Forward design parameter prediction and evaluation method for composite cooling structure of turbine blade leading edge

Abstract

The present invention discloses a method for predicting and evaluating the forward design parameters of a composite cooling structure at the leading edge of a turbine blade, and belongs to the field of thermal protection of high-temperature components of an aero-engine. First, a correction formula for the theoretical relationship of comprehensive cooling efficiency is established. Then, a design envelope of the forward cooling structure is established. Afterwards, the film cooling efficiency of the leading edge outer wall surface and the cold air side heat transfer coefficient of the leading edge inner wall surface that meet the conditions are obtained by screening the envelope. Finally, the comprehensive cooling efficiency of the leading edge outer wall surface is calculated by combining the correction formula for the theoretical relationship of comprehensive cooling efficiency, and the comprehensive cooling efficiency prediction is realized. The composite cooling structure at the leading edge is evaluated through the prediction results, and the design scheme of the composite cooling structure at the leading edge is obtained. The present invention is directed to a forward design method for a composite cooling structure at the leading edge of a turbine blade with a large curvature change and a strong dense hole heat transfer effect, a method for predicting cooling design parameters and a method for evaluating structural design, and solves the problem of inaccuracy of one-dimensional formulas and analysis methods in actually predicting the leading edge wall temperature.

Description

Technical Field

[0001] The invention belongs to the field of thermal protection of high-temperature parts of aircraft engines, and in particular relates to a method for predicting and evaluating forward design parameters of a composite cooling structure at the leading edge of a turbine blade. Background Art

[0002] The leading edge of the turbine blade is directly impacted by the high-temperature combustion gas, and is one of the areas on the blade that bears the greatest heat load and is also the most difficult to cool effectively. The main reason why efficient cooling of the leading edge is difficult to implement is that the high-temperature combustion gas there has the characteristics of low speed, high pressure, and high turbulence. In addition, the large curvature of the leading edge also limits the effective coverage of the air film. In the study of the comprehensive cooling effect and coupled heat transfer of turbine blades, some scholars have devoted themselves to the mechanism of the heat transfer process and have conducted research on the factors affecting the comprehensive cooling efficiency. The theoretical basis of most current related research is based on Natham [1] The theoretical relationship of the one-dimensional comprehensive cooling efficiency of the impingement divergent cooling structure is derived. The derivation result is:

[0003]

[0004] From formula (1), it can be seen that the comprehensive cooling efficiency Φ is the main and mainstream side Biot number Bi g , heat transfer coefficient ratio on both sides of the wall h g / h c and the film cooling efficiency η. This one-dimensional theoretical relationship and heat transfer model have become the basis for many researchers to develop a comprehensive cooling efficiency influencing factor theory, and based on this theory, methods for matching heat transfer parameters and methods for rapid prediction of comprehensive cooling efficiency have been proposed. For example, Li Mingfei et al. [2] The dimensionless parameters that affect the comprehensive cooling efficiency were analyzed using a one-dimensional model. The authors used the conclusions to study the relevant influencing parameters and used the above one-dimensional formula to predict the comprehensive cooling efficiency. Currently, most of the publicly published literature is about the influence of turbine blade geometry and flow parameters on wall temperature, as well as a comprehensive cooling efficiency rapid prediction method based on formula (1).

[0005] The prior art records that the cooling design parameters of turbine blades are determined by obtaining the gas side inlet parameters, one-dimensional flow channel parameters, and blade parameters of the turbine blades, which provides ideas for the design parameter analysis of the leading edge of the turbine blades.

[0006] However, for the design goal of turbine blade surface temperature under the influence of coupled heat transfer of composite cooling structure, the existing structural design methods and design parameter analysis and evaluation of turbine blade leading edge are prone to inaccuracy. The reason is that the geometric characteristics of large curvature of turbine blade leading edge make the one-dimensional comprehensive cooling efficiency prediction formula produce large errors; at the same time, the dense film hole heat exchange effect and temperature rise effect, heat transfer area change and other reasons of turbine blade leading edge also make the existing one-dimensional design parameter analysis method unable to adapt to the structural design of turbine leading edge. At the same time, the existing technical methods are often more specific and targeted, but less systematic, and no systematic method based on heat transfer theory has been developed to guide and evaluate cooling structure design and optimization.

[0007] In addition, the existing technology lacks an equation-based evaluation and analysis theory for the analysis of leading edge cooling structure design parameters. Compared with the iterative algorithm, the equation-based calculation method can provide a more complete mathematical relationship, thereby establishing more information output structural design analysis and evaluation.

[0008] Therefore, it is necessary to conduct a secondary derivation and correction of the theoretical relationship of the comprehensive cooling efficiency according to the characteristics of the leading edge of the turbine blade, establish a forward design method for the composite cooling structure of the leading edge of the turbine blade based on the theoretical equation, and propose accurate prediction measures for the forward design parameters and evaluation measures for the structural design, so as to provide theoretical guidance and technical support for the design and optimization of the actual turbine blade leading edge high-efficiency composite cooling system. Summary of the invention

[0009] Technical issues to be solved:

[0010] In order to avoid the shortcomings of the prior art, the present invention provides a method for predicting and evaluating forward design parameters of a composite cooling structure at the leading edge of a turbine blade, a forward design method for a composite cooling structure at the leading edge of a turbine blade with a large curvature change and a strong dense hole heat exchange effect, and a method for predicting cooling design parameters and evaluating structural design in the process, which solves the inaccuracy problem of one-dimensional formulas and analysis methods in the actual prediction of the leading edge wall temperature.

[0011] The technical solution of the present invention is: a method for predicting and evaluating forward design parameters of a composite cooling structure at the leading edge of a turbine blade, characterized in that the specific steps are as follows:

[0012] Step 1: Calculate the design parameters of the composite cooling structure through the geometric parameters of the turbine blade leading edge, and derive the correction formula of the comprehensive cooling efficiency theoretical relationship based on the characteristics of the blade leading edge:

[0013]

[0014] Step 2: Combine the allowable / target comprehensive cooling efficiency with the composite cooling structure design parameters and the comprehensive cooling efficiency theoretical formula in step 1 to obtain the leading edge film cooling efficiency η and the corresponding cold air side heat transfer coefficient h that satisfies the equation c The two-dimensional array thus formed forms a design envelope for the forward cooling structure;

[0015] Step 3: Based on η-h obtained in step 2 c The envelope is used to screen the actual parameter values ​​and obtain the film cooling efficiency η of the leading edge outer wall that meets the conditions. * The heat transfer coefficient of the cold air side of the leading edge inner wall h c * ;

[0016] Step 4: The η confirmed after screening in step 3 * 、h c * , and the heat transfer coefficient of the film hole on the inner wall of the film hole h e Substitute it into the comprehensive cooling efficiency theoretical formula (2) in step 1 to calculate the comprehensive cooling efficiency of the outer wall of the leading edge, realize the prediction of the comprehensive cooling efficiency of the outer wall of the leading edge, and use the predicted comprehensive cooling efficiency result to calculate the η * 、h c * The combined leading edge composite cooling structure is evaluated;

[0017] Step 5: According to the comprehensive cooling efficiency η that meets the design requirements * 、h c * The corresponding composite cooling structure combination obtains the design scheme of the leading edge composite cooling structure.

[0018] A further technical solution of the present invention is: in step 1, the dimensionless temperature comprehensive cooling efficiency is defined as Leading edge film cooling efficiency T g is the incoming gas temperature, dimensionless cooling gas flow m c + , gas side Bi g , the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side C, the ratio of the product of the equivalent heat transfer coefficient and the heat transfer area in the air film hole to the product of the heat transfer coefficient and the external heat transfer area on the gas side C e , dimensionless equivalent integrated heat transfer area ratio A g * Based on the thermal resistance analysis method, the modified formula (2) of the comprehensive cooling efficiency theoretical relationship for the characteristics of the blade leading edge is derived.

[0019] A further technical solution of the present invention is: the dimensionless equivalent integrated heat transfer area ratio is:

[0020]

[0021] Where Ag is the external heat transfer area of ​​the leading edge, R 1 is the outer curvature radius of the leading edge, R 2 is the inner curvature radius of the leading edge, N is the central angle of curvature of the longitudinal section of the leading edge, and L is the height of the turbine blade.

[0022] A further technical solution of the present invention is: the gas side Biot number is In the formula, h g is the heat transfer coefficient of the gas side of the leading edge of the turbine blade, δ is the wall thickness of the leading edge of the blade, k s is the thermal conductivity.

[0023] A further technical solution of the present invention is: the dimensionless cold air flow In the formula, m c is the mass flow rate of cooling air, c p,c is the specific heat capacity at constant pressure, T w , T aw , T c,e , T c They are the leading edge wall temperature, the adiabatic temperature of the wall when there is an air film, the air film hole outlet temperature, and the cold air temperature.

[0024] A further technical solution of the present invention is: the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side is In the formula, h c is the heat transfer coefficient of the cold air side of the leading edge of the turbine blade, A c is the internal heat exchange area of ​​the leading edge.

[0025] A further technical solution of the present invention is: the equivalent heat transfer coefficient in the air film hole and the heat transfer area A in the air film hole e The ratio of the product of the heat transfer coefficient on the gas side and the product of the external heat transfer area In the formula, h e is the heat transfer coefficient in the air film pore, St e is the Stanton number of the fluid in the air film hole, l is the length of the air film hole, and d is the diameter of the air film hole;

[0026] According to the temperature rise principle and the temperature node correspondence principle of the thermal resistance analysis method, the equivalent heat transfer coefficient in the air film hole is derived:

[0027] A further technical solution of the present invention is: in step 2, first, the comprehensive cooling efficiency of the target leading edge outer wall surface is determined and input, and the variation range and step length of the air film cooling efficiency η of the leading edge outer wall surface are determined and input; then, according to the comprehensive cooling efficiency theoretical formula (2), the one-dimensional array of the air film cooling efficiency η is calculated to obtain the cold air side heat transfer coefficient h of the leading edge inner wall surface corresponding to the equation c Finally, the output is the film cooling efficiency η of the leading edge outer wall and the cold air side heat transfer coefficient h of the leading edge inner wall corresponding to the equation. c The two-dimensional array formed forms the design envelope of the forward cooling structure.

[0028] A further technical solution of the present invention is to optimize the comprehensive cooling efficiency of the leading edge outer wall surface obtained in step 4, the steps are as follows:

[0029] First, according to the theoretical equation (2) that relates the comprehensive cooling efficiency to the internal and external cooling parameters in step 1, the partial derivative expression of the leading edge comprehensive cooling efficiency with respect to the following forward design parameters is derived:

[0030] The partial derivative of the comprehensive cooling efficiency with respect to the mainstream side Biot number is derived as follows:

[0031]

[0032] The partial derivative of the comprehensive cooling efficiency to the film cooling efficiency is derived as follows:

[0033]

[0034] The comprehensive cooling efficiency is the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side C, the ratio of the product of the equivalent heat transfer coefficient and the heat transfer area in the air film hole to the product of the heat transfer coefficient and the external heat transfer area on the gas side C e The partial derivative of derives:

[0035]

[0036] The comprehensive cooling efficiency is derived from the dimensionless cooling air flow rate:

[0037]

[0038] Then, according to the solution of the above partial derivative equation, the key adjustable design point parameter (h c ,η,m c ), the quantitative expression of the influence of typical forward design parameters on the sensitivity of the comprehensive cooling efficiency of the leading edge wall is obtained:

[0039]

[0040] Finally, based on the quantitative influence of typical forward design parameters on the comprehensive cooling efficiency, according to the variation range of adjustable design point parameters in actual engineering design, the quantitative influence of each forward design parameter on the comprehensive cooling efficiency under various working conditions is processed and output by mathematical statistics; in the quantitative influence diagram of the forward design parameters on the comprehensive cooling efficiency, the η that needs to be evaluated and analyzed is found. * 、h c * The corresponding composite cooling structure combination can be used to quantitatively analyze the improvement potential of the external and internal cooling structures of the composite cooling structure, and the current cooling characteristics and improvement measures of the composite cooling structure can be quantitatively evaluated in combination with the actual turbine blade aerodynamic and geometric parameters.

[0041] A further technical solution of the present invention is: in actual engineering design, the method for data processing and mathematical statistics output of the quantitative influence of each forward design parameter on the comprehensive cooling efficiency under various working conditions is as follows:

[0042] Step 1: According to equations (3)-(7), respectively solve the sensitivity array of the comprehensive cooling efficiency corresponding to the film cooling efficiency without considering the hole heat exchange condition; the sensitivity array of the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side to the comprehensive cooling efficiency; the sensitivity array of the dimensionless cold air flow rate to the comprehensive cooling efficiency; the sensitivity array of the gas side Biot number to the comprehensive cooling efficiency;

[0043] Step 2: According to equations (3)-(7), respectively solve the sensitivity array of the film cooling efficiency under the hole heat exchange condition to the comprehensive cooling efficiency; the sensitivity array of the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side to the comprehensive cooling efficiency; the sensitivity array of the ratio of the dimensionless heat transfer coefficient in the film hole to the comprehensive cooling efficiency; the sensitivity array of the dimensionless cold air flow rate to the comprehensive cooling efficiency; the sensitivity array of the gas side Biot number to the comprehensive cooling efficiency;

[0044] Step 3: Output a three-dimensional array consisting of the film cooling efficiency, the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side, and the sensitivity of the related forward design parameters to the comprehensive cooling efficiency under various working conditions;

[0045] Step 4: Referring to the above steps, according to the actual design requirements, change the two independent variables of the comprehensive cooling efficiency sensitivity described in the three-dimensional array, change the relevant forward design parameters corresponding to the relevant independent variables, and output the three-dimensional array composed of the two forward design parameters and the comprehensive cooling efficiency sensitivity respectively; output the series of three-dimensional arrays as mathematical statistics charts.

[0046] Beneficial Effects

[0047] The beneficial effects of the present invention are as follows: the present invention proposes a derivation and correction method of a theoretical relationship of the comprehensive cooling efficiency of the leading edge of a turbine blade with a large curvature change and a strong dense hole heat exchange effect, and defines the dimensionless parameters of the boundary conditions (C, m c + ,Bi g ,A g * ,η) is used to predict the comprehensive cooling efficiency through mathematical deduction, thereby guiding the engineering forward design and solving the inaccuracy problem of the one-dimensional formula and analysis method in the actual prediction of the leading edge wall temperature. At the same time, the present invention proposes the C of the heat transfer effect in the air film hole e ,A e The introduction of parameters and the correction of formulas solve the problem of ignoring the hole heat transfer effect in the existing design method. The prediction of comprehensive cooling efficiency by the technology invented in this study is similar to the application of Natham formula. [1] The specific example of the prediction of the simulation data processing results are compared in Figure 5 As shown. It shows that the prediction accuracy of the design method invented in this study has achieved significant beneficial effects.

[0048] At the same time, the analysis of the leading edge cooling structure design parameters of the present invention is an equation-based calculation method, which can provide a more complete mathematical relationship compared to the numerical algorithm of traditional technology, and solves the problem that the actual blade leading edge structure design cannot be quantitatively analyzed and evaluated. Figure 7 The waterfall diagram shows the quantitative effect of the film cooling efficiency of the leading edge of the turbine blade under typical working conditions obtained by numerical simulation data processing in an exemplary embodiment of the present invention and the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side and the product of the heat transfer coefficient and the external heat transfer area on the comprehensive cooling efficiency of the leading edge of the turbine blade. This shows that the quantitative evaluation of the design method of the present invention and the refined analysis of the cooling structure have achieved significant beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram showing a typical guide turbine blade and its leading edge structure in an exemplary embodiment of the present invention is shown;

[0050] Figure 2 A schematic diagram of a typical turbine leading edge air film single hole structure in an exemplary embodiment of the present invention is shown;

[0051] Figure 3 A schematic flow chart showing a forward design method for a composite cooling structure at a leading edge of a turbine blade and a cooling parameter prediction and structural design evaluation method in the process in an exemplary embodiment of the present invention;

[0052] Figure 4 Figure η-h shows the design of the turbine blade leading edge positive cooling structure under typical operating conditions and design objectives in an exemplary embodiment of the present invention. c Schematic diagram of the wire envelope;

[0053] Figure 5 A schematic diagram showing a quick prediction of the comprehensive cooling efficiency of the leading edge of a turbine blade under typical operating conditions and a comparison of points and lines predicted by the Natham formula in an exemplary embodiment of the present invention;

[0054] Figure 6 A schematic diagram showing a point-line comparison of the comprehensive cooling efficiency of different turbine blade leading edge structures under typical operating conditions in an exemplary embodiment of the present invention is shown;

[0055] Figure 7 A waterfall diagram showing the quantitative effect of the film cooling efficiency of the leading edge of a turbine blade and the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side and the product of the heat transfer coefficient and the external heat transfer area on the comprehensive cooling efficiency of the leading edge of a turbine blade under typical operating conditions in an exemplary embodiment of the present invention;

[0056] Explanation of the reference numerals: 1. Typical guide turbine blade body; 2. Typical guide turbine blade leading edge outer wall surface; 3. Typical guide turbine blade leading edge inner wall surface; 4. Typical guide turbine blade leading edge air film hole. DETAILED DESCRIPTION

[0057] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0058] The following are typical exemplary embodiments of the present invention with reference to the accompanying drawings. The design, analysis and evaluation methods provided by the present invention can be implemented under multiple working conditions, and the present invention is not limited to the typical exemplary embodiments described herein; the following exemplary embodiments are intended to clearly and comprehensively guide researchers in the field to more effectively perform forward design and design parameter prediction analysis and evaluation on the leading edge of turbine blades. Figure 3 As shown, the specific forward design method and the design parameter prediction and evaluation method in the process include the following steps:

[0059] In an exemplary embodiment of the present invention, the leading edge film cooling efficiency, the cold air side heat transfer coefficient technical indicators and the quantitative matching mode prediction corresponding to the turbine blade leading edge forward design method and the forward cooling structure design η-h cThe steps to export the envelope are:

[0060] Step 1: Determine and input the blade leading edge related geometric parameters: the equivalent integrated heat transfer area A of a longitudinal section of the blade wall leading edge * The external heat exchange area A of the leading edge outer wall 2 g The internal heat exchange area A of the front inner wall surface 3 c ; Heat exchange area A in the leading edge air film hole 4 air film hole e ; The leading edge air film hole 4 air film aperture d, the air film hole geometry structure of the exemplary embodiment of the present invention is as follows Figure 2 As shown;

[0061] Step 2: Determine, calculate and input main and cold air related parameters, including the gas side heat transfer coefficient h of the main flow on the leading edge outer wall 2 obtained by empirical formula g The mainstream side Biot number Bi calculated based on the determined parameters and mainstream physical parameters g ; The cooling air flow m c , the constant pressure specific heat capacity of cold air c p,c The heat transfer coefficient h of the cold air in the film hole 4 on the inner wall of the leading edge film hole is obtained by the empirical formula e . ;

[0062] Step 3: Determine and input the comprehensive cooling efficiency Φ of the target leading edge outer wall surface 2, and determine and input the variation range and step length of the air film cooling efficiency η of the leading edge outer wall surface 2;

[0063] Step 4: Calculate the film cooling efficiency η according to equation (2). The one-dimensional array satisfies the cold air side heat transfer coefficient h of the leading edge inner wall surface 3 corresponding to the equation. c The one-dimensional array formed;

[0064] Step 5: Output the film cooling efficiency η described by the leading edge outer wall surface 2 and the cold air side heat transfer coefficient h described by the leading edge inner wall surface 3 that satisfies the equation c The two-dimensional array formed forms the design envelope of the forward cooling structure.

[0065] In an exemplary embodiment of the present invention, the forward cooling structure design η-h under typical working conditions can be obtained through the above steps. c Envelope, such as Figure 4 As shown: the design envelope of the forward cooling structure of a turbine blade leading edge under certain incoming flow and certain geometric conditions under different cooling air flow rates. The cooling air flow rate change has been converted into an average blowing ratio.

[0066] Step 6: Based on the η-h obtained in step 5 cThe envelope, the film cooling efficiency η of the leading edge outer wall surface corresponding to the leading edge composite cooling structure of this embodiment * The heat transfer coefficient of the cold air side of the leading edge inner wall h c * Screen and get η that meets the conditions * 、h c * Combine the corresponding leading edge composite cooling structure.

[0067] In an exemplary embodiment of the present invention, in order to quickly evaluate the cooling performance of the composite cooling structure at the leading edge of the blade and determine whether the composite cooling structure meets the design requirements, the comprehensive cooling efficiency can be quickly predicted, specifically including the following steps:

[0068] Step 7: Determine, calculate and input the main flow and cold air related parameters, including the gas side heat transfer coefficient h of the main flow on the leading edge outer wall 2 obtained by the empirical formula g The mainstream side Biot number Bi calculated based on the determined parameters and mainstream physical parameters g ; The cooling air flow m c , the constant pressure specific heat capacity of cold air c p,c The heat transfer coefficient h of the cold air in the film hole 4 on the inner wall of the leading edge film hole is obtained by the empirical formula e ;

[0069] Step 8: The η confirmed after screening in step 6 * 、h c * , and the heat transfer coefficient of the film hole on the inner wall of the film hole h e , and the geometric parameters described in step 1, the mainstream and cold air related parameters described in step 7 are brought into the comprehensive cooling efficiency theoretical formula (2) to calculate the comprehensive cooling efficiency of the leading edge outer wall surface, realize the comprehensive cooling efficiency prediction of the leading edge outer wall surface, and use the predicted comprehensive cooling efficiency result to calculate the η * 、h c * The combined leading edge composite cooling structure is evaluated;

[0070] Step 9: By changing the geometric parameters described in step 1 and the mainstream, cold air related parameters, and boundary condition cooling parameters described in step 7, a scatter plot of the comprehensive cooling efficiency under different geometric and flow conditions can be obtained.

[0071] In an exemplary embodiment of the present invention, a comprehensive cooling efficiency prediction and simulation comparison diagram of a turbine blade leading edge under different cooling air flow rates and different internal cooling structures can be obtained, such as Figure 6It can be seen that the exemplary embodiment of the present invention can not only effectively predict whether the composite cooling structure meets the design requirements, but also has a higher prediction accuracy compared with the numerical simulation results.

[0072] In an exemplary embodiment of the present invention, the forward design method of the composite cooling structure of the leading edge refers to obtaining the leading edge air film cooling efficiency and the required level of the cold air side heat transfer coefficient through mathematical calculation when the maximum temperature resistance of the leading edge wall is known, and selecting and optimizing the leading edge external air film hole structure / layout and the internal heat exchange structure based on this;

[0073] According to the allowable comprehensive cooling efficiency design target and the forward cooling structure design η-hc envelope, the external film cooling structure and the internal cooling structure of the turbine blade leading edge can be selected and optimized. Combined with the rapid prediction of the comprehensive cooling efficiency value of the turbine blade leading edge, the applicability of the established structure in the corresponding incoming flow conditions can be evaluated.

[0074] In an exemplary embodiment of the present invention, partial derivatives can be solved for typical forward design parameters of the leading edge of a turbine blade according to formula (2), and the influence of the forward design parameters on the leading edge wall temperature can be quantitatively evaluated according to the influence of the change process of each forward design parameter within its respective range on the comprehensive cooling efficiency on the result of its partial derivative.

[0075] According to the theoretical equation (2) established by the present invention to relate the comprehensive cooling efficiency to the internal and external cooling parameters, the partial derivative expression of the leading edge comprehensive cooling efficiency with respect to the following forward design parameters can be derived and solved:

[0076] The comprehensive cooling efficiency is derived from the partial derivative of the mainstream side Biot number:

[0077]

[0078] The partial derivative of the comprehensive cooling efficiency to the film cooling efficiency is derived as follows:

[0079]

[0080] The comprehensive cooling efficiency is the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side C, the product of the equivalent heat transfer coefficient and the heat transfer area in the air film hole to the product of the heat transfer coefficient and the external heat transfer area on the gas side C e The partial derivative of derives:

[0081]

[0082] The comprehensive cooling efficiency is derived from the dimensionless cold air flow rate to obtain:

[0083]

[0084] The key adjustable design point parameters (h c ,η,m c ) The quantitative expression of the influence of the typical forward design parameters on the sensitivity of the comprehensive cooling efficiency of the leading edge wall is obtained:

[0085]

[0086] In an exemplary embodiment of the present invention, the quantitative influence of typical forward design parameters on the comprehensive cooling efficiency and the derivation of mathematical statistics graphs include the following steps:

[0087] Step 10: Determine and input the geometric parameters described in step 1 and the mainstream and cold air related parameters described in step 7, determine and input the range and step size of the film cooling efficiency η of the leading edge outer wall surface 2, and the cold air side heat transfer coefficient h of the leading edge inner wall surface 3 c Range and step length of change;

[0088] Step 11: According to equations (3)-(7), respectively solve the sensitivity array of the comprehensive cooling efficiency corresponding to the film cooling efficiency without considering the hole heat exchange condition; the sensitivity array of the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side to the comprehensive cooling efficiency; the sensitivity array of the dimensionless cold air flow rate to the comprehensive cooling efficiency; the sensitivity array of the gas side Biot number to the comprehensive cooling efficiency.

[0089] Step 12: According to equations (3)-(7), respectively solve the sensitivity array of the film cooling efficiency under the hole heat exchange condition to the comprehensive cooling efficiency; the sensitivity array of the ratio of the product of the cold air side heat transfer coefficient and the internal heat exchange area to the product of the gas side heat transfer coefficient and the external heat exchange area to the comprehensive cooling efficiency; the sensitivity array of the dimensionless film hole heat transfer coefficient ratio to the comprehensive cooling efficiency; the sensitivity array of the dimensionless cold air flow rate to the comprehensive cooling efficiency; the sensitivity array of the gas side Biot number to the comprehensive cooling efficiency.

[0090] Step 13: Output a three-dimensional array consisting of the film cooling efficiency, the ratio of the product of the cold air side heat transfer coefficient and the internal heat transfer area to the product of the gas side heat transfer coefficient and the external heat transfer area, and the sensitivity of the related forward design parameters to the comprehensive cooling efficiency under various working conditions.

[0091] Step 14: Referring to the above steps, according to the actual design requirements, change the two independent variables of the comprehensive cooling efficiency sensitivity in the three-dimensional array, change the relevant forward design parameters corresponding to the relevant independent variables, and output the three-dimensional arrays composed of the two forward design parameters and the comprehensive cooling efficiency sensitivity. Output the series of three-dimensional arrays as mathematical statistics charts.

[0092] In an exemplary embodiment of the present invention, the quantitative influence of typical forward design parameters on the comprehensive cooling efficiency and the derivation of mathematical statistics graphs can be obtained through the above steps. Figure 7 The figure shows the waterfall distribution diagram of sensitivity of the film cooling efficiency to the product of the heat exchange coefficient on the cold air side and the internal heat exchange area and the product of the heat exchange coefficient on the gas side and the external heat exchange area under the changes of the film cooling efficiency and the heat exchange coefficient on the cold air side under certain working conditions. It can be seen that in this exemplary embodiment, the quantitative influence of the film cooling efficiency to the product of the heat exchange coefficient on the cold air side and the internal heat exchange area and the product of the heat exchange coefficient on the gas side and the external heat exchange area on the comprehensive cooling efficiency can be clearly obtained at different quantitative levels of the film cooling efficiency and the heat exchange coefficient on the cold air side.

[0093] It should be noted that the relevant mathematical and statistical results presented in the accompanying drawings describe the implementation results of the present invention after executing the implementation steps of the relevant methods in the invention under certain specific working conditions. This does not mean that only the results of the exemplary embodiments related to the accompanying drawings can be obtained according to the relevant methods of the present invention. In the present invention, there are multiple steps merged into one step, and one step is decomposed into multiple steps for execution, as well as repetitive steps with only different input parameters. The relevant steps have been explained in the exemplary embodiments of the present invention, and the implementation methods that can be achieved by the theoretical methods provided by the present invention for the relevant forward design parameters should be regarded as part of the present invention. In addition, the detailed structures of the relevant components provided in the drawings of this specification do not limit the model. The exemplary embodiments of this specification illustrate the best way known to the inventor to implement the design, analysis and evaluation methods of the present invention, and provide reference and clear instructions for use for researchers and designers in this field.

[0094] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for predicting and evaluating the forward design parameters of a composite cooling structure at the leading edge of a turbine blade, characterized in that The specific steps are as follows: Step 1: Calculate the design parameters of the composite cooling structure through the geometric parameters of the turbine blade leading edge, and derive the correction formula of the comprehensive cooling efficiency theoretical relationship based on the characteristics of the blade leading edge: In the formula, C represents the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side. e A is the ratio of the product of the equivalent heat transfer coefficient and the heat transfer area in the air film hole to the product of the heat transfer coefficient on the gas side and the external heat transfer area. g * represents the dimensionless equivalent integrated heat transfer area ratio, m c + represents the dimensionless cooling air flow, Bi g represents the Biot number on the gas side, and η represents the leading edge film cooling efficiency; Step 2: Combine the allowable target comprehensive cooling efficiency with the composite cooling structure design parameters and comprehensive cooling efficiency theoretical formula in step 1 to obtain the leading edge film cooling efficiency η and the corresponding cold air side heat transfer coefficient h that satisfies the equation c The two-dimensional array thus formed forms a design envelope for the forward cooling structure; Step 3: Based on η-h obtained in step 2 c The envelope is used to screen the actual parameter values ​​and obtain the film cooling efficiency η of the leading edge outer wall that meets the conditions. * The heat transfer coefficient of the cold air side of the leading edge inner wall h c * ; Step 4: The η confirmed after screening in step 3 * 、h c * , and the heat transfer coefficient of the film hole on the inner wall of the film hole h e Substitute it into the comprehensive cooling efficiency theoretical formula (1) in step 1 to calculate the comprehensive cooling efficiency of the outer wall of the leading edge, realize the prediction of the comprehensive cooling efficiency of the outer wall of the leading edge, and use the predicted comprehensive cooling efficiency result to calculate the η * 、h c * The combined leading edge composite cooling structure is evaluated; Step 5: According to the comprehensive cooling efficiency η that meets the design requirements * 、h c * The corresponding composite cooling structure combination obtains the design scheme of the leading edge composite cooling structure.

2. According to claim 1, a method for predicting and evaluating forward design parameters of a composite cooling structure at the leading edge of a turbine blade is characterized by: In step 1, the dimensionless temperature comprehensive cooling efficiency is defined as Leading edge film cooling efficiency T g is the incoming gas temperature, dimensionless cooling gas flow m c + , gas side Bi g , the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side C, the ratio of the product of the equivalent heat transfer coefficient and the heat transfer area in the air film hole to the product of the heat transfer coefficient and the external heat transfer area on the gas side C e , dimensionless equivalent integrated heat transfer area ratio A g * , according to the thermal resistance analysis method, the theoretical relationship correction formula (1) of the comprehensive cooling efficiency based on the characteristics of the blade leading edge is derived; The dimensionless equivalent integrated heat transfer area ratio is: Where Ag is the external heat exchange area of ​​the leading edge, R1 is the outer radius of curvature of the leading edge, R2 is the inner radius of curvature of the leading edge, N is the central angle of curvature of the longitudinal section of the leading edge, and L is the height of the turbine blade.

3. The method for predicting and evaluating forward design parameters of a composite cooling structure for a leading edge of a turbine blade according to claim 2, characterized in that: The gas side Biot number is: In the formula, h g is the heat transfer coefficient of the gas side of the leading edge of the turbine blade, δ is the wall thickness of the leading edge of the blade, k s is the thermal conductivity.

4. The method for predicting and evaluating forward design parameters of a composite cooling structure for a leading edge of a turbine blade according to claim 2, characterized in that: The dimensionless cooling air flow In the formula, m c is the mass flow rate of cooling air, c p,c is the specific heat capacity at constant pressure, T w , T aw , T c,e , T c They are the leading edge wall temperature, the adiabatic temperature of the wall when there is an air film, the air film hole outlet temperature, and the cold air temperature.

5. The method for predicting and evaluating forward design parameters of a composite cooling structure for a leading edge of a turbine blade according to claim 2, characterized in that: The ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side is In the formula, h c is the heat transfer coefficient of the cold air side of the leading edge of the turbine blade, A c is the internal heat exchange area of ​​the leading edge.

6. The method for predicting and evaluating forward design parameters of a composite cooling structure at the leading edge of a turbine blade according to claim 2, characterized in that: The equivalent heat transfer coefficient in the air film hole and the heat transfer area A in the air film hole e The ratio of the product of the heat transfer coefficient on the gas side and the product of the external heat transfer area In the formula, h e is the heat transfer coefficient in the air film pore, St e is the Stanton number of the fluid in the air film hole, l is the length of the air film hole, and d is the diameter of the air film hole; According to the temperature rise principle and the temperature node correspondence principle of the thermal resistance analysis method, the equivalent heat transfer coefficient in the air film hole is derived:

7. The method for predicting and evaluating forward design parameters of a composite cooling structure at the leading edge of a turbine blade according to claim 1, characterized in that: In step 2, first, the comprehensive cooling efficiency of the target leading edge outer wall surface is determined and input, and the range and step size of the film cooling efficiency η of the leading edge outer wall surface are determined and input; then, according to the comprehensive cooling efficiency theoretical formula (1), the one-dimensional array of the film cooling efficiency η is calculated to obtain the cold air side heat transfer coefficient h of the leading edge inner wall surface corresponding to the equation c Finally, the output is the film cooling efficiency η of the leading edge outer wall and the cold air side heat transfer coefficient h of the leading edge inner wall corresponding to the equation. c The two-dimensional array formed forms the design envelope of the forward cooling structure.

8. The method for predicting and evaluating forward design parameters of a composite cooling structure at the leading edge of a turbine blade according to claim 1, characterized in that: The comprehensive cooling efficiency of the leading edge outer wall surface obtained in step 4 is optimized as follows: First, according to the theoretical equation (1) that relates the comprehensive cooling efficiency to the internal and external cooling parameters in step 1, the partial derivative expression of the leading edge comprehensive cooling efficiency with respect to the following forward design parameters is derived: The partial derivative of the comprehensive cooling efficiency to the mainstream side Biot number is derived as follows: The partial derivative of the comprehensive cooling efficiency to the film cooling efficiency is derived as follows: The comprehensive cooling efficiency is the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side C, the ratio of the product of the equivalent heat transfer coefficient and the heat transfer area in the air film hole to the product of the heat transfer coefficient and the external heat transfer area on the gas side C e The partial derivative of derives: The comprehensive cooling efficiency is derived from the dimensionless cooling air flow rate: Then, according to the solution of the above partial derivative equation, the key adjustable design point parameter (h c ,η,m c ), the quantitative expression of the influence of typical forward design parameters on the sensitivity of the comprehensive cooling efficiency of the leading edge wall is obtained: Finally, based on the quantitative influence of typical forward design parameters on the comprehensive cooling efficiency, according to the variation range of adjustable design point parameters in actual engineering design, the quantitative influence of each forward design parameter on the comprehensive cooling efficiency under various working conditions is processed and output by mathematical statistics; in the quantitative influence diagram of the forward design parameters on the comprehensive cooling efficiency, the η that needs to be evaluated and analyzed is found. * 、h c * The corresponding composite cooling structure combination can be used to quantitatively analyze the improvement potential of the external and internal cooling structures of the composite cooling structure, and the current cooling characteristics and improvement measures of the composite cooling structure can be quantitatively evaluated in combination with the actual turbine blade aerodynamic and geometric parameters.

9. A method for predicting and evaluating forward design parameters of a composite cooling structure at the leading edge of a turbine blade according to claim 8, characterized in that: In actual engineering design, the method for data processing and mathematical statistics output of the quantitative influence of each forward design parameter on the comprehensive cooling efficiency under various working conditions for the variation range of the adjustable design point parameters is as follows: Step 1: According to equations (2)-(6), respectively solve the sensitivity array of the comprehensive cooling efficiency corresponding to the film cooling efficiency without considering the hole heat exchange condition; the sensitivity array of the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side to the comprehensive cooling efficiency; the sensitivity array of the dimensionless cold air flow rate to the comprehensive cooling efficiency; the sensitivity array of the gas side Biot number to the comprehensive cooling efficiency; Step 2: According to equations (2)-(6), respectively solve the sensitivity array of the film cooling efficiency under the hole heat exchange condition to the comprehensive cooling efficiency; the sensitivity array of the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side to the comprehensive cooling efficiency; the sensitivity array of the ratio of the dimensionless heat transfer coefficient in the film hole to the comprehensive cooling efficiency; the sensitivity array of the dimensionless cold air flow rate to the comprehensive cooling efficiency; the sensitivity array of the gas side Biot number to the comprehensive cooling efficiency; Step 3: Output a three-dimensional array consisting of the film cooling efficiency, the ratio of the product of the heat transfer coefficient and the internal heat transfer area on the cold air side to the product of the heat transfer coefficient and the external heat transfer area on the gas side, and the sensitivity of the related forward design parameters to the comprehensive cooling efficiency under various working conditions; Step 4: Referring to the above steps, according to the actual design requirements, the two independent variables of the comprehensive cooling efficiency sensitivity in the three-dimensional array are changed, and the relevant forward design parameters corresponding to the relevant independent variables are changed, and the three-dimensional arrays composed of the two forward design parameters and the comprehensive cooling efficiency sensitivity are output respectively; Output a series of three-dimensional arrays as a mathematical statistics graph.

Images