Wake flow continuous scanning and measuring device for temporary impact type wind tunnel airfoil test and use method of wake flow continuous scanning and measuring device

Abstract

The invention discloses a wake flow continuous scanning and measuring device for a transient wind tunnel airfoil test and a use method, and belongs to the technical field of wind tunnel tests. The problem that the test requirement of any airfoil profile cannot be met in the prior art is solved. The technical key points are as follows: the wake flow continuous scanning rake and the middle part of the up-down sliding carriage are both in a wind tunnel, and a universal joint is fixedly connected to the middle of the front edge of the up-down sliding carriage; the up-down sliding rail is installed on the wind tunnel shell, and the upper end and the lower end of the up-down sliding carriage are in sliding fit with the up-down sliding rail through the up-down sliding chute; the electric cylinder is installed on the wind tunnel shell, the top of the up-down sliding carriage is fixedly connected with the bottom of the electric cylinder, the horizontal sliding groove of the horizontal sliding block is installed on the wind tunnel shell, the upper end of the lever is hinged to the horizontal sliding block, and the lower end of the lever is hinged to the top of the up-down sliding carriage. The driving system is high in control precision and small in interference to the flow field, and has the advantages that wake flow parameter measuring points are accurately positioned, the number of the measuring points can be infinitely encrypted, and the obtained wing type wake flow field parameters are rich.

Description

Technical Field

[0001] This invention relates to the field of wind tunnel testing technology, specifically to a wake continuous scanning measurement device and its usage method for airfoil testing in a transient wind tunnel. Background Technology

[0002] Airfoil testing is a routine test in wind tunnel testing, and airfoil drag is one of the key measurement parameters in airfoil testing. In 1-meter-class transient wind tunnels, due to the small tunnel size and short blowing time, fixed total and static pressure rakes (commonly called fixed wake measurement rakes) are generally used to measure the flow field parameters in the airfoil wake. The wake measurement rake is typically designed in a "1" shape, consisting of dozens or even hundreds of total pressure tubes, several static pressure tubes, and a rake support. During the test, the "1" rake is vertically supported behind the airfoil model at an appropriate distance and fixed in place. This allows for the measurement of the total and static pressure distribution of the flow field in the vertical plane of the airfoil wake region, thereby calculating the drag and drag coefficient of the airfoil model. The accuracy of airfoil drag measurement depends primarily on the design of the wake measurement rake. The height of the wake measurement rake needs to be able to capture the entire airfoil wake. For airfoil tests at high angles of attack, the wake region is larger, requiring a larger wake measurement rake.

[0003] However, using a fixed wake measurement rake in a 1-meter-scale transient wind tunnel has several limitations: First, the pressure changes in the airfoil wake in the vertical plane near the airfoil's trailing edge are drastic. Installing the wake measurement rake close to the airfoil model results in an overly narrow pressure distribution in the measured airfoil wake, compromising the accuracy of the obtained airfoil drag. Therefore, the wake measurement rake needs to be installed at an appropriate location away from the airfoil model. The wake height in the vertical plane increases dramatically away from the airfoil, requiring sufficient height from the rake to capture the flow field parameters across the entire vertical wake region. Increasing the rake height weakens its stiffness, increasing its blockage and affecting the pressure distribution at the airfoil's trailing edge, thus distorting the measurement results.

[0004] Secondly, to obtain sufficient airfoil wake parameters, besides needing a sufficiently tall wake measurement rake to capture the flow field parameters of the entire vertical wake region, the total pressure tubes of the wake measurement rake should be arranged as densely as possible to improve the accuracy of the airfoil drag calculation results. However, if the total pressure tubes are too dense, interference will occur between them, affecting the accuracy of pressure measurement. Therefore, with a limited number of total pressure tubes, the accuracy of the airfoil drag calculation results is relatively low. It is necessary to design and manufacture wake measurement rakes that match the chord length of the airfoil model and the required angle of attack for different chord lengths and test angles of attack.

[0005] Therefore, there is an urgent need to propose a wake continuous scanning measurement device and its usage method for transient wind tunnel airfoil testing, in order to solve the problem that the existing technology cannot meet the testing requirements of arbitrary airfoils. Summary of the Invention

[0006] In view of the above facts, in order to solve the problem that the prior art cannot meet the requirements of arbitrary airfoil testing, the present invention designs a wake continuous scanning measurement device and a method of using it for transient wind tunnel airfoil testing.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] Option 1: A wake continuous scanning measurement device for transient wind tunnel airfoil testing, including a wake continuous scanning rake and a drive system;

[0009] The wake continuous scanning rake includes a total pressure pipe, a static pressure pipe, a rake body, a support rod, a universal connector, a pin hole, and fixing screws;

[0010] The drive system includes an upper and lower sliding slide plate, an upper and lower sliding rail, a horizontal slider, a lever, and an electric cylinder;

[0011] The middle part of the wake continuous scanning rake and the upper and lower sliding slides are both inside the wind tunnel, and the universal connector is fixedly connected to the middle of the front edge of the upper and lower sliding slides.

[0012] The upper and lower sliding rails are installed on the wind tunnel shell, and the upper and lower ends of the upper and lower sliding slide plates slide in cooperation with the upper and lower sliding rails through the upper and lower sliding grooves.

[0013] The electric cylinder is mounted on the wind tunnel housing, and the top of the upper and lower sliding slide is fixedly connected to the bottom of the electric cylinder. The upper and lower sliding slide moves up and down along the vertical plane.

[0014] The horizontal slide groove of the horizontal slider is installed on the wind tunnel housing. The horizontal slider slides horizontally in the horizontal slide groove. The upper end of the lever is hinged to the horizontal slider, and the lower end of the lever is hinged to the top of the upper and lower sliding slide plates.

[0015] The upper and lower sliding plates, upper and lower sliding rails, horizontal sliders, and levers are all on the same plane.

[0016] Furthermore: the total pressure pipe and the static pressure pipe are respectively connected to the rake body, the rake body is connected to the support rod by fixing screws, and the support rod is connected to the universal connector by pin holes for positioning.

[0017] Furthermore: the tip length of the total pressure pipe is 35mm;

[0018] The tip length of the static pressure tube is 60 mm.

[0019] Furthermore, the universal connector is fixedly connected to the upper and lower sliding plates in a conical fit.

[0020] Furthermore, the upper and lower sliding plates have a leading edge wedge structure with a wedge angle of 30° and a thickness of 140mm.

[0021] Furthermore, the electric cylinder has a stroke of 1200mm, an accuracy of ±0.01mm, and a speed range of 0-400mm / s.

[0022] Option 2: A method for using the wake continuous scanning measurement device for the transient wind tunnel airfoil test described in Option 1, specifically as follows:

[0023] Step 1: Preset the angle of attack to the first angle of attack required for the test, and continuously scan the wake with the rake facing the airfoil;

[0024] Step 2: The electric cylinder extends, the upper and lower sliding plates sink down, the upper and lower sliding plates move horizontally along the upper and lower sliding rails, the rear end of the lever swings down with the upper and lower sliding plates, driving the horizontal slider to slide horizontally backward, driving the wake continuous scanning rake to sink to near the lower wall of the wind tunnel test section.

[0025] Step 3: The wind tunnel is started. After the flow field is established, data acquisition begins. After the data at the current position is collected, the electric cylinder retracts, the upper and lower sliding slides rise, the upper and lower sliding slides move horizontally along the upper and lower sliding rails, the rear end of the lever swings up with the upper and lower sliding slides, driving the horizontal slider to slide forward horizontally, driving the wake continuous scanning rake to rise.

[0026] Step 4: The wake continuous scanning rake rises to the next position to collect data until the wake continuous scanning rake rises to near the upper wall of the wind tunnel test section.

[0027] Step 5: When the test is completed, preset the angle of attack to the next angle of attack position required by the test, and repeat steps 2 to 4 until all tests are completed.

[0028] Furthermore, in step five, the rotating window on the rotating test section drives the airfoil installed on the rotating window to rotate, thereby changing the angle of attack.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. Except for the middle part of the upper and lower sliding slides, the rest of the drive system of the present invention is located outside the wind tunnel, and the upper and lower sliding slides are located downstream of the airfoil, thus avoiding interference of the device with the flow field.

[0031] 2. The drive system of the present invention has high control precision and has the advantages of accurate positioning of wake parameter measurement points, infinitely fine-grained number of measurement points, and rich airfoil wake flow field parameters.

[0032] 3. This invention achieves stepless continuous scanning measurement of the wake sweeper in the vertical plane by driving an electric cylinder, obtaining a sufficient number of airfoil wake flow field parameters. The position of a set of pin holes on the rear section of the support rod can be adjusted to meet the different spacing requirements between the wake sweeper and the airfoil. The wake sweeper can meet the testing requirements of any airfoil and has strong applicability. Attached Figure Description

[0033] Figure 1 This is a general structural diagram of the present invention;

[0034] Figure 2 This is a diagram showing the positional relationship between the wake continuous scanning rake and the drive system in this invention;

[0035] Figure 3 This is a schematic diagram showing the dimensions of the total pressure pipe in this invention;

[0036] Figure 4 This is a schematic diagram showing the dimensions of the static pressure tube in this invention;

[0037] Figure 5 A comparison diagram of the pressure coefficients at two points on the trailing edge of the upper surface of an airfoil;

[0038] Figure 6 A comparison diagram of the pressure coefficients at two points on the trailing edge of the lower surface of the airfoil;

[0039] Figure 7 This is a comparison chart of airfoil wake curves.

[0040] In the diagram: 1-Main pressure pipe, 2-Static pressure pipe, 3-Rake body, 4-Support rod, 5-Universal connector, 6-Pin hole, 7-Fixing screw, 8-Up and down sliding slide plate, 9-Up and down sliding rail, 10-Horizontal slider, 11-Lever, 12-Electric cylinder, 13-Wind tunnel shell, 14-Test section, 15-Upper wall panel of test section, 16-Lower wall panel of test section, 17-Airfoil, 18-Rotating window. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0042] The terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0045] Example 1: Reference Figures 1 to 4 This embodiment describes the wake continuous scanning measurement device for the transient wind tunnel airfoil test, which includes a wake continuous scanning rake and a drive system.

[0046] The wake continuous scanning rake includes a total pressure pipe 1, a static pressure pipe 2, a rake body 3, a support rod 4, a universal connector 5, a pin hole 6, and a fixing screw 7.

[0047] The drive system includes an upper and lower sliding slide plate 8, an upper and lower sliding rail 9, a horizontal slider 10, a lever 11, and an electric cylinder 12;

[0048] The middle part of the wake continuous scanning rake and the upper and lower sliding slides 8 are both inside the wind tunnel, and the universal connector 5 is fixedly connected to the middle of the front edge of the upper and lower sliding slides 8.

[0049] The upper and lower sliding rails 9 are installed on the wind tunnel housing 13, and the upper and lower ends of the upper and lower sliding slide plates 8 are slidably engaged with the upper and lower sliding rails 9 through the upper and lower sliding grooves.

[0050] The electric cylinder 12 is installed on the wind tunnel housing 13, and the top of the upper and lower sliding slide 8 is fixedly connected to the bottom of the electric cylinder 12. The upper and lower sliding slide 8 moves up and down along the vertical plane.

[0051] The horizontal slide groove of the horizontal slider 10 is installed on the wind tunnel housing 13. The horizontal slider 10 slides horizontally in the horizontal slide groove. The upper end of the lever 11 is hinged to the horizontal slider 10, and the lower end of the lever 11 is hinged to the top of the upper and lower sliding slide plate 8.

[0052] The upper and lower sliding slide plate 8, the upper and lower sliding rail 9, the horizontal slider 10, and the lever 11 are all on the same plane.

[0053] More specifically: the total pressure pipe 1 and the static pressure pipe 2 are respectively connected to the rake body 3, the rake body 3 is connected to the support rod 4 by fixing screws 7, and the support rod 4 is connected to the universal connector 5 by pin holes 6.

[0054] More specifically: the tip length of the total pressure pipe 1 is 35mm;

[0055] The tip length of the static pressure pipe 2 is 60mm.

[0056] More specifically: the universal connector 5 and the upper and lower sliding plates 8 are fixedly connected in a conical fit.

[0057] More specifically: the upper and lower sliding slide plate 8 has a leading edge wedge structure with a wedge angle of 30° and a thickness of 140mm.

[0058] More specifically: the electric cylinder 12 has a stroke of 1200mm, an accuracy of ±0.01mm, and a speed range of 0-400mm / s, which meets the requirements for measuring the wake of airfoils in 1-meter-scale transient wind tunnel tests.

[0059] More specifically: the electric cylinder 12 is the power unit of the drive system.

[0060] More specifically: the upper and lower sliding rails 9 can ensure that the upper and lower sliding slide plates 8 move up and down on a fixed vertical plane, thereby realizing the continuous scanning of the wake rake moving up and down on a fixed vertical plane, and finally realizing the continuous scanning measurement of the airfoil wake.

[0061] More specifically: After the wake continuous scanning rake is installed, the total pressure pipe 1 and the static pressure pipe 2 are aligned with the airflow. The wake continuous scanning rake at the middle of the leading edge of the upper and lower sliding slide plate 8 is driven by the electric cylinder 12 to continuously scan and measure the flow field parameters in the wake region of the airfoil in the vertical plane downstream of the airfoil model.

[0062] Example 2: A method for using the wake continuous scanning measurement device for the transient wind tunnel airfoil test described in Example 1, specifically as follows:

[0063] Step 1: Preset the angle of attack to the first angle of attack position required for the test, and continuously scan the wake with the rake facing the airfoil 17.

[0064] Step 2: The electric cylinder 12 extends, the upper and lower sliding slide plate 8 sinks, the upper and lower sliding slide plate 8 moves horizontally along the upper and lower sliding slide rail 9, the rear end of the lever 11 swings down with the upper and lower sliding slide plate 8, driving the horizontal slider 10 to slide horizontally backward, driving the wake continuous scanning rake to sink to near the lower wall plate 16 of the test section.

[0065] Step 3: The wind tunnel is started. After the flow field is established, data acquisition begins. After the data at the current position is collected, the electric cylinder 12 retracts, the upper and lower sliding slide plate 8 rises, the upper and lower sliding slide plate 8 moves horizontally along the upper and lower sliding rail 9, and the rear end of the lever 11 swings up with the upper and lower sliding slide plate 8, driving the horizontal slider 10 to slide forward horizontally, driving the wake continuous scanning rake to rise.

[0066] Step 4: The wake continuous scanning rake rises to the next position to collect data until the wake continuous scanning rake rises to a position close to the upper wall of the test section at 15.

[0067] Step 5: When the test is completed, preset the angle of attack to the next angle of attack position required by the test, and repeat steps 2 to 4 until all tests are completed.

[0068] More specifically: In step five, the rotating window 18 on the rotating test section 14 drives the airfoil 17 installed on the rotating window 18 to rotate, thereby changing the angle of attack.

[0069] More specifically: During the test, the continuous wake scanning rake can start from outside the wake region and gradually scan the wake region from top to bottom (or from bottom to top). The size of the scanning area can be adjusted according to the local airfoil wake region height, and the scanning step length can be adjusted according to the measurement requirements. Finally, the total and static pressure values ​​in the airfoil wake region are obtained, and the airfoil drag is calculated by the momentum method.

[0070] More specifically: For airfoil tests with different chord lengths, the pin hole 6 at the rear end of the support rod 4 along the axial direction can be adjusted to meet the different spacing requirements between the wake continuous scanning rake and the airfoil 17.

[0071] More specifically: the formula for the pressure coefficient is:

[0072] ;

[0073] in: This corresponds to the pressure coefficient;

[0074] The static pressure (Pa) at the measurement point;

[0075] The static pressure (Pa) of the incoming flow into the wind tunnel;

[0076] q represents the inflow velocity pressure in the wind tunnel (Pa);

[0077] q=0.7 ;

[0078] in: For the Mach number of the wind tunnel flow;

[0079] The formula for calculating the drag coefficient using the momentum method is:

[0080] ;

[0081] in: This refers to the airfoil drag coefficient;

[0082] C is the airfoil chord length (m);

[0083] wl is the integration region, i.e., the tail region;

[0084] As resistance;

[0085] The drag coefficient of the wake region;

[0086] ;

[0087] in: The total pressure in the wake region (Pa);

[0088] The total pressure of the wind tunnel incoming flow (Pa);

[0089] The static pressure (Pa) of the incoming flow into the wind tunnel;

[0090] P is the average static pressure (Pa) in the wake region.

[0091] k is 1.4.

[0092] More specifically: Reference Figures 5 to 7 Comparison of experimental results between continuous wake scanning measurement device and fixed wake measurement rake:

[0093] A: The fixed wake measurement rake has a large height and a large degree of blockage, which affects the pressure distribution at the trailing edge of the airfoil, and the measured values ​​are somewhat different from those without a wake rake.

[0094] The wake continuous scanning measurement device has the advantages of minimal impact on the flow field and high accuracy in wake parameter measurement. The data obtained by the wake continuous scanning measurement device is more consistent with the data without a wake rake.

[0095] B: The wake continuous scanning rake of the wake continuous scanning measurement device is small in size, and its drive system is set outside the wind tunnel shell, which has little interference with the flow field. Its measurement step size can be infinitely refined, and the distance between the wake continuous scanning measurement device and the airfoil can be adjusted according to the requirements.

[0096] C: The wake continuous scanning measurement device has high control precision, and has the advantages of accurate positioning of wake parameter measurement points, infinitely increasing the number of measurement points to obtain a sufficient number of airfoil wake flow field parameters, and more rounded and smooth airfoil wake curves (the curve in the figure is more rounded and smooth). Moreover, the device can meet the test requirements of any airfoil and size, and has strong applicability.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; as long as there is no structural conflict, the various features in the specific embodiments disclosed in this application can be combined with each other in any way, and will not cause the substance of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

[0098] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A continuous scanning measurement device for the wake of a transient wind tunnel airfoil test, characterized in that, Includes wake continuous scanning rake and drive system; The wake continuous scanning rake includes a total pressure pipe (1), a static pressure pipe (2), a rake body (3), a support rod (4), a universal connector (5), a pin hole (6), and a fixing screw (7); The drive system includes an upper and lower sliding slide plate (8), an upper and lower sliding rail (9), a horizontal slider (10), a lever (11), and an electric cylinder (12). The middle part of the wake continuous scanning rake and the upper and lower sliding slides (8) are both inside the wind tunnel, and the universal connector (5) is fixedly connected to the middle of the front edge of the upper and lower sliding slides (8). The upper and lower sliding rails (9) are installed on the wind tunnel shell (13), and the upper and lower ends of the upper and lower sliding slide plates (8) are slidably engaged with the upper and lower sliding rails (9) through the upper and lower sliding grooves; The electric cylinder (12) is installed on the wind tunnel shell (13), and the top of the upper and lower sliding slide (8) is fixedly connected to the bottom of the electric cylinder (12). The upper and lower sliding slide (8) moves up and down along the vertical plane. The horizontal slide groove of the horizontal slider (10) is installed on the wind tunnel housing (13). The horizontal slider (10) slides horizontally in the horizontal slide groove. The upper end of the lever (11) is hinged to the horizontal slider (10), and the lower end of the lever (11) is hinged to the top of the upper and lower sliding plates (8). The upper and lower sliding slide (8), upper and lower sliding rail (9), horizontal slider (10), and lever (11) are all on the same plane.

2. The wake continuous scanning measurement device for transient wind tunnel airfoil testing according to claim 1, characterized in that, The total pressure pipe (1) and static pressure pipe (2) are respectively connected to the rake body (3), the rake body (3) is connected to the support rod (4) by fixing screws (7), and the support rod (4) is connected to the universal connector (5) by pin holes (6).

3. The wake continuous scanning measurement device for transient wind tunnel airfoil testing according to claim 2, characterized in that, The tip length of the main pressure pipe (1) is 35 mm; The tip length of the static pressure tube (2) is 60 mm.

4. The wake continuous scanning measurement device for transient wind tunnel airfoil testing according to claim 1, characterized in that, The universal connector (5) is fixedly connected to the upper and lower sliding plates (8) in a conical fit.

5. The wake continuous scanning measurement device for transient wind tunnel airfoil testing according to claim 1, characterized in that, The upper and lower sliding slide (8) has a leading edge wedge structure with a wedge angle of 30° and a thickness of 140mm.

6. The wake continuous scanning measurement device for transient wind tunnel airfoil testing according to claim 1, characterized in that, The electric cylinder (12) has a stroke of 1200mm, an accuracy of ±0.01mm, and a speed range of 0-400mm / s.

7. A method of using the wake continuous scanning measurement device for the transient wind tunnel airfoil test as described in claim 1, characterized in that, Specifically: Step 1: Set the angle of attack to the first angle of attack position required for the test, and continuously scan the wake with the rake facing the airfoil (17). Step 2: The electric cylinder (12) extends, the upper and lower sliding slide (8) sinks, the upper and lower sliding slide (8) moves horizontally along the upper and lower sliding rail (9), the rear end of the lever (11) swings down with the upper and lower sliding slide (8), driving the horizontal slider (10) to slide horizontally backward, driving the wake continuous scanning rake to sink to the lower wall plate (16) near the wind tunnel test section. Step 3: The wind tunnel is started. After the flow field is established, data acquisition begins. After the data at the current position is collected, the electric cylinder (12) is retracted, the upper and lower sliding slide (8) rises, the upper and lower sliding slide (8) moves along the upper and lower sliding rail (9), and the rear end of the lever (11) swings up with the upper and lower sliding slide (8), driving the horizontal slider (10) to slide forward horizontally, driving the wake continuous scanning rake to rise. Step 4: The wake continuous scanning rake rises to the next position to collect data until the wake continuous scanning rake rises to the position close to the upper wall panel (15) of the wind tunnel test section; Step 5: When the test is completed, preset the angle of attack to the next angle of attack position required by the test, and repeat steps 2 to 4 until all tests are completed.

8. The method of using the wake continuous scanning measurement device for transient wind tunnel airfoil testing according to claim 7, characterized in that, In step five, the rotating window (18) on the rotating test section (14) drives the airfoil (17) installed on the rotating window (18) to rotate, thereby changing the angle of attack.

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