A flow parameter measuring device and measuring method suitable for a wide range of angles of attack

Abstract

The application discloses a flow parameter measuring device and method suitable for a wide range of angles of attack, and the measuring device comprises a ball head, a connecting rod, a pressure sensor and a data processing system; the pressure distribution on the surface of the ball head can be measured through the pressure sensor arranged on the ball head; the windward area is determined by the pressure data processing system, and the position of the stagnation point and the flow dynamic pressure are determined according to the position and the pressure measurement value of the multiple measuring points with the maximum pressure measurement value in the windward area, so that the flow speed direction and size are obtained. The measuring device of the application has no moving parts, is simple in structure and high in reliability, and solves the problem of quickly and accurately obtaining flow parameters when the moving device moves in a wide range of angles of attack.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of flow parameter measurement, and relates to a flow parameter measurement device and method suitable for a wide range of angles of attack. BACKGROUND

[0002] Fluid motion exists widely in daily life and is closely related to many fields such as aviation, aerospace, environment, chemistry, biology, medicine, machinery, transportation and the like. In order to study the law of fluid motion and apply the law to production and life practice, it is necessary to accurately measure parameters such as velocity, direction and pressure of flow.

[0003] In the fields of aviation and wind tunnel test, the prior art usually uses an air speed tube and a multi-hole probe to measure the magnitude and direction of flow velocity. The air speed tube includes a total pressure tube, a static pressure tube, a wind vane and the like. According to the measured total pressure and static pressure, the flow velocity magnitude of a moving device is calculated from the Bernoulli equation of incompressible flow. The angle of attack and the angle of sideslip are measured by the wind vane to determine the flow velocity direction of the moving device. The multi-hole probe is in the shape of a cylinder as a whole, with a conical, faceted or hemispherical tip and three, five or seven pressure measuring holes. According to the pressure test values measured by each hole, the flow velocity, direction and the like can be calculated by substituting the values into a specific probe algorithm.

[0004] With the increasing application of flow by human beings, the flow problems studied are becoming more and more complex, and therefore the demand for measurement of flow parameters is becoming increasingly urgent. In the field of aviation, the situation of large angle of attack of aircraft is becoming more and more common. The angle of attack of the domestic J-20 fighter aircraft can reach more than 110° when performing "cobra maneuver". In order to study the aerodynamic and handling characteristics of the aircraft under the condition of large angle of attack, it is necessary to quickly and accurately measure the velocity, pressure and the like of complex flow under large angle of attack. In the field of wind tunnel test, in order to accurately reproduce complex flow in real environment, it is also necessary to accurately measure the parameters of complex flow. The complex flow comes from all directions, so that the flow stagnation point is no longer directly opposite the pressure measuring holes of the air speed tube and the multi-hole probe, which affects the measurement accuracy.

[0005] In view of the problem, the air speed tube increases the chamfer and guide sleeve of the total pressure tube in order to improve the insensitivity of the total pressure tube to the direction of airflow and increase the measurement accuracy. However, the chamfer significantly weakens the structural strength, and the guide sleeve increases the structural complexity, which is not effective. In addition, the wind vane of the air speed tube has moving parts such as blades and shafts. The moment of inertia of the blades and the frictional damping of the shafts reduce the measurement accuracy and response speed, which is difficult to meet the requirements of accurate measurement of complex flow. The multi-hole probe increases the number of pressure measuring holes to improve the measurement accuracy. However, after increasing the number of pressure measuring holes, the workload of calibration test and data processing is significantly increased, which greatly increases the calibration cost. Moreover, the angle of attack that can be measured by the multi-hole probe does not exceed 90°, which is difficult to meet the measurement demand of airflow from all directions. SUMMARY

[0006] To address the issue of low accuracy in measuring complex flows using existing flow parameter measurement devices, this invention provides a flow parameter measurement device and method for a wide angle-of-attack range. This device and method are suitable for measuring fluid parameters such as velocity and pressure. The device has no moving parts, a simple structure, and high reliability, maintaining high measurement accuracy and speed across a wide angle-of-attack range.

[0007] To address the aforementioned problems, one aspect of the present invention provides a flow parameter measuring device suitable for a wide angle of attack range, comprising a ball head, a connecting rod, a pressure sensor, and a data processing system;

[0008] The ball head is connected to the motion device via a connecting rod; a pressure sensor is located on the ball head.

[0009] Optionally, multiple pressure sensors may be provided.

[0010] Optionally, the angle between the lines connecting two adjacent pressure sensors to the center of the ball head is no greater than 35°.

[0011] Optionally, the ball head is a hollow sphere, and the connecting rod is a hollow tube.

[0012] In another aspect, the present invention provides a flow parameter measurement method applicable to a wide angle of attack range, using the aforementioned flow parameter measurement device, and the specific steps are as follows:

[0013] Obtain the pressure distribution at the ball head;

[0014] The location, pressure, and dynamic pressure of the stagnation point are obtained based on the pressure distribution at the ball head.

[0015] The direction and magnitude of the flow velocity around the spherical head are obtained based on the location, pressure, and hydrodynamic pressure of the stagnation point.

[0016] Optionally, based on the obtained pressure distribution of the ball head, the position of the reverse pressure gradient is obtained, and the windward region of the ball head is determined according to the position of the reverse pressure gradient. The pressure sensors with the highest pressure test values ​​in the windward region are selected, and the stagnation point position and the flow dynamic pressure around the ball head are determined according to their positions and pressure test values.

[0017] Optionally, the selected pressure sensor position is the angle ψ between the line connecting the selected pressure sensor and the center position O of the ball head, and the line connecting the stagnation point position and the center position O. i The expression is:

[0018]

[0019] Where, ψ iis the angle between the line connecting the i-th selected pressure sensor and the ball center position O and the line connecting the stagnation point position and the ball center position O, i=1, 2, …, N, N is the total number of selected pressure sensors; is the coordinate of the stagnation point position, θ0is the pitch angle of the stagnation point position, is the azimuth angle of the stagnation point position; is the coordinate of the i-th selected pressure sensor; θ i is the pitch angle of the i-th selected pressure sensor, is the azimuth angle of the i-th selected pressure sensor; |r0| is the distance from the stagnation point to the origin; |r i is the distance from the i-th selected pressure sensor to the origin;

[0020] The expression of the pressure test value of the selected pressure sensor is:

[0021]

[0022] wherein, p i is the pressure test value of the i-th selected pressure sensor; p0is the stagnation point pressure; q is the dynamic pressure of the flow around the ball head;

[0023] The obtained position and pressure test value of the plurality of selected pressure sensors are substituted into equations (1) and (2), so as to calculate the stagnation point position coordinate r0and the dynamic pressure q of the flow around the ball head.

[0024] Optionally, the flow velocity direction around the ball head is obtained based on the obtained stagnation point position coordinate r0.

[0025] The flow velocity direction around the ball head includes the angle of attack α and the sideslip angle β, and the expression is:

[0026]

[0027]

[0028] wherein, the angle of attack α represents the angle between the projection of the flow velocity around the ball head in the xz plane and the -x axis, and the sideslip angle β represents the angle between the flow velocity around the ball head and its projection in the xz plane.

[0029] Optionally, the flow velocity V pre around the ball head is estimated based on the obtained dynamic pressure q of the flow around the ball head, and the expression is:

[0030]

[0031] wherein, ρ is the atmospheric density.

[0032] Optionally, based on the measurement data of the plurality of selected pressure sensors, the inverse pressure gradient position and the angle ψ sep; the angle ψ of separation of the flow around the ball head according to the position of the adverse pressure gradient sep obtaining a flow Reynolds number Re; determining a correction coefficient K of the flow velocity according to the flow Reynolds number Re; obtaining a corrected flow velocity V according to the correction coefficient, the expression being:

[0033] V = K · V pre .(5)

[0034] In specific use, the flow parameter measuring device of the application obtains the pressure distribution data of the ball head through the pressure sensor; determines the stagnation point pressure p0, the flow dynamic pressure q and the stagnation point position further determines the velocity angle of attack a and the side slip angle β; the pressure distribution data is analyzed by the pressure data processing system to determine the position of the adverse pressure gradient, and the angle ψ of separation of the flow around the ball head is obtained sep , in combination with the experimental / numerical simulation results of the flow around the ball head, the flow Reynolds number Re is estimated; the flow velocity V is obtained according to the flow dynamic pressure q and the Reynolds number Re.

[0035] The application has at least the following beneficial effects:

[0036] (1) The flow parameter measuring device and the measuring method of the application can measure the flow parameters only by arranging the ball head, the pressure sensor, the connecting rod and the pressure data processing system, without movable parts, and have simple structure and high reliability, and are not easily affected by the environment.

[0037] (2) The flow parameter measuring device and the measuring method of the application have small ball head diameter, and thus have small disturbance to the fluid flow, and can improve the measurement accuracy.

[0038] (3) The flow parameter measuring device and the measuring method of the application are provided with pressure sensors in all directions of the ball head, and can maintain high measurement accuracy and fast measurement speed in a wide angle of attack range.

[0039] (4) The flow parameter measuring device and the measuring method of the application can solve the flow parameters in real time through the pressure data processing system, have short response time, and can quickly measure the flow parameters such as pressure and velocity.

[0040] In the application, the above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the application. The purposes and other advantages of the application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0041] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0042] Figure 1 A schematic diagram of the measuring device structure of the present application.

[0043] Figure 2 A schematic diagram of the pitch angle θ and azimuth angle φ of a certain point on the spherical head surface.

[0044] Figure 3 A schematic diagram of the pitch angle θ0 and azimuth angle φ0 of the stagnation point position according to the pressure measurement values of the four pressure sensors and and the determination of the stagnation point position and the stagnation point pressure p0.

[0045] Figure 4 A schematic diagram of the angle of attack α and the side slip angle β obtained according to the pitch angle θ0 and azimuth angle φ0 of the stagnation point position.

[0046] Reference signs:

[0047] 1 - spherical head; 2 - connecting rod; 3 - pressure sensor; 4 - data processing system. DETAILED DESCRIPTION

[0048] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which constitute a part of this specification, and are used to explain the principles of the embodiments of the present application, but are not used to limit the scope of the present application.

[0049] One specific embodiment of the present application, as shown in Figures 1-4 discloses a flow parameter measuring device for a wide range of angles of attack, for measuring the flow parameters of a moving device in complex flow, comprising a spherical head 1, a connecting rod 2, a pressure sensor 3 and a data processing system 4; wherein the spherical head 1 is connected to the moving device through the connecting rod 2; the pressure sensor 3 is arranged on the spherical head 1.

[0050] Optionally, to ensure measurement accuracy, the spherical head 1 is arranged in front of the moving device through the connecting rod 2; preferably, the axis of the connecting rod 2 is parallel to the direction of the symmetry axis or the rotation axis of the moving device and points forward.

[0051] Optionally, the diameter of the spherical head 1 is less than 30 mm, so that the spherical head 1 has less interference with the flow of the fluid, which can reduce the measurement response time, improve the measurement accuracy and reduce the manufacturing cost.

[0052] ​​​Optionally, multiple pressure sensors 3 are provided, and the multiple pressure sensors 3 are evenly distributed on the surface of the ball head 1, which can sense the real-time pressure in all directions of the ball head 1. Preferably, the angle between the line connecting two adjacent pressure sensors 3 and the center of the ball head is no greater than 35°, so as to ensure the accuracy of the flow velocity calculation based on the pressure measurement value.

[0053] Optionally, the ball head 1 is a hollow sphere, and the connecting rod 2 is a hollow tube. Each pressure sensor 3 is connected to the data processing system 4 via a signal transmission line passing through the hollow ball head 1 and the connecting rod 2, or via wireless transmission.

[0054] Optionally, the motion device is an airplane; the ball head 1 is positioned directly in front of the nose or wingtip of the airplane via the connecting rod 2; further, the axis of the connecting rod 2 is parallel to the axis of the airplane body and points forward.

[0055] Optionally, the motion device is a wind tunnel testing device; the ball head 1 is set at the position of the wind tunnel testing device to be tested for flow parameters via the connecting rod 2; further, the axis of the connecting rod 2 is parallel to the main axis of the wind tunnel testing device and points upstream of the wind tunnel.

[0056] like Figure 2 As shown, in the spherical coordinate system of ball head 1, the center position O of ball head 1 is the origin, the x-axis is parallel to the axis of connecting rod 2 and points backward, the z-axis is perpendicular to the x-axis and points upward, and the y-axis is determined according to the right-hand rule.

[0057] Another specific embodiment of the present invention, such as Figures 2-4 As shown, a method for measuring flow parameters over a wide angle of attack range is disclosed, and the specific steps are as follows:

[0058] Step 1: Obtain the pressure distribution at the ball head;

[0059] Obtain the pressure test values ​​of multiple pressure sensors 3 on the ball head 1, and obtain the pressure distribution of the ball head from the pressure test values.

[0060] Step 2: Obtain the stagnation pressure, the flow dynamic pressure around the ball head, and the stagnation point location;

[0061] The specific method is as follows:

[0062] Step 21: The data processing system 4 analyzes the pressure distribution of the ball head obtained in Step 1 to obtain the location of the reverse pressure gradient, and determines the windward area of ​​the ball head 1 based on the location of the reverse pressure gradient.

[0063] Step 22: As Figure 3 As shown, select the four pressure sensors with the highest pressure test values ​​in the windward area, and obtain the location and pressure test value of each pressure sensor;

[0064] Step 23: Based on the location of the selected pressure sensor and the pressure test value, determine the stagnation point location, the flow dynamic pressure around the ball head, and the stagnation point pressure;

[0065] The selected pressure sensor position is defined by the angle ψ between the line connecting the selected pressure sensor and the center position O of the ball head, and the line connecting the stagnation point position and the center position O. i The expression is:

[0066]

[0067] in, Let θ be the coordinates of the stationary point, and θ0 be the pitch angle of the stationary point. The azimuth of the station location; Let θ be the coordinate of the i-th selected pressure sensor, where i = 1, 2, ..., N, and N is the total number of selected pressure sensors; i Let i be the pitch angle of the i-th selected pressure sensor. Let |r0| be the azimuth angle of the i-th selected pressure sensor; |r0| is the distance from the stagnation point to the origin; |r i | represents the distance from the i-th selected pressure sensor to the origin;

[0068] Understandably, the pitch angle represents the angle between the line connecting a point on the surface of the ball head and the center of the ball and the x-axis, with an angle range of 0 to π; the azimuth angle represents the angle between the projection of this line onto the yz plane and the y-axis, with an angle range of 0 to 2π.

[0069] The pressure test value p of the i-th selected pressure sensor i The expression is:

[0070]

[0071] Where p0 is the stagnation pressure and q is the dynamic pressure around the ball head.

[0072] By substituting the positions and pressure test values ​​of the four largest selected pressure sensors in the windward region into equations (1) and (2), the stagnation point coordinates r0, the dynamic pressure q around the spherical head, and the stagnation point pressure p0 can be calculated.

[0073] Step 3: As Figure 4 As shown, the direction of the flow velocity around the sphere head is obtained based on the stationary point position coordinates r0 obtained in step 2;

[0074] The direction of the flow velocity around the sphere's head includes the angle of attack α and the sideslip angle β, expressed as:

[0075]

[0076]

[0077] wherein the angle of attack a represents the angle between the projection of the flow velocity around the ball head in the xz plane and the -x axis, and the side slip angle b represents the angle between the flow velocity around the ball head and the projection of the flow velocity in the xz plane.

[0078] Step 4: estimating the flow velocity V based on the dynamic pressure q around the ball head obtained in Step 2 pre , and the expression is:

[0079]

[0080] wherein p is the atmospheric density.

[0081] Step 5: correcting the flow velocity;

[0082] determining the position of the adverse pressure gradient and the angle ψ at which the flow around the ball head separates, based on the positions and pressure test values of the selected pressure sensors corresponding to the at least top 4 pressure test values in the windward region sep , wherein the angle ψ is obtained based on a round ball flow experiment or computational fluid dynamics (CFD) method sep - the Re curve, based on the position of the adverse pressure gradient and the angle ψ at which the flow around the ball head separates sep to estimate the flow Reynolds number Re.

[0083] determining the correction coefficient K of the flow velocity based on the flow Reynolds number Re; the flow Reynolds number Re of the flow around the ball head 1 is about 10 4 ~ 10 5 , and the corresponding correction coefficient is about 0.97~1.03, thereby obtaining the corrected flow velocity V, and the expression is:

[0084] V = K · V pre .(5)

[0085] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical range disclosed by the present application can be easily thought by those skilled in the art, and should be covered within the protection scope of the present application.

Claims

1. A flow parameter measurement method suitable for a wide angle of attack range, using a flow parameter measurement device suitable for a wide angle of attack range, characterized by, The flow parameter measuring device comprises a ball head, a connecting rod, a pressure sensor and a data processing system; the ball head is connected with the motion device through the connecting rod; the pressure sensor is arranged on the ball head; the method comprises the following specific steps: obtaining the pressure distribution of the ball head; obtaining the stagnation point position, the stagnation point pressure and the flow dynamic pressure based on the pressure distribution of the ball head; wherein, based on the obtained pressure distribution of the ball head, the adverse pressure gradient position is obtained, and the windward region of the ball head is determined according to the adverse pressure gradient position; the pressure sensors with the top four pressure test values in the windward region are selected, and the stagnation point position and the flow dynamic pressure around the ball head are determined according to the position and the pressure test value of the pressure sensors; obtaining the flow velocity direction and the flow velocity magnitude around the ball head based on the stagnation point position, the stagnation point pressure and the flow dynamic pressure; wherein, the flow velocity direction around the ball head is obtained based on the pitch and azimuth angles of the obtained stagnation point position; the flow velocity direction around the ball head comprises the angle of attack and the sideslip angle; the flow velocity magnitude is obtained based on the flow dynamic pressure.

2. The flow parameter measurement device of claim 1, wherein, The pressure sensor is arranged in multiple.

3. The flow parameter measurement device of claim 2, wherein, The included angle between the connecting line of the adjacent two pressure sensors and the center position of the ball head is not greater than 35°.

4. The flow parameter measuring device according to any one of claims 1-3, characterized in that, The ball head is a hollow sphere, and the connecting rod is a hollow pipe.

5. The method of claim 1, wherein: The position of the selected pressure sensor is the angle ψ between the line connecting the selected pressure sensor and the ball center position O and the line connecting the stagnation point position and the ball center position O i The expression is: wherein ψ i is the angle between the line connecting the i-th selected pressure sensor and the ball center position O and the line connecting the stagnation point position and the ball center position O, i = 1, 2, …, N, N is the total number of selected pressure sensors; is the coordinate of the stagnation point position, θ0is the pitch angle of the stagnation point position, is the azimuth angle of the stagnation point position; is the coordinate of the i-th selected pressure sensor; θ i is the pitch angle of the i-th selected pressure sensor, is the azimuth angle of the i-th selected pressure sensor; |r0| is the distance from the stagnation point to the origin; |r i is the distance from the i-th selected pressure sensor to the origin; The expression of the pressure test value of the selected pressure sensor is: where p i is the pressure test value of the ith selected pressure sensor; p0is the stagnation pressure; q is the dynamic pressure of the flow around the nose cone. the obtained position and pressure test value of the multiple selected pressure sensors are substituted into formula (1) and (2) to obtain the stagnation point position coordinate r0 and the flow dynamic pressure q around the ball head.

6. The method of measuring of claim 5, wherein: The flow velocity direction around the ball head is obtained based on the obtained stagnation point position coordinate r0; The flow velocity direction around the ball head comprises the angle of attack α and the sideslip angle β, and the expression is: wherein, the angle of attack α represents the included angle between the projection of the flow velocity around the ball head in the xz plane and the -x axis, and the sideslip angle β represents the included angle between the flow velocity around the ball head and its projection in the xz plane.

7. The method of measuring according to claim 6, wherein, The flow velocity is obtained based on the obtained flow dynamic pressure q around the ball head, and the expression is: wherein, ρ is the atmospheric density.

8. The measurement method according to claim 7, characterized in that, determining the inverse pressure gradient position and the angle ψ at which the flow around the bulb head separates based on the measurement data of the plurality of selected pressure sensors sep ; determining the inverse pressure gradient position and the angle ψ at which the flow around the bulb head separates based on the measurement data of the plurality of selected pressure sensors sep obtaining a flow Reynolds number Re; determining a correction factor K for the flow velocity based on the flow Reynolds number Re; obtaining a corrected flow velocity V based on the correction factor, expressed as: V = K · V pre .(5).

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