A swirl velocity calibration device and method

Abstract

The application discloses a swirl velocity calibration device and method, and belongs to the field of aero-engine air systems; the method steps are as follows: a swirl velocity calibration device is constructed; measuring points are arranged; a probe for measuring static characteristic indexes is arranged at the outlet section, and a calibration probe for measuring dynamic characteristic indexes is arranged downstream of the outlet section and along the axial direction of the airflow; a deflection angle variation range of the calibration probe is set; a velocity relative error is determined as an evaluation index of a swirl velocity calibration result; a flow field is set to perform a calibration test, and a calibration probe deflection angle range for generating the velocity relative error is determined; a velocity coefficient correction formula is obtained based on a relationship diagram of the velocity coefficient and the calibration probe deflection angle, so as to eliminate a measurement error, that is, the calibration is completed. The application solves the problem of a large deviation in swirl velocity measurement in the prior art.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aero-engine air system, and particularly relates to a swirl velocity calibration device and method. BACKGROUND

[0002] In aero-engine and gas turbine, air system is an indispensable part, which can ensure the engine to operate normally in any working state. There are a large number of rotating-to-static interfaces in the engine air system, so the sealing device is an indispensable part of the gas turbine engine air system.

[0003] The labyrinth seal at the compressor can reduce the pressure loss caused by the leakage of high-pressure gas to ensure the compression efficiency of the compressor; the labyrinth seal at the turbine can prevent the main flow gas from invading the disc cavity, so as to ensure the stable work of the turbine disc, bearing and other components. At the same time, the labyrinth seal at the turbine can also reduce the energy loss of the gas to ensure the work efficiency of the turbine.

[0004] The main function of the labyrinth seal is to reduce the leakage of gas. At present, the focus of the research on the labyrinth seal is mainly on the leakage characteristics. In recent years, with the progress of industrial level, the high pursuit of engine performance makes the research on the labyrinth seal more in-depth. The airflow in the engine air system will be subjected to a large shear force due to the existence of rotating-to-static interface, which will significantly increase the swirl and wind resistance temperature rise of the airflow in the labyrinth flow passage. In the turbine disc pre-rotation system, the size of the swirl will affect the cooling airflow flow provided by the pre-rotation system for the turbine moving blade. Therefore, with the requirement of high safety and reliability of the engine, it is of great significance to systematically study the swirl characteristics of the labyrinth. To study the swirl characteristics of the labyrinth, it is inevitable to measure the swirl velocity in the experiment. That is, it is of great significance to accurately obtain the swirl velocity of the labyrinth for the design of the aero-engine air system.

[0005] In the prior art, the method for measuring the swirl velocity is usually to indirectly calculate the velocity of the airflow by measuring the total temperature, total pressure and static pressure of the airflow. However, due to the deviation of the velocity direction of the airflow, the measured total pressure also deviates, so the swirl velocity measured by the traditional method has a large deviation, and there is also a lack of a relatively accurate calibration method. SUMMARY

[0006] The technical problem to be solved is:

[0007] In order to avoid the shortcomings of the prior art, the present application provides a swirl velocity calibration device and method, based on the calibration device, the static characteristic indexes of the device are measured through experiments, the directional total pressure under different deflection angles is measured by combining the deflection angle adjustability of the calibration probe, the velocity separation after deflection angle is calculated, and then the relative error between the theoretical value and the measured value under the same deflection angle is obtained as the evaluation index of the swirl velocity calibration result. The deflection angle of the calibration probe is adjusted to obtain the relative velocity error corresponding to each deflection angle, the probe deflection angle range causing the velocity relative error is obtained, the velocity coefficient in the range is corrected to eliminate the error, so that the accurate measurement accuracy is obtained. The present application solves the problem of large deviation in the swirl velocity measurement in the prior art.

[0008] The technical scheme of the present application is: a swirl velocity calibration method, the specific steps are as follows:

[0009] A swirl velocity calibration device is constructed; the calibration device is a wind tunnel capable of measuring the static characteristic indexes of the airflow at the outlet section;

[0010] The measuring points are arranged; the probe for measuring the static characteristic indexes is arranged at the outlet section, and the calibration probe for measuring the dynamic characteristic indexes is arranged downstream of the outlet section and along the airflow axis;

[0011] The deflection angle change range of the calibration probe is set;

[0012] The velocity relative error is determined as the evaluation index of the swirl velocity calibration result;

[0013] The flow field is set to perform the calibration test, and the calibration probe deflection angle range causing the velocity relative error is determined;

[0014] The velocity coefficient correction formula is fitted based on the relationship diagram of the velocity coefficient and the calibration probe deflection angle, so as to eliminate the measurement error, that is, the calibration is completed.

[0015] The further technical scheme of the present application is: the outlet section of the swirl velocity calibration device is sequentially provided with a contraction section and a straight section along the airflow direction, a plurality of radially arranged probes are uniformly distributed in the circumferential direction near the inlet end of the contraction section, and are used for measuring the total temperature of the airflow at the inlet of the contraction section and the total pressure of the airflow at the inlet of the contraction section; a plurality of probes parallel to the axial direction are uniformly distributed in the circumferential direction near the outlet end of the straight section, and are used for measuring the static pressure of the airflow at the outlet of the contraction section.

[0016] The further technical scheme of the present application is: the calibration probe is installed on the coordinate frame through the index plate, the x, y and z axial positions of the calibration probe are adjusted through the coordinate frame, and the deflection angle of the calibration probe is adjusted through the index plate.

[0017] The further technical scheme of the present application is: the calculation formula of the velocity relative error is as follows:

[0018]

[0019] In the formula, V θ represents the measured velocity component in the direction after the calibration probe is deflected by an angle θ, V θ ' represents the theoretical velocity after the calibration probe is deflected by an angle θ; V θ ' = V0 cos θ, V0 represents the axial flow velocity at the outlet of the contraction section.

[0020] A further technical solution of the present application is that the calculation formula of the axial flow velocity V0 at the outlet of the contraction section is as follows:

[0021]

[0022] In the formula, P1 is the total pressure of the flow at the inlet of the contraction section / Pa; P2 is the static pressure of the flow at the outlet of the contraction section / Pa; P1 is the total temperature of the flow at the inlet of the contraction section / K; κ is the isentropic index; R g is the gas constant / J·(kg·K) -1 .

[0023] A further technical solution of the present application is that the method for determining the calibration probe deflection angle range generating the velocity relative error is that, in the deflection angle variation range of the calibration probe, a calibration test is performed in steps with a set deflection angle; the measured characteristic index at each deflection angle is recorded, and the velocity relative error at each deflection angle is calculated to establish a deflection angle-velocity relative error relationship graph, and the deflection angle range in which the velocity relative error approximately linearly increases with the deflection angle of the calibration probe is obtained from the graph, that is, the calibration probe deflection angle range generating the velocity relative error is obtained.

[0024] A further technical solution of the present application is that the calibration probe deflection angle range generating the velocity relative error is 8°-24°.

[0025] A further technical solution of the present application is that the method for obtaining the velocity coefficient correction formula is as follows:

[0026] The velocity coefficient ζ is defined as:

[0027]

[0028] The velocity coefficient at each deflection angle of the calibration probe is calculated, and a deflection angle-velocity coefficient relationship graph is established;

[0029] The deflection angle-velocity coefficient curve is fitted to obtain the velocity coefficient correction formula.

[0030] A rotational flow velocity calibration device, comprising an inlet section, a diffusion section, a straightening section, a steady flow section and an outlet section connected in sequence along the flow direction of the airflow; a hole plate, a honeycomb and a damping net are arranged in sequence along the flow direction of the airflow in the straightening section, respectively used for straightening the airflow so that the airflow can enter the contraction section uniformly; the steady flow section allows the airflow to decay the small vortex in the airflow after passing through the damping net; the outlet section comprises a contraction section and a straight section arranged in sequence along the flow direction of the airflow, the contraction section adopts a Vickers curve as a profile curve to ensure the uniformity of the velocity distribution of the airflow at the outlet section; a calibration probe with an adjustable angle of attack is arranged at the outlet of the outlet section along the airflow axial direction.

[0031] An application of a rotational flow velocity calibration method, the specific steps are as follows:

[0032] Two rotational flow measuring points are arranged at the inlet of the grate teeth, and total pressure probes for measuring the axial total pressure and the circumferential total pressure of the airflow at the inlet of the grate teeth are arranged respectively;

[0033] The velocity components of the airflow at the inlet of the grate teeth in the direction of the probe installation are calculated based on the measured values of the two total pressure probes, and the formula is as follows:

[0034]

[0035] In the formula, P 轴 represents the total pressure of the airflow measured by the first total pressure probe deviated from the axial direction of the grate disc, P 周 represents the total pressure of the airflow measured by the second total pressure probe deviated from the radial direction of the grate disc, P represents the static pressure of the airflow, and p represents the density of the airflow; V1 represents the velocity component of the airflow at the inlet of the grate teeth in the direction of the first total pressure probe, and V2 represents the velocity component of the airflow at the inlet of the grate teeth in the direction of the second total pressure probe;

[0036] The component velocities are corrected based on the velocity coefficient, and then the velocity V of the airflow at the inlet of the grate teeth is calculated, and the formula is as follows:

[0037] ζ (θ-θ1) V1=V*cos (θ-θ1)

[0038] ζ (90-θ-θ2) V2=V*cos (90-θ-θ2)

[0039] In the formula, θ1 represents the included angle between the first total pressure probe and the axial direction of the grate disc, θ2 represents the included angle between the second total pressure probe and the radial direction of the grate disc, and θ represents the included angle between the velocity of the airflow at the inlet of the grate teeth and the axial direction of the grate disc;

[0040] The axial total pressure P and the circumferential total pressure P of the airflow at the inlet of the grate teeth are calculated, and the formula is as follows:

[0041]

[0042] Advantages

[0043] The application has the advantages that the application provides a rotational flow velocity calibration device and method, which can calibrate the measurement result of rotational flow velocity in complex rotation experiments under static conditions. The calibration experiment is performed on the rotational flow velocity calibration device under static conditions, and the variation law of the velocity coefficient with the probe deflection angle under different flow fields is obtained, so that the sealing problem between the rotating and static parts is eliminated, the leakage flow does not need to be measured, and the calibration accuracy is greatly improved. Meanwhile, since the calibration is performed under static conditions, the calibration of rotational flow velocity under rotation conditions is not needed, and the calibration cost is greatly reduced. The rotation experiment involves vibration and other problems, and the danger coefficient of the experiment is high, and safety accidents are prone to occur. The calibration under static conditions greatly improves the safety of the calibration experiment.

[0044] The calibration method has mature theoretical support, the calibration result is accurate and reliable, and the measurement accuracy of the rotational flow velocity is greatly improved. When the probe deflection angle is within a certain range, the relative error of the velocity approximately increases linearly with the probe deflection angle. Based on this, the velocity coefficient is introduced to calibrate and correct the rotational flow velocity. After correction, the relative error of the rotational flow velocity measurement is less than 0.3%. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The structure of the rotational flow velocity calibration device in the embodiment of the application is shown in the figure.

[0046] Figure 2 The measurement point arrangement of the calibration device in the embodiment of the application is shown in the figure.

[0047] Figure 3 The rotational flow velocity calibration result in the embodiment of the application is shown in the figure.

[0048] Figure 4 The decomposition of the rotational flow velocity at the grid inlet in the embodiment of the application is shown in the figure.

[0049] Figure 5 The variation law of the velocity relative deviation with the calibration probe deflection angle in the embodiment of the application is shown in the figure.

[0050] Figure 6 The variation law of the velocity coefficient with the calibration probe deflection angle in the embodiment of the application is shown in the figure.

[0051] The reference signs are explained as follows: 1. inlet section, 2. diffusion section, 3. orifice plate, 4. honeycomb, 5. damping net, 6. contraction section, 7. straight section, 8. calibration probe, 9. first cross section, 10. second cross section, 11. first total pressure probe, and 12. second total pressure probe. DETAILED DESCRIPTION

[0052] The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0053] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0054] Based on the method for measuring the rotational flow velocity in the prior art, the velocity of the gas flow is usually indirectly calculated by measuring the total temperature, total pressure and static pressure of the gas flow, and due to the deviation of the direction of the gas flow, the measured total pressure also deviates, and the like. The present application provides a rotational flow velocity calibration device, as shown in Figure 1 The present application provides a rotational flow velocity calibration device, as shown in

[0055] The present application provides a rotational flow velocity calibration method, and the specific steps are as follows:

[0056] Step 1: Construct a rotational flow velocity calibration device;

[0057] Step 2: Arrange the measuring points; arrange the probes for measuring the static characteristic indexes in the outlet section, and arrange the calibration probes for measuring the dynamic characteristic indexes downstream of the outlet section along the windward axial direction of the gas flow;

[0058] Multiple radially arranged probes are evenly distributed circumferentially near the inlet end of the contraction section to measure the total temperature and total pressure of the airflow at the inlet end of the contraction section; multiple probes parallel to the axial direction are evenly distributed circumferentially near the outlet end of the straight section to measure the static pressure of the airflow at the outlet end of the contraction section.

[0059] The calibration probe is mounted on a coordinate frame via a graduated disk. The x, y, and z axial positions of the calibration probe are adjusted via the coordinate frame, and the deflection angle of the calibration probe is adjusted via the graduated disk.

[0060] Step 3: Set the deflection angle range of the calibration probe;

[0061] Step 4: Determine the velocity relative error as an evaluation index of the swirl velocity calibration result; the calculation formula of the velocity relative error is as follows:

[0062]

[0063] Where V θ It represents the measured velocity component in the direction after the calibration probe is deflected by angle θ, V θ ′ represents the theoretical velocity after the calibration probe is deflected by an angle of θ; V θ ′=V0·cosθ, V0 represents the axial air flow velocity at the outlet of the contraction section, and the calculation formula is as follows:

[0064]

[0065] Where, is the total airflow pressure at the inlet of the contraction section / Pa; P2 is the static airflow pressure at the outlet of the contraction section / Pa; is the total temperature of the airflow at the inlet of the contraction section / K; κ is the constant entropy index; R g is the gas constant / J·(kg·K) -1 .

[0066] Step 5: Set up the flow field for calibration test to determine the deflection angle range of the calibration probe that produces relative velocity error;

[0067] The calibration test is performed at a set deflection angle step within the deflection angle variation range of the calibration probe; the characteristic indicators measured at each deflection angle are recorded, and the velocity relative error at each deflection angle is calculated, and a deflection angle-velocity relative error relationship diagram is established (e.g. Figure 5 As shown in FIG, the deflection angle range in which the relative speed error increases approximately linearly with the change of the deflection angle of the calibration probe is obtained, that is, the deflection angle range of the calibration probe that produces the relative speed error is obtained.

[0068] In order to ensure that the experimental results can be applied to the rotational velocity calibration of the grid inlet, it is necessary to ensure that the flow field in the calibration experiment is the same as that of the grid inlet. It is known from numerical simulation that when the design gap C'0=0.8mm, the Mach number of the airflow at the grid inlet is Ma=0.15, and therefore the flow field of the present calibration experiment is set to Ma=0.15. It can be seen from Figure 3 that when the deflection angle of the probe and the airflow is 0°-8°, the relative error of the velocity changes less than 1% with the deflection angle of the probe. This is caused by the insensitivity of the airflow to the deflection angle of the probe due to the small deflection angle of the probe. When the deflection angle of the probe is 8°-24°, the relative error of the velocity changes approximately linearly with the deflection angle of the probe, and therefore the measured values of the velocity in this range are corrected.

[0069] Step 6: The velocity coefficient correction formula is obtained based on the fitting of the velocity coefficient and the calibration probe deflection angle, so as to eliminate the measurement error, that is, the calibration is completed.

[0070] The method for obtaining the velocity coefficient correction formula is as follows:

[0071] Step 6.1: The velocity coefficient ζ is defined as:

[0072]

[0073] Step 6.2: The velocity coefficient at each deflection angle of the calibration probe is calculated, and a deflection angle-velocity coefficient relationship graph (as shown in Figure 6 ) is established.

[0074] Step 6.3: The velocity coefficient correction formula is obtained by fitting the deflection angle-velocity coefficient curve.

[0075] The change of the velocity coefficient with the deflection angle of the probe is shown in Figure 3 . After the correction of the velocity coefficient, the relative error of the velocity measurement can be less than 0.3%. In the same way, the flow fields of Ma=0.10, 0.20, 0.30, 0.40 are calibrated, and the velocity coefficient correction formulas are ζ=-0.001θ+1.0251, ζ=-0.0012θ+1.0055, ζ=-0.0015θ+1.0088, and ζ=-0.0015θ+1.009.

[0076] The application of the rotational velocity calibration method can increase the measurement error of the rotational velocity with the increase of the deflection angle of the total pressure probe and the airflow, and the measurement result of the total pressure probe is corrected in the range of 8°-24°. When the rotational velocity measuring point is arranged at the grid inlet, the deflection angle of the total pressure probe and the airflow should be in the range of 8°-24°, so that the velocity coefficient obtained through the wind tunnel calibration experiment can be applied. The specific steps are as follows:

[0077] Step 1: Two total pressure probes are arranged at the inlet of the grate to measure the axial and circumferential total pressure of the inlet flow of the grate, respectively;

[0078] Referring to Figure 4 Fig. 1 shows a schematic diagram of the inlet flow of the grate. It is assumed that the speed of the inlet flow of the grate is V, and the angle between the speed and the axial direction of the grate is θ. The axial and circumferential total pressures of the inlet flow of the grate are obtained by arranging two total pressure probes, wherein the first total pressure probe has an angle θ1 with the axial direction of the grate, and the measured value is P 轴 ; the second total pressure probe has an angle θ2 with the circumferential direction of the grate, and the measured value is P 周 .

[0079] Step 2: The speed components of the inlet flow of the grate in the directions of the probe installation are calculated based on the measured values of the two total pressure probes, and the formula is as follows:

[0080]

[0081] In the formula, P 轴 represents the total pressure of the flow measured by the first total pressure probe deviated to the axial direction of the grate, P 周 represents the total pressure of the flow measured by the second total pressure probe deviated to the radial direction of the grate, P represents the static pressure of the flow, and ρ represents the density of the flow. V1 represents the speed component of the inlet flow of the grate in the direction of the first total pressure probe, and V2 represents the speed component of the inlet flow of the grate in the direction of the second total pressure probe.

[0082] Step 3: According to the known angles in Figure 4 , the angle between the first total pressure probe and the flow direction is (θ-θ1), and the angle between the second probe and the flow direction is (90-θ-θ2). After substituting the measured values of the total pressure probes into formula (4) and formula (5), the speeds V1 and V2 of the flow in the directions of the first and second total pressure probes can be obtained. There is an error between the speeds V1 and V2 measured by the total pressure probes and the speed component of the flow V in the direction. The measurement error can be reduced by introducing a speed coefficient ζ to correct V1 and V2. Therefore, after the speed coefficient correction and the application of the speed decomposition principle, the relationship between V1, V2 and the speed V is as follows:

[0083] ζ(θ-θ1)V1=V·cos(θ-θ1)(6)

[0084] ζ(90-θ-θ2)V2=V·cos(90-θ-θ2)(7)

[0085] In the formula, θ1 represents the angle between the first total pressure probe and the axial direction of the grate, θ2 represents the angle between the second total pressure probe and the radial direction of the grate, and θ represents the angle between the speed of the inlet flow of the grate and the axial direction of the grate.

[0086] Step 4: the velocity V and direction θ of the airflow can be obtained from formula (6) and formula (7), the velocity in the axial direction and the velocity in the circumferential direction are V*cosθ and V*sinθ respectively by the principle of orthogonal decomposition, and the axial total pressure and the circumferential total pressure of the airflow can be obtained by Bernoulli equation:

[0087]

[0088]

[0089] The above technical solutions are further described in combination with the drawings and examples as follows:

[0090] This embodiment is to calibrate the flow field of the airflow Mach number Ma=0.2 by using a swirl velocity calibration device and method, including the following steps:

[0091] Step 1: calibration device installation;

[0092] The swirl velocity calibration device, as shown in Figure 1 , is a small wind tunnel, which includes an inlet section, a diffusion section, a straightening section, a steady flow section and an outlet section arranged in sequence along the axial direction.

[0093] Step 2, measurement point arrangement;

[0094] Referring to Figure 2 , the measurement point arrangement diagram of the swirl velocity calibration device, three total temperature measurement points and four total pressure measurement points are arranged uniformly at different circumferential positions of the first radial section near the inlet of the contraction section, for measuring the total temperature and total pressure of the airflow at the inlet of the contraction section. Four static pressure measurement points are arranged uniformly at different circumferential positions of the second radial section near the outlet of the straight section, for measuring the static pressure of the airflow at the outlet of the contraction section.

[0095] The pressure and temperature parameters are collected by pressure scanning valve, thermocouple and temperature scanning valve respectively. When calibration is performed, the measured probe needs to be able to rotate and move within a certain range, so the calibration probe is installed on the protractor and the coordinate frame. The coordinate frame can realize the three-dimensional movement of the measured probe, and the travel of x, y and z directions is 100mm, 110mm and 100mm respectively. The coordinate frame adopts double scale reading, the minimum reading of the coordinate scale is 0.1mm, and double locking device is adopted, which can enhance the stability of the calibration probe during movement. The protractor can realize 360° rotation, and the minimum scale is 1°.

[0096] Step 3, calibration experiment;

[0097] The probe deflection angle range of this calibration experiment is set to 0°-40°. In order to reduce the influence of random error on the experimental results, the experimental data is recorded every 2° during the experiment, and the experimental data is shown in Table 1.

[0098] Table 1: Swirl velocity calibration experiment data of Ma=0.2

[0099]

[0100]

[0101] The total pressure probe measured velocity V θ and the theoretical velocity V θ The calculation results are shown in Table 2 below.

[0102]

[0103]

[0104] Step 4, fitting the correction formula of the velocity coefficient;

[0105] Referring to Figure 5 The velocity relative deviation changes with the probe deflection angle, and it can be seen that the velocity relative deviation increases first and then decreases with the increase of the probe deflection angle. In the range of 8°-28° of the deflection angle, the velocity relative deviation changes approximately linearly with the probe deflection angle, and the maximum deviation is 2.77%, so the velocity measurement value in this range is corrected.

[0106] In the range of 8°-28° of the deflection angle, the least square method is used to fit the change trend of the velocity coefficient with the deflection angle, as shown in the following figure, and the correction formula of the velocity coefficient is ζ=-0.0012θ+1.0055.

[0107] Step 5, using a new way to arrange the measuring points for measurement;

[0108] Referring to Figure 4 The schematic diagram of the decomposition of the inlet swirl velocity of the grate is shown. It is assumed that the velocity of the inlet airflow of the grate is V, and the angle between the velocity and the axial direction of the grate disc is θ. The axial total pressure and the circumferential total pressure of the inlet airflow of the grate are obtained by arranging two total pressure probes, wherein the angle between the first total pressure probe and the axial direction of the grate disc is θ1=9°, and the measurement value is The angle between the second total pressure probe and the circumferential direction of the grate disc is θ2=27°, and the measurement value is

[0109] The velocity of the airflow at the inlet of the grate is very small (Ma<0.3), so the total pressure and the static pressure of the airflow satisfy the Bernoulli equation:

[0110]

[0111]

[0112] According to the static pressure and temperature measuring point of the grid tooth entrance, P=175.05kpa, T=298.14K, V1=65.21m / s, V2=64.46m / s can be calculated according to formula (1) and (2).

[0113] Step 6, introduce the velocity coefficient correction swirl velocity;

[0114] According to Figure 4 The angle between the No. 1 total pressure probe and the flow direction is (θ-θ1), and the angle between the No. 2 probe and the flow direction is (90-θ-θ2). The velocity V1 and V2 measured by the total pressure probe have errors with the velocity component of the flow V in the direction. By introducing the velocity coefficient ζ to correct V1 and V2, the measurement error can be reduced. Therefore, after the velocity coefficient correction and the application of the velocity decomposition principle, the relationship between V1, V2 and the velocity V can be obtained as follows:

[0115] ζ(θ-θ1)V1=V·cos(θ-θ1)(3)

[0116] ζ(90-θ-θ2)V2=V·cos(90-θ-θ2)(4)

[0117] Solving the above equation set can obtain V=70.80m / s, θ=35.24°.

[0118] According to Figure 4 The decomposition of the swirl velocity can obtain the axial velocity and the circumferential velocity of the swirl at the grid tooth entrance:

[0119] V x =V·cosθ=70.80×cos35.24°=57.82 (5)

[0120] V y =V·sinθ=70.80×sin35.24°=40.85 (6)

[0121] After the calibration of the device and method, the measurement error of the swirl velocity can be reduced to below 0.3%.

[0122] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments without departing from the principles and purposes of the present application within the scope of the present application.

Claims

1. A swirl speed calibration method characterized by The specific steps are as follows: A swirl velocity calibration device is constructed; the calibration device is a wind tunnel capable of measuring the static characteristic indexes of the airflow at the outlet section; Measurement points are arranged; probes for measuring the static characteristic indexes are arranged at the outlet section, and calibration probes for measuring the dynamic characteristic indexes are arranged downstream of the outlet section and along the axial direction of the airflow; The deflection angle variation range of the calibration probes is set; The velocity relative error is determined as the evaluation index of the swirl velocity calibration result; The flow field is set to perform the calibration test, and the calibration probe deflection angle range that produces the velocity relative error is determined; The velocity coefficient correction formula is obtained based on the relationship diagram of the velocity coefficient and the calibration probe deflection angle, so as to eliminate the measurement error, that is, the calibration is completed; The calculation formula of the velocity relative error is as follows: wherein V θ Vp represents the calibrated probe deflection Vp represents the calibrated probe deflection Vp represents the calibrated probe deflection Vp represents the calibrated probe deflection , V 0 represents the axial gas flow velocity at the exit of the converging section the axial gas flow velocity at the outlet of the converging section V The formula for calculating 0 is as follows: wherein P2 is the total pressure of the gas stream at the inlet of the convergent section / Pa; P 2 is the static pressure of the gas stream at the outlet of the convergent section / Pa; T2 is the total temperature of the gas stream at the inlet of the convergent section / K; The outlet section of the swirl velocity calibration device is sequentially provided with a contraction section and a straight section along the flow direction of the airflow, a plurality of radially arranged probes are uniformly distributed around the inlet end of the contraction section, and the probes are used to measure the total temperature of the airflow at the inlet of the contraction section and the total pressure of the airflow at the inlet of the contraction section; a plurality of probes parallel to the axial direction are uniformly distributed around the outlet end of the straight section, and the probes are used to measure the static pressure of the airflow at the outlet of the contraction section. is the isentropic exponent; R g is the gas constant / J (kg K) -1 .

2. The method of claim 1, wherein: The calibration probe is installed on the coordinate frame through the index plate, the x, y and z axial positions of the calibration probe are adjusted through the coordinate frame, and the deflection angle of the calibration probe is adjusted through the index plate.

3. The method of claim 1, wherein: The method for determining the calibration probe deflection angle range that produces the velocity relative error is as follows: in the deflection angle variation range of the calibration probe, the calibration test is performed in a set deflection angle step; 4. The method of claim 1, wherein: The measured characteristic indexes at each deflection angle are recorded, the velocity relative error at each deflection angle is calculated, the relationship diagram of the deflection angle and the velocity relative error is established, and the deflection angle range in which the velocity relative error approximately increases linearly with the deflection angle of the calibration probe is obtained from the diagram, that is, the calibration probe deflection angle range that produces the velocity relative error is obtained. The calibration probe deflection angle range that produces the velocity relative error is 8°-24°.

5. The method of claim 4, wherein: The method for obtaining the velocity coefficient correction formula is as follows:

6. The swirl speed calibration method of claim 5, wherein: The velocity coefficient ζ is defined as: The velocity coefficients of the calibration probe at each deflection angle are calculated, and the relationship diagram of the deflection angle and the velocity coefficient is established; The velocity coefficient correction formula is obtained by fitting the deflection angle-velocity coefficient curve. The swirl velocity calibration method according to any one of claims 1-6 is used for implementation; the swirl velocity calibration method comprises an inlet section, a diffusion section, a straightening section, a steady flow section and an outlet section connected in sequence along the flow direction of the airflow; the straightening section is provided with a hole plate, a honeycomb device and a damping net in sequence along the flow direction of the airflow, and is respectively used for straightening the airflow so that the airflow can uniformly enter the contraction section; the steady flow section enables the airflow to have sufficient time to attenuate small eddies in the airflow after passing through the damping net; the outlet section comprises a contraction section and a straight section provided in sequence along the flow direction of the airflow, the contraction section adopts a Vickers curve as a profile curve to ensure the uniformity of the velocity distribution of the airflow at the outlet section; and a deflection angle adjustable calibration probe is arranged at the outlet of the outlet section and along the axial direction of the airflow.

7. A swirl speed calibration device, characterized by: The specific steps are as follows:

8. Use of the method for calibrating rotational flow velocity according to any one of claims 1 to 6, characterized in that Two swirl measurement points are arranged at the inlet of the grate teeth, and total pressure probes for measuring the axial total pressure and the circumferential total pressure of the airflow at the inlet of the grate teeth are arranged. ​ The velocity component of the bar inlet airflow in the direction of the probe installation is calculated based on the measured values of the two total pressure probes, according to the following formula: wherein P 轴 P1 represents the total pressure of the gas flow measured by the first total pressure probe oriented in the axial direction of the grate disc, P 周 P2 represents the total pressure of the gas flow measured by the second total pressure probe oriented in the radial direction of the grate disc, P P0 represents the static pressure of the gas flow, p P represents the density of the gas flow, V 1 represents the velocity component of the grate inlet gas flow velocity in the direction of the first total pressure probe, V 2 represents the velocity component of the grate inlet gas flow velocity in the direction of the second total pressure probe; The component velocity is corrected based on the speed coefficient, and then the speed of the inlet airflow of the grid is calculated V , and the formula is as follows: wherein p 1 represents the angle between the first total pressure probe and the axial direction of the grid disc, p 2 represents the angle between the second total pressure probe and the radial direction of the grid disc, p represents the angle between the velocity of the grid inlet gas flow and the axial direction of the grid disc; Computing the axial total pressure of the grid inlet airflow and the circumferential total pressure as follows: 。

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