A method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions

Abstract

The purpose of the present invention is to provide a method for optimizing the flow layout of a wide-operating-condition low-loss transition section of a marine gas turbine compressor, which can solve the problems of gas turbine matching imbalance and performance degradation caused by flow loss and uneven flow in the compressor transition section. Based on the working characteristics of the marine gas turbine compressor, the present invention adopts parameterization means and combined optimization strategies to achieve parameterized customized design and rapid optimization of a wide-operating-condition low-loss compressor transition section, effectively improves the aerodynamic performance of the marine gas turbine compressor transition section, and can save a lot of design iteration time and shorten the design cycle. At the same time, the present invention is not limited to marine gas turbine compressors, but can be applied to various types of three-rotor simple cycle gas turbines, and is also applicable to aircraft engines and various industrial compressors with flow transition structures.

Description

Technical Field

[0001] The present invention relates to a gas turbine aerodynamic optimization design method, in particular to a compressor aerodynamic optimization design method. Background Art

[0002] As one of the three most important core components of a gas turbine, the performance of the compressor directly determines the technical indicators of the entire machine. The three-rotor simple cycle layout is a very common layout in marine gas turbines. In its compressor, there is a transition section, a key component that plays a "connecting" role. The transition section is located between the low-pressure and high-pressure compressors, and determines the flow matching of the two upstream and downstream compressors. The high-performance, low-loss transition section flow layout can effectively reduce the outlet flow resistance of the low-pressure compressor and provide a good inlet flow state for the high-pressure compressor, which is of great significance to the matching of the high and low-pressure rotors of the entire gas turbine.

[0003] In current marine gas turbine products, the end wall flow channel profile of the transition section is mainly straight or simple curve, and the support plate profile is mostly runway-shaped, column-shaped or shuttle-shaped. The flow layout formed by this has poor aerodynamic performance and often leads to large flow losses and unevenness in the high-pressure compressor flow. In order to solve the above problems, some transition section flow design methods have been introduced, mainly focusing on the design and adjustment of the end wall profile and the support plate profile. However, most of the existing methods have the following shortcomings: (1) They are often designed only for the end wall or the support plate, and the transition section end wall and the support plate are not designed and optimized as a whole from the perspective of the overall spatial flow field. (2) Some methods involve fewer parameters for the structural design of the profile, and the control of the flow field is relatively rough; other methods use complex curve description equations and parameter control, but the resulting spatial geometric structures are not very practical in engineering and have poor scalability, resulting in the lack of mature engineering structures that match the transition section flow design method; (3) The design is only carried out for a single operating condition, and the impact of transition section losses under the wide operating conditions of marine gas turbines is not fully considered.

[0004] As the technical indicators of marine gas turbines such as power, efficiency, and life continue to rise, the influence of the transition section flow layout with a wide operating condition and low loss on the compressor and even the gas turbine as a whole is becoming increasingly prominent. By designing a compressor transition section that is suitable for the operating characteristics of marine gas turbines and has low loss performance, the matching effect of the marine gas turbine as a whole can be adjusted and the performance of the whole machine can be improved. This has become a key technical link in the design system of marine gas turbines. Summary of the invention

[0005] The purpose of the present invention is to provide a method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions, which can solve the problems of gas turbine matching imbalance and performance degradation caused by flow loss and uneven flow in the compressor transition section.

[0006] The object of the present invention is achieved in that:

[0007] The present invention provides a method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions, which is characterized by comprising the following steps:

[0008] (1) Perform parametric design of flow layout;

[0009] (2) Carry out optimization design based on combinatorial optimization strategy;

[0010] (3) If the design requirements are not met, the sample library and objective function are further modified to ultimately obtain an aerodynamic design scheme for the transition section flow layout that meets the performance requirements.

[0011] The present invention may also include:

[0012] 1. The total pressure loss coefficient ω and the outlet total pressure unevenness coefficient δ are used as the performance index parameters of the transition section, which are defined as:

[0013]

[0014] in, is the total pressure at the inlet of the transition section, is the total pressure at the transition section outlet, p in is the static pressure at the transition section inlet;

[0015]

[0016] in, is the maximum total pressure at the transition section outlet, is the average total pressure at the transition section outlet.

[0017] 2. The parametric design of the flow layout in step (1) includes the parametric design of the flow end wall flow channel profile and the parametric design of the flow internal support plate profile, wherein the parametric design of the flow end wall flow channel profile adopts a customized curve design method based on Bezier curves; the parametric design of the support plate profile adopts a customized blade design method.

[0018] 3. The optimization design based on the combined optimization strategy in step (2) is carried out as follows: determine the objective function that characterizes the aerodynamic performance of the transition section flow, select the key control parameters of the end wall flow channel profile and the support plate profile of the flow section, and adopt a combined optimization strategy that combines DOE experimental design with a gradient optimization algorithm to achieve the overall optimization design of the transition section flow.

[0019] 4. The customized curve design method based on Bezier curve uses the fourth-order Bezier curve to describe the inner and outer wall flow channel lines, and realizes customized design through the coordinates of the five control points and constraints of the inner and outer wall lines.

[0020] 5. The customized blade design method uses two arcs or a fourth-order polynomial regular curve with controlled diffusion blade CDA characteristics to describe the thickness distribution of the support plate profile, and determines the number, thickness and length constraints of the support plates through the constraints of the support plate structure to achieve customized design.

[0021] 6. The objective function to characterize the aerodynamic performance of the transition section flow is the function OBF:

[0022]

[0023] The variables in the above formula are defined as follows:

[0024] Subscripts i=1-3 correspond to different incoming flow Mach number conditions, i=1 is the incoming flow Mach number condition of the transition section under the design point of the marine gas turbine, i=2 is the incoming flow Mach number condition of the transition section under the common working condition of the marine gas turbine, and i=3 is the incoming flow Mach number condition of the transition section under the minimum working condition of the marine gas turbine;

[0025] ω ref is the reference value of the total pressure loss coefficient of the transition section, δ ref is the reference value of the total pressure loss coefficient of the transition section;

[0026] a1 and a2 are weight factors between flow loss and outlet uniformity;

[0027] c i is the weight factor for different incoming flow Mach number conditions.

[0028] 7. The key control parameters of the end wall flow channel profile are the horizontal coordinate values ​​of the 2nd, 3rd and 4th control points of the 5 control points of the fourth-order Bezier curve on the inner and outer walls of the transition section, and the vertical coordinate value of the 3rd control point.

[0029] 8. The key control parameters of the support plate profile are the maximum thickness of the customized blade, the relative position of the maximum thickness, the leading edge radius, the trailing edge radius, the leading edge wedge angle, and the trailing edge wedge angle.

[0030] 9. The DOE experimental design method in the combination optimization strategy adopts the optimal Latin hypercube design method.

[0031] 10. The gradient optimization algorithm in the combination optimization strategy adopts the sequential quadratic programming algorithm.

[0032] 11. The constraints of the inner and outer wall flow channel profiles are the end point positions and flow channel slopes of the inner and outer flow channels at the outlet of the low-pressure compressor, and the end point positions and flow channel slopes of the inner and outer flow channels at the inlet of the high-pressure compressor. According to the end point and tangent vector properties of the Bezier curve, the coordinate values ​​of the corresponding control points and the tangent slopes of the Bezier curve at the end points are obtained.

[0033] 12. Constraints on the support plate structure, including the requirements on the number of support plates for the resonance frequency margin between the low-pressure compressor outlet moving blades and the high-pressure compressor inlet moving blades, the spatial size requirements for the internal components of the support plate such as the oil supply and return pipelines, air ducts, speed sensors, and turning tool channels, and the size restrictions on the connection between the support plate and the outer casing.

[0034] 13. In step (3), the sample library and the objective function are further modified. For the sample library, the value range of key control parameters of the sample space, the number of samples, and the distribution mode are modified; for the objective function, a1, a2, c i The weight value is modified.

[0035] The advantages of the present invention are:

[0036] (1) The present invention adopts a fourth-order Bezier curve as the flow channel profile of the flow end wall, and adopts a customized blade profile with controlled diffusion blade profile (CDA) characteristics as the flow internal branch plate profile, so that the flow field structure of the airflow from the low-pressure compressor outlet through the transition section is close to an ideal state, the spatial pressure gradient distribution is more uniform, and the flow field disturbance phenomena such as the corner separation at the intersection of the branch plate and the end wall and the branch plate wake are effectively suppressed, thereby effectively reducing the flow loss of the transition section flow section.

[0037] (2) The present invention constructs a comprehensive objective function covering the common operating characteristics of gas turbines, so that the optimization design of the transition section is no longer limited to a single operating condition, and the optimization work is expanded to the entire operating condition range of the gas turbine, which fully reflects the unique characteristics of the large-scale variable operating conditions of marine gas turbines, and realizes the multi-operating point collaborative optimization design of the flow layout parameters of the transition section of the marine gas turbine compressor, effectively improving the performance level of the marine gas turbine within the full operating condition range.

[0038] (3) The present invention effectively reduces the outlet flow resistance of the low-pressure compressor and significantly improves the inlet flow state of the high-pressure compressor by controlling the flow field structure inside the transition section, making the load distribution of the low-pressure and high-pressure compressors of the gas turbine more ideal, and achieving fine control of the matching effect of the high- and low-pressure rotors of the whole machine, thereby effectively improving the overall performance and stable operation capability of the marine gas turbine.

[0039] (4) According to the actual needs of optimizing the flow layout of the transition section during the design of a marine gas turbine, the present invention uses Bezier curves and polynomial curves of appropriate order to respectively describe the end wall flow channel profile and the internal support plate profile. By adjusting the curve control parameters, the main parts of the transition section that are prone to flow losses are given priority consideration. While achieving parameterized and refined design of the flow layout, the number of parameter combination samples is reduced, effectively shortening the design cycle.

[0040] (5) The present invention adopts a combined optimization strategy in the design process. Through the optimal Latin hypercube experimental design, the sensitivity of the key control parameters of the transition section flow layout to the performance is analyzed, the number of optimization variables is reduced, and the number of iterations is reduced through the sequential quadratic programming algorithm. While obtaining a wide-operating-condition low-loss transition section flow layout solution, the optimization time is saved, which is very suitable for engineering applications.

[0041] (6) The present invention is not limited to marine gas turbine compressors, but can be applied to various types of three-rotor simple cycle gas turbines, and is also applicable to aircraft engines and various industrial compressors with flow transition structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in more detail below with reference to the accompanying drawings:

[0044] Combination Figure 1 The present invention provides a method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions, which is achieved by the following steps:

[0045] Step 1: Parametric design of flow layout, including parametric design of flow end wall flow channel profile and parametric design of flow internal support plate profile.

[0046] The performance index parameters of the transition section are the total pressure loss coefficient ω and the outlet total pressure unevenness coefficient δ, which are defined as:

[0047]

[0048] in, is the total pressure at the inlet of the transition section, is the total pressure at the transition section outlet, p in is the static pressure at the transition section inlet;

[0049]

[0050] in, is the maximum total pressure at the transition section outlet, is the average total pressure at the transition section outlet.

[0051] For the parametric design of the flow channel profile of the flow end wall, the specific implementation method of the present invention is as follows:

[0052] A custom curve design method based on Bezier curve is adopted to describe the inner and outer wall flow channel profiles through fourth-order Bezier curves, and the custom design is realized through the coordinates of the five control points and constraints of the inner and outer wall profiles. The constraints of the inner and outer wall flow channel profiles include: the end point position and flow channel slope of the inner and outer flow channels at the outlet of the low-pressure compressor, the end point position and flow channel slope of the inner and outer flow channels at the inlet of the high-pressure compressor, and according to the end point property and tangent vector property of the Bezier curve, the coordinate values ​​of the corresponding control points and the tangent slope of the Bezier curve at the end point are obtained.

[0053] For the parametric design of the internal support plate profile of the flow passage, the specific implementation method of the present invention is as follows:

[0054] The customized blade design method is adopted to describe the thickness distribution of the support plate profile through two arcs or fourth-order polynomial regular curves with controlled diffusion blade (CDA) characteristics, and the number, thickness and length constraints of the support plates are determined through the constraints of the support plate structure to achieve customized design. The constraints of the support plate structure include: the requirements for the number of support plates for the resonance frequency margin of the low-pressure compressor outlet moving blades and the high-pressure compressor inlet moving blades, the spatial size requirements of the internal parts structure of the support plate, such as the oil supply and return pipelines, air ducts, speed sensors, turning tool channels, etc., and the size limit requirements for the connection position between the support plate and the outer casing.

[0055] Step 2: Optimization design based on combined optimization strategy. The following method is used: determine the objective function that characterizes the aerodynamic performance of the transition section flow, select the key control parameters of the end wall flow channel profile and the support plate profile of the flow section, and use a combined optimization strategy combining DOE (experimental design) and gradient optimization algorithm to achieve the overall optimization design of the transition section flow.

[0056] Among them, for the objective function, the specific implementation method of the present invention is:

[0057] The objective function that characterizes the aerodynamic performance of the transition section flow is the following function OBF:

[0058]

[0059] The variables in the above formula are defined as follows:

[0060] Subscript i=1~3, corresponding to different inlet Mach number conditions, determined according to the commonly used inlet Mach number range of the transition section components. Usually, when i=1, it is the inlet Mach number condition of the transition section under the design point of the marine gas turbine, when i=2, it is the inlet Mach number condition of the transition section under the commonly used working conditions of the marine gas turbine, and when i=3, it is the inlet Mach number condition of the transition section under the minimum working conditions of the marine gas turbine;

[0061] ω ref is the reference value of the total pressure loss coefficient of the transition section, δref It is the reference value of the total pressure loss coefficient of the transition section, which is usually preliminarily given based on experience according to the transition section difference-length ratio.

[0062] a1 and a2 are weight factors between flow loss and outlet uniformity, usually a1 = 0.5 and a2 = 0.5, which can be adjusted according to the specific work emphasis of the transition section of different units;

[0063] c i is the weight factor for different incoming Mach number conditions, which is determined according to the common degree of incoming Mach number of transition section components. Usually, when i=1 design point Mach number, c1=0.6, when i=2 common working condition Mach number, c2=0.25, when i=3 minimum working condition Mach number, c3=0.15, which can be adjusted according to the specific work emphasis of transition section of different units.

[0064] Regarding the key control parameters of the flow channel profile of the end wall of the flow passage, the specific implementation method of the present invention is as follows:

[0065] The key control parameters of the end wall flow channel profile are the horizontal coordinate values ​​of the second, third, and fourth control points of the five control points of the fourth-order Bezier curve on the inner and outer walls of the transition section, and the vertical coordinate value of the third control point.

[0066] For the key control parameters of the support plate profile, the specific implementation method of the present invention is:

[0067] The key control parameters of the support plate profile are the maximum thickness of the customized blade, the relative position of the maximum thickness, the leading edge radius, the trailing edge radius, the leading edge wedge angle, and the trailing edge wedge angle.

[0068] For the DOE (experimental design) method, the specific implementation of the present invention is to adopt the optimal Latin hypercube design method.

[0069] For the gradient optimization algorithm, the specific implementation method of the present invention is to adopt a sequential quadratic programming algorithm.

[0070] Through automatic optimization iteration, the optimal solution of the optimization variables that satisfies the best calculation result of the objective function is found.

[0071] Step 3: If the design requirements are not met, the sample library and objective function can be further modified to finally obtain an aerodynamic design scheme for the transition section flow layout that meets the performance requirements.

[0072] For the modified sample library, the specific implementation of the present invention is as follows: the value range of key control parameters of the sample space, the number of samples, the distribution mode, etc. can be modified;

[0073] The specific implementation method of the present invention for modifying the objective function is: a1, a2, c in the objective function can be modified. iThe weight value is modified.

[0074] The method for optimizing the flow layout of a wide-operating-condition low-loss transition section of a marine gas turbine compressor proposed in the present invention is universal and is not limited to marine gas turbine compressors. It can be applied to various types of three-rotor simple cycle gas turbines, and is also suitable for aircraft engines and various industrial compressors with flow transition structures.

Claims

1. A method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions, characterized by: The steps include: (1) Perform parametric design of flow layout; (2) Carry out optimization design based on combinatorial optimization strategy; (3) If the design requirements are not met, the sample library and the objective function are further modified to finally obtain an aerodynamic design scheme for the flow layout of the transition section that meets the performance requirements; In step (1), the total pressure loss coefficient ω and the outlet total pressure unevenness coefficient δ are used as transition section performance index parameters, which are defined as: in, is the total pressure at the inlet of the transition section, is the total pressure at the transition section outlet, p in is the static pressure at the transition section inlet; in, is the maximum total pressure at the transition section outlet, is the average total pressure at the transition section outlet; The optimization design based on the combined optimization strategy in step (2) is carried out in the following manner: determining the objective function characterizing the aerodynamic performance of the transition section flow, selecting the key control parameters of the end wall flow channel profile and the support plate profile of the flow section, and adopting a combined optimization strategy combining DOE experimental design and gradient optimization algorithm to achieve the overall optimization design of the transition section flow; The objective function that characterizes the aerodynamic performance of the transition section flow is the function OBF: The variables in the above formula are defined as follows: Subscripts i=1-3 correspond to different incoming flow Mach number conditions, i=1 is the incoming flow Mach number condition of the transition section under the design point of the marine gas turbine, i=2 is the incoming flow Mach number condition of the transition section under the common working condition of the marine gas turbine, and i=3 is the incoming flow Mach number condition of the transition section under the minimum working condition of the marine gas turbine; ω ref is the reference value of the total pressure loss coefficient of the transition section, δ ref is the reference value of the total pressure non-uniformity coefficient of the transition section; a1 and a2 are weight factors between flow loss and outlet uniformity; c i is the weight factor for different incoming flow Mach number conditions.

2. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 1 is characterized by: The parametric design of the flow layout in step (1) includes the parametric design of the flow end wall flow channel profile and the parametric design of the flow internal support plate profile, wherein the parametric design of the flow end wall flow channel profile adopts a customized curve design method based on Bezier curves; the parametric design of the support plate profile adopts a customized blade design method.

3. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 2 is characterized by: The customized curve design method based on Bezier curve uses fourth-order Bezier curve to describe the inner and outer wall flow channel profiles, and realizes customized design through the coordinates of 5 control points and constraints of the inner and outer wall profiles.

4. The method for optimizing the flow layout of a wide-operating-condition low-loss transition section of a marine gas turbine compressor according to claim 2 is characterized by: The blade design method uses two arcs or a fourth-order polynomial regular curve with controlled diffusion blade CDA characteristics to describe the thickness distribution of the support plate profile, and determines the number, thickness and length constraints of the support plates through the constraints of the support plate structure to achieve customized design.

5. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 1 is characterized by: The key control parameters of the end wall flow channel profile are the horizontal coordinate values ​​of the second, third, and fourth control points of the five control points of the fourth-order Bezier curve on the inner and outer walls of the transition section, and the vertical coordinate value of the third control point.

6. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 1 is characterized by: The key control parameters of the support plate profile are the maximum thickness of the customized blade, the relative position of the maximum thickness, the leading edge radius, the trailing edge radius, the leading edge wedge angle, and the trailing edge wedge angle.

7. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 1 is characterized by: The DOE experimental design method in the combinatorial optimization strategy adopts the optimal Latin hypercube design method.

8. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 1 is characterized by: The gradient optimization algorithm in the combination optimization strategy adopts the sequential quadratic programming algorithm.

9. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 3 is characterized by: The constraints of the inner and outer wall flow channel profiles are the end point positions and flow channel slopes of the inner and outer flow channels at the outlet of the low-pressure compressor, and the end point positions and flow channel slopes of the inner and outer flow channels at the inlet of the high-pressure compressor. According to the endpoint and tangent properties of the Bezier curve, the coordinate values ​​of the corresponding control points and the tangent slopes of the Bezier curves at the endpoints are obtained.

10. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 4, characterized in that: The constraints of the support plate structure include the requirements for the number of support plates to meet the resonance frequency margin of the low-pressure compressor outlet moving blades and the high-pressure compressor inlet moving blades, the spatial size requirements for the lubricating oil supply and return pipelines, air ducts, speed sensors, and turning tool channels of the built-in components inside the support plate, and the size restrictions on the connection between the support plate and the outer casing.

11. The method for optimizing the flow layout of a low-loss transition section of a marine gas turbine compressor under wide operating conditions according to claim 1, characterized in that: In step (3), the sample library and the objective function are further modified. For the sample library, the value range of key control parameters of the sample space, the number of samples, and the distribution mode are modified; for the objective function, a1, a2, c i The weight value is modified.

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