Water surface aircraft cavitation resistance reduction single hull model test device and test method

Abstract

The invention discloses a water surface aircraft cavitation resistance reduction single hull model test device and method, and the device comprises an industrial oxygen cylinder which is provided with a pressure reducing valve, and the pressure reducing valve, a gas conveying hose, a front straight pipe, a mass flow controller and a rear straight pipe are connected in sequence. The rear straight pipe is connected to an air hole in the cavitation resistance reduction single hull model through another air conveying hose. The device is stable in blowing amount, fast in response and high in flow control precision.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrodynamic test, and in particular relates to a single-hull model test device and a test method for cavitation drag reduction of a water surface aircraft. Background Art

[0002] Towing tank test models such as cavitation drag reduction hydrodynamic model tests, supercavitation vehicle hydrodynamic model tests, and amphibious aircraft boundary layer hydrodynamic model tests all require continuous, stable, controllable, and measurable quantitative air supply to accurately obtain the drag reduction effect. In the past, towing tank test models used air compressors or blowers and other air sources connected to rotor flowmeters and other gas flow control methods for air supply, which had disadvantages such as large air supply flow error and long response time.

[0003] Chinese patent CN201910444077.0 provides a high-speed vehicle that combines microbubble drag reduction technology with groove turbulence drag reduction technology. In this solution, a microbubble generator generates bubbles and transports them to the bottom of the ship through an air pipe, but it does not explain what the microbubble generator is. The air pipe plays the role of gas flow transportation, but whether there is gas flow control is not explained.

[0004] Chinese Patent 202011583928.9 provides an air layer drag reduction device jet structure, a ship air layer drag reduction system and an air layer drag reduction ship. The solution states that the pressure-stabilizing tube and the external air supply pipeline are connected through a check valve, but does not specify what kind of gas source the external air supply pipeline is connected to. The solution also does not mention the method of gas flow control.

[0005] In summary, the current patent solutions for microbubble drag reduction / air layer drag reduction are all concentrated on pipeline settings and air hole / jet structures, and none of them involve the form of gas source and gas flow control method. The gas flow control is not precise enough and is more suitable for real ships but not suitable for towing tank model tests. Summary of the invention

[0006] Purpose of the Invention

[0007] Aiming at the problem that the gas flow control in the existing towing tank test model is not precise enough and is more suitable for real ships but not suitable for towing tank model tests, the present invention provides a single-hull model test device and test method for cavitation drag reduction of surface aircraft.

[0008] Inventing technical solutions

[0009] A test device for a single-hull model of a water-surface aircraft with cavitation drag reduction comprises an industrial oxygen cylinder, on which a pressure reducing valve is arranged, the pressure reducing valve, a gas delivery hose, a front straight pipe, a mass flow controller and a rear straight pipe are connected in sequence, and the rear straight pipe is connected to an air hole on the single-hull model of cavitation drag reduction through another gas delivery hose.

[0010] Preferably, the industrial oxygen cylinder 1 releases industrial oxygen through a pressure reducing valve, and controls the output gas pressure within the range of 300 kPa to 400 kPa.

[0011] Preferably, the inner diameter of the gas delivery hose is greater than 20 mm.

[0012] Preferably, the mass flow controller can reach the set output gas flow rate within 0.1 s.

[0013] Preferably, the length of the front straight pipe is greater than 10 times the diameter of the pipeline.

[0014] Preferably, the length of the rear straight pipe is greater than 2.5 times the diameter of the pipeline.

[0015] Preferably, the front straight pipe and the rear straight pipe are both made of metal hard straight pipes.

[0016] Preferably, there are several pores evenly distributed at a position of 30 mm after the step.

[0017] Preferably, each air hole is connected to a separate rear straight pipe; or the rear straight pipe is connected to the air holes after being connected to a corresponding number of gas hoses via a connector having a plurality of joints, and all the air holes are connected to the gas hoses.

[0018] A test method using a single-hull model test device for cavitation drag reduction of a water surface aircraft comprises the following steps:

[0019] Step 1: Open the valve of the industrial oxygen cylinder and rotate the valve of the pressure reducing valve to control the output gas pressure within the set range; set the oxygen flow value of the mass flow controller, start the data acquisition equipment, and record the test parameters, including resistance, heave, and trim;

[0020] Step 2: Start the trailer, which drives the cavitation drag reduction single hull model to reach the test speed, start the mass flow controller, and oxygen is transported to the air hole through the gas hose, so as to form and maintain a thin air layer after the cavitation drag reduction single hull model is broken;

[0021] Step 3: After the test speed stabilizes for about 5 to 10 seconds, stop the mass flow controller input, stop the trailer, stop the data acquisition equipment, close the pressure reducing valve, and close the industrial oxygen cylinder valve.

[0022] Advantages of the present invention:

[0023] The present invention has stable blowing volume, fast response, high flow control accuracy, and can reach the set output gas flow within 0.1s. The power required for gas flow control is small; the gas source volume of the test device is small, and it is convenient to carry and disassemble; the blowing volume is measurable and controllable, and the consistency of the cavitation drag reduction model test results is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of a single-hull model test device for cavitation drag reduction of a surface aircraft.

[0025] Figure 2 This is a map of the locations of cavitation drag reduction pores.

[0026] Figure 3 It is the resistance test result of a single-hull model of cavitation drag reduction for a surface aircraft.

[0027] In the figure: industrial oxygen cylinder 1, pressure reducing valve 2, gas delivery hose 3, mass flow controller 4, front straight pipe 4-1, rear straight pipe 4-2, cavitation drag reduction single hull model 5, air hole 6. DETAILED DESCRIPTION

[0028] The present invention is achieved through the following technical solutions.

[0029] like Figure 1 As shown, a single-hull model test device for cavitation drag reduction of a water surface aircraft includes an industrial oxygen cylinder 1, a pressure reducing valve 2, a gas delivery hose 3, a mass flow controller 4, and a single-hull model 5 for cavitation drag reduction.

[0030] The volume of industrial oxygen cylinder 1 is 40L, the oxygen pressure is 10MPa, and the empty cylinder should have a residual pressure of 1MPa.

[0031]

[0032] According to the ideal gas state equation, we have

[0033]

[0034] Therefore, the air mass M stored in the industrial oxygen cylinder 1 air It is 4.65kg, and the usable air mass is 90% of the stored air mass, that is, 4.19kg.

[0035] When the pipeline diameter is DN10, the maximum flow rate of the pipeline is 400L / min. At this time, the working pressure of the mass flow controller 4 is 300kPa~400kPa, and the mass of air lost per second is 0.023kg~0.031kg. A bottle of industrial oxygen cylinder can be used for 135s~180s and can be used five to ten times during the test.

[0036] If industrial oxygen cylinders are not used, and high-pressure air compressors and gas cylinders are used, then in order to achieve a maximum pipeline flow of 400L / min, the technical parameters of the high-pressure air machine should be an output pressure of 35MPa and a compression flow of 0.65m 3 / min, the motor power is 15kW, and the air compressor dimensions are 1700mm×1050mm×1100mm, which is larger than the space that the trailer can carry, and the power provided by the trailer cannot meet the needs of the high-pressure air compressor.

[0037] The industrial oxygen cylinder 1 releases industrial oxygen through the pressure reducing valve 2 and controls the output gas pressure within the range of 300 kPa to 400 kPa, meeting the use conditions of the mass flow controller 4.

[0038] The pressure reducing valve 2 is connected to the front straight pipe 4-1, the mass flow controller 4, and the rear straight pipe 4-2 in sequence through the gas delivery hose 3.

[0039] The inner diameter of the gas delivery hose 3 is greater than 20 mm. The larger the diameter, the slower the flow rate and the more stable the airflow at the same flow rate.

[0040] The gas flow rate control accuracy of the mass flow controller 4 is high, and the set output gas flow rate is reached within 0.1 s.

[0041] The length of the front straight pipe 4-1 is greater than 10 times the diameter of the pipeline, and the length of the rear straight pipe 4-2 is greater than 2.5 times the diameter of the pipeline. The front straight pipe 4-1 and the rear straight pipe 4-2 are both made of hard straight pipes made of metal, which play a role in stabilizing the quality of oxygen input, making the gas input and output of the mass flow controller 4 stable and improving the flow measurement accuracy.

[0042] The rear straight pipe 4 - 2 is connected to the air hole 6 on the cavitation drag reduction single hull model 5 through the air delivery hose 3 .

[0043] like Figure 2 As shown, the pores 6 of this embodiment are circular with a diameter of 6 to 10 mm, and the diameter is equivalent to 1 / 60 to 1 / 30 of the step width.

[0044] There are 4 pores 6, evenly distributed at a position of 30 mm after the step.

[0045] One set of gas pipelines can correspond to one air hole, and a tee or other device can also be arranged behind the rear straight pipe 4 - 2, so that one set of gas pipelines can correspond to multiple air holes.

[0046] like Figure 3 As shown in the figure, the resistance test results of the cavitation drag reduction single hull model with a single air hole without blowing, blowing at 10g / s, blowing at 20g / s, and blowing at 30g / s. The results show that the cavitation drag reduction effect is obvious in the low and medium speed stages; in the high-speed stage, the cavitation drag reduction effect did not reach the expected effect due to the rise of the single hull model of the surface aircraft, which caused gas leakage after the step; the cavitation drag reduction test technology made the resistance peak of the surface aircraft move backward, effectively improving the rapidity of the surface aircraft during takeoff.

[0047] The method comprises the following steps:

[0048] Step 1: Follow Figure 1 As shown, an industrial oxygen cylinder 1, a pressure reducing valve 2, a gas supply hose 3, a mass flow controller 4, and the gas supply hose 3 are connected to the air hole 6 on the cavitation drag reduction single hull model 5 in sequence.

[0049] Step 2: Open the valve of industrial oxygen cylinder 1 and rotate the valve of pressure reducing valve 2 to control the output pressure in the range of 300kPa to 400kPa. Set the oxygen flow value of mass flow controller 4. Start the data acquisition equipment and record the test parameters, including resistance, heave, trim, etc.

[0050] Step 3: Start the trailer, which drives the cavitation drag reduction single hull model 5 to reach the test speed, start the mass flow controller 4, and within 0.1 seconds, oxygen is transported to the air hole 6 through the gas hose 3, so that a thin air layer is formed and maintained after the cavitation drag reduction single hull model 5 is broken, that is, the cavitation drag reduction area, to achieve the purpose of drag reduction.

[0051] Step 4: After the test speed stabilizes for about 5 to 10 seconds, stop the mass flow controller input, stop the trailer, stop the collection equipment, close the valve of the pressure reducing valve 2, and close the valve of the industrial oxygen cylinder 1.

[0052] The protection scope of the present invention is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the scope of the present invention. If these changes and modifications fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and modifications.

Claims

1. A single-hull model test device for cavitation drag reduction of a water-surface aircraft, characterized in that: The invention comprises an industrial oxygen cylinder (1), on which a pressure reducing valve (2) is arranged, wherein the pressure reducing valve (2), a gas delivery hose (3), a front straight pipe (4-1), a mass flow controller (4), and a rear straight pipe (4-2) are connected in sequence, and the rear straight pipe (4-2) is connected to an air hole (6) on a cavitation drag reduction single hull model (5) through another gas delivery hose (3).

2. A single-hull model test device for cavitation drag reduction of a water surface aircraft as claimed in claim 1, characterized in that: The industrial oxygen cylinder (1) releases industrial oxygen through a pressure reducing valve (2), and controls the output gas pressure within the range of 300 kPa to 400 kPa.

3. A single-hull model test device for cavitation drag reduction of a water-surface aircraft as claimed in claim 1, characterized in that: The inner diameter of the gas delivery hose (3) is greater than 20 mm.

4. A single-hull model test device for cavitation drag reduction of a water-surface aircraft as claimed in claim 1, characterized in that: The mass flow controller (4) can reach the set output gas flow rate within 0.1 s.

5. A single-hull model test device for cavitation drag reduction of a water-surface aircraft as claimed in claim 1, characterized in that: The length of the front straight pipe (4-1) is greater than 10 times the diameter of the pipeline.

6. A single-hull model test device for cavitation drag reduction of a water-surface aircraft as claimed in claim 1, characterized in that: The length of the rear straight pipe (4-2) is greater than 2.5 times the diameter of the pipeline.

7. A single-hull model test device for cavitation drag reduction of a water-surface aircraft as claimed in claim 1, characterized in that: The front straight pipe (4-1) and the rear straight pipe (4-2) are both made of metal hard straight pipes.

8. A single-hull model test device for cavitation drag reduction of a water-surface aircraft as claimed in claim 1, characterized in that: There are a number of pores (6) evenly distributed at a position 30 mm after the step.

9. A single-hull model test device for cavitation drag reduction of a water-surface aircraft as claimed in claim 8, characterized in that: Each air hole (6) is connected to a separate rear straight pipe (4-2); or the rear straight pipe (4-2) is connected to a corresponding number of gas delivery hoses (3) via a connector having a plurality of joints and then connected to the air hole (6), and all the air holes (6) are connected to the gas delivery hoses (3).

10. A test method using a single-hull model test device for cavitation drag reduction of a water surface aircraft as claimed in any one of claims 1 to 9, characterized in that: The steps include: Step 1: Open the valve of the industrial oxygen cylinder (1), rotate the valve of the pressure reducing valve (2) so that the output gas pressure is controlled within the set range; set the oxygen flow value of the mass flow controller (4), start the data acquisition device, and record the test parameters, which include resistance, heave, and trim; Step 2: Start the trailer, the trailer drives the cavitation drag reduction single hull model (5) to reach the test speed, start the mass flow controller (4), oxygen is transported to the air hole (6) through the air delivery hose (3), so that a thin air layer is formed and maintained after the cavitation drag reduction single hull model (5) is broken; Step 3: After the test speed is stable for about 5 to 10 seconds, stop the mass flow controller (4) input, stop the trailer, stop the data acquisition equipment, close the valve of the pressure reducing valve (2), and close the valve of the industrial oxygen cylinder (1).

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