sand dust into the air tank. In addition, the sand dust concentration and the inlet flow rate can be flexibly adjusted, and the experimental device is suitable for simulating various working conditions of sand dust environment and has a wide range of applications. Furthermore, the experimental device has simple structure, small size, low maintenance cost and experimental cost, low requirement for experimental site and no air source requirement, and provides a feasible experimental device for the research on the sand dust movement mechanism in the inlet channel of the turboshaft engine and the sand dust environment sensing principle.

Claims

1. An air intake experimental device for simulating and sensing a sand dust environment, characterized in that, The device comprises a rectifying contraction section (2), an expansion section (5) and a ducted fan (10), the rectifying contraction section (2) comprises a large inner diameter section and a small inner diameter section, the large inner diameter section and the small inner diameter section are smoothly connected through a curved surface, the rectifying contraction section (2) is provided with a static pressure hole (21) for a static pressure probe to extend into for measuring static pressure and a total pressure hole (22) for a total pressure probe to extend into for measuring total pressure; the rectifying contraction section (2) is provided with a plurality of sand and dust concentration measuring probes (3); the expansion section (5) also comprises a large inner diameter section and a small inner diameter section, the large inner diameter section and the small inner diameter section are smoothly connected through a curved surface, the small inner diameter section of the expansion section (5) is connected with the small inner diameter section of the rectifying contraction section (2), and the ducted fan (10) is installed at the connection position of the rectifying contraction section (2) and the expansion section (5).

2. The air intake tunnel test device of claim 1, wherein The sand and dust concentration measuring probe (3) comprises a plurality of first sand and dust concentration measuring probes (31) which are uniformly distributed on the wall surface of the large inner diameter section of the rectifying contraction section (2) and a second sand and dust concentration measuring probe (32) which is arranged on the wall surface of the small inner diameter section of the rectifying contraction section (2).

3. The air intake tunnel test device of claim 1, wherein The depth of the measuring end of the sand and dust concentration measuring probe (3) is 50%-90% of the inner diameter of the position where the probe is located.

4. The air intake tunnel test device of claim 1, wherein The rectifying contraction section (2) and the expansion section (5) have the same cross-sectional shape, the diameter of the large inner diameter section of the rectifying contraction section (2) is equal to the diameter of the large inner diameter section of the expansion section (5), and the diameter of the small inner diameter section of the rectifying contraction section (2) is equal to the diameter of the small inner diameter section of the expansion section (5).

5. The air intake tunnel test device of claim 1, wherein, The inlet of the large inner diameter section of the rectifying contraction section (2) is provided with a blunt rectifying lip (23) with a double-clothoid cross section.

6. The air intake tunnel test device of claim 1, wherein, The end of the small inner diameter section of the rectifying contraction section (2) and the expansion section (5) is provided with a ducted fan fixing plate (24), the ducted fan (10) is provided with a mounting ring (4), and the mounting ring (4) is fixedly connected with the ducted fan fixing plate (24).

7. The air intake tunnel test device of claim 1, wherein The device further comprises a sand throwing device for throwing sand and dust into the rectifying contraction section (2).

8. The air intake tunnel test device of claim 1, wherein, The device further comprises a filtering device which is connected to the tail end of the expansion section (5) and used for filtering sand and dust in the airflow, and the filtering device comprises a sand and dust filtering cylinder (7) and a filter core (8) installed in the sand and dust filtering cylinder (7).

9. The air intake tunnel test device of claim 8, wherein, The filtering device is connected with the expansion section (5) through an adapter pipe (6), and the bending angle of the adapter pipe (6) is ≤90°.

10. A method of testing the air intake passage testing device according to any one of claims 1 to 9, characterized by, The device provides a sand throwing device, a static pressure probe, a total pressure probe and a scanning valve, and comprises the following steps: Step 1, vertically install the rectifying contraction section (2), the expansion section (5) and the ducted fan (10) relative to the ground; insert the static pressure probe and the total pressure probe into the static pressure hole (21) and the total pressure hole (22) respectively; Step 2, start the ducted fan (10) to make the rectifying contraction section (2) intake air, obtain the static pressure and the total pressure measured by the static pressure probe and the total pressure probe through the scanning valve, calculate the inlet flow rate, and adjust the rotating speed of the ducted fan (10) to obtain a preset inlet flow rate; Step 3, after the flow field is stable, start the sand throwing device to throw sand to simulate a sand and dust environment, and the sand and dust concentration measuring probe (3) measures the sand and dust concentration in the rectifying contraction section (2), and the tail gas is discharged from the expansion section (5).

Images