Air inlet duct experimental device and experimental method for simulating and sensing sand and dust environment

Abstract

The invention discloses an air inlet duct experimental device and experimental method.The experimental device comprises a rectification contraction section, an expansion section and a ducted fan, the rectification contraction section comprises a large-inner-diameter section and a small-inner-diameter section, and the large-inner-diameter section and the small-inner-diameter section are smoothly connected through a curved surface; the rectification contraction section is provided with a static pressure hole used for measuring static pressure and a total pressure hole used for measuring total pressure. A plurality of sand dust concentration measuring probes are arranged on the rectification 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 rectification contraction section, and the ducted fan is installed at the joint of the rectification contraction section and the expansion section. Through cooperation of the rectification contraction section, the ducted fan and the expansion section, the working state of the engine air inlet channel can be simulated without an additional air source, so that the experimental device can be used for simulating a sand dust environment, and the risk that sand dust is sucked into a low-pressure air tank to damage the air tank is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of air intake duct environmental adaptability, and in particular to an air intake duct experimental device and an experimental method for measuring sand and dust concentration. Background Art

[0002] The air inlet is called the "throat" of the engine. It is mainly responsible for capturing, compressing and regulating the free flow, providing the engine with sufficient flow, pressure and uniformity of airflow, and the helicopter turboshaft engine air inlet, i.e., the particle separator, also shoulders the function of discharging foreign matter (such as sand and dust). The flight performance characteristics of helicopters determine that helicopters often need to fly at low altitude and low speed, and need to take off and land at simple sites or even random field sites. When used in deserts, wastelands and dry environments with poor surface vegetation and exposed soil, the sand and dust particles on the ground will be blown up by the airflow to varying degrees and suspended in the air under the effect of the rotor downwash, and a high-concentration sand and dust cloud will be generated in a short period of time to cover the helicopter, forming a "sand blind" or "sand cloud", and a large amount of sand and dust will be sucked into the engine. If the turboshaft engine is not protected, its performance will deteriorate rapidly due to sand and dust erosion, corrosion, pore blockage and other damage, greatly shortening the service life of the engine.

[0003] At present, common helicopter dust protection devices include vortex tube separators, air intake blocking filters, and integral inertial particle separators. The integral inertial particle separator has the advantages of high separation efficiency, simple structure, and light weight, which has attracted widespread attention from scholars at home and abroad. However, due to its fixed structure, it cannot meet the requirements of high aerodynamic performance and high sand separation performance at the same time, and can only be selected according to actual needs. In addition, when flying at high speed, the total pressure loss increases accordingly due to the excessive curvature of its flow channel. Therefore, the concept of a surface adaptive variable geometry particle separator with intelligent perception of dust environment is proposed, and the dust environment perception technology is the premise of the study of environmental adaptive particle separator. The traditional inlet suction test bench needs to be connected to a low-pressure air source at the rear end of the inlet. If the inlet sand throwing experiment is carried out on the traditional inlet test bench, the sand and dust will be sucked into the air tank and difficult to be discharged. In addition, excessive sand and dust inhalation will damage the vacuum pump, which is very dangerous. Summary of the invention

[0004] Purpose of the invention: In view of the shortcoming that the existing air intake duct experimental device cannot carry out the air intake duct sand throwing experiment, the present invention provides an air intake duct experimental device and experimental method for simulating and sensing the sand and dust environment, which can be used to simulate the sand and dust environment and sense and measure the sand and dust concentration at the air intake duct entrance.

[0005] Technical solution: To solve the above problems, the present invention adopts an air intake duct experimental device for simulating and sensing sand and dust environment, including a rectifying and contracting section, an expanding section, and a ducted fan. The rectifying and contracting section includes a large inner diameter section and a small inner diameter section, and the large inner diameter section and the small inner diameter section are smoothly connected by a curved surface. The rectifying and contracting section is provided with a static pressure hole for a static pressure probe to extend to measure the static pressure and a total pressure hole for a total pressure probe to extend to measure the total pressure; a plurality of sand and dust concentration measuring probes are provided on the rectifying and contracting section; the expanding section also includes a large inner diameter section and a small inner diameter section, and the large inner diameter section and the small inner diameter section are smoothly connected by a curved surface, and the small inner diameter section of the expanding section is connected to the small inner diameter section of the rectifying and contracting section, and the ducted fan is installed at the connection between the rectifying and contracting section and the expanding section.

[0006] Furthermore, the sand and dust concentration measuring probe includes a plurality of first sand and dust concentration measuring probes evenly distributed on the wall of the large inner diameter section of the rectifying and contracting section and a second sand and dust concentration measuring probe arranged on the wall of the small inner diameter section of the rectifying and contracting section.

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

[0008] Furthermore, the cross-sectional shape of the rectifying contraction section is the same as that of the expansion section, the diameter of the large inner diameter section of the rectifying 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 rectifying contraction section is equal to the diameter of the small inner diameter section of the expansion section.

[0009] Furthermore, a blunt rectifying lip with a double-twist curve in cross section is provided at the entrance of the large inner diameter section of the rectifying and contracting section.

[0010] Furthermore, a ducted fan fixing plate is provided at the end of the small inner diameter section of the rectifying contraction section and the expansion section, and a mounting ring is provided on the ducted fan, and the mounting ring is fixedly connected to the ducted fan fixing plate.

[0011] Furthermore, it also includes a sand throwing device, which is used to throw sand and dust into the rectifying and contracting section.

[0012] Furthermore, it also includes a filtering device, which is connected to the tail end of the expansion section and is used to filter sand and dust in the airflow. The filtering device includes a sand and dust filter cartridge and a filter element installed in the sand and dust filter cartridge.

[0013] Furthermore, the filtering device is connected to the expansion section via a switching pipe, and a bending angle of the switching pipe is ≤90°.

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

[0015] Step 1: Install the rectifier contraction section, expansion section, and ducted fan vertically on the ground as a whole; insert the static pressure probe and the total pressure probe into the static pressure hole and the total pressure hole respectively;

[0016] Step 2, turning on the ducted fan to allow air to enter the rectifier contraction section, obtaining the static pressure and total pressure measured by the static pressure probe and the total pressure probe through the scanning valve, and calculating the inlet flow rate, and adjusting the 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 and dust environment. The sand and dust concentration measurement probe measures the sand and dust concentration in the rectifier contraction section, and the exhaust gas is discharged from the expansion section.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) through the coordination of the rectifier contraction section, the duct fan and the expansion section, the working state of the engine intake duct can be simulated without an additional air source, so that the experimental device can be used to simulate a dust environment without the risk of dust being sucked into the low-pressure gas tank and damaging the gas tank; (2) the dust concentration and inlet flow rate can be flexibly adjusted, which is suitable for simulating dust environments under various working conditions and has a wide range of applications; (3) in addition, the experimental bench device has a simple structure, small size, low maintenance and experimental costs, and low requirements for experimental sites and air sources, providing a practical experimental device for conducting research on the dust movement mechanism in the intake duct of a turboshaft engine and the principle of dust environment perception. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the air intake duct experimental device of the present invention;

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

[0021] Figure 3 This is a schematic diagram of the rectifying contraction section structure of the present invention;

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

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

[0024] Figure 6 It is the total pressure profile of the section where the total pressure probe is located when the inlet velocity of the rectifier contraction section is 45m / s. DETAILED DESCRIPTION

[0025] like Figures 1 to 5As shown, an air intake duct experimental device for simulating and sensing a sand and dust environment in this embodiment includes a sand throwing device, an experimental measuring device and a filtering device. The sand throwing device in this embodiment uses an electric screen sand throwing device 1. The experimental measuring device includes a rectifying contraction section 2, an expansion section 5, and a duct fan 10. The duct fan 10 is installed between the rectifying contraction section 2 and the expansion section 5. The rectifying contraction section 2 includes 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 by a curved surface. In this embodiment, the diameter of the large inner diameter section is 142 mm, and the diameter of the small inner diameter section is 100 mm. A blunt rectifying lip 23 with a double twisted line cross section is provided at the entrance of the large inner diameter section of the rectifying contraction section 2 to avoid flow separation at the inlet when the flow velocity is high. A static pressure hole 21 is set at a position 45mm away from the inlet of the rectifying contraction section 2, and a total pressure hole 22 is set at a position 65mm 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 total pressure of the intake duct. The measuring 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 extend into the rectifying contraction section 2. Figure 6 It can be seen that the flow field is stable at a distance of 40mm from the inlet. From the total pressure profile curve, it can be seen that the total pressure is basically stable at a distance of about 25mm from the pipe wall. Therefore, the length of the total pressure probe extending into the flow field should be ≥25mm to accurately measure the total pressure.

[0026] The rectifying and contracting section 2 is also provided with a first probe mounting seat (9 / 9' / 9"' / 9"") uniformly distributed on the wall of its large inner diameter section in a circumference and a second probe mounting seat 9" arranged on the wall of the small inner diameter section of the rectifying and contracting section 2. The first sand and dust concentration measuring probe 31 and the second sand and dust concentration measuring probe 32 are respectively installed in the corresponding probe mounting seats, wherein the first sand and dust concentration measuring probe 31 is used to measure the sand and dust concentration at the inlet of the air intake duct, and the second sand and dust concentration probe 32 is used to measure the sand and dust concentration at the inlet of the fan. Arranging multiple probes to cover the entire cross-section of the large inner diameter section and the small inner diameter section of the air intake duct makes the measurement result more accurate. The sand and dust concentration measuring probe of this embodiment adopts the principle of frictional electricity generation. The sand and dust and the sand and dust concentration measuring probe collide and rub against each other to generate static electricity. The static electricity signal is measured and converted into a concentration signal to achieve the purpose of measuring the sand and dust concentration. The penetration depth of the measuring end of each sand and dust concentration measuring probe is 50%-90% of the inner diameter of the probe. While ensuring that it is fully extended into the air intake duct, the measuring ends of each sand and dust concentration measuring probe are separated by a certain distance, and the probes will not interfere with each other and affect the measurement results.

[0027] The expansion section 5 has the same cross-sectional shape as the rectification and contraction section 2. In this embodiment, the diameter of the large inner diameter section of the expansion section 5 is 142 mm, and the diameter of the small inner diameter section is 100 mm. The ends of the rectification and contraction section 2 and the small inner diameter section of the expansion section 5 are provided with a duct fan fixing plate 24. The duct fan 10 is provided with a mounting ring 4, which is connected to the duct fan fixing plate to fix the duct fan 10 between the rectification and contraction section 2 and the expansion section 5. This installation method can ensure that the duct fan 10 is installed stably and reduce the displacement in the flow direction and radial direction caused by excessive thrust and fan rotation. The thrust of the duct fan 10 should be no less than 3 kg to simulate the working state of the intake duct with different flow rates.

[0028] The filter device includes a sand and dust filter cartridge 7 and a filter element 8 installed in the sand and dust filter cartridge 7. The filter device is connected to the expansion section 5 through a transfer pipe 6. The transfer pipe 6 is made of PVC. The total length of the transfer pipe 6 should be greater than 1000mm. The bending angle of the transfer pipe 6 is ≤90° to avoid excessive curvature of the outlet flow channel to cause flow separation and affect the upstream flow. The filter device can filter sand and dust with an efficiency of more than 99%, effectively handling sand and dust in the exhaust gas. The airflow filtered by the filter system is basically clean airflow. The rectifying and contracting section 2, the duct fan fixing ring 4, the expansion section 5, and the filter cartridge 7 are processed by additive manufacturing to reduce the overall weight of the experimental piece and the number of connectors, thereby reducing the experimental cost and processing difficulty.

[0029] The specific experimental method of the present invention is as follows: install the experimental measurement device vertically to the ground to avoid the influence of gravity on the movement trajectory of sand and dust, insert the static pressure probe and the total pressure probe into the static pressure hole 21 and the total pressure hole 22 respectively, turn on the duct fan 10 to start the experimental measurement device to intake air, first obtain the static pressure and 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 speed of the duct fan 10 to obtain different inlet flow rates required for the experiment. After the flow field is stable, turn on the electric screen sand thrower 1 to throw sand to simulate the operation of the air intake in a sand and dust environment. The height of the electric screen sand thrower 1 from the inlet surface of the rectifier contraction section 2 should be not less than 500mm to avoid the obstruction of the electric screen sand thrower 1 to the inlet flow field. Each sand and dust concentration measurement probe measures the sand and dust concentration in the air intake duct, and enters the filter device through the expansion section 5 and is finally discharged. The experimental device of this embodiment can be used for inlet flow rates of 5m / s~80m / s, sand and dust diameters of 1-200μm, and sand and dust concentrations of 1-2000mg / m 3 various working conditions.

[0030] The present invention can simulate the working state of the engine air intake duct without an additional air source through the coordination of the rectifier contraction section, the duct fan, and the expansion section, so that the experimental device can be used to simulate the sand and dust environment without the risk of sand and dust being sucked into the low-pressure gas tank to damage the gas tank. The sand and dust concentration and the inlet flow rate can be flexibly adjusted, which is suitable for simulating sand and dust environments of various working conditions and has a wide range of applications. In addition, the experimental bench device has a simple structure, small size, low maintenance and experimental costs, low requirements for the experimental site and no air source requirements, providing a practical experimental device for conducting research on the sand and dust movement mechanism in the turboshaft engine air intake duct and the principle of sand and dust environment perception.

Claims

1. An air intake test device for simulating and sensing a dusty environment, characterized in that: The invention comprises a rectifying contraction section (2), an expansion section (5), and a ducted fan (10), wherein 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 via a curved surface, the rectifying contraction section (2) is provided with a static pressure hole (21) for a static pressure probe to extend to measure the static pressure, and a total pressure hole (22) for a total pressure probe to extend to measure the 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 via a curved surface, the small inner diameter section of the expansion section (5) is connected to the small inner diameter section of the rectifying contraction section (2), and the ducted fan (10) is installed at the connection between the rectifying contraction section (2) and the expansion section (5).

2. The air intake test device according to claim 1, characterized in that: The sand and dust concentration measuring probe (3) comprises a plurality of first sand and dust concentration measuring probes (31) uniformly distributed in a circumferential manner on the wall surface of the large inner diameter section of the rectifying and contracting section (2), and a second sand and dust concentration measuring probe (32) arranged on the wall surface of the small inner diameter section of the rectifying and contracting section (2).

3. The air intake test device according to claim 1, characterized in that: The penetration 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 test device according to claim 1, characterized in that: 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 test device according to claim 1, characterized in that: A blunt-type rectifying lip (23) with a lemniscate cross section is provided at the entrance of the large inner diameter section of the rectifying and contracting section (2).

6. The air intake test device according to claim 1, characterized in that: A ducted fan fixing plate (24) is provided at the end of the small inner diameter section of the rectifying contraction section (2) and the expansion section (5), and a mounting ring (4) is provided on the ducted fan (10), and the mounting ring (4) is fixedly connected to the ducted fan fixing plate (24).

7. The air intake test device according to claim 1, characterized in that: It also comprises a sand throwing device, which is used to throw sand and dust into the rectifying and contracting section (2).

8. The air intake test device according to claim 1, characterized in that: It also comprises a filtering device, which is connected to the tail end of the expansion section (5) and is used for filtering sand and dust in the airflow. The filtering device comprises a sand and dust filter cartridge (7) and a filter element (8) installed in the sand and dust filter cartridge (7).

9. The air intake test device according to claim 8, characterized in that: The filtering device is connected to the expansion section (5) via a switching pipe (6), and the bending angle of the switching pipe (6) is ≤90°.

10. An experimental method for the air intake test device according to any one of claims 1 to 9, characterized in that: Providing a sand injection device, a static pressure probe, a total pressure probe and a scanning valve includes the following steps: Step 1, vertically install the rectifier contraction section (2), the expansion section (5), and the ducted fan (10) on the ground as a whole; 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, turning on the ducted fan (10) to allow air to enter the rectifying contraction section (2), obtaining the static pressure and total pressure measured by the static pressure probe and the total pressure probe through the scanning valve, and calculating the inlet flow rate, and adjusting the speed of the ducted fan (10) to obtain a preset inlet flow rate; Step 3: After the flow field is stabilized, the sand throwing device is turned on to throw sand to simulate a sand and dust environment. The sand and dust concentration measurement 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).

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