Total pressure probe with low incoming flow angle sensitivity and calibration method

Abstract

The invention discloses a total pressure probe with low incoming flow angle sensitivity and a calibration method, and relates to the field of high-speed wind tunnel test equipment.The total pressure probe comprises a bent frame, a plurality of mounting holes for mounting sleeve assemblies are formed in the position, matched with an incoming flow surface, of the bent frame, and pressure measuring holes for arranging pressure measuring pipes are formed in the bent frame in the spanwise direction; one side of the cross section of the framed bent is in a water drop shape matched with an incoming flow surface, the other side of the cross section of the framed bent is in an oval shape, a through hole which is communicated with the mounting hole and has the aperture of 3.6 mm is formed in the oval cross section in the chordwise direction, and inclined holes with the aperture of 1.5 mm are symmetrically formed in the left side and the right side of the rear portion of the through hole. According to the total pressure probe with the low incoming flow angle sensitivity and the calibration method provided by the invention, the total pressure probe with the low incoming flow angle sensitivity, which is simple in structure, excellent in performance and reliable in operation, is realized by optimally designing a proper bent frame structure and a sleeve assembly, and the total pressure loss is reduced by more than 10 times compared with that of a traditional probe at a large flow direction angle.

Description

Technical Field

[0001] The present invention relates to the field of high - speed wind tunnel test equipment. More specifically, the present invention relates to a total pressure probe with low sensitivity to the incoming flow angle and a calibration method therefor. Background Art

[0002] In the integrated test of aircraft airframe / inlet / fan, it is necessary to use a turbine - driven fan simulator and accurately measure the total pressure distribution at the fan inlet and outlet. However, due to the small cross - section of the fan outlet, large flow - field distortion, large flow - direction angle, and strong flow pulsation, it is very difficult to measure the outlet pressure distribution. Traditionally, a sheathed probe (also known as a Kirl probe) is used for total pressure measurement at the fan outlet section. The probe consists of a support frame, an outer sleeve, and an inner tube. The inner tube is used for pressure measurement, and the outer sleeve is used for incoming flow rectification to reduce the influence of unsteady and non - uniform flow at the fan inlet and outlet sections.

[0003] However, as Figure 5 shown, the rear part of the traditionally used outer sleeve is welded to the support frame, the rear part of the outer sleeve is blocked, and only two very small pressure - measuring holes are opened on both sides of the root of the outer sleeve for pressure relief. This causes air flow stagnation (i.e., air flow congestion generated when relieving pressure and flowing back) in the outer sleeve, affecting the total pressure measurement value of the inner tube. At the same time, in order to avoid the pulsation of the inner tube with the external flow field, a metal pressure - measuring tube with a larger thickness and diameter needs to be used, resulting in a reduction in the effective flow area of the outer sleeve and a weakening of the pressure - relief ability.

[0004] Therefore, the above reasons cause the total pressure measurement at the traditional fan inlet and outlet to be greatly affected by flow - field pulsation and flow - direction angle. Therefore, a new measuring device is needed to solve the problem of total pressure measurement in the complex flow field during the integrated test of airframe / inlet / fan. Summary of the Invention

[0005] One object of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0006] To achieve these objects and other advantages of the present invention, a total pressure probe with low sensitivity to the incoming flow angle is provided, which includes a support frame. At the position where the support frame cooperates with the incoming flow surface, a plurality of mounting holes for mounting sleeve components are provided. A pressure - measuring hole for laying a pressure - measuring tube is opened along the span direction inside the support frame. One side of the cross - section of the support frame is a water - droplet shape that cooperates with the incoming flow surface, and the other side is an ellipse. A through - hole with a diameter of 3.6 mm that is connected to the mounting hole and is opened along the chord direction is provided at the ellipse - shaped cross - section position. And symmetrically arranged on the left and right sides at the rear of the through - hole are inclined holes with a diameter of 1.5 mm. The sleeve component is configured to include: An inner sleeve that is spatially connected to the pressure - measuring tube; An outer sleeve that is in communication with the rear end of the through hole and the inclined hole, and two sets of mounting grooves are evenly distributed in the circumferential direction at the front and rear ends of the outer sleeve; A support mechanism disposed on each mounting groove to position the inner sleeve inside the outer sleeve in a supported manner.

[0007] Preferably, the inclined hole forms a 30° angle with the through hole in space, and the inclination direction of the inclined hole is adapted to the discharge flow direction.

[0008] Preferably, the inner and outer diameters of the outer sleeve gradually increase along the oncoming flow direction; Among them, the small end diameter of the outer sleeve is 3 mm, the length is 6 - 25 mm, the large end diameter of the outer sleeve is 3.6 mm, the length is 5 - 10 mm, and the wall thickness of the outer sleeve is 0.4 mm; A 45° chamfer α is provided on the inner hole edge of the air inlet end of the outer sleeve, and a 60° chamfer β is provided on the inner hole edge of the exhaust end of the outer sleeve.

[0009] Preferably, the inner sleeve is configured to be a thin-walled steel pipe with an outer diameter of 0.8 mm and a wall thickness of 0.1 mm; Among them, the front end face of the inner sleeve is at a predetermined distance L from the inlet of the outer sleeve.

[0010] Preferably, the support mechanism includes: a front support piece disposed near the oncoming flow side and a rear support piece away from the oncoming flow side; Among them, the front support piece is 2 - 10 mm long, and the leading edge of the front support piece is 3 - 5 mm away from the inlet of the inner sleeve; The rear support piece is 2 - 5 mm long; The front support piece and the rear support piece both have a thickness of 0.25 mm, and there is a spacing greater than 7 mm between the front support piece and the rear support piece; The upper and lower surfaces of each support piece are flush with the outer surfaces of the outer sleeve and the inner sleeve respectively, and 30° wedge surfaces for flow rectification are provided at the front and rear end faces of each support piece.

[0011] Preferably, it further includes: a cover plate that cooperates with the external structure of the rack; Among them, the cover plate is fixedly connected to the rack by screws.

[0012] A calibration method for calibrating a total pressure probe with low oncoming flow angle sensitivity, including: S1. Fix the oncoming flow total pressure, install the probe on the moving mechanism of the external device, and connect the inner sleeve of the probe to the pressure measuring device; S2. Change the angle between the probe and the oncoming flow through the moving mechanism to test the maximum insensitive angle range of the probe at different angles with respect to the oncoming flow direction; By moving the inner sleeve to change the distance L, the measurement pressure of the probe at different distances L and the recovery coefficient of the total pressure of the oncoming flow are tested, so as to determine the optimal value of the distance L.

[0013] The present invention has at least the following beneficial effects: A total pressure probe with low incoming flow angle sensitivity of the present invention realizes a total pressure probe with low incoming flow angle sensitivity, simple structure, excellent performance and reliable operation by optimizing and designing a suitable rack structure and a sleeve assembly and adopting a reasonable preparation process. At the same time, the non-sensitive range of the incoming flow angle of the probe can be expanded to more than ±40°. Within Mach 0.7 and within the range of ±40° flow angle, the total pressure recovery coefficient can reach more than 0.998, and the loss rate is lower than 1‰, and the total pressure loss at a large flow angle is reduced by more than 10 times compared with the traditional probe.

[0014] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will be understood by those skilled in the art through the research and practice of the present invention. Brief Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of the total pressure probe of the present invention; Figure 2 It is a schematic cross-sectional view of the sleeve assembly of the present invention; Figure 3 It is a calibration result diagram of the probe of the present invention at Mach 0.7; Figure 4 It is a calibration diagram of the total pressure probe of the present invention; Figure 5 It is a structural diagram of a sheathed probe for measuring the total pressure at the outlet of a traditional fan in the prior art; Among them, the rack - 1, the sleeve assembly - 2, the cover plate - 3, the screw - 4, the through hole - 5, the inclined hole - 6, the outer sleeve - 7, the inner sleeve - 8, the front support piece - 9, the rear support piece - 10, the moving mechanism 11, the rack I - 11, the pressure relief hole 12. Detailed Embodiments

[0016] The following further detailed description of the present invention is made in conjunction with the accompanying drawings, so that those skilled in the art can implement it according to the description in the specification.

[0017] As Figure 1 、 Figure 2 shown, the total pressure probe for low sensitivity to the incoming flow angle of the present invention mainly includes 5 sleeve assemblies 2 and a rack 1 and a cover plate 3 for installing and fixing the sleeve assemblies 2. The cover plate 3 is connected and fixed to the rack 1 by screws 4 and firmly clamps the sleeve assemblies 2. The sleeve assemblies 2 mainly include an outer sleeve 7, an inner sleeve 8, a front support piece 9 and a rear support piece 10.

[0018] Further, the upper end of the rack 1 is connected to the test equipment. Small holes for arranging piezometric tubes are opened along the span direction inside the rack. The small holes are composed of two round holes with a spacing of 1 mm and a diameter of 2 mm. The cross-section of the rack 1 has an alternating shape of oval and water droplet shape (here, the alternation means that one side is oval and the other side is water droplet shape). At the oval cross-section position, a Ø3.6 mm through hole 5 is opened along the chord direction for the drainage of the outer sleeve 7 and the fixation of the sleeve assembly 2. On the left and right sides symmetrically at the rear of the through hole 5, there is a Ø1.5 mm inclined hole 6 each. The inclined hole 6 forms a 30° angle with the through hole 5 for enhancing the drainage capacity.

[0019] Further, there are 5 sleeve assemblies 2 evenly distributed along the span direction on the rack 1. The inner and outer diameters of the outer sleeve 7 of the sleeve assembly 2 gradually increase. The small end diameter is Ø3 mm, the length is 6 - 25 mm, the large end diameter is Ø3.6 mm, the length is 5 - 10 mm, and the wall thickness is 0.4 mm for all. The large end is clamped on the rack 1 by the cover plate 3 and firmly bonded with epoxy resin glue, or can also be welded by argon arc welding. The chamfer angle α of the inner hole edge at the air inlet end of the outer sleeve 7 is 45°, and the chamfer angle β of the inner hole edge at the exhaust end is 60°. There are 2 groups of notches for installing support pieces arranged before and after the outer sleeve 7, and each group is evenly distributed circumferentially by 3.

[0020] Further, the inner sleeve 8 of the sleeve assembly 2 uses a thin-walled steel pipe with an outer diameter of Ø0.8 mm and a wall thickness of 0.1 mm. The front end face of the inner sleeve 8 has a distance L from the inlet of the outer sleeve 7. Usually, the value range of L is 3 - 4 mm. The inner sleeve 8 is positioned and fixed by 3 front support pieces 9 and 3 rear support pieces 10 to prevent the inner sleeve 8 from vibrating in the strong pulsating flow field and affecting the pressure measurement result.

[0021] Further, the front support piece 9 is 2 - 10 mm long, the rear support piece 10 is 2 - 5 mm long. The front edge of the front support piece is 3 - 5 mm from the inlet of the inner sleeve 8. The distance between the front and rear support pieces 10 is 7 mm. The thickness of the support pieces is 0.25 mm for all. The front and rear end faces of the support pieces are rectified with 30° wedge surfaces. The upper surface of the support piece is flush with the outer surface of the outer sleeve 7, and the lower surface is flush with the outer surface of the inner sleeve 8. The support piece is firmly bonded with the inner sleeve 8 and the notch of the outer sleeve 7 with epoxy resin glue, or welded firmly by argon arc welding. The inner sleeve is led out from the outlet end of the outer sleeve and connected to the pressure measurement instrument. This probe has a simple structure, excellent performance, and stable operation. Through testing, it is proved that this probe is insensitive to the oncoming flow angle in the range of -40° to +40°.

[0022] Example 1 A total pressure probe with low sensitivity to the oncoming flow angle in this example has a total structural length of 165 mm and weighs about 132 g.

[0023] The bent frame uses F141. Small holes for arranging piezometric tubes are opened along the span direction inside the bent frame. The small holes are composed of two round holes with a diameter of 2 mm and a spacing of 1 mm. The cross-section of the bent frame has two shapes: oval and water-drop shape. At the oval cross-section position, a Ø3.6 mm through-hole is opened along the chord direction for installing and fixing the sleeve assembly. At the rear of the through-hole, there is a Ø1.5 mm inclined hole, and the inclined hole forms a 30° angle with the through-hole.

[0024] The cover plate uses 304 stainless steel. The cover plate is connected and fixed to the bent frame by screws and firmly clamps the sleeve assembly. The cross-section of the cover plate also has two shapes: oval and water-drop shape. At the oval cross-section position, a Ø3.6 mm through-hole is opened along the chord direction for installing and fixing the sleeve assembly. At the rear of the through-hole, there is a Ø1.5 mm inclined hole, and the inclined hole forms a 30° angle with the through-hole. After the cover plate and the bent frame are combined and installed, they form a complete streamlined shape.

[0025] The sleeve assembly uses 304 stainless steel, and 5 sleeve assemblies are evenly distributed along the span direction on the bent frame. The inner and outer diameters of the outer sleeve of the sleeve assembly gradually increase, so that the outer sleeve has a large end and a small end. The diameter of the small end is Ø3 mm, and the length is 25 mm. The diameter of the large end is Ø3.6 mm, and the length is 10 mm. The wall thickness is 0.4 mm for both. The large end is clamped on the bent frame by the cover plate and firmly bonded with epoxy resin glue. The inner hole edge at the left end of the outer sleeve is chamfered at 45°, and the inner hole edge at the right end is chamfered at 60°. There are 2 groups of notches for installing support pieces arranged at the front and rear of the outer sleeve, and 3 notches are evenly distributed along the circumferential direction in each group. The inner sleeve of the sleeve assembly uses a thin-walled steel pipe with an outer diameter of Ø0.8 mm and a wall thickness of 0.1 mm. The front end face of the inner sleeve is 3.6 mm away from the inlet of the outer sleeve. The inner sleeve is positioned and fixed by 3 front support pieces and 3 rear support pieces. The front support piece is 5 mm long, the rear support piece is 5 mm long. The front edge of the front support piece is 3 mm away from the inlet of the inner sleeve, and the distance between the front and rear support pieces is 7 mm. The thickness of the support pieces is 0.25 mm for both. The front and rear end faces of the support pieces use a 30° wedge surface for flow rectification. The upper surface of the support piece is flush with the outer surface of the outer sleeve, and the lower surface is flush with the outer surface of the inner sleeve. The support piece is firmly bonded with the inner sleeve and the notch of the outer sleeve with epoxy resin glue.

[0026] In actual application, as Figure 5 shown, the distance L between the inlet of the inner sleeve and the inlet of the outer sleeve will have a greater impact on the probe measurement accuracy. In order to determine the optimal value of the distance L and the range insensitive to the incoming flow angle, the probe needs to be calibrated on a special calibration device before use. The present invention provides a calibration and measurement method, including: First, fix the total incoming flow pressure. As Figure 4 shown, install the probe on the equipment movement mechanism, and connect the inner sleeve of the probe to the pressure measurement equipment; Secondly, the angle between the probe and the oncoming flow is changed by the motion mechanism, and the distance L is changed by moving the inner sleeve. To test the recovery coefficient of the pressure measured by the probe and the total pressure of the oncoming flow when the probe is at different angles and different distances L from the oncoming flow direction, so as to determine the optimal value of the distance L and the maximum insensitive angle range; After calibration, the optimal value of the distance L is 1 to 1.5 times the inner diameter of the outer sleeve, and the maximum insensitive angle range reaches ±40°.

[0027] And as Figure 3 The calibration results shown indicate that the insensitive range of the oncoming flow angle of this probe can be extended to more than ±40°. Within Mach 0.7 and within the flow angle range of ±40°, the total pressure recovery coefficient can reach more than 0.998, and the loss rate is less than 1‰, and the total pressure loss at large flow angles is reduced by more than 10 times compared with traditional probes.

[0028] The above solution is only an illustration of a preferred example, but is not limited thereto. When implementing the present invention, appropriate substitutions and / or modifications can be made according to the needs of users.

[0029] Although the embodiments of the present invention have been disclosed above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A total pressure probe with low incoming flow angle sensitivity, comprising a bracket, and at the position where the bracket is matched with the incoming flow surface, there are a plurality of mounting holes for mounting sleeve assemblies. The bracket is internally provided with pressure measuring holes for arranging pressure measuring tubes along the span direction, and is characterized in that, One side of the cross-section of the bent frame is in the shape of a water droplet that matches the oncoming flow surface, and the other side is oval. A through hole with a diameter of 3.6 mm that communicates with the mounting hole is provided along the chord direction at the oval cross-section position. Oblique holes with a diameter of 1.5 mm are symmetrically arranged on the left and right sides at the rear of the through hole; The sleeve assembly is configured to include: An inner sleeve that is spatially connected to the piezometer tube; An outer sleeve that is in communication with the rear end of the through hole and the oblique holes. Two sets of mounting grooves are evenly distributed in the circumferential direction at the front and rear ends of the outer sleeve; A support mechanism disposed on each mounting groove to position the inner sleeve inside the outer sleeve in a supported manner.

2. The total pressure probe with low incoming flow angle sensitivity according to claim 1, characterized in that, The oblique holes form a 30° angle with the through hole in space, and the inclination direction of the oblique holes is adapted to the discharge direction.

3. The total pressure probe with low incoming flow angle sensitivity according to claim 1, characterized in that, The inner and outer diameters of the outer sleeve gradually increase along the oncoming flow direction; Among them, the small end diameter of the outer sleeve is 3 mm, the length is 6 - 25 mm, the large end diameter of the outer sleeve is 3.6 mm, the length is 5 - 10 mm, and the wall thickness of the outer sleeve is 0.4 mm; A 45° chamfer α is provided on the inner hole edge of the air inlet end of the outer sleeve, and a 60° chamfer β is provided on the inner hole edge of the exhaust end of the outer sleeve.

4. The total pressure probe with low incoming flow angle sensitivity according to claim 1, characterized in that The inner sleeve is configured to use a thin-walled steel tube with an outer diameter of 0.8 mm and a wall thickness of 0.1 mm; Among them, the front end face of the inner sleeve is at a predetermined distance L from the inlet of the outer sleeve.

5. The total pressure probe with low incoming flow angle sensitivity according to claim 1, characterized in that, The support mechanism includes: a front support piece disposed near the oncoming flow side and a rear support piece away from the oncoming flow side; Among them, the front support piece is 2 - 10 mm long, and the leading edge of the front support piece is 3 - 5 mm away from the inlet of the inner sleeve; The rear support piece is 2 - 5 mm long; The front support piece and the rear support piece have a thickness of 0.25 mm, and there is a distance greater than 7 mm between the front support piece and the rear support piece; The upper and lower surfaces of each support piece are flush with the outer surfaces of the outer sleeve and the inner sleeve respectively. 30° wedge surfaces for flow rectification are provided at the front and rear end faces of each support piece.

6. The total pressure probe with low incoming flow angle sensitivity according to claim 1, characterized in that It further includes: A cover plate that matches the external structure of the bent frame; Among them, the cover plate is fixedly connected to the bent frame by screws.

7. A calibration method for calibrating a total pressure probe with low incoming flow angle sensitivity as described in any one of claims 1-6, characterized in that, It includes: S1. Fix the total pressure of the oncoming flow, install the probe on the moving mechanism of the external device, and connect the inner sleeve of the probe to the pressure measurement device; S2. Change the angle between the probe and the oncoming flow through the moving mechanism to test the maximum insensitive angle range of the probe at different angles with respect to the oncoming flow direction; Change the distance L by moving the inner sleeve to test the recovery coefficient of the measured pressure of the probe and the total pressure of the oncoming flow at different distances L, so as to determine the optimal value of the distance L.

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