Constant-rotating-speed multi-stage power turbine and pneumatic matching design method thereof

Abstract

The invention provides a constant-rotating-speed multi-stage power turbine and a pneumatic matching design method thereof, and belongs to the technical field of gas turbines.The method comprises the steps that blade modeling is subjected to adjustment matching design to obtain a preliminary blade profile; and on the basis of the preliminary blade profile, sequentially carrying out pneumatic matching design on the Mach number of a blade discharge port, carrying out pneumatic matching design on the expansion ratio of each stage of the power turbine and carrying out pneumatic matching design on the airflow angle of an outlet of the power turbine, so that the constant-rotating-speed multi-stage power turbine suitable for the wide working condition of 0.4-1.0 is obtained. According to the pneumatic matching design method for the constant-rotating-speed multi-stage power turbine, the power turbine with the high relative efficiency within the working condition range of 0.4-1.0 can be obtained, the relative efficiency of the power turbine is reduced slowly, and the relative efficiency of the working condition of 0.4 can reach 0.99.

Description

Technical Field

[0001] The present application belongs to the field of gas turbine technology, and in particular relates to a constant-speed multi-stage power turbine and an aerodynamic matching design method thereof. Background Art

[0002] In the aerodynamic design of a gas turbine's constant-speed multi-stage power turbine, the 1.0 operating condition is generally selected as the design point of the power turbine. In order to meet the high efficiency of the power turbine design point, it is usually necessary to perform aerodynamic matching design on the power turbine, such as turbine blade shape matching design, blade outlet Mach number matching design, stage expansion ratio matching design, outlet airflow angle matching design, etc.

[0003] In the prior art, the 1.0 operating condition is generally used as the design point for high efficiency of the power turbine, so that the power turbine matching is in the lowest loss state under the 1.0 operating condition. During the design, the blade shape design with a small negative attack angle (for example, -5°), the blade outlet Mach number design, and the turbine outlet airflow angle average value deviating from the axial direction by no more than 5° are generally used. Matching methods are combined with iterative optimization and improvement to achieve high efficiency of the power turbine design point. However, the aerodynamic matching of the constant speed multi-stage power turbine in the prior art only achieves high efficiency under the 1.0 operating condition, and the efficiency drops significantly when the operating condition decreases. For example, the efficiency characteristics of a certain type of gas turbine constant speed multi-stage power turbine are as follows: Figure 1 , the horizontal axis is the working condition, and the vertical axis is the relative efficiency Relative efficiency It is the turbine efficiency at the current operating condition divided by the efficiency at the design point (1.0 operating condition). As can be seen from the figure, the efficiency at 1.0 operating condition is close to the highest point. However, as the operating condition decreases, the relative efficiency of the turbine decreases significantly. At 0.4 operating condition, the relative efficiency is 0.97, which is a 3% decrease compared to 1.0 operating condition. This will have an adverse effect on the overall performance of the gas turbine, increasing energy consumption and operating costs. Summary of the Invention

[0004] The purpose of this application is to provide a method for designing aerodynamic matching of a constant-speed multi-stage power turbine to solve or alleviate at least one problem in the background technology.

[0005] The technical solution of this application is: a method for designing aerodynamic matching of a constant speed multi-stage power turbine, comprising:

[0006] Adjust and match the blade shape to obtain the preliminary blade shape;

[0007] Based on the preliminary blade profile, the blade outlet Mach number is aerodynamically matched with the expansion ratio of each stage of the power turbine, and the power turbine outlet airflow angle is aerodynamically matched with the design, thereby obtaining a constant speed multi-stage power turbine suitable for a wide operating condition of 0.4 to 1.0.

[0008] In the preferred embodiment of the present application, the blade shape is adjusted and matched to design the inlet structural angle β 1k , outlet structural angle β 2k , the adjustment and matching design of the blade installation angle γ, wherein the inlet structural angle β 1k According to the inlet airflow angle β1 and the angle of attack i, the blade outlet structural angle β 2k The blade installation angle γ is determined according to the turbine flow capacity and the throat area of ​​the blade cascade, and the blade installation angle γ is determined according to the inlet structural angle β 1k , outlet structural angle β 2k Sure.

[0009] In a preferred embodiment of the present application, the inlet configuration angle β 1k The determination is made based on the inlet airflow angle β1 and the angle of attack i, including: selecting the blade profile angle of attack of the 1.0 operating condition design point as a small positive angle of attack, so that the blade profile angle of attack of the corresponding 0.4 operating condition is within the blade profile low-loss angle of attack range, and the small positive angle of attack is an angle of attack ≤+10°.

[0010] In a preferred embodiment of the present application, the blade profile installation angle γ satisfies:

[0011]

[0012] Among them, a~j are coefficients, and a~j are 1.792641E-01, 4.017817E+00, -3.742113E-02, -4.706101E-04, -6.706349E-03, 1.100128E-05, 4.047619E-04, 6.944444E-06, -5.000000E-04 and -5.235119E+00, respectively.

[0013] In a preferred embodiment of the present application, the aerodynamic matching design of the blade outlet Mach number includes:

[0014] Based on the preliminary blade profile, the overall blade profile is rotated and matched so that the average Mach number at the outlet of each row of blades of the power turbine under 1.0 working condition increases with the increase of the blade sequence number.

[0015] In a preferred embodiment of the present application, the average Mach number at the outlet of each row of blades of the power turbine increases in an average interval as the blade sequence number increases, and the Mach number at the outlet of the first-stage guide vane is not less than 0.6, and the relative Mach number at the outlet of the last-stage moving blade is not greater than 0.9.

[0016] In a preferred embodiment of the present application, the aerodynamic matching design of the expansion ratios of each stage of the power turbine includes:

[0017] Based on the preliminary blade profile, the overall blade profile is rotated and matched so that the expansion ratio of each stage of the power turbine in the 1.0 working condition increases with the increase of the blade sequence number.

[0018] In a preferred embodiment of the present application, the growth ratio of the expansion ratio of each stage ranges from 5% to 10%.

[0019] In a preferred embodiment of the present application, the aerodynamic matching design of the power turbine outlet airflow angle includes:

[0020] Based on the preliminary blade profile, the profiles of each section of the blade are rotated and matched so that the average outlet airflow angle of the power turbine under 1.0 working condition is Between 75° and 80°, the installation angle of the tip of the last stage moving blade is reduced and the installation angle of the root is increased to achieve the outlet airflow angle α out The radial distribution angle difference is within 5°.

[0021] On the other hand, the present application provides a constant speed multi-stage power turbine, which is designed using any of the above-described constant speed multi-stage power turbine aerodynamic matching design methods.

[0022] The aerodynamic matching design method for a constant-speed multi-stage power turbine of the present application can obtain a power turbine with a high relative efficiency in the operating range of 0.4 to 1.0. The relative efficiency of the power turbine decreases slowly, and the relative efficiency in the 0.4 operating condition can reach 0.99. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions provided by this application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0024] Figure 1 Schematic diagram of the efficiency characteristics of a conventional constant-speed multi-stage power turbine.

[0025] Figure 2 Schematic diagram of the aerodynamic matching design method for a constant speed multi-stage power turbine of this application.

[0026] Figure 3 This is a schematic diagram of the power turbine blade parameters in this application.

[0027] Figure 4 This is a schematic diagram of the conventional blade angle selection method in this application.

[0028] Figure 5 This is a schematic diagram of the blade angle of attack selection for this application.

[0029] Figure 6 Schematic diagram of the power turbine characteristics and benefits of the method of this application and the conventional method DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0031] The present application provides a constant-speed multi-stage power turbine and an aerodynamic matching design method thereof, and provides an aerodynamic matching method for the power turbine in terms of blade shape matching design, blade outlet Mach number matching design, stage expansion ratio matching design, outlet airflow angle matching design, etc., to achieve high-efficiency design of the constant-speed power turbine under wide operating conditions (0.4 to 1.0 operating conditions), and achieve relative efficiency of the constant-speed power turbine ≮0.99 within a wide operating condition range (0.4 to 1.0 operating conditions).

[0032] like Figure 2 As shown, the aerodynamic matching design method for a constant speed multi-stage power turbine provided in this application includes the following steps:

[0033] Step S10, adjust and match the blade shape, including the inlet structural angle β 1k , outlet structural angle β 2k , the adjustment and matching design of the blade installation angle γ, among which the inlet structural angle β 1k According to the inlet airflow angle β1 and the angle of attack i, the blade outlet structural angle β 2k The blade installation angle γ is determined according to the turbine flow capacity and the throat area of ​​the blade cascade, and the blade installation angle γ is determined according to the inlet structural angle β 1k , outlet structural angle β 2k Sure.

[0034] like Figure 3 The figure shows the blade parameters of the constant speed multi-stage power turbine in this application. In front of the inlet frontal line, the tangent line of the mid-arc line at the center of the leading edge small circle intersects with the side frontal line of the inlet blade basin. The angle between the tangent line of the mid-arc line and the side frontal line of the inlet blade basin is the blade inlet structural angle β. 1k , its theoretical angle range is 0°~180°. In front of the inlet frontal line, the air inlet direction arrow and the inlet blade basin side frontal line converge at the leading edge of the blade, indicating that the angle from the air inlet direction to the inlet blade basin side frontal line is the blade inlet airflow angle β1 (the guide vane is an absolute value, the moving blade is a relative value), and its theoretical angle range is 0°~180°. The angle of attack i is the difference between the blade inlet structural angle and the inlet airflow angle, angle of attack i=β 1k -β1. Behind the outlet forehead line, the tangent line of the mid-arc at the center of the small circle on the trailing edge intersects the side forehead line of the outlet blade basin. The angle between the tangent line of the mid-arc and the side forehead line of the outlet blade basin is the blade outlet structural angle β. 2k , its theoretical angle range is 0°~90°. The blade installation angle γ is the angle between the blade chord line and the side line of the inlet blade basin, and its theoretical angle range is 0°~90°. The turbine outlet airflow angle α outThat is, the absolute airflow angle at the outlet of the last stage moving blade, the angle from the turbine outlet direction to the side line of the blade basin at the outlet of the last stage moving blade, α out =90° is axial exhaust, α out <90° means exhaust is biased towards the blade basin side, α out >90° means exhaust is biased towards the back side of the blade, and the theoretical angle range is 0°~180°.

[0035] In this application, the inlet configuration angle β 1k According to the inlet airflow angle β1 and the angle of attack i, the conventional method selects the design point (1.0 working condition) blade profile angle of attack i as a small negative angle of attack, for example, i = -5°. Although the loss of the 1.0 working condition is close to the lowest, it will cause the 0.4 working condition to exceed the blade profile low loss angle of attack range, such as Figure 4 In this application, the blade angle of attack at the design point (1.0 working condition) is selected as a small positive angle of attack, so that the corresponding 0.4 working condition angle of attack is within the low-loss blade angle range. For example, if the low-loss blade angle range is -20° to +5°, the 1.0 working condition can be selected as a +5° angle of attack and the 0.4 working condition can be selected as a -20° angle of attack, which is beneficial for the blade to be in the low-loss area under a wide range of working conditions, such as Figure 5 .

[0036] In this application, the blade outlet configuration angle β 2k Determined based on turbine flow capacity and blade throat area.

[0037] In this application, the blade installation angle γ is based on the inlet configuration angle β 1k , outlet structural angle β 2k Based on the summary and refinement of the subsonic blade profile under wide working conditions (0.4~1.0 working conditions), this application proposes a functional relationship for determining the blade profile installation angle γ, where the dependent variable is the blade profile installation angle γ and the independent variable is the inlet structural angle β. 1k and outlet structural angle β 2k The blade installation angle determined by this method can well adapt to the design of low-loss subsonic blades under wide operating conditions.

[0038]

[0039] The coefficients in the formula are shown in Table 1.

[0040] Coefficients in the formulas in Table 1

[0041]

[0042]

[0043] The blade installation angle γ is adjusted and optimized within ±38 based on the above formula, with a tendency to select a slightly smaller blade installation angle, which is conducive to wide operating condition design.

[0044] In some embodiments of the present application, the inlet configuration angle β 1k The reliable application range is 20°~120°, and the outlet structural angle β 2k The reliable applicable range is 10°~40°, and it can be used as a reference when it exceeds the applicable range.

[0045] Step S20: performing aerodynamic matching design on the blade outlet Mach number.

[0046] In this application, the blade profile is rotated and matched based on the preliminary profile, so that the average Mach number at the outlet of each row of blades (the absolute value for guide vanes and the relative value for rotor blades) increases with the blade sequence number (the first-stage guide vanes are numbered 1, and the blade sequence numbers increase one by one along the airflow direction) under the 1.0 operating condition. In a preferred embodiment of this application, the Mach number at the outlet of the first-stage guide vanes is no less than 0.6, and the relative Mach number at the outlet of the last-stage rotor blades is no more than 0.9. The Mach number increment interval can be close to the average interval.

[0047] Conventional methods employ a design with nearly equal Mach numbers for each row of blades in the 1.0 operating condition, which helps ensure high efficiency in the 1.0 operating condition. However, as the operating condition decreases, the Mach number at the exit of the subsequent blades drops sharply, significantly reducing efficiency. For example, a three-stage power turbine employing the method of this application can achieve exit Mach numbers of six rows of blades of 0.6, 0.64, 0.68, 0.72, 0.76, and 0.8, respectively, with increments of +0.04. This allows the Mach number of the subsequent stages to decrease relatively gradually as the operating condition decreases, helping to ensure performance over a wide range of operating conditions.

[0048] Step S30: Adjust the expansion ratio of each stage of the power turbine to π i Carry out aerodynamic matching design.

[0049] This application performs overall rotation matching of the blade profile based on the preliminary blade profile, so that the expansion ratio distribution of the power turbine stage in the 1.0 working condition adopts a step-by-step increase. Similar to step S20, when the working condition decreases, the expansion ratio of the subsequent stages decreases relatively slowly, which is conducive to ensuring wide working condition performance. The growth ratio of each stage expansion ratio (π i+1 -π i ) / π i The range is preferably 5% to 10%. For example, the total expansion ratio of a three-stage power turbine is π T is 4.5, and the average stage expansion ratio is The corresponding first level can be 0.9* The second level can be The third level can be The expansion ratio of each level increases by about 10%.

[0050] When it is necessary to explain, the stage expansion ratio of the power turbine is π iThe total expansion ratio of the power turbine is π, which is the total pressure at the inlet of the power turbine at stage i divided by the total pressure at the outlet of stage i. T It is the total pressure at the power turbine inlet divided by the total pressure at the power turbine outlet.

[0051] Step S40: Adjust the power turbine outlet airflow angle α out Carry out aerodynamic matching design.

[0052] This application proposes to rotate and match the profiles of each section of the blade on the basis of the preliminary blade profile so that the average outlet airflow angle of the power turbine under 1.0 working condition is The angle between 75° and 80° is beneficial to reduce the degree of deviation of the outlet direction from the axial direction when the working conditions are reduced, ensuring the performance under wide working conditions. At the same time, the outlet airflow angle α is achieved by closing the tip of the last stage moving blade (reducing the installation angle) and opening the root (increasing the installation angle). out The radial distribution angle difference (the difference between the maximum angle and the minimum angle) is controlled within 5°, which is beneficial to reducing exhaust losses.

[0053] The average outlet airflow angle of the power turbine at 1.0 working condition in the conventional method (Outlet airflow angle α out The average value along the radial direction is generally between 85° and 95°, and the deviation from the axial direction is not more than 5°, which is conducive to the exhaust loss of the 1.0 working condition at a low level, but when the working condition is reduced, the average outlet airflow angle The exhaust loss will increase significantly. For example, the average outlet airflow angle of 1.0 working condition determined by conventional method of a power turbine is The radial angle difference is 10°, and the average outlet airflow angle is 0.4. The 0.4 working condition deviates from the axial direction by 40°, which will cause a significant increase in exhaust loss. The method of this application determines the average outlet airflow angle of the 1.0 working condition. The radial angle difference is 4°, and the average outlet airflow angle is 0.4°. The 0.4 operating condition deviates 25° from the axial direction, and the power turbine has good performance in a wide range of operating conditions.

[0054] like Figure 6 The figure shows a comparison diagram of the characteristics of a power turbine completed by a conventional method and a power turbine completed by the method of the present application. The relative efficiency of the power turbine in the operating range of 0.4 to 1.0 under the conventional method drops sharply, and the relative efficiency in the 0.4 operating condition is only 0.97. The power turbine completed by the aerodynamic matching design method of the present application has a higher relative efficiency in the operating range of 0.4 to 1.0, and the relative efficiency drops slowly, and the relative efficiency in the 0.4 operating condition reaches 0.99.

[0055] Compared with the existing technology, the constant speed multi-stage power turbine obtained through the above steps of the present application can achieve a high efficiency level of the power turbine within a wide operating condition range (0.4 to 1.0 operating conditions), thereby improving the wide operating condition performance of the entire machine.

[0056] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for designing aerodynamic matching of a constant speed multi-stage power turbine, characterized in that: include: Adjust and match the blade shape to obtain the preliminary blade shape; Based on the preliminary blade profile, the blade outlet Mach number is aerodynamically matched with the expansion ratio of each stage of the power turbine, and the power turbine outlet airflow angle is aerodynamically matched with the design, thereby obtaining a constant speed multi-stage power turbine suitable for a wide operating condition of 0.4 to 1.

0.

2. The aerodynamic matching design method for a constant speed multi-stage power turbine according to claim 1, characterized in that: Adjust the blade shape to match the design including the inlet structural angle β 1k , outlet structural angle β 2k , the adjustment and matching design of the blade installation angle γ, wherein the inlet structural angle β 1k According to the inlet airflow angle β1 and the angle of attack i, the blade outlet structural angle β 2k The blade installation angle γ is determined according to the turbine flow capacity and the throat area of ​​the blade cascade, and the blade installation angle γ is determined according to the inlet structural angle β 1k , outlet structural angle β 2k Sure.

3. The aerodynamic matching design method for a constant speed multi-stage power turbine according to claim 2, characterized in that: The inlet configuration angle β 1k The determination is made based on the inlet airflow angle β1 and the angle of attack i, including: selecting the blade profile angle of attack of the 1.0 operating condition design point as a small positive angle of attack, so that the blade profile angle of attack of the corresponding 0.4 operating condition is within the blade profile low-loss angle of attack range, and the small positive angle of attack is an angle of attack ≤+10°.

4. The aerodynamic matching design method for a constant speed multi-stage power turbine according to claim 3, characterized in that: The blade profile installation angle γ satisfies: Among them, a~j are coefficients, and the coefficients a~j are 1.792641E-01, 4.017817E+00, -3.742113E-02, -4.706101E-04, -6.706349E-03, 1.100128E-05, 4.047619E-04, 6.944444E-06, -5.000000E-04 and -5.235119E+00, respectively.

5. The aerodynamic matching design method for a constant speed multi-stage power turbine according to claim 1, characterized in that: The aerodynamic matching design of the blade outlet Mach number includes: Based on the preliminary blade profile, the overall blade profile is rotated and matched so that the average Mach number at the outlet of each row of blades of the power turbine under 1.0 working condition increases with the increase of blade sequence number.

6. The aerodynamic matching design method for a constant speed multi-stage power turbine according to claim 5, characterized in that: The average Mach number at the outlet of each row of blades of the power turbine increases in an average interval as the blade sequence number increases, and the Mach number at the outlet of the first-stage guide vane is not less than 0.6, and the relative Mach number at the outlet of the last-stage moving blade is not greater than 0.

9.

7. The aerodynamic matching design method for a constant speed multi-stage power turbine according to claim 1, characterized in that: Aerodynamic matching design of each stage expansion ratio of the power turbine includes: Based on the preliminary blade profile, the overall blade profile is rotated and matched so that the expansion ratio of each stage of the power turbine in the 1.0 working condition increases with the increase of the blade sequence number.

8. The aerodynamic matching design method for a constant speed multi-stage power turbine according to claim 7, characterized in that: The growth rate of expansion ratio at each level ranges from 5% to 10%.

9. The aerodynamic matching design method for a constant speed multi-stage power turbine according to claim 1, characterized in that: Aerodynamic matching design of the power turbine outlet airflow angle includes: Based on the preliminary blade profile, the profiles of each section of the blade are rotated and matched so that the average outlet airflow angle of the power turbine under 1.0 working condition is Between 75° and 80°, the installation angle of the tip of the last stage moving blade is reduced and the installation angle of the root is increased to achieve the outlet airflow angle α out The radial distribution angle difference is within 5°.

10. A constant speed multi-stage power turbine, characterized in that: The power turbine is designed using the aerodynamic matching design method for a constant speed multi-stage power turbine as described in any one of claims 1 to 9.

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