A method for evaluating the amount of cooling air for turbine guide vanes

Abstract

The present invention discloses a method for evaluating the cooling air volume of turbine guide vanes. Parameters influencing the cooling air volume of turbines are extracted from existing semi-empirical formulas; used as input parameters of a fitting function, and the air volume required for cooling turbine blades is used as an output parameter of the fitting formula; different working conditions are constructed according to the selected influencing parameters to perform three-dimensional numerical calculations, and a database for cooling air volume of turbine blades is obtained; a semi-empirical evaluation formula for cooling air volume of turbine guide vanes is established using the database for cooling air volume of turbine blades, determined input-output parameters, and a determined fitting function form; based on the semi-empirical evaluation formula for cooling air volume of turbine guide vanes, the cooling air volume required for turbine guide vanes under specific geometric structures and flow parameters is obtained, i.e., a method for evaluating the cooling air volume of turbine guide vanes. The method solves the problem that when the existing semi-empirical formula is used to predict the cooling air volume of turbine blades, there is a large error between the predicted result and the actual result, and the air volume required for cooling turbine blades cannot be accurately predicted.

Description

Technical Field

[0001] The invention relates to a gas turbine turbine guide vane, and in particular to a method for evaluating the cooling air volume of a turbine guide vane. Background Art

[0002] Gas turbines are widely used in power generation, aviation, navigation and other fields, and are an important part of a country's comprehensive strength. As a symbol of a country's national defense, industrial and scientific and technological strength, advanced countries in the world have prioritized it as a strategic industry. As one of the core components of a gas turbine, the gas turbine works in a harsh environment of high temperature and high pressure. At present, the temperature before the turbine of an advanced gas turbine has reached an astonishing 2000K, far exceeding the temperature resistance limit of the metal material of the turbine blade. Therefore, it is very necessary to adopt advanced cooling technology for it.

[0003] In the cooling of turbine blades, the flow rate of cooling gas plays an important role. On the one hand, the increase in the temperature before the turbine requires a corresponding increase in the flow rate of cooling gas, and the cooling gas comes from the compressor part of the engine. The increase in the flow rate of cooling gas leads to a reduction in the mainstream fuel gas, that is, a reduction in the working medium, which is not conducive to the improvement of the efficiency of the entire cycle; on the other hand, the outflow of cooling gas will also mix with the mainstream, causing more mixing losses. At the same time, the increase in cooling gas will also cause it to have more unpredictable adverse effects on the aerodynamic performance of the turbine. Therefore, accurately evaluating the amount of cooling air required for turbine blades is of great significance to improving the overall efficiency of the turbine of the gas turbine. Summary of the invention

[0004] The present invention provides a method for evaluating the amount of cooling air for turbine guide vanes, which is used to solve the problem that when the existing semi-empirical formula is used to predict the amount of cooling air for turbine blades, there is a large error between the predicted result and the actual amount, and the amount of air required for cooling the turbine blades cannot be accurately predicted.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for evaluating the amount of cooling air for a turbine guide vane, the method comprising the following steps:

[0007] Step 1: Extract the parameters that affect the amount of turbine cooling air from the existing semi-empirical formula;

[0008] Step 2: Use the parameters in step 1 as input parameters of the fitting function, and the amount of air required for cooling the turbine blades as the output parameter of the fitting formula;

[0009] Step 3: construct different working conditions according to the influencing parameters selected in step 2 to perform three-dimensional numerical calculations and obtain a turbine blade cooling air volume database;

[0010] Step 4: using the turbine blade cooling air volume database in step 3, the determined input-output parameters, and the determined fitting function form to establish a semi-empirical evaluation formula for turbine guide vane cooling air volume;

[0011] Step 5: Based on the semi-empirical evaluation formula for turbine guide vane cooling air volume in step 4, the required cooling air volume for the turbine guide vane under specific geometric structure and flow parameters is obtained, that is, the turbine guide vane cooling air volume evaluation method.

[0012] A method for evaluating the amount of cooling air for turbine guide vanes, wherein the existing semi-empirical formula in step 1 is specifically:

[0013]

[0014] The semi-empirical formula is used to extract parameters, and the turbine guide vanes are modeled in the modeling software based on the extracted parameters to obtain the geometric structure required for numerical calculation, which is then meshed to obtain the required calculation domain.

[0015] A method for evaluating the amount of cooling air for a turbine guide vane, wherein the geometric parameters include the surface area A of the turbine guide vane. b And the mainstream outlet area A g The modeling software is UG and the meshing software is ICEM.

[0016] A method for evaluating the cooling air volume of a turbine guide vane, wherein step 3 specifically includes importing the divided grid into numerical calculation software, setting boundary conditions of the calculation domain according to different cooling air volumes, obtaining calculation conditions corresponding to each cooling air volume, and obtaining a turbine blade cooling air volume database based on the calculation conditions.

[0017] A method for evaluating the amount of cooling air for a turbine guide vane, wherein the numerical calculation software is ANSYS CFX, and the calculation conditions are set to different flow ratio conditions, and the flow ratios are 0.025, 0.035, 0.045, 0.055, and 0.065 respectively.

[0018] A method for evaluating the amount of cooling air for turbine guide vanes, wherein step 4 establishes a new semi-empirical evaluation formula for the amount of cooling air for turbine guide vanes, specifically, numerical simulation calculations are performed on various calculation conditions to obtain the temperature field distribution of the turbine guide vanes under different cooling air amounts, and various dimensionless parameters affecting the amount of cooling air are calculated in post-processing software and used as the input part of the semi-empirical formula.

[0019] A method for evaluating the cooling air volume of a turbine guide vane, wherein the post-processing software is CFD-POST, and the dimensionless parameters affecting the cooling air volume are K cool , ε 0 , ε f , η int, B.

[0020] A method for evaluating the cooling air volume of a turbine guide vane is disclosed. The geometric parameters and the calculated dimensionless parameters affecting the cooling air volume are used as input variables, the required cooling air volume is used as an output variable, and a new semi-empirical evaluation formula for the cooling air volume of a turbine guide vane is established.

[0021] A method for evaluating the cooling air volume of a turbine guide vane comprises inputting the above-mentioned semi-empirical formula expression containing undetermined parameters and the parameters to be fitted into a function fitting software, running the software for calculation, obtaining the values ​​of the undetermined parameters in the function expression and substituting them into the established new semi-empirical formula, and obtaining a new semi-empirical formula for evaluating the cooling air volume of the turbine guide vane.

[0022] A method for evaluating the cooling air volume of a turbine guide vane, wherein the step 5 obtains the cooling air volume required for the turbine guide vane under a specific geometric structure and flow parameters by adding undetermined parameters based on the existing semi-empirical formula to obtain a new semi-empirical formula containing undetermined parameters, wherein the input variables are K cool , ε 0 , ε f , η int , B, the output variable is The parameters to be determined are a, b, c, d, e, f, g, h, i, j, k, and the semi-empirical formula function form is:

[0023]

[0024] in:

[0025]

[0026]

[0027]

[0028]

[0029]

[0030] Among them, m c is the cooling air mass flow rate, m g is the mainstream gas mass flow rate, B is the dimensionless cooling flow parameter, K cool is the cooling flow coefficient, ε 0 is the blade cooling efficiency, ε f is the film cooling efficiency, η int is the internal cooling efficiency, c pg is the specific heat capacity of the gas at constant pressure, J / (kg·K), c pcis the constant pressure specific heat capacity of the cooling gas, J / (kg·K), St g is the mainstream gas Stanton number, Bi met is the metal Biot number, T 0g is the total temperature of the mainstream gas inlet, T met,ext is the blade outer surface temperature, T 0c,in is the total temperature of the cold air inlet, T ad is the adiabatic wall temperature, T 0c,exit is the film hole outlet temperature, T met,int is the inner surface temperature of the blade, A b is the surface area of ​​the turbine guide vane, m 2 , A g is the mainstream outlet area, m 2 ;The function fitting software is 1stOpt;

[0031] Substituting the new blade geometric parameters and dimensionless parameters into the new semi-empirical formula for evaluating the amount of cooling air required for the turbine can obtain the amount of cooling air required for the blade under the corresponding operating conditions.

[0032] The beneficial effects of the present invention are:

[0033] Based on the existing semi-empirical formula for estimating the amount of cooling air required for turbine blades, the present invention sets new undetermined parameters to obtain a new undetermined functional relationship for evaluating the amount of cooling air required for turbine guide vanes, obtains the database required for function fitting through numerical simulation, and uses function fitting software to fit the new semi-empirical formula to obtain the undetermined parameters. The mean square error of the fitting result is reduced to 0.0025, and the determination coefficient is as high as 0.9686, achieving very good evaluation results.

[0034] The present invention uses a semi-empirical formula to estimate the amount of cooling air required for the turbine guide vanes with high efficiency. The results obtained based on numerical simulation can ensure high accuracy. The time for predicting the amount of cooling air required for new parameters using this semi-empirical formula is greatly shortened to only a few seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of the method of the present invention.

[0036] Figure 2 It is a comparison chart of the predicted value of the semi-empirical formula and the numerical simulation value results of the present invention.

[0037] Figure 3 It is a bar graph of relative errors between the semi-empirical formula predicted values ​​and numerical simulation values ​​of the present invention. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Based on the semi-empirical model for calculating the cooling air volume obtained by previous studies, by resetting the relevant unknown parameters and the turbine cooling database obtained through numerical simulation, the functional relationship between the input and output was re-fitted using function fitting software to obtain a semi-empirical formula for evaluating the cooling air volume of turbine blades. This formula can accurately evaluate the cooling air volume required under certain conditions within a certain range.

[0040] Based on the existing semi-empirical formula and computational fluid dynamics simulation results, combined with function fitting software, a new semi-empirical formula for predicting the amount of cooling air required for turbine guide vanes is constructed to quickly and accurately obtain the cooling air volume under the corresponding geometric parameters and aerodynamic parameters.

[0041] To estimate the amount of cooling air required by turbine guide vanes using a semi-empirical formula, it is first necessary to clarify the factors that affect the amount of cooling air and select the main influencing factors. The present invention uses a pre-set cooling air flow ratio as the output parameter of the semi-empirical formula and sets it as the initial boundary condition required for numerical simulation. The various parameters that affect the amount of cooling air are obtained by calculation and used as the input of the fitting function.

[0042] According to the form of the new semi-empirical formula, the geometric parameters that affect the amount of cooling air for turbine blades are determined. Based on this, a geometric model of the cooling turbine is established in the modeling software and meshed. Different cooling air flow rates are set as boundary conditions required for numerical simulation. Numerical simulation calculations are performed in ANSYS to obtain the physical field under the corresponding working conditions. In the post-processing program, various dimensionless parameters that affect the amount of cooling air are calculated to obtain the input part of the semi-empirical formula.

[0043] Thus, the database required for fitting the new semi-empirical formula is obtained, which is input into the function fitting software 1stOpt, and the fitting function form and pending parameters are specified, and the fitting results can be obtained by running the program. The new semi-empirical formula obtained in this way has a more accurate prediction effect than the original semi-empirical formula, and can achieve a more accurate prediction of the amount of cooling air required for the turbine guide vanes under the new aerodynamic parameters and geometric parameters.

[0044] Function fitting is performed on the above semi-empirical formula using function fitting software, and the various unknown parameters obtained by fitting are shown in Table 1.

[0045]

[0046] Combination Figure 2 as well as Figure 3 The comparison chart of the results of numerical simulation values ​​and semi-empirical formula prediction values ​​shows that the mean square error between the predicted values ​​of the fitting function and the numerical simulation values ​​is 0.0025, the determination coefficient is 0.9686, the average relative error of the prediction is about 4.37%, and the maximum relative error is 12.47%, indicating that the cooling air volume prediction model obtained in this embodiment can accurately estimate the cooling air volume required for the turbine guide vanes.

[0047] A method for evaluating the amount of cooling air for a turbine guide vane, the method comprising the following steps:

[0048] Step 1: Extract the parameters that affect the amount of turbine cooling air from the existing semi-empirical formula;

[0049] Step 2: Use the parameters in step 1 as input parameters of the fitting function, and the amount of air required for cooling the turbine blades as the output parameter of the fitting formula;

[0050] Step 3: construct different working conditions according to the influencing parameters selected in step 2 to perform three-dimensional numerical calculations and obtain a turbine blade cooling air volume database;

[0051] Step 4: using the turbine blade cooling air volume database in step 3, the determined input-output parameters, and the determined fitting function form to establish a semi-empirical evaluation formula for turbine guide vane cooling air volume;

[0052] Step 5: Based on the semi-empirical evaluation formula for turbine guide vane cooling air volume in step 4, the required cooling air volume for the turbine guide vane under specific geometric structure and flow parameters is obtained, that is, the turbine guide vane cooling air volume evaluation method.

[0053] A method for evaluating the amount of cooling air for turbine guide vanes, wherein the existing semi-empirical formula in step 1 is specifically:

[0054]

[0055] The semi-empirical formula is used to extract parameters, and the turbine guide vanes are modeled in the modeling software based on the extracted parameters to obtain the geometric structure required for numerical calculation, which is then meshed to obtain the required calculation domain.

[0056] A method for evaluating the amount of cooling air for a turbine guide vane, wherein the geometric parameters include the surface area A of the turbine guide vane. b And the mainstream outlet area A g The modeling software is UG and the meshing software is ICEM.

[0057] A method for evaluating the cooling air volume of a turbine guide vane, wherein step 3 specifically includes importing the divided grid into numerical calculation software, setting boundary conditions of the calculation domain according to different cooling air volumes, obtaining calculation conditions corresponding to each cooling air volume, and obtaining a turbine blade cooling air volume database based on the calculation conditions.

[0058] A method for evaluating the amount of cooling air for turbine guide vanes, wherein the numerical calculation software is ANSYS CFX, and the calculation conditions are set to different flow ratio conditions, and the flow ratios are 0.025, 0.035, 0.045, 0.055, and 0.065 respectively.

[0059] A method for evaluating the amount of cooling air for turbine guide vanes, wherein step 4 establishes a new semi-empirical evaluation formula for the amount of cooling air for turbine guide vanes, specifically, numerical simulation calculations are performed on various calculation conditions to obtain the temperature field distribution of the turbine guide vanes under different cooling air amounts, and various dimensionless parameters affecting the amount of cooling air are calculated in post-processing software and used as the input part of the semi-empirical formula.

[0060] A method for evaluating the cooling air volume of a turbine guide vane, wherein the post-processing software is CFD-POST, and the dimensionless parameters affecting the cooling air volume are K cool , ε 0 , ε f , η int , B;

[0061] According to the semi-empirical model for calculating the amount of cooling air obtained by previous studies:

[0062]

[0063] It is used as the basis of the new semi-empirical formula, and a new semi-empirical formula with undetermined parameters is obtained by adding undetermined parameters:

[0064]

[0065] in:

[0066]

[0067]

[0068]

[0069]

[0070]

[0071] A method for evaluating the cooling air volume of a turbine guide vane is disclosed. The geometric parameters and the calculated dimensionless parameters affecting the cooling air volume are used as input variables, the required cooling air volume is used as an output variable, and a new semi-empirical evaluation formula for the cooling air volume of a turbine guide vane is established.

[0072] A method for evaluating the cooling air volume of a turbine guide vane comprises inputting the above-mentioned semi-empirical formula expression containing undetermined parameters and the parameters to be fitted into a function fitting software, running the software for calculation, obtaining the values ​​of the undetermined parameters in the function expression and substituting them into the established new semi-empirical formula, and obtaining a new semi-empirical formula for evaluating the cooling air volume of the turbine guide vane.

[0073]

[0074]

[0075] Iterations: 106

[0076] Calculation time (hours: minutes: seconds: microseconds): 00:00:35:276

[0077] Optimization algorithm: Levenberg-Marquardt + general global optimization method

[0078] Calculation end reason: reached convergence judgment criteria

[0079] RMSE:0.00250589186569271

[0080] Residual Sum of Squares (SSE): 9.41924106381737E-5

[0081] Correlation coefficient (R): 0.984230831055884

[0082] Square of correlation coefficient (R^2): 0.968710328800956

[0083] Coefficient of determination (DC): 0.968602529787275

[0084] Chi-Square: 0.000999290342893553

[0085] F-Statistic:402.472566563664

[0086]

[0087] Result Output

[0088]

[0089]

[0090] The above is the calculation report of the fitting software.

[0091] A method for evaluating the cooling air volume of a turbine guide vane, wherein the step 5 obtains the cooling air volume required for the turbine guide vane under a specific geometric structure and flow parameters by adding undetermined parameters based on the existing semi-empirical formula to obtain a new semi-empirical formula containing undetermined parameters, wherein the input variables are K cool , ε 0 , ε f , η int , B, the output variable is The parameters to be determined are a, b, c, d, e, f, g, h, i, j, k, and the semi-empirical formula function form is:

[0092]

[0093] in:

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] Among them, m c is the cooling air mass flow rate, kg / s, m g is the mainstream gas mass flow rate, kg / s, B is the dimensionless cooling flow parameter, K cool is the cooling flow coefficient, ε 0 is the blade cooling efficiency, ε f is the film cooling efficiency, η int is the internal cooling efficiency, c pg is the specific heat capacity of the gas at constant pressure, J / (kg·K), c pc is the constant pressure specific heat capacity of the cooling gas, J / (kg·K), St g is the mainstream gas Stanton number, Bi met is the metal Biot number, T 0g is the total temperature of the mainstream gas inlet, K, T met,ext is the blade outer surface temperature, K, T 0c,in is the total temperature of the cold air inlet, K, T ad is the adiabatic wall temperature, K, T 0c,exit is the film hole outlet temperature, K, Tmet,int is the inner surface temperature of the blade, K, A b is the surface area of ​​the turbine guide vane, m 2 , A g is the mainstream outlet area, m 2 ;

[0100] The function fitting software is 1stOpt;

[0101] Substituting the new blade geometric parameters and dimensionless parameters into the new semi-empirical formula for evaluating the amount of cooling air required for the turbine can obtain the amount of cooling air required for the blade under the corresponding operating conditions.

Claims

1. A method for evaluating the amount of cooling air for turbine guide vanes, It is characterized in that The evaluation method comprises the following steps: Step 1: Extract the parameters that affect the amount of turbine cooling air from the existing semi-empirical formula; Step 2: Use the parameters in step 1 as input parameters of the fitting function, and the amount of air required for cooling the turbine blades as the output parameter of the fitting formula; Step 3: construct different working conditions according to the influencing parameters selected in step 2 to perform three-dimensional numerical calculations and obtain a turbine blade cooling air volume database; Step 4: using the turbine blade cooling air volume database in step 3, the determined input-output parameters, and the determined fitting function form to establish a semi-empirical evaluation formula for turbine guide vane cooling air volume; Step 5: Based on the semi-empirical evaluation formula for the cooling air volume of the turbine guide vanes in step 4, the cooling air volume required for the turbine guide vanes under specific geometric structures and flow parameters is obtained, that is, the turbine guide vane cooling air volume evaluation method; The existing semi-empirical formula in step 1 is specifically, the semi-empirical formula is, The semi-empirical formula is used to extract parameters, and the turbine guide vanes are modeled in the modeling software based on the extracted parameters to obtain the geometric structure required for numerical calculation, and the mesh is divided to obtain the required calculation domain; The parameters of the geometric structure include the surface area A of the turbine guide vane b And the mainstream outlet area A g , the modeling software is UG; The step 4 of establishing a new semi-empirical evaluation formula for the amount of cooling air for the turbine guide vanes is specifically to perform numerical simulation calculations on each calculation condition to obtain the temperature field distribution of the turbine guide vanes under different cooling air amounts, calculate various dimensionless parameters affecting the amount of cooling air in the post-processing software, and use them as the input part of the semi-empirical formula; the dimensionless parameters affecting the amount of cooling air are K cool , ε 0 , ε f , η int , B; The parameters of the geometric structure and the calculated dimensionless parameters affecting the cooling air quantity are used as input variables, the required cooling air quantity is used as an output variable, and a new semi-empirical evaluation formula for the cooling air quantity of the turbine guide vanes is established; The step 5 obtains the amount of cooling air required for the turbine guide vane under the specific geometric structure and flow parameters by adding the undetermined parameters based on the existing semi-empirical formula to obtain a new semi-empirical formula containing the undetermined parameters. The input variables are K cool , ε 0 , ε f , η int , B, the output variable is The parameters to be determined are a, b, c, d, e, f, g, h, i, j, k, and the semi-empirical formula function form is: in: Among them, m c is the cooling air mass flow rate, m g is the mainstream gas mass flow rate, B is the dimensionless cooling flow parameter, K cool is the cooling flow coefficient, ε 0 is the blade cooling efficiency, ε f is the film cooling efficiency, η int is the internal cooling efficiency, c pg is the specific heat capacity of the gas at constant pressure, J / (kg·K), c pc is the constant pressure specific heat capacity of the cooling gas, J / (kg·K), St g is the mainstream gas Stanton number, Bi met is the metal Biot number, T 0g is the total temperature of the mainstream gas inlet, T met,ext is the blade outer surface temperature, T 0c,in is the total temperature of the cold air inlet, T ad is the adiabatic wall temperature, T 0c,exit is the film hole outlet temperature, T met,int is the inner surface temperature of the blade, A b is the surface area of ​​the turbine guide vane, m 2 , A g is the mainstream outlet area, m 2 ;The function fitting software is 1stOpt; Substituting the parameters of the new blade geometry and various dimensionless parameters into the new semi-empirical formula for evaluating the amount of cooling air required for the turbine can obtain the amount of cooling air required for the blade under the corresponding operating conditions.

2. A method for evaluating the amount of cooling air for turbine guide vanes according to claim 1, It is characterized in that The parameter meshing software of the geometric structure is ICEM.

3. A method for evaluating the amount of cooling air for turbine guide vanes according to claim 1, It is characterized in that Specifically, step 3 includes importing the divided grid into numerical calculation software, setting boundary conditions of the calculation domain according to different cooling air volumes, obtaining calculation conditions corresponding to each cooling air volume, and obtaining a turbine blade cooling air volume database based on the calculation conditions.

4. A method for evaluating the amount of cooling air for turbine guide vanes according to claim 3, It is characterized in that The numerical calculation software is ANSYS CFX, and the calculation conditions are set to different flow ratio conditions, and the flow ratios are 0.025, 0.035, 0.045, 0.055, and 0.065 respectively.

5. A method for evaluating the amount of cooling air for turbine guide vanes according to claim 1, It is characterized in that The post-processing software is CFD-POST.

6. A method for evaluating the amount of cooling air for turbine guide vanes according to claim 1, It is characterized in that Input the above semi-empirical formula expression containing the unknown parameters and the parameters to be fitted into the function fitting software, run the software for calculation, obtain the values ​​of the unknown parameters in the function expression and substitute them into the established new semi-empirical formula, and obtain a new semi-empirical formula for evaluating the cooling air volume of the turbine guide vanes.

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