A device for measuring the flow field at the inlet and outlet of a fan

Abstract

The present invention belongs to the technical field of flow field pressure testing. A device for measuring the inlet and outlet flow fields of a fan is disclosed, characterized in that it comprises a four-hole probe, a four-hole probe lower hole, a four-hole probe middle hole, a four-hole probe upper hole, a four-hole probe right hole, a three-hole probe, a three-hole probe left hole, a three-hole probe middle hole, and a three-hole probe right hole; the four-hole probe head faces the expected incoming flow direction at the root and the tip area respectively; the four-hole probe and the three-hole probe are fixed by special grooves opened in the probe comb support rod; the pressure-inducing tube is encapsulated in the probe comb support rod and the mounting seat, and is led out from the top of the mounting seat. Compared with the existing probe comb, the present invention improves the test space resolution, simplifies the test operation, reduces the test cost, and at the same time reduces the interference of the probe comb support rod on the measured flow field, and increases the measurement range of the probe comb on the secondary flow of the end wall.

Description

Technical Field

[0001] The invention belongs to the technical field of flow field pressure testing, and relates to a device for measuring aerodynamic parameters such as flow field pressure and velocity, and in particular to a device for measuring the inlet and outlet flow fields of a fan. Background Art

[0002] At present, in internal flow tests, for example, when measuring the three-dimensional flow field parameters of the inlet and outlet of the compressor fan, including the distribution of the incoming flow pitch angle, deflection angle, total pressure, static pressure and Mach number along the blade height direction, a three-hole, four-hole or five-hole pressure probe comb is generally used.

[0003] Pressure probe combs are used because of their sensitive and effective characteristics. However, the porous pressure probe comb requires a large number of pressure pipes, especially when the number of measuring points in the height direction increases, which causes the size of the probe comb support rod to increase. The probe comb support rod will cause certain interference to the measured flow field, causing flow mixing loss and flow blockage, and even affecting the normal operation of the test piece in severe cases. For example, when the pressure probe comb is inserted into the inlet of a small-sized compressor fan for measurement, the support rod wake will cause a relatively serious wake. A blockage effect will occur, which will interfere with the measured flow field and affect the measurement of downstream flow field parameters. In addition, the installation angles of the probe heads of the pressure probe comb are all aligned with the mainstream direction, and the airflow at the fan inlet is affected by the casing and hub profiles. The pitch angle of the airflow is large, and the secondary flow intensity at the end wall is high. This arrangement method makes it difficult to achieve accurate measurement of the flow field at the end wall. Summary of the invention

[0004] The main technical problem solved by the present invention is: when using an inserted multi-hole probe comb to measure the compressor fan inlet and outlet flow field parameters, the number of lead-in and pressure-inducting pipes is large, the probe comb is large in size, and the clogging effect caused by the wake of the probe comb support rod will interfere with the measured flow field and affect the measurement of the downstream flow field parameters. At the same time, the airflow pitch angle at the end walls on both sides is large, and the flow field measurement accuracy is not high. The present invention is a device for measuring the fan inlet and outlet flow fields, and the probe heads along the fan inlet blade height direction are precisely designed. The airflow pitch angle at the middle blade height is close to zero, and a three-hole probe is used, and the probe head is aligned with the mainstream direction; the airflow near the end walls on both sides has a strong three-dimensionality, and a four-hole probe is used, and the probe heads are respectively oriented to the expected incoming flow direction, which not only reduces the number of lead-in and pressure-inducting pipes and the size of the measuring device, but also can achieve accurate measurement of the fan inlet and outlet end wall flow fields.

[0005] In order to solve the above technical problems, the design scheme of the present invention is:

[0006] 1. It comprises a four-hole probe (1), a four-hole probe lower hole (2), a four-hole probe middle hole (3), a four-hole probe upper hole (4), a four-hole probe right hole (5), a three-hole probe (6), a three-hole probe left hole (7), a three-hole probe middle hole (8), and a three-hole probe right hole (9); the four-hole probe (1) is encapsulated and fixed by a four-hole probe dedicated groove (12) opened in a probe comb support rod (10); the head of the four-hole probe (1) faces the expected incoming flow direction at the root and the tip area respectively; the three-hole probe (6) is fixed by a three-hole probe dedicated groove (11) opened in the probe comb support rod (10); the probe comb support rod (10) is welded to the mounting seat (13); the pressure lead pipe (14) is encapsulated in the probe comb support rod (10) and the mounting seat (13), and is led out from the top of the mounting seat (13).

[0007] 2. Furthermore, the four-hole probe (1) and the three-hole probe (6) may only retain the probe head, the probe head is welded to the probe comb support rod (10), and the pressure-inducing tube (14) extends from the internal groove of the probe comb support rod (10).

[0008] 3. Furthermore, the installation angles of the probe heads of the four-hole probe (1) are different, and the centerline directions of the probe heads of the two side end walls can be respectively oriented toward the expected incoming flow direction, thereby increasing the measurement range of the four-hole probe for measuring the secondary flow of the end wall, achieving accurate measurement of various airflow parameters of the three-dimensional flow field, and reducing measurement errors.

[0009] 4. Furthermore, the number of probes of the four-hole probe (1) and the three-hole probe (6) can be determined according to the measurement situation. The probes can be arranged along the blade height direction in a way that the probes are denser at both ends and thinner in the middle mainstream area. The arrangement can be based on the equal annular surface, Chebyshev integral method and logarithmic linear method.

[0010] 5. Furthermore, the four-hole probe (1) and the three-hole probe (6) can be in the shape of a truncated cone, a wedge, a prism or a hemispherical head.

[0011] 6. Furthermore, the windward surface of the probe comb support rod (10) is a contracted shape with a wide upper portion and a narrow lower portion, and can also be precisely designed according to equal strength; the cross section is a circular, rounded rectangular, waist-shaped, or wedge-shaped structure.

[0012] 7. Furthermore, the interior of the probe comb support rod (10) may be a completely or partially hollow structure, and the probe support rod or the pressure-inducing tube (14) may be fixed by internal filling.

[0013] The present invention can reduce the number of pressure-inducing pipes and the size of the probe comb, reduce the interference of the probe comb support rod on the measured flow field, simplify the test operation, reduce the test cost, and improve the test accuracy. After calibration experiments, the total pressure, static pressure, Mach number, deflection angle, and pitch angle of the three-dimensional steady-state flow field at different radial positions of the compressor fan inlet and outlet can be measured simultaneously.

[0014] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0015] 1. A device for measuring the flow field of a fan inlet and outlet of the present invention can simultaneously measure the total pressure, static pressure, Mach number, deflection angle, and pitch angle at different radial positions of the fan inlet and outlet;

[0016] Second, the number of probe holes is precisely designed. The secondary flow intensity at the end wall is high and the three-dimensionality of the airflow is strong, so a four-hole probe is used. The airflow pitch angle at the middle blade height is small, so a three-hole probe is used. This combination arrangement effectively reduces the number of pressure pipes used, reduces the size of the probe head and the size of the probe comb support rod, thereby improving the spatial resolution of the test, simplifying the test operation, reducing the test cost, and at the same time reducing the interference of the probe comb support rod on the measured flow field;

[0017] 3. The installation angle of the probe head is precisely designed, and the center lines of the probe heads of the four-hole probes at the end wall are respectively oriented towards the expected incoming flow direction, which increases the measurement range of the probe comb for the secondary flow of the end wall and reduces the measurement error.

[0018] The present invention discloses a device for measuring the inlet and outlet flow field of a fan, which has the characteristics of relatively small size, high spatial resolution, high reliability, wide measurement range and high measurement accuracy. It can be applied to the measurement of internal flow field parameters of impeller machines such as compressor fans and turbines, and can also be used for the measurement of pipeline and external flow fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a device for measuring the inlet and outlet flow fields of a fan according to the present invention;

[0020] Figure 2 yes Figure 1 AA cross-section diagram.

[0021] Figure 3 yes Figure 1 Right view of .

[0022] Figure 4 yes Figure 1 Schematic diagram of further deflection of the four-hole probe shown.

[0023] Among them: 1. Four-hole probe; 2. Lower hole of four-hole probe; 3. Middle hole of four-hole probe; 4. Upper hole of four-hole probe; 5. Right hole of four-hole probe; 6. Three-hole probe; 7. Left hole of three-hole probe; 8. Middle hole of three-hole probe; 9. Right hole of three-hole probe; 10. Probe comb support rod; 11. Special groove for three-hole probe; 12. Special groove for four-hole probe; 13. Mounting seat; 14. Pressure pipe.

[0024] Figure 5It is a schematic diagram of the probe of the present invention being used to measure the three-dimensional flow field at the compressor fan inlet.

[0025] Among them: 1-casing wall, 2-hub wall, 3-fan blades, 4-probe comb of the present invention, 5-airflow direction.

[0026] Figure 6 It is a schematic diagram of the probe of the present invention being used to measure the three-dimensional flow field at the compressor fan outlet.

[0027] Among them: 1-casing wall, 2-hub wall, 3-fan blades, 4-probe comb of the present invention, 5-airflow direction. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0029] Example

[0030] like Figure 1 As shown, this embodiment introduces a device for measuring the inlet and outlet flow fields of a fan, characterized in that it comprises a four-hole probe (1), a four-hole probe lower hole (2), a four-hole probe middle hole (3), a four-hole probe upper hole (4), a four-hole probe right hole (5), a three-hole probe (6), a three-hole probe left hole (7), a three-hole probe middle hole (8), and a three-hole probe right hole (9); the four-hole probe (1) is packaged and fixed by a four-hole probe dedicated groove (12) opened in a probe comb support rod (10); the head of the four-hole probe (1) faces the expected incoming flow direction at the root and the tip area respectively; the three-hole probe (6) is fixed by a three-hole probe dedicated groove (11) opened in the probe comb support rod (10); the probe comb support rod (10) is welded to the mounting seat (13); the pressure lead pipe (14) is packaged in the probe comb support rod (10) and the mounting seat (13), and is led out from the top of the mounting seat (13).

[0031] In this embodiment, the number of four-hole probes (1) is 2, the number of three-hole probes (6) is 4, and the probes are arranged along a radially equal annular surface; the probe comb support rod (10) is a waist-shaped rod with a radial length of 330 mm, a thickness and a radially equal strength design, and a groove on the back to facilitate the installation of the four-hole probe (1) and the three-hole probe (6); the cylindrical support rod of the four-hole probe (1) has a diameter of 5 mm, the probe protruding length is 10 mm, and the angle between it and the probe comb support rod is 60°; the cylindrical support rod of the three-hole probe (6) has a diameter of 3 mm, the probe protruding length is 10 mm, and the angle between it and the probe comb support rod is 90°;

[0032] The device for measuring the flow field at the inlet and outlet of a fan of the present invention can simultaneously measure the total pressure, static pressure, Mach number, deflection angle, and pitch angle of the three-dimensional steady-state flow field at different radial positions of the inlet and outlet of a compressor fan and a turbine. The specific method of use is as follows:

[0033] The probe of the present invention needs to be calibrated before use to obtain the aerodynamic calibration curve of the probe. The four-hole probe calibration is carried out in a calibration wind tunnel. Within the calibration range, the deflection angle and pitch angle of the four-hole probe are changed at different Mach numbers. The curves of the deflection angle coefficient, pitch angle coefficient, total pressure coefficient, and static pressure coefficient of the four-hole probe as they change with the pitch angle and deflection angle are determined through aerodynamic calibration; the deflection angle coefficient, pitch angle coefficient, total pressure coefficient, and static pressure coefficient are defined as follows:

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] Among them, C py is the deflection angle coefficient, C pp is the pitch angle coefficient, C pt is the total pressure coefficient, C ps is the static pressure coefficient, P t and P s are the total pressure and static pressure of the calibrated wind tunnel, respectively; P2, P3, P4 and P5 are the pressure values ​​measured by the lower hole (2), middle hole (3), upper hole (4) and right hole (5) of the four-hole probe (1).

[0040] The three-hole probe calibration is carried out in a calibration wind tunnel. Within the calibration range, the three-hole probe deflection angle is changed at different Mach numbers. The curves of the three-hole probe deflection angle coefficient, total pressure coefficient, and static pressure coefficient as a function of the deflection angle are determined by aerodynamic calibration. The deflection angle coefficient, total pressure coefficient, and static pressure coefficient are defined as follows:

[0041]

[0042]

[0043]

[0044]

[0045] Among them, C py is the deflection angle coefficient, C pt is the total pressure coefficient, C ps is the static pressure coefficient, P t and P sare the total pressure and static pressure of the calibrated wind tunnel, respectively; P7, P8, and P9 are the pressure values ​​measured by the left hole (7), middle hole (8), and right hole (9) of the three-hole probe (6).

[0046] When in use, the device of the present invention is inserted into the measured flow field to obtain the pressure measured by each pressure measuring hole. According to the known calibration coefficient curve, combined with the following formula, the total pressure, static pressure, Mach number, deflection angle and pitch angle of the three-dimensional steady-state flow field are obtained.

[0047]

[0048] Among them, P t and P s is the total pressure and static pressure of the flow field to be measured, γ is the adiabatic index of the flow field, and Ma is the Mach number of the flow field.

Claims

1. A device for measuring the inlet and outlet flow field of a fan, characterized in that: The probe comprises a four-hole probe (1), a four-hole probe lower hole (2), a four-hole probe middle hole (3), a four-hole probe upper hole (4), a four-hole probe right hole (5), a three-hole probe (6), a three-hole probe left hole (7), a three-hole probe middle hole (8), and a three-hole probe right hole (9); the four-hole probe (1) is encapsulated and fixed by a four-hole probe dedicated groove (12) opened in a probe comb support rod (10); the head of the four-hole probe (1) faces the expected incoming flow direction at the root and the tip respectively; the three-hole probe (6) is fixed by a three-hole probe dedicated groove (11) opened in the probe comb support rod (10); the probe comb support rod (10) is welded to the mounting seat (13); the pressure lead pipe (14) is encapsulated in the probe comb support rod (10) and the mounting seat (13), and is led out from the top of the mounting seat (13); A three-hole probe (6) is used at the middle lobe height, with the probe head facing the mainstream direction; four-hole probes (1) are used at the two side end walls, with the probe heads facing the expected incoming flow directions, thereby increasing the measurement range of the four-hole probe (1) for measuring the secondary flow of the end wall; The number of probes of the four-hole probe (1) and the three-hole probe (6) is determined according to the measurement situation, and the probes are arranged along the blade height direction in a manner that the probes are densely packed at both ends and thinned out in the middle mainstream area; The four-hole probe (1) and the three-hole probe (6) are in the shape of a truncated cone, a wedge, a prism or a hemispherical head; The windward surface of the probe comb support rod (10) is a contracted shape with a wide upper portion and a narrow lower portion, and the thickness is designed to have equal strength along the radial direction, and the cross section is a circular, rounded rectangular, waist-shaped or wedge-shaped structure; The back of the probe comb support rod (10) is grooved to facilitate the installation of the four-hole probe (1) and the three-hole probe (6); The interior of the probe comb support rod (10) may be a completely or partially hollow structure, and the probe or the pressure-inducing tube (14) may be fixed by filling the interior.

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