Experimental device for measuring antifriction effect of wall surface blowing and sucking technology

Abstract

The invention discloses an experimental device for measuring the antifriction effect of a wall surface blowing and sucking technology. The experimental device comprises a perforated plate, a uniform flow cavity, a hollow hard pipe, an air pipe, a three-way adapter, a rolling bearing, a force sensor, a supporting block, an ejector pin and a base. The perforated plate is integrally embedded into a wind tunnel experiment model, the edge is flush with the surface of the experiment model, and tiny gaps are reserved around the perforated plate. The porous plate, the flow uniformizing cavity, the hollow hard pipe and the air pipe jointly form an air flow channel. The two sides of the hollow hard tube are respectively provided with a force sensor, one end of each force sensor is fixed on the supporting block, and the other end of each force sensor contacts with the surface of the hollow hard tube through an ejector pin and applies pre-tightening force to adjust the porous plate to a reasonable position. After a wind tunnel is started, the perforated plate sprays out or sucks gas to change a flow field boundary layer structure on the surface of the perforated plate by adjusting the pressure of an inlet of the gas pipe, and the resistance change of the perforated plate before and after blowing and suction can be calculated according to output signals of the two force sensors, so that the friction reduction effect of the wall surface blowing and suction technology is quantitatively researched.

Description

Technical Field

[0001] The invention relates to a device for measuring friction resistance near a wall surface, in particular to an experimental device for measuring the change of friction resistance on the surface of an aircraft model lifted by wall blowing. Background Art

[0002] Lift-to-drag ratio is one of the important parameters that determine the flight performance and flight revenue of an aircraft. How to achieve long-term and efficient drag reduction at a low cost has always been a key basic issue in the design and development of aircraft. Publicly reported data show that for wide-body aircraft, the fuel revenue brought by each 0.01% drag reduction can reach 2 million yuan / aircraft / year. Frictional drag is one of the main drag components of an aircraft, especially when the flow is in a turbulent state, the frictional drag caused by the turbulent boundary layer can account for up to 50~60% of the total drag of the aircraft. Domestic and foreign studies have shown that delaying the transition by wall suction or raising the boundary layer by wall blowing can effectively reduce the boundary layer friction drag, but the measurement of friction drag under the wall blowing and suction state has always been a major problem that has plagued academia and industry.

[0003] CN110823499A discloses a friction resistance measuring device based on a translational design. The translational design structure is relatively simple, but there are two obvious defects. First, the friction resistance of the linear bearing is much greater than that of the rolling bearing. Second, the physical signal input by the floating plate is directly transmitted to the force sensor without physical amplification. The above two reasons make the friction resistance measuring device based on the translational design only suitable for measuring occasions with relatively large friction resistance. In order to reduce the interference resistance of the supporting mechanism and improve the measurement range of the friction resistance measuring device with a translational design, CN114397050A proposed the idea of ​​using magnetic levitation technology to reduce the movement resistance of the floating plate, and CN116296231A proposed the idea of ​​using air flotation technology to reduce the movement resistance of the floating plate. However, both designs significantly increase the complexity of the system, put forward higher requirements on the size and environment of the wind tunnel, and reduce the versatility of the friction resistance measuring device.

[0004] CN113670567A discloses a friction resistance measuring device based on a rotary design. The advantage of the rotary design is that the force arm of the interference force of the rotary support method such as the knife edge or rolling bearing is much shorter than the friction resistance to be measured, so it can measure extremely small friction resistance values. However, the rotary friction resistance measuring device designed by CN113670567A has a large installation space and is only suitable for wind tunnels with large diameters. It does not have good versatility and cannot measure friction resistance in complex flow control situations such as wall blowing and suction. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide an experimental device for measuring the friction reduction effect of wall blowing and suction technology, that is, an experimental device for measuring the local surface friction resistance of an aircraft test model under the condition of wall blowing or suction control. Based on the rotary design concept, the present invention proposes a method for accurately measuring the local friction resistance of an aircraft test model under the condition of wall blowing and suction. The rotary friction resistance measuring device proposed by the present invention has a compact structure and a small interference torque. It is suitable for various occasions such as small friction resistance and small wind tunnel diameter, and has good measurement accuracy and a wide range of application.

[0006] The technical solution proposed by the present invention is as follows: An experimental device for measuring the friction reduction effect of the wall blowing and suction technology, comprising a porous plate, a uniform flow chamber, a hollow hard tube, an air pipe, a three-way adapter, a rolling bearing, a force sensor, a support block, an ejector pin and a base; The surface of the porous plate is arranged with a regular or irregular micropore array structure according to the experimental requirements, and the porous plate is embedded in the wind tunnel experimental model as a whole; the edge of the porous plate is flush with the surface of the experimental model; and a gap is left between the porous plate and the experimental model. The porous plate, uniform flow cavity, hollow hard tube and air pipe together constitute the air flow path. By adjusting the pressure of the air pipe outlet, the porous plate ejects or inhales gas to change the flow field boundary layer structure on the surface, thereby reducing friction resistance. The geometric centers of the porous plate (, uniform flow cavity, hollow hard tube, and air tube are collinear with the rotation center of the rolling bearing, thereby reducing the interference torque of the reaction force of the airflow; There is a force sensor on each side of the hollow rigid tube, one end of the force sensor is fixed on the support block, and the other end contacts the surface of the hollow rigid tube through a pin and applies a pre-tightening force to adjust the porous plate to a reasonable position; when the wind tunnel is started, the change in friction resistance on the surface of the porous plate before and after blowing and suction is calculated based on the output signals of the two force sensors, thereby quantitatively studying the friction reduction effect of the wall blowing and suction technology.

[0007] In the experimental device for measuring the friction reduction effect of the wall blowing and suction technology, a porous medium material layer is arranged inside the uniform flow chamber to provide a pressure drop to achieve rectification; according to experimental requirements, by adjusting the porosity of each area of ​​the porous medium material layer, a specified blowing or suction mass flow spatial distribution can be achieved on the surface of the porous plate.

[0008] In the experimental device for measuring the friction reduction effect of the wall blowing and suction technology, the gap between the porous plate and the experimental model does not exceed 0.5 mm.

[0009] In the experimental device for measuring the friction reduction effect of the wall blowing and suction technology, the contact point between the ejector pin and the hollow hard tube is set at the bottom of the hollow hard tube near the three-way adapter, and the friction resistance on the surface of the porous plate is physically amplified through the lever effect.

[0010] Compared with the prior art, the advantages of the present invention are: first, the rotational design is adopted to reduce the torque of the interference resistance, and the target signal is physically amplified by the lever effect, so that a smaller friction resistance can be measured; second, the friction resistance measuring device proposed in the present invention adopts a compact design, with a small overall installation space and good versatility, and can be applied to wind tunnel equipment with a smaller caliber; third, the friction resistance measuring device proposed in the present invention is designed for the local friction resistance measurement needs under the situation of complex blowing and suction active flow control on the surface of the aircraft model. The interference torque caused by the blowing and suction reaction forces is avoided through reasonable structural design, and the local friction resistance under the wall blowing and suction conditions can be accurately measured, which can provide an important testing means for the research on the aircraft blowing and suction drag reduction technology and the verification of the drag reduction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0012] Figure 1 It is a schematic structural diagram of the device for measuring the wall blowing and suction friction reduction effect of the present invention.

[0013] Figure 2 It is a schematic diagram of the installation method of the device for measuring the wall blowing and suction friction reduction effect of the present invention.

[0014] Figure 3 It is a top view of the device for measuring the wall blowing and suction friction reduction effect of the present invention.

[0015] Figure 4 for Figure 3 AA section view.

[0016] Explanation of the reference numerals in the accompanying drawings: 1. porous plate; 2. uniform flow chamber; 3. hollow hard tube; 4. air pipe; 5. three-way adapter; 6. rolling bearing; 7. force sensor; 8. support block; 9. ejector pin; 10. base; 11. experimental model; 12. porous medium material layer. DETAILED DESCRIPTION

[0017] The technical solution and detailed description of the present invention will be described as follows with reference to the accompanying drawings. However, the attached drawings are only for illustrative purposes and are not intended to limit the protection scope of the present invention.

[0018] like Figure 1 As shown, an experimental device for measuring the friction reduction effect of wall blowing and suction technology proposed by the present invention includes a porous plate 1, a uniform flow chamber 2, a hollow hard tube 3, an air pipe 4, a three-way adapter 5, a rolling bearing 6, a force sensor 7, a support block 8, a ejector pin 9 and a base 10.

[0019] like Figure 1 , Figure 2 As shown, the surface of the porous plate 1 is arranged with a regular or irregular micropore array structure according to the experimental requirements, and the porous plate 1 is entirely embedded in the wind tunnel experimental model 11. The edge of the porous plate 1 is flush with the surface of the experimental model 11. A small gap is left between the porous plate 1 and the experimental model 11.

[0020] like Figure 1 As shown, there is a force sensor 7 on each side of the hollow rigid tube 3, one end of the force sensor 7 is fixed on the support block 8, and the other end contacts the surface of the hollow rigid tube 3 through the ejector pin 9 and applies a pre-tightening force to adjust the porous plate 1 to a reasonable position. When the wind tunnel is started, the change in friction resistance on the surface of the porous plate 1 before and after blowing and suction can be calculated based on the output signals of the two force sensors 7, so as to quantitatively study the friction resistance reduction effect of the wall blowing and suction technology.

[0021] like Figure 1 , Figure 3 , Figure 4 As shown, the geometric centers of the porous plate 1, the uniform flow chamber 2, the hollow hard tube 3, and the air tube 4 are collinear with the rotation center of the rolling bearing 6, so that the reaction force of the airflow will not cause additional interference torque.

[0022] like Figure 1 As shown, the porous plate 1, the uniform flow chamber 2, the hollow hard tube 3, and the air pipe 4 together constitute an air flow passage. By adjusting the pressure at the outlet of the air pipe 4, the porous plate 1 ejects or inhales gas to change the flow field boundary layer structure on its surface, thereby reducing friction.

[0023] like Figure 3 , Figure 4 As shown, a porous medium material layer 12 is arranged inside the uniform flow chamber 2, and the porous medium material layer 12 is used to provide a larger pressure drop to achieve rectification. According to experimental requirements, the porosity of each area of ​​the porous medium material layer 12 can be adjusted to achieve a specified blowing or suction mass flow spatial distribution on the surface of the porous plate 1.

[0024] like Figure 2 As shown, the tiny gap between the porous plate 1 and the experimental model 11 does not exceed 0.5 mm.

[0025] like Figure 1 As shown, the contact point between the ejector pin 9 and the hollow hard tube 3 is arranged at the bottom of the hollow hard tube 3 near the three-way adapter 5, and the friction resistance on the surface of the porous plate 1 is physically amplified by the lever action.

[0026] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above implementation cases. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. An experimental device for measuring the friction reduction effect of wall blowing and suction technology, characterized in that: The device comprises, in sequence, a porous plate (1), a uniform flow chamber (2), a hollow hard tube (3), an air tube (4), a three-way adapter (5), a rolling bearing (6), a force sensor (7), a support block (8), an ejector pin (9) and a base (10); The surface of the porous plate (1) is arranged with a regular or irregular micropore array structure according to experimental requirements, and the porous plate (1) is entirely embedded in the wind tunnel experimental model (11); the edge of the porous plate (1) is flush with the surface of the experimental model (11); and a gap is left around the porous plate (1) and between the experimental model (11); The porous plate (1), the uniform flow cavity (2), the hollow hard tube (3), and the air pipe (4) together constitute an air flow passage, and the porous plate (1) ejects or inhales gas to change the flow field boundary layer structure on the surface by adjusting the pressure at the outlet of the air pipe (4), thereby achieving friction reduction; The geometric centers of the porous plate (1), the uniform flow chamber (2), the hollow hard tube (3), and the air tube (4) are collinear with the rotation center of the rolling bearing (6), thereby reducing the interference torque of the reaction force of the airflow; A force sensor (7) is provided on each side of the hollow rigid tube (3); one end of the force sensor (7) is fixed on a support block (8); the other end of the force sensor (7) contacts the surface of the hollow rigid tube (3) through a pin (9) and applies a pre-tightening force to adjust the porous plate (1) to a reasonable position; when the wind tunnel is started, the change in friction resistance of the porous plate (1) surface before and after blowing and suction is calculated based on the output signals of the two force sensors (7), thereby quantitatively studying the friction resistance reduction effect of the wall blowing and suction technology.

2. The experimental device for measuring the friction reduction effect of the wall blowing and suction technology as claimed in claim 1, characterized in that: A porous medium material layer (12) is arranged inside the uniform flow chamber (2) to provide a pressure drop to achieve rectification; according to experimental requirements, by adjusting the porosity of each area of ​​the porous medium material layer (12), a specified blowing or suction mass flow spatial distribution can be achieved on the surface of the porous plate (1).

3. The experimental device for measuring the friction reduction effect of the wall blowing and suction technology as claimed in claim 1, characterized in that: The gap between the porous plate (1) and the experimental model (11) does not exceed 0.5 mm.

4. The experimental device for measuring the friction reduction effect of the wall blowing and suction technology as claimed in claim 1, characterized in that: The contact point between the ejector pin (9) and the hollow hard tube (3) is arranged at a position close to the three-way adapter (5) at the bottom of the hollow hard tube (3), and the friction resistance on the surface of the porous plate (1) is physically amplified through the lever action.

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