A performance test method for a low-pressure turbine with guide vanes

Abstract

The present application provides a method for testing the performance of a low-pressure turbine with a stator vane. The method includes: Step 1, before the performance recording test at each state point of the turbine, conduct a blowing test on the loss characteristics of the inlet stator vane of the low-pressure turbine test piece, and respectively use a radial multi-point total pressure tube and a circumferential multi-point total pressure rake with a stagnation chamber located in front of and behind the stator vane, and the wall static pressure measurement in front of the stator vane to obtain the inlet total pressure loss coefficient of the stator vane at different inlet Mach numbers; Step 2, remove the circumferential multi-point total pressure rake behind the stator vane, and use the total pressure and static pressure in front of the stator vane and the previously obtained inlet total pressure loss coefficient of the stator vane to obtain the total pressure behind the stator vane, and control the state to conduct the performance recording test at each state point of the single-stage turbine. The method of the present application can completely avoid the influence of the inserted probe on the turbine inlet flow field, and the measurement and test accuracy are higher.

Description

Technical Field

[0001] The present application belongs to the technical field of gas turbine testing, and in particular relates to a method for testing the performance of a low-pressure turbine with straightening blades. Background Art

[0002] The low-pressure turbine is a key component of turbomachinery such as aircraft engines or gas turbines. Its aerodynamic performance level directly determines the performance and reliability of turbomachinery. The flow and heat transfer process inside the turbine components is extremely complex, and it is difficult to accurately obtain its characteristics by relying on numerical simulation. Therefore, in the development and optimization of low-pressure turbines, experimental verification plays an indispensable and important role.

[0003] The method of turbine aerodynamic performance test is based on the similarity principle. The turbine inlet and outlet total pressure expansion ratio (the ratio of the turbine guide vane inlet total pressure to the turbine rotor outlet total pressure) is one of the main parameters controlled during the turbine test. Therefore, the accuracy of the turbine inlet total pressure measurement directly determines the accuracy of the turbine total pressure expansion ratio. The low-pressure turbine matched with aircraft engines and gas turbines is a single-stage turbine with a relatively small design expansion ratio (about 1.7 to 2.0). The slight measurement deviation of the inlet total pressure will bring great errors to the overall performance evaluation of the turbine.

[0004] For the aerodynamic performance test of a single-stage low-pressure turbine, due to the presence of the upstream high-pressure turbine, the airflow at the low-pressure turbine inlet is generally non-axial. Therefore, in order to simulate the outlet angle of the high-pressure turbine in the test, a row of straightening blades is usually arranged at the low-pressure turbine inlet. The main flow channel layout of the low-pressure turbine test piece 10 with straightening blades is as follows: Figure 1 As shown, there are, in sequence, a test piece inlet 11, a straightening blade 12, a turbine inlet 13, a turbine guide blade 14, a turbine rotor blade 15 and a turbine outlet 16.

[0005] In the prior art low-pressure turbine performance test with rectifying blades, there are two main methods for measuring the turbine inlet total pressure:

[0006] 1) Ignoring the influence of the straightening blade 12 on the total pressure, the total pressure directly measured by the radial multi-point total pressure pipe 17 in the straight section in front of the straightening blade 12 represents the turbine inlet total pressure. The form of the radial multi-point total pressure pipe 17 is shown in Figure 2, the end of the radial multi-point total pressure tube 17 has a stagnation chamber 172 and radially arranged pressure guiding tubes 171. In this method, due to the presence of the rectifying vane 12, there will be a certain loss in the total pressure of the gas flowing through the rectifying vane 12, and there is a difference in the total pressure before and after the rectifying vane 12. The specific magnitude of the loss varies greatly due to different design difficulties. Especially for a small expansion ratio turbine, directly ignoring the influence of the rectifying vane 12 and using the total pressure at the straight section at the inlet of the test piece as the total pressure at the turbine inlet is inaccurate and will have a great impact on the evaluation of turbine efficiency. For example, the total pressure loss coefficient of the rectifying vane is 0.985, and the designed expansion ratio of the turbine is 1.8. The deviation of the turbine efficiency obtained by considering this loss and not considering this loss is nearly 1.1 percentage points.

[0007] 2) Uniformly distribute radial multi-point total pressure tubes 17 directly behind the rectifying vane 12 to directly measure the total pressure at the turbine inlet. In this method, the main purpose of the rectifying vane 12 is to change the airflow angle at the inlet of the turbine test piece. The distance between it and the turbine guide vane 14 is small and does not meet the requirement of the length of the straight section at the turbine inlet. Moreover, the outlet of the rectifying vane 12 has strong three-dimensional characteristics (such as wakes, etc.). It is also very inaccurate to use the total pressure obtained by the radial multi-point total pressure tubes directly arranged at the outlet of the rectifying vane 12 to represent the total pressure at the turbine inlet. For example, the total pressure at a certain radial height at the outlet of the rectifying vane obtained by two measurement methods, namely a certain test total pressure tube and a total pressure rake, is as Figure 3 shown. The measurement deviation between the two is nearly 0.5%, and it is obvious that the total pressure rake can better represent the flow field characteristics of this section.

[0008] Neither of the above two methods well considers the great influence of the rectifying vane on the measurement of the total pressure at the turbine inlet. Therefore, a performance test method for a low-pressure turbine with a rectifying vane is needed to overcome the above problems. Summary of the Invention

[0009] The purpose of the present application is to provide a performance test method for a low-pressure turbine with a rectifying vane to solve or alleviate at least one problem in the background art.

[0010] The technical solution of the present application is: A performance test method for a low-pressure turbine with a rectifying vane, the method comprising:

[0011] Step 1. Before the performance recording test at each state point of the turbine, conduct a blowing test on the loss characteristics of the rectifying vane at the inlet of the low-pressure turbine test piece, and respectively obtain the total pressure loss coefficient at the inlet of the rectifying vane at different inlet Mach numbers by using a radial multi-point total pressure tube and a circumferential multi-point total pressure rake with stagnation chambers located in front of and behind the rectifying vane and the wall static pressure measurement in front of the rectifying vane.

[0012] Step 2: Remove the circumferential multi-point total pressure rake at the rear side of the stator vane. By using the total pressure and static pressure at the front side of the stator vane and the total pressure loss coefficient of the stator vane inlet obtained previously, obtain the total pressure at the rear side of the stator vane, and conduct the performance recording test of each state point of the single-stage turbine based on this control state.

[0013] Further, the specific steps of Step 1 include:

[0014] Step 1.1: Arrange radial multi-point total pressure tubes at the inlet of the test piece of the low-pressure turbine to measure the inlet total pressure P of the stator vane 0t ;

[0015] Step 1.2: Arrange multiple wall static pressure measurement points along the circumferential direction on the inner and outer walls of the inlet of the low-pressure turbine test piece to measure the wall static pressure P at the inlet of the stator vane 0s ;

[0016] Step 1.3: According to the measured inlet total pressure P of the stator vane 0t and the wall static pressure P 0s construct a relationship to obtain the inlet Mach number M0 of the low-pressure turbine test piece;

[0017] Step 1.4: Arrange circumferential multi-point total pressure rakes at multiple radial positions between the stator vane and the turbine guide vane. Among them, the circumferential multi-point total pressure rake has multiple pressure guiding small tubes in the circumferential direction, and obtain the turbine inlet total pressure P containing the wake characteristics of the upstream stator vane through the multiple pressure guiding small tubes 1t ;

[0018] Step 1.5: Conduct a blowing test on the turbine test piece before the turbine performance recording test. By collecting and fitting the inlet Mach number and total pressure recovery coefficient data of the low-pressure turbine test piece, obtain the relationship σ = f(M0) between the total pressure recovery coefficients at the inlet and outlet of the stator vane and the inlet Mach number of the test piece.

[0019] Further, the inlet of the test piece is a straight section, and the inlet total pressure of the stator vane can be measured by arranging radial multi-point total pressure tubes at the inlet of the straight section of the test piece.

[0020] Further, the inlet total pressure P of the stator vane 0t and the wall static pressure P 0s and the inlet Mach number M0 of the low-pressure turbine test piece satisfy the following relationship:

[0021]

[0022] where k is a coefficient.

[0023] Further, the radial arrangement position of the circumferential multi-point total pressure rake is greater than one pitch of the stator vane.

[0024] Further, the specific steps of step two include:

[0025] Step 2.1: During the turbine performance measurement test, remove the circumferential multi-point total pressure rake behind the stator vane, and measure the inlet total pressure P 0t of the low-pressure turbine test piece and the wall static pressure P 0s . Combining with the relationship σ = f(M0) obtained from the blowing test of the low-pressure turbine test piece, obtain the relationship of the turbine inlet total pressure P 1t : P 1t = f(P 0t , M0);

[0026] Step 2.2: Control the turbine test state with the obtained turbine inlet total pressure P 1t and record the total characteristics of the turbine;

[0027] Step 2.3: Measure the turbine outlet total pressure P 2t . Obtain the turbine performance through the total pressure ratio P 1t / P 2t of the turbine inlet and outlet.

[0028] In the method of this application, since the circumferential measurement range of the total pressure rake is greater than 1 times the stator vane pitch, the total pressure obtained in this way can include the wake characteristics of the stator vane. Compared with the radial multi-point total pressure tube with sleeve test method that cannot consider the wake effect, the total pressure at the outlet of the stator vane obtained by the total pressure rakes arranged at multiple radial positions is more accurate; in addition, during the turbine performance measurement test, no plug-in test probe needs to be arranged between the stator vane and the turbine guide vane, so that the influence of the plug-in probe on the turbine inlet flow field can be completely avoided, and the measurement and test accuracy is higher. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions provided by this application, the drawings will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application.

[0030] Figure 1 Schematic diagram of a low-pressure turbine test piece with a stator vane of a typical structure.

[0031] Figure 2 Schematic diagram of a radial multi-point total pressure tube with sleeve used in the prior art.

[0032] Figure 3 Schematic diagram of the comparison of the measurement results of the total pressure tube and the total pressure rake at a single radial height.

[0033] Figure 4 Flow chart of the low-pressure turbine performance test method of this application.

[0034] Figure 5 Schematic diagram of the multi-point total pressure rake structure in this application.

[0035] Figure 6 This is the loss characteristic curve of the stator vane in an embodiment of the present application.

[0036] Reference numerals:

[0037] 10 - Low-pressure turbine test piece

[0038] 11 - Test piece inlet

[0039] 12 - Stator vane

[0040] 13 - Turbine inlet

[0041] 14 - Turbine guide vane

[0042] 15 - Turbine rotor blade

[0043] 16 - Turbine outlet

[0044] 17 - Radial multi-point total pressure tube

[0045] 18 - Circumferential multi-point total pressure target Detailed implementation manners

[0046] To make the objectives, technical solutions, and advantages of the implementation of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application.

[0047] The present application aims to solve the problem of inaccurate measurement of the total pressure at the turbine inlet of a low-pressure turbine test piece with stator vanes, thereby improving the measurement accuracy of the total pressure expansion ratio of the low-pressure turbine test piece with stator vanes.

[0048] Aiming at the problem that the stator vane affects the measurement of the total pressure at the turbine inlet in the performance test of a low-pressure turbine with stator vanes, the method provided by the present application is a method for accurately obtaining the total pressure at the turbine inlet by using the total pressure measurement at the test piece inlet in combination with the loss characteristics of the stator vane. The method includes:

[0049] Step 1. First, before the performance recording test at each state point of the single-stage turbine, conduct a blowing test on the loss characteristics of the inlet stator vane of the low-pressure turbine test piece. Use the radial multi-point total pressure tube and circumferential multi-point total pressure rake with stagnation chambers on the front and rear sides of the stator vane and the wall static pressure measurement on the front side of the stator vane to obtain the total pressure loss coefficient of the stator vane inlet at different inlet Mach numbers.

[0050] Step 2. Then, remove the circumferential multi-point total pressure rake at the rear side of the stator vane to avoid its influence on the turbine performance. Using the total pressure, static pressure at the front side of the stator vane and the previously obtained total pressure loss coefficient at the inlet of the stator vane, inversely calculate the total pressure at the inlet of the turbine at the rear side of the stator vane, and conduct the performance recording test for each state point of the single-stage turbine with this control state.

[0051] The specific steps of the above method include:

[0052] Step 1.1. Arrange radial multi-point total pressure tubes 17 at the inlet 11 of the test piece of the low-pressure turbine test piece 10 to measure the total pressure P at the inlet of the stator vane 12 0t .

[0053] Generally, the inlet 11 of the test piece is a straight section that meets the specification requirements. Arranging the radial multi-point total pressure tubes 17 on this straight section can accurately measure the total pressure at the inlet of the stator vane 12.

[0054] Step 1.2. Arrange multiple wall static pressure measurement points along the circumferential direction on the inner and outer wall surfaces of the inlet 11 of the test piece to accurately measure the wall static pressure P at the inlet of the stator vane 12 0s .

[0055] Step 1.3. Construct the relationship formula among the total pressure P 0t , wall static pressure P 0s at the inlet of the low-pressure turbine test piece 10 and the inlet Mach number M0 of the low-pressure turbine test piece 10. According to the measured total pressure P 0t and wall static pressure P 0s at the inlet of the low-pressure turbine test piece 10, calculate the inlet Mach number M0 of the low-pressure turbine test piece 10.

[0056] Among them, the relationship formula among the total pressure P 0t , wall static pressure P 0s at the inlet of the low-pressure turbine test piece 10 and the inlet Mach number M0 of the low-pressure turbine test piece 10 is:

[0057] In the formula, k is the specific heat ratio of the working medium.

[0058] Step 1.4. Arrange circumferential multi-point total pressure rakes 18 with a circumferential pitch greater than one pitch of the stator vane 12 at multiple radial positions between the stator vane 12 and the turbine guide vane 14. The structure of the circumferential multi-point total pressure rake 18 is shown in Figure 4 . The circumferential multi-point total pressure rake 18 has multiple pressure guiding small tubes 181 in the circumferential direction. After the multiple pressure guiding small tubes 182 converge through the rake body 182, they extend out from the radial tube 183, so that the total pressure P 1t at the inlet of the turbine including the wake characteristics of the upstream stator vane 12 can be accurately obtained.

[0059] Step 1.5, the total pressure recovery coefficient σ of the 12 - blade cascade of the stator vanes = P 0t / P 1t , which satisfies a certain fixed relationship with the Mach number M0 at the inlet 11 of the test piece. By conducting a blowing test on the turbine test piece before the turbine performance recording test, the relationship formula σ = f(M0) between the inlet total pressure recovery coefficient of the stator vanes 12 and the Mach number at the inlet of the test piece can be obtained.

[0060] As Figure 5 shown in the schematic diagram of the acquisition points and fitting relationship between the Mach number at the inlet of the test piece and the total pressure recovery coefficient obtained in an embodiment of the present application, the relationship formula between the total pressure recovery coefficients at the inlet and outlet of the stator vanes 12 and the Mach number at the inlet of the test piece can be obtained by fitting the collected point data.

[0061] Step 2.1, since the windward area of the circumferential multi - point total pressure rake 18 is larger than that of the radial multi - point total pressure tube 17, and the circumferential width is relatively large, the presence of the circumferential multi - point total pressure rake 18 will have a certain impact on the performance of the downstream turbine guide vanes 14 (also called the turbine nozzle), thus bringing uncertainty to the performance of the low - pressure turbine. Therefore, the circumferential multi - point total pressure rake 18 behind the stator vanes 12 is removed during the turbine performance recording test.

[0062] During the turbine performance recording process, by measuring the inlet total pressure P 0t and the wall static pressure P 0s of the turbine test piece 10, and combining with the relationship formula σ = f(M0) between the inlet total pressure recovery coefficient of the stator vanes 12 and the Mach number at the inlet of the test piece obtained from the blowing test of the low - pressure turbine test piece, the relationship formula P 1t = f(P 0t , M0) can be obtained, and thus the inlet total pressure P 1t of the turbine can be accurately obtained.

[0063] Step 2.2, control the turbine test state and record the total characteristics of the turbine according to the inlet total pressure P 1t of the turbine obtained in Step 2.1.

[0064] Step 2.3, the turbine performance is evaluated by the total pressure ratio P 1t / P 2t at the inlet and outlet of the turbine. Among them, the total pressure P 2t at the outlet of the turbine can be directly measured.

[0065] In the method of the present application, since the circumferential measurement range of the total pressure rake is greater than one pitch of the stator vane, the total pressure obtained in this way can include the wake characteristics of the stator vane. Compared with the radial multi-point total pressure tube test method with a sleeve that cannot consider the wake effect, the total pressure at the outlet of the stator vane obtained by the total pressure rakes arranged at multiple radial positions is more accurate. In addition, in the turbine performance recording test, no plug-in test probe needs to be arranged between the stator vane and the turbine guide vane, so that the influence of the plug-in probe on the turbine inlet flow field can be completely avoided, and the measurement and test accuracy are higher.

[0066] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A performance test method for a low-pressure turbine with a stator vane, characterized in that, The method includes: Step 1: Before the performance recording test of each state point of the turbine, conduct a blowing test on the loss characteristics of the inlet guide vanes of the low-pressure turbine test piece. Respectively use the radial multi-point total pressure tubes and circumferential multi-point total pressure rakes with stagnation chambers located in front of and behind the guide vanes, and the wall static pressure measurement on the front side of the guide vanes to obtain the inlet total pressure loss coefficient of the guide vanes at different inlet Mach numbers. Specifically, it includes: Step 1.1: Arrange radial multi-point total pressure tubes at the inlet of the test piece of the low-pressure turbine to measure the inlet total pressure P of the stator blades 0t ; Step 1.2: Arrange a plurality of wall static pressure measurement points circumferentially on the inner and outer wall surfaces at the inlet of the low-pressure turbine test piece, so as to measure the wall static pressure P at the inlet of the stator vane 0s ; Step 1.

3. Based on the measured total inlet pressure P of the stator vane 0t and the static wall pressure P 0s establish a relationship to obtain the inlet Mach number M0 of the low-pressure turbine test piece; Step 1.4: Arrange circumferential multi-point total pressure rakes at multiple radial positions between the stator vanes and the turbine guide vanes. Among them, the circumferential multi-point total pressure rake has multiple pressure guiding small tubes in the circumferential direction, and the total pressure P at the turbine inlet containing the wake characteristics of the upstream stator vanes is obtained through the multiple pressure guiding small tubes 1t ; Step 1.5: Conduct a blowing test on the turbine test piece before the turbine performance recording test. By collecting and fitting the data of the inlet Mach number and total pressure recovery coefficient of the low-pressure turbine test piece, obtain the relationship σ = f(M0) between the total pressure recovery coefficients at the inlet and outlet of the guide vanes and the inlet Mach number of the test piece; Step 2: Remove the circumferential multi-point total pressure rake behind the guide vanes. Use the total pressure, static pressure on the front side of the guide vanes and the previously obtained inlet total pressure loss coefficient of the guide vanes to obtain the total pressure behind the guide vanes, and conduct the performance recording test of each state point of the single-stage turbine by controlling the state according to this. Specifically, it includes: Step 2.

1. During the turbine performance recording test, remove the circumferential multi-point total pressure rake behind the stator blades, and measure the inlet total pressure P of the low-pressure turbine test piece 0t , the wall static pressure P 0s . Combine the relationship σ = f(M0) obtained from the blowing test of the low-pressure turbine test piece to obtain the relationship P of the turbine inlet total pressure P1t 1t = f(P 0t , M0); Step 2.2: Using the obtained total pressure P at the turbine inlet 1t Control the turbine test conditions and record the overall turbine characteristics; Step 2.3, measure the total pressure P at the turbine outlet 2t , and obtain the turbine performance through the total pressure ratio P 1t / P 2t at the turbine inlet and outlet 2. The performance test method of the low-pressure turbine with guide vanes according to claim 1, wherein The inlet of the test piece is a straight section. By arranging radial multi-point total pressure tubes at the inlet of the test piece in the straight section, the inlet total pressure of the guide vanes can be measured.

3. The performance test method of the low-pressure turbine with a stator vane according to claim 1, characterized in that, The total inlet pressure P of the stator vane 0t and the wall static pressure P 0s and the inlet Mach number M0 of the low-pressure turbine test piece satisfy the following relationship: In the formula, k is a coefficient.

4. The performance test method of the low-pressure turbine with a rectifying vane according to claim 1, characterized in that The radial arrangement position of the circumferential multi-point total pressure rake is greater than one pitch of the guide vanes.

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