Design method of power turbine and gas turbine starter

Abstract

The invention discloses a design method of a power turbine and a gas turbine starter, and the design method comprises the following steps: S1, determining parameters of rotor blades of the power turbine through design of the rotor blades of the power turbine; s2, reducing an inlet structure angle of a blade root section of the power turbine rotor blade by 10-15 degrees, and reducing an inlet structure angle of a blade tip section of the power turbine rotor blade by 35-45 degrees; s3, the maximum thickness of the blade tip parts of the power turbine rotor blades is reduced by 0.3 mm-0. 5mm, meanwhile, the number of the power turbine rotor blades is increased by 4-6, and the axial width of the power turbine rotor blades is reduced by 1 mm-2mm; s4, the mounting angle of the section of the blade root of the power turbine rotor blade is reduced by 8-10 degrees, and the mounting angle of the section of the blade tip of the power turbine rotor blade is increased by 4-6 degrees; s5, the thickness of the tail edge of the power turbine rotor blade is increased by 0.1 mm-0. 2 mm; compared with the prior art, the power turbine is high in efficiency, low in exhaust temperature and good in starting performance, and the cracking or fracture risk of the power turbine rotor blades in the working process is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power turbine design, in particular, to a design method of a power turbine. In addition, the present application also relates to a gas turbine starter. BACKGROUND

[0002] At present, in the actual use process of the gas turbine starter, it is found that the large cold start condition accounts for a large proportion, and the working speed of the large cold start condition is relatively low. For the power turbine of the gas turbine starter, since the speed changes constantly in the actual working process, the inlet attack angle of the rotor blade changes greatly with the speed. When working in the large cold start condition, the working speed is lower than the design speed, and the rotor blade is in the large positive attack angle working state. The large positive attack angle will cause the flow separation of the blade suction surface, the power turbine efficiency is low, the exhaust temperature of the starter is high, the acceleration ability of the front section of the starter is low, thereby leading to the poor starting performance of the gas turbine starter. In addition, since the inlet temperature of the power turbine of the gas turbine starter is high in the large cold start condition, the stress of the root region of the rotor blade is large, which leads to that the rotor blade is prone to fatigue cracks in the working process, and even there is a risk of rupture. SUMMARY

[0003] The present application provides a design method of a power turbine and a gas turbine starter, so as to solve the technical problems that the existing gas turbine starter is low in power turbine efficiency, high in exhaust temperature, poor in starting performance, and high in risk of rotor blade crack or rupture in the large cold start condition.

[0004] According to one aspect of the present application, a design method of a power turbine is provided, comprising the following steps: S1: determining, through power turbine rotor blade design, a power turbine rotor blade root section inlet configuration angle, a power turbine rotor blade tip section inlet configuration angle, a power turbine rotor blade tip section maximum thickness, a power turbine rotor blade number, a power turbine rotor blade axial width, a power turbine rotor blade root section installation angle, a power turbine rotor blade tip section installation angle, and a power turbine rotor blade tail edge thickness; S2: based on a matching relationship between the rotor blade inlet configuration angle and the rotor blade attack angle, reducing the power turbine rotor blade root section inlet configuration angle by 10-15° and reducing the power turbine rotor blade tip section inlet configuration angle by 35-45°; S3: based on power turbine efficiency design requirements and rotor blade lift coefficient design requirements, reducing the power turbine rotor blade tip section maximum thickness by 0.3-0.5 mm, increasing the power turbine rotor blade number by 4-6 pieces, and reducing the power turbine rotor blade axial width by 1-2 mm; S4: based on the power turbine rotor blade root section inlet configuration angle, the power turbine rotor blade tip section inlet configuration angle, and the power turbine rotor blade number, reducing the power turbine rotor blade root section installation angle by 8-10° and increasing the power turbine rotor blade tip section installation angle by 4-6°; and S5: based on power turbine efficiency design requirements and rotor blade anti-vibration capability design requirements, increasing the power turbine rotor blade tail edge thickness by 0.1-0.2 mm.

[0005] As a further improvement of the above technical solution:

[0006] Further, before step S1, there is also a step of: determining, through power turbine one-dimensional flow passage design, a power turbine internal flow passage height, based on a matching relationship between the power turbine load coefficient and the power turbine efficiency, increasing the power turbine internal flow passage height by 1.5-2 mm.

[0007] Further, before step S1, there is also a step of: determining, through power turbine one-dimensional flow passage design, a power turbine rotor-stator axial spacing, and then based on power turbine efficiency design requirements and a functional relationship between the airflow excitation force and the power turbine rotor-stator axial spacing, increasing the power turbine rotor-stator axial spacing by 2-2.5 mm.

[0008] Further, the functional relationship between the airflow excitation force and the power turbine rotor-stator axial spacing is as follows:

[0009]

[0010] Where: F is the airflow exciting force, k is the proportional coefficient related to the power turbine geometry and flow characteristics, Cd is the aerodynamic drag coefficient, ρ is the airflow density, A is the effective area of ​​the power turbine rotor blade, V is the airflow velocity, n is the empirical index, and s is the axial distance between the power turbine rotor and stator.

[0011] Furthermore, before step S1, the following steps are also included: when designing the shape of the power turbine guide vane, first calculate and obtain the airflow field of the guide vane, analyze its flow conditions to obtain the flow separation area, re-match the required rate of change of the guide vane channel area according to the flow separation area, and adjust the curvature of its outer flow channel at the same time.

[0012] Furthermore, before step S1, the method further includes the following steps: optimizing the blade profile of the power turbine guide vane and adopting a combined design of large and small blades of the power turbine guide vane to make the trailing edge diameters of the large and small blades of the power turbine identical.

[0013] Furthermore, the trailing edge diameters of the large and small blades of the power turbine are 0.5 mm.

[0014] Furthermore, before step S1, the method further includes the following steps: optimizing the design of the large and small blades of the power turbine guide vane so as to keep the tail shapes of the large and small blades of the power turbine consistent.

[0015] Furthermore, between step S1 and step S2, there is also a step: when designing the power turbine rotor blade, determining the throat area of ​​the power turbine guide vane and the throat area of ​​the power turbine rotor blade, and then through the matching design of the gas turbine and the power turbine, increasing the throat area of ​​the power turbine guide vane by 1.5% to 2.5%, and reducing the throat area of ​​the power turbine rotor blade by 0.5% to 1%.

[0016] According to another aspect of the present invention, a gas turbine starter is provided, comprising a power turbine, wherein the power turbine adopts the above-mentioned design method for the power turbine.

[0017] The present invention has the following beneficial effects:

[0018] The design method of the power turbine of the application, firstly through the design of the power turbine rotor blade, in the design of the power turbine guide vane, firstly the guide vane airflow flow field is calculated and obtained, the flow condition is analyzed to obtain the flow separation area, the required guide vane passage area change rate is obtained according to the flow separation area, and the outer flow channel curvature is adjusted; again, based on the matching relationship of the rotor blade inlet structure angle and the rotor blade angle of attack, the rotor blade root section inlet structure angle is reduced by 10-15°, and the rotor blade tip section inlet structure angle is reduced by 35-45°, so as to reduce the positive angle of attack of the rotor blade under the large power cold state by reducing the inlet structure angle of the rotor blade, increase the negative angle of attack of the rotor blade under the large power starting state, improve the power turbine power under the large power cold state. The ability of the turbine starter front section is improved; again, based on the power turbine efficiency design requirement and the rotor blade lift coefficient design requirement, the maximum thickness of the rotor blade tip part is reduced by 0.3-0.5mm, the number of the rotor blade is increased by 4-6, and the axial width of the rotor blade is reduced by 1-2mm, so as to reduce the rotor blade lift coefficient, improve the power turbine efficiency, and after the number of the rotor blade is increased, the axial width of the rotor blade is reduced to avoid the increase of the rotor blade friction loss and ensure the power turbine efficiency; then, based on the rotor blade root section inlet structure angle, the rotor blade tip section inlet structure angle and the number of the rotor blade, the rotor blade root section installation angle is reduced by 8-10°, and the rotor blade tip section installation angle is increased by 4-6°, so as to reduce the difference between the root section installation angle and the tip section installation angle, so as to improve the strength of the rotor blade while improving the turbine efficiency, and reduce the risk of rotor blade crack or fracture; finally, based on the power turbine efficiency design requirement and the rotor blade anti-vibration ability design requirement, the thickness of the rotor blade tail edge is increased by 0.1-0.2mm, so as to improve the power turbine efficiency and the rotor blade anti-vibration ability; and through the above design steps, the rotor blade can be changed from "slim twist" to "short and fat straight", which greatly improves the rigidity of the rotor blade, reduces the root stress of the rotor blade, and greatly reduces the risk of rotor blade crack or fracture. Compared with the prior art, under the large power cold state, the power turbine has high efficiency, low exhaust temperature, good starting performance, low risk of rotor blade crack or fracture, high practicability, and is suitable for wide promotion and application.

[0019] In addition to the purposes, features and advantages described above, the application has other purposes, features and advantages. The application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which form a part of this application, are intended to provide further understanding of the application and are incorporated herein in their entirety, and they illustrate one exemplary embodiment of the present application and together with the description explain the present application. In the drawings:

[0021] Fig. 1 is a step block diagram of a design method of a power turbine of a preferred embodiment of the present application;

[0022] Fig. 2 is a graph of efficiency speed attack angle characteristics of a power turbine;

[0023] Fig. 3 is a graph of comparison of efficiency speed characteristics of a power turbine before and after improvement. DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following description.

[0025] As shown in Figs. 1-3 the design method of the power turbine of the present embodiment includes the following steps: S1: determining, through power turbine rotor blade design, a power turbine rotor blade root section inlet configuration angle, a power turbine rotor blade tip section inlet configuration angle, a power turbine rotor blade tip section maximum thickness, a power turbine rotor blade number, a power turbine rotor blade axial width, a power turbine rotor blade root section installation angle, a power turbine rotor blade tip section installation angle, and a power turbine rotor blade tail edge thickness; S2: based on a matching relationship between the rotor blade inlet configuration angle and the rotor blade attack angle, reducing the power turbine rotor blade root section inlet configuration angle by 10°-15° and reducing the power turbine rotor blade tip section inlet configuration angle by 35°-45°; S3: based on power turbine efficiency design requirements and rotor blade lift coefficient design requirements, reducing the power turbine rotor blade tip section maximum thickness by 0.3mm-0.5mm, while increasing the power turbine rotor blade number by 4-6 pieces and reducing the power turbine rotor blade axial width by 1mm-2mm; S4: based on the power turbine rotor blade root section inlet configuration angle, the power turbine rotor blade tip section inlet configuration angle, and the power turbine rotor blade number, reducing the power turbine rotor blade root section installation angle by 8°-10° and increasing the power turbine rotor blade tip section installation angle by 4°-6°; S5: based on power turbine efficiency design requirements and rotor blade anti-vibration capability design requirements, increasing the power turbine rotor blade tail edge thickness by 0.1mm-0.2mm.

[0026] Specifically, the design method of the power turbine of the present application, firstly, through the design of the power turbine rotor blade, in the design of the power turbine guide vane, firstly, the guide vane airflow flow field is calculated and obtained, the flow condition is analyzed to obtain the flow separation area, the required guide vane passage area change rate is obtained by re-matching the flow separation area, and the outer flow channel curvature is adjusted; secondly, based on the matching relationship of the rotor blade inlet structure angle and the rotor blade attack angle, the rotor blade root section inlet structure angle is reduced by 10°-15°, and the rotor blade tip section inlet structure angle is reduced by 35°-45°, so as to reduce the positive attack angle of the rotor blade under the large power cold rotation state, increase the negative attack angle of the rotor blade under the large power starting state, improve the power turbine doing function and the power turbine efficiency under the large power cold rotation state, reduce the exhaust temperature, and improve the front stage acceleration ability of the gas turbine starter; thirdly, based on the power turbine efficiency design requirement and the rotor blade lift coefficient design requirement, the maximum thickness of the rotor blade tip part is reduced by 0.3mm-0.5mm, the number of the rotor blade is increased by 4-6, and the axial width of the rotor blade is reduced by 1mm-2mm, so as to reduce the rotor blade lift coefficient, improve the power turbine efficiency, and after the number of the rotor blade is increased, the axial width of the rotor blade is reduced to avoid the increase of the rotor blade friction loss, and the power turbine efficiency is ensured; then, based on the rotor blade root section inlet structure angle, the rotor blade tip section inlet structure angle and the number of the rotor blade, the rotor blade root section installation angle is reduced by 8°-10°, and the rotor blade tip section installation angle is increased by 4°-6°, so as to reduce the difference between the root section installation angle and the tip section installation angle, so as to improve the strength of the rotor blade while improving the turbine efficiency, and reduce the risk of rotor blade crack or fracture; finally, based on the power turbine efficiency design requirement and the rotor blade anti-vibration ability design requirement, the thickness of the rotor blade tail edge is increased by 0.1mm-0.2mm, so as to balance the power turbine efficiency and the rotor blade anti-vibration ability; and through the above design steps, the rotor blade can be changed from "slim twist" to "short and fat straight", which greatly improves the rigidity of the rotor blade, reduces the root stress of the rotor blade, and greatly reduces the risk of rotor blade crack or fracture, so that the power turbine efficiency is high, the exhaust temperature is low, the starting performance is good, and the risk of rotor blade crack or fracture is low under the large power cold rotation state, the practicality is strong, and it is suitable for wide promotion and application.

[0027] Specifically, when the inlet configuration angle reduction value of the power turbine rotor blade root section is between 10°-15°, the positive and negative attack angles are appropriate, and the power turbine efficiency is high; when the inlet configuration angle reduction value of the power turbine rotor blade root section is less than 10°, the positive attack angle is large, and the power turbine efficiency is low; when the inlet configuration angle reduction value of the power turbine rotor blade root section is greater than 15°, the negative attack angle is large, and the power turbine efficiency is low.

[0028] Specifically, when the inlet configuration angle reduction value of the power turbine rotor blade tip section is between 35°-45°, the positive and negative attack angles are appropriate, and the power turbine efficiency is high; when the inlet configuration angle reduction value of the power turbine rotor blade tip section is less than 35°, the positive attack angle is large, and the power turbine efficiency is low; when the inlet configuration angle reduction value of the power turbine rotor blade tip section is greater than 45°, the negative attack angle is large, and the power turbine efficiency is low.

[0029] Specifically, when the maximum thickness reduction value of the power turbine rotor blade tip portion is between 0.3mm-0.5mm, the root-tip area ratio can be increased while ensuring that the flow loss is basically unchanged; when the maximum thickness reduction value of the power turbine rotor blade tip portion is less than 0.3mm or greater than 0.5mm, the flow loss increases.

[0030] Specifically, when the number of power turbine rotor blades increases by a value between 4-6, the load of each power turbine rotor blade is low, and the power turbine efficiency is high.

[0031] Specifically, when the axial width reduction value of the power turbine rotor blade is between 1mm-2mm, the rotor blade friction loss and rotor blade lift coefficient are reduced, and the power turbine efficiency is high; when the axial width reduction value of the power turbine rotor blade is less than 1mm, the rotor blade friction loss increases due to the increase in the number of power turbine rotor blades, resulting in a decrease in the power turbine efficiency; when the axial width reduction value of the power turbine rotor blade is greater than 2mm, the rotor blade lift coefficient increases, resulting in a decrease in the power turbine efficiency.

[0032] Specifically, when the installation angle reduction value of the power turbine rotor blade root section is between 8°-10°, and the installation angle increase value of the power turbine rotor blade tip section is between 4°-6°, the power turbine efficiency is high, and the power turbine rotor blade strength is high; when the installation angle reduction value of the power turbine rotor blade root section is not between 8°-10° and / or the installation angle increase value of the power turbine rotor blade tip section is not between 4°-6°, the power turbine efficiency and the power turbine rotor blade strength cannot be considered, i.e., it is possible that the power turbine efficiency is high but the power turbine rotor blade strength is low, or the power turbine rotor blade strength is high but the power turbine efficiency is low.

[0033] Specifically, when the tail edge thickness increase value of the power turbine rotor blade is between 0.1 mm and 0.2 mm, the anti-vibration capability is strong, and the turbine efficiency is high; when the tail edge thickness increase value of the power turbine rotor blade is less than 0.1 mm, the tail edge of the power turbine rotor blade is relatively thin, the anti-vibration capability is poor, and the risk of crack or fracture is high; when the tail edge thickness increase value of the power turbine rotor blade is greater than 0.2 mm, the tail edge of the power turbine rotor blade is relatively thick, the wake loss is large, and the power turbine efficiency is low.

[0034] In the embodiment, before step S1, the step of determining the inner flow passage height of the power turbine by one-dimensional flow passage design of the power turbine, and increasing the inner flow passage height of the power turbine by 1.5 mm to 2 mm based on the matching relationship between the load coefficient of the power turbine and the efficiency of the power turbine is further included.

[0035] Specifically, the inner flow passage height of the power turbine can be preliminarily determined in the one-dimensional flow passage design of the power turbine, and the inner flow passage height of the power turbine is increased by 1.5 mm to 2 mm based on the matching relationship between the load coefficient of the power turbine and the efficiency of the power turbine under the conditions of structural strength constraint design and consistent interface size adjustment, so as to increase the tangential velocity at the mean diameter of the power turbine rotor, reduce the load coefficient of the power turbine at low speed states such as cold start, improve the efficiency of the power turbine at low speed states, and meanwhile, keep the performance of the power turbine at high speed states unchanged.

[0036] Specifically, when the inner flow passage height increase value of the power turbine is between 1.5 mm and 2 mm, the power turbine efficiency is high, and the strength reserve coefficient meets the requirement; when the inner flow passage height increase value of the power turbine is less than 1.5 mm, the load coefficient of the power turbine is still relatively high, and the power turbine efficiency is low; when the inner flow passage height increase value of the power turbine is greater than 2 mm, the tangential velocity of the power turbine is too high, the stress of the power turbine impeller is large, and the strength reserve coefficient is too small.

[0037] It should be understood that the load coefficient of the power turbine is the ratio of the turbine rim work to the square of the tangential velocity at the mean diameter, that is, the load coefficient of the power turbine can be reduced by increasing the tangential velocity at the mean diameter of the power turbine rotor.

[0038] In the embodiment, before step S1, the step of determining the axial spacing between the rotor and stator of the power turbine by one-dimensional flow passage design of the power turbine, and increasing the axial spacing between the rotor and stator of the power turbine by 2 mm to 2.5 mm based on the functional relationship between the airflow excitation force and the axial spacing between the rotor and stator of the power turbine is further included.

[0039] Specifically, by the above steps, the influence of the upstream wake aerodynamic excitation force can be effectively reduced, the reliability and service life of the power turbine can be improved, and the risk of crack or fracture of the power turbine rotor blade can be reduced.

[0040] It should be understood that the airflow excitation force is mainly caused by the unsteady nature of the airflow, including turbulence, wake flow and pressure fluctuation, etc.; the change of the axial spacing will affect the transmission and distribution of these unsteady aerodynamic forces; the airflow excitation force directly affects the vibration response of the blade; larger airflow excitation force may cause blade fatigue crack or fracture, shorten the service life.

[0041] Specifically, when the increase value of the axial spacing between the power turbine rotor and stator is between 2mm-2.5mm, the power turbine efficiency is high, and the airflow excitation force is small; when the increase value of the axial spacing between the power turbine rotor and stator is less than 2mm, the airflow excitation force is large, the reliability of the power turbine is low, and the risk of power turbine rotor blade crack or fracture is high; when the increase value of the axial spacing between the power turbine rotor and stator is greater than 2.5mm, the power turbine efficiency is low.

[0042] In this embodiment, the functional relationship between the airflow excitation force and the axial spacing between the power turbine rotor and stator is as follows:

[0043]

[0044] Wherein: F is the airflow excitation force, k is a proportional coefficient related to the geometric shape and flow characteristics of the power turbine, Cd is the aerodynamic drag coefficient, p is the airflow density, A is the effective area of the power turbine rotor blade, V is the airflow velocity, n is the empirical index, and s is the axial spacing between the power turbine rotor and stator.

[0045] Specifically, by the above formula, the change of the airflow excitation force can be accurately estimated by changing the axial spacing between the power turbine rotor and stator, so as to provide effective data support for the optimization iteration of the design step.

[0046] In this embodiment, before step S1, there is also a step: when designing the power turbine guide vane, first calculate the guide vane airflow flow field, analyze the flow condition to obtain the flow separation area, and according to the flow separation area, re-match to obtain the required change rate of the guide vane passage area, and adjust the curvature of the outer flow channel.

[0047] Specifically, by the above steps, local airflow acceleration or deceleration can be avoided, the power turbine guide vane outlet flow field can be improved, and the performance of the power turbine can be improved, thereby improving the efficiency of the power turbine.

[0048] In this embodiment, before step S1, there is also a step: by optimizing the power turbine guide vane profile, adopting the combined modeling design of large and small power turbine guide vane blades, and making the tail edge diameters of the large and small power turbine guide vane blades the same.

[0049] Specifically, by the above steps, the airflow flow in the power turbine variable-pitch blade passage can be effectively organized, the power turbine guide vane outlet flow field can be improved, the airflow loss can be minimized and the influence of wake vortex excitation can be reduced, the performance of the power turbine can be improved, and thus the efficiency of the power turbine can be improved.

[0050] In this embodiment, the trailing edge diameter of the power turbine variable-pitch blade is 0.5 mm. Specifically, when the trailing edge diameter of the power turbine variable-pitch blade is 0.5 mm, the anti-vibration capability is strong, and the turbine efficiency is high; when the trailing edge diameter of the power turbine variable-pitch blade is less than 0.5 mm, the trailing edge of the power turbine rotor blade is thin, the anti-vibration capability is poor, and the risk of cracking or breaking is high; when the trailing edge diameter of the power turbine variable-pitch blade is greater than 0.5 mm, the trailing edge of the power turbine rotor blade is thick, the wake loss is large, and the efficiency of the power turbine is low.

[0051] In this embodiment, before step S1, there is further a step of: through the optimization design of the power turbine guide vane variable-pitch blade, the trailing edge shape of the power turbine variable-pitch blade is kept consistent.

[0052] Specifically, by the above steps, the airflow flow in the power turbine variable-pitch blade passage can be effectively organized, the power turbine guide vane outlet flow field can be improved, the airflow loss can be minimized and the influence of wake vortex excitation can be reduced, the performance of the power turbine can be improved, and thus the efficiency of the power turbine can be improved.

[0053] In this embodiment, between step S1 and step S2, there is further a step of: when the power turbine rotor blade is designed, the power turbine guide vane throat area and the power turbine rotor blade throat area are determined, and then through the matching design of the gas turbine and the power turbine, the power turbine guide vane throat area is increased by 1.5% to 2.5%, and the power turbine rotor blade throat area is reduced by 0.5% to 1%.

[0054] Specifically, by the above steps, the power turbine reaction force can be improved, and thus the efficiency of the power turbine can be improved.

[0055] Specifically, when the increase of the power turbine guide vane throat area is between 1.5% and 2.5%, the exhaust temperature is low, the power turbine reaction force is high, and the bearing load is appropriate; when the increase of the power turbine guide vane throat area is less than 1.5%, the exhaust temperature is high, the power turbine reaction force is low, and the efficiency of the power turbine is low; when the increase of the power turbine guide vane throat area is greater than 2.5%, the axial force is too large, and the bearing load is large.

[0056] Specifically, when the decrease of the power turbine rotor blade throat area is between 0.5% and 1%, the power turbine reaction force is high, and the bearing load is appropriate; when the decrease of the power turbine rotor blade throat area is less than 0.5%, the power turbine reaction force is low, and the efficiency of the power turbine is low; when the decrease of the power turbine rotor blade throat area is greater than 1%, the axial force is too large, and the bearing load is large.

[0057] The gas turbine starter of the embodiment comprises a power turbine, which is designed by using the design method of the power turbine. Specifically, the power turbine in the gas turbine starter is designed by using the design method of the power turbine, so as to improve the efficiency of the power turbine in the large cold rotation state, reduce the exhaust temperature of the starter, thereby improving the starting performance of the gas turbine starter, and also reducing the risk of cracks or fracture of the power turbine rotor blade and prolonging the service life.

[0058] The application has been applied to a certain type of gas turbine starter, and the whole machine test verification has been completed. Compared with the original type of gas turbine starter, the efficiency of the power turbine in the large cold rotation state is improved by more than 3%, the exhaust temperature is reduced by 10-20℃, the power turbine doing function in the low speed state is improved, the front acceleration performance of the gas turbine starter is improved, the maximum stress of the power turbine rotor blade is reduced by more than 25%, the risk of cracks or fracture of the power turbine rotor blade is greatly reduced, and the expected goal is achieved.

[0059] The above only describes the preferred embodiments of the application and is not intended to limit the application. The application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

[0060] It should be noted that in this document, the term "comprising" or "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0061] The principles and implementation modes of the application are described by using specific examples in this document, and the above example is only used to help understand the method of the application and its core idea. The above only describes the preferred embodiments of the application, and it should be pointed out that due to the limited nature of the language expression, there are infinite specific structures, and those skilled in the art can make some improvements, decorations or changes without departing from the principles of the application, or the above technical features can be combined in a proper way; these improvements, decorations, changes or combinations, or the application of the ideas and technical solutions of the application to other occasions without improvement, shall be regarded as the protection of the application.

Claims

1. A method for designing a power turbine, characterized in that: The following steps are involved: S1: through the design of the power turbine rotor blade, determine the power turbine rotor blade root section inlet structural angle, the power turbine rotor blade tip section inlet structural angle, the power turbine rotor blade tip portion maximum thickness, the number of power turbine rotor blades, the power turbine rotor blade axial width, the power turbine rotor blade root section installation angle, the power turbine rotor blade tip section installation angle and the power turbine rotor blade trailing edge thickness; S2: Based on the matching relationship between the rotor blade inlet structural angle and the rotor blade attack angle, the inlet structural angle of the power turbine rotor blade root section is reduced by 10°-15°, and the inlet structural angle of the power turbine rotor blade tip section is reduced by 35°-45°; S3: Based on the power turbine efficiency design requirements and the rotor blade lift coefficient design requirements, the maximum thickness of the power turbine rotor blade tip is reduced by 0.3mm-0.5mm, the number of power turbine rotor blades is increased by 4-6, and the axial width of the power turbine rotor blade is reduced by 1mm-2mm; S4: Based on the power turbine rotor blade root section inlet structural angle, the power turbine rotor blade tip section inlet structural angle and the number of power turbine rotor blades, reducing the power turbine rotor blade root section installation angle by 8°-10° and increasing the power turbine rotor blade tip section installation angle by 4°-6°; S5: Based on the power turbine efficiency design requirements and the rotor blade vibration resistance design requirements, the power turbine rotor blade trailing edge thickness is increased by 0.1mm-0.2mm.

2. The method for designing a power turbine according to claim 1, characterized in that: Step S1 also includes the following steps: Through the one-dimensional flow channel design of the power turbine, the height of the inner flow channel of the power turbine is determined. Based on the matching relationship between the power turbine load coefficient and the power turbine efficiency, the height of the inner flow channel of the power turbine is increased by 1.5mm-2mm.

3. The method for designing a power turbine according to claim 1, characterized in that: Before step S1, the following steps are also included: Through the one-dimensional flow channel design of the power turbine, the axial spacing between the power turbine rotor and stator is determined. Then, based on the power turbine efficiency design requirements and the functional relationship between the airflow excitation force and the axial spacing between the power turbine rotor and stator, the axial spacing between the power turbine rotor and stator is increased by 2mm-2.5mm.

4. The method for designing a power turbine according to claim 3, characterized in that: The functional relationship between the airflow exciting force and the axial distance between the power turbine rotor and stator is as follows: Where: F is the airflow excitation force, k is the proportional coefficient related to the power turbine geometry and flow characteristics, C d is the aerodynamic drag coefficient, ρ is the airflow density, A is the effective area of ​​the power turbine rotor blade, V is the airflow velocity, n is the empirical index, and s is the axial distance between the power turbine rotor and stator.

5. The method for designing a power turbine according to any one of claims 1 to 4, characterized in that: Before step S1, the following steps are also included: When designing the power turbine guide vane, the airflow field of the guide vane is first calculated, and its flow conditions are analyzed to obtain the flow separation area. The required rate of change of the guide vane channel area is re-matched according to the flow separation area, and the curvature of its outer flow channel is adjusted at the same time.

6. The method for designing a power turbine according to any one of claims 1 to 4, characterized in that: Before step S1, the following steps are also included: By optimizing the blade shape of the power turbine guide vane and adopting a combined modeling design of large and small blades of the power turbine guide vane, the trailing edge diameters of the large and small blades of the power turbine are made the same.

7. The method for designing a power turbine according to claim 6, characterized in that: The trailing edge diameter of the power turbine blades is 0.5 mm.

8. The method for designing a power turbine according to any one of claims 1 to 4, characterized in that: Before step S1, the following steps are also included: By optimizing the design of the large and small blades of the power turbine guide, the tail shapes of the large and small blades of the power turbine are kept consistent.

9. The method for designing a power turbine according to any one of claims 1 to 4, characterized in that: The following steps are included between step S1 and step S2: When designing the power turbine rotor blades, the throat area of ​​the power turbine guide vane and the throat area of ​​the power turbine rotor blades are determined, and then through the matching design of the gas turbine and the power turbine, the throat area of ​​the power turbine guide vane is increased by 1.5% to 2.5%, and the throat area of ​​the power turbine rotor blade is reduced by 0.5% to 1%.

10. A gas turbine starter comprising a power turbine, characterized in that: The power turbine adopts the design method of the power turbine described in any one of claims 1-9.

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