A turbine rotor performance experiment method based on temperature correction

Abstract

The application provides a turbine rotor performance experiment method based on temperature correction, and relates to the technical field of turbine characteristic processing, and the method comprises the following steps: simulating simulated turbine rotor characteristic curves under different working condition types, wherein the working condition types comprise high-temperature working conditions and medium-temperature working conditions; based on the isentropic expansion process theory and the similarity criterion, an expansion isentropic correlation formula is calculated, combined with the simulated turbine rotor characteristic curves of the medium-temperature working conditions, total pressure expansion ratio prediction values and total-to-total isentropic efficiency prediction values under the high-temperature working conditions are obtained; based on the simulated turbine rotor characteristic curves of the high-temperature working conditions, the expansion isentropic correlation formula is corrected; experiments are conducted on the turbine rotor to be tested, experimental turbine rotor characteristics are obtained, and combined with the corrected expansion isentropic correlation formula, turbine rotor characteristic curves are obtained; and the application can solve the technical problem that the temperature difference between the traditional medium-temperature working conditions and the high-temperature working conditions in the prior art changes the specific heat ratio of the working medium and affects the accuracy of the high-temperature working condition prediction.

Description

Technical Field

[0001] This invention relates to the field of turbine characteristic processing technology, and specifically to a temperature-corrected experimental method for turbine rotor performance. Background Technology

[0002] The turbine is a core component in an aero-engine that directly utilizes the energy of combustion gases to perform work. According to thermodynamic principles, within a certain range, the higher the temperature of the combustion gases at the turbine inlet, the higher the efficiency of converting the thermal energy contained in the combustion gases into mechanical work, and the higher the engine's output power. Therefore, increasing this temperature is a key way to improve engine performance. However, due to the extreme operating environment of turbines and the dual constraints of experimental facilities, full-temperature and full-pressure turbine experiments pose significant safety hazards and high experimental costs. Therefore, simulation experiments under medium-temperature and medium-pressure conditions that satisfy similarity criteria are an effective and economical means of exploring turbine performance.

[0003] To ensure that the results of "intermediate-temperature / intermediate-pressure simulation experiments" accurately reflect real turbine performance, the "similarity criterion" must be met, meaning that the equivalent rotational speed, equivalent flow rate, Reynolds number, and specific heat ratio must be consistent with actual operating conditions. However, since the specific heat ratio of the working fluid is a function of temperature, it is difficult to guarantee that the specific heat ratio of the working fluid is consistent with that of actual operating conditions during intermediate-temperature and intermediate-pressure simulation experiments. Therefore, "intermediate-temperature / intermediate-pressure simulation experiments" cannot accurately reflect turbine performance. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a temperature-corrected experimental method for turbine rotor performance, which aims to solve the technical problem that the temperature difference between traditional medium-temperature and high-temperature operating conditions will change the specific heat ratio of the working fluid and affect the accuracy of high-temperature operating condition prediction.

[0005] This invention provides a temperature-corrected experimental method for turbine rotor performance, the method comprising:

[0006] A physical model of the turbine rotor under test is performed and meshed to obtain a mesh file. The operating condition type and corresponding boundary conditions are set for the mesh file, and the simulated turbine rotor characteristic curves under different operating conditions are simulated. The simulated turbine rotor characteristic curves include the simulated total pressure expansion ratio characteristic curve and the simulated total-to-total isentropic efficiency characteristic curve. The operating condition type includes high temperature condition and medium temperature condition. The boundary conditions of the high temperature condition are the actual operating conditions, and the boundary conditions of the medium temperature condition are to keep the reduced speed and reduced flow rate consistent with those of the high temperature condition.

[0007] Based on the theory of isentropic expansion process and similarity criteria, the expansion isentropic correlation under different working conditions is calculated. Combined with the simulated turbine rotor characteristic curve under medium temperature conditions, the predicted values ​​of total pressure expansion ratio and total isentropic efficiency under high temperature conditions are obtained.

[0008] Based on the simulated turbine rotor characteristic curve under high temperature conditions, the expansion isentropic correlation is corrected by comparing it with the predicted values ​​of total pressure expansion ratio and total isentropic efficiency.

[0009] Based on the boundary conditions of the medium-temperature operating condition, an experiment was conducted on the turbine rotor under test to obtain the characteristics of the experimental turbine rotor. Combined with the corrected expansion isentropic correlation, the characteristic curve of the turbine rotor was obtained.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: By using the temperature-corrected turbine rotor performance experimental method provided by the present invention, the expansion isentropic correlation between medium-temperature and high-temperature operating conditions is calculated based on the isentropic expansion process theory and similarity criteria. This breaks through the limitation that the specific heat ratio of the working fluid is constant in the traditional method, quantifies the coupling effect of temperature on the specific heat ratio of the working fluid and the inlet relative Mach number, establishes a mathematical framework for performance mapping across temperature domains (medium temperature → high temperature), realizes cross-temperature domain performance prediction, provides accurate mathematical basis for preliminary prediction of high-temperature operating conditions, and then compensates for the cumulative deviation of the nonlinear change of the specific heat ratio of the working fluid by inverting the correction coefficient through numerical simulation data, thereby improving the prediction accuracy of wide temperature domain. This solves the technical problem in the prior art that the temperature difference between the traditional medium-temperature and high-temperature operating conditions changes the specific heat ratio of the working fluid and affects the accuracy of high-temperature operating condition prediction.

[0011] Furthermore, the expansion isentropic correlation includes expansion ratio correlation, isentropic efficiency correlation, and Mach number correlation.

[0012] Furthermore, the method for calculating the Mach number correlation includes:

[0013] Based on the fitting formula of air specific heat ratio with temperature, the specific heat ratio of the working fluid under different inlet temperatures is obtained.

[0014] Dimensionless mass flow rate and equivalent flow rate, based on the consistency of equivalent rotational speed and equivalent flow rate under high temperature and medium temperature conditions, are constrained by flow field similarity criteria to obtain the correlation of relative stagnation parameters.

[0015] Based on the correlation of the relative stagnation parameter and the specific heat ratio of the working fluid under different inlet temperatures, the Mach number correlation under different inlet temperatures is calculated and expressed as follows:

[0016] ,

[0017] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat capacity of the working fluid under constant pressure under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The relative Mach number of the import under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions.

[0018] Furthermore, the method for calculating the expansion ratio correlation includes:

[0019] Based on the consistency of the equivalent speed and equivalent flow rate under high temperature and medium temperature conditions, constraints are established using the aerodynamic similarity criterion, and the correlation of load coefficients under different inlet temperatures is calculated.

[0020] Based on the specific heat ratio and total isentropic efficiency of the working fluid under different inlet temperatures, the stagnation enthalpy drop during the isentropic expansion process under different inlet temperatures is calculated.

[0021] Based on the load factor correlation and the stagnation enthalpy drop, the expansion ratio correlation under different inlet temperatures is calculated and expressed as:

[0022] ,

[0023] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions.

[0024] Furthermore, the method for calculating the isentropic efficiency correlation includes:

[0025] Based on the enthalpy drop during adiabatic expansion and the second law of thermodynamics, the correlation parameters were calculated.

[0026] Based on the consistency of the equivalent rotational speed and equivalent flow rate under high-temperature and medium-temperature conditions, constraints are established using the flow similarity criterion to analyze the correlation of losses.

[0027] Based on the correlation parameters and loss correlation, the isentropic efficiency correlation under different inlet temperatures is calculated and expressed as:

[0028] ,

[0029] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The relative Mach number of the import under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions.

[0030] Furthermore, based on the simulated turbine rotor characteristic curve under high-temperature conditions, and compared with the predicted values ​​of total pressure expansion ratio and total isentropic efficiency, the expansion isentropic correlation is corrected, and the calculation formula is as follows:

[0031] ,

[0032] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The relative Mach number of the import under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions. To correct the index.

[0033] Furthermore, based on the boundary conditions under intermediate temperature conditions, experiments were conducted on the turbine rotor under test to obtain the experimental turbine rotor characteristics. Combined with the corrected expansion isentropic correlation, the turbine rotor characteristic curve was obtained. The specific steps include:

[0034] Based on the boundary conditions of the medium-temperature working condition, an experiment was conducted on the turbine rotor under test to obtain the experimental turbine rotor characteristics.

[0035] Based on the fitting formula of air specific heat ratio with temperature, the specific heat ratio of the working fluid under different inlet temperatures is obtained.

[0036] By inputting the specific heat ratio of the working fluid and the experimental turbine rotor characteristics under different inlet temperatures into the Mach number correlation, the relative inlet Mach number under different inlet temperatures is obtained.

[0037] By inputting the relative Mach number of the inlet and the specific heat ratio of the working fluid under different inlet temperatures, as well as the experimental turbine rotor characteristics, into the expansion ratio correlation and the corrected isentropic efficiency correlation, the turbine rotor characteristic curves are obtained. Attached Figure Description

[0038] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0039] Figure 1 This is a geometric schematic diagram of the 50% spanwise section of the theoretical calculation model in this embodiment of the invention;

[0040] Figure 2 This is a comparison chart of the fitting curve between the temperature and specific heat ratio of the air working fluid in the embodiments of the present invention and the actual data.

[0041] Figure 3 The above are the prediction effect diagram and prediction error diagram of the expansion ratio correlation in the embodiments of the present invention;

[0042] Figure 4 The above are the prediction effect diagram and prediction error diagram of the isentropic efficiency correlation in the embodiments of the present invention;

[0043] Figure 5 The above are the prediction effect diagram and prediction error diagram of the modified expansion ratio correlation in the embodiments of the present invention;

[0044] Figure 6 The images show the prediction results and prediction error of the modified isentropic efficiency correlation in this embodiment of the invention. Detailed Implementation

[0045] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0046] An embodiment of the present invention provides a temperature-corrected experimental method for turbine rotor performance, the method comprising steps S10-S13:

[0047] Step S10: Physically model and mesh the turbine rotor under test to obtain a mesh file. Set the operating condition type and corresponding boundary conditions for the mesh file, and simulate the characteristic curves of the turbine rotor under different operating conditions. The simulated turbine rotor characteristic curves include the simulated total pressure expansion ratio characteristic curve and the simulated total-to-total isentropic efficiency characteristic curve. The operating condition type includes high temperature condition and medium temperature condition. The boundary conditions of the high temperature condition are the actual operating conditions. The boundary conditions of the medium temperature condition are to keep the reduced speed and reduced flow rate consistent with those of the high temperature condition.

[0048] The boundary conditions for the medium-temperature operating condition are to maintain the equivalent rotational speed and equivalent flow rate consistent with those for the high-temperature operating condition, expressed as:

[0049] ,

[0050] in, To convert the rotational speed, To convert the flow rate, This refers to the turbine blade rotation speed. The turbine rotor inlet temperature, The specific heat ratio of the working fluid. The mass flow rate of the turbine rotor. This is the total pressure at the turbine rotor inlet.

[0051] As an example, and not a limitation, the experimental part was physically modeled and meshed using the autogrid5 module in UGNX and NUMECA. A schematic diagram of the 50% spanwise section geometry of this physical model is shown below. Figure 1 As shown, where C is the chord length of the turbine rotor, C ax Let α be the axial chord length of the turbine rotor, β be the geometric inlet angle of the turbine rotor, and β be the geometric outlet angle of the turbine rotor. When meshing the physical model, the topology is a HOH structure, and the thickness of the first mesh layer should satisfy Y+ < 1. A combination of UGNX (geometric modeling) and NUMECA autogrid5 (meshing) is used. For the complex topology of the turbine blade cascade, the HOH mesh topology is selected to adapt to the periodic structure of the blades and improve mesh quality.

[0052] Furthermore, the working condition type and corresponding boundary conditions are set for the mesh file, including but not limited to, preprocessing settings for the component model using ANSYS-CFX, including determining the boundaries of the physical model, selecting the turbulence model, determining the boundary conditions, and selecting the working fluid.

[0053] The computational domain turbulence model selected is the SST turbulence model without transition, the working fluid is air, and the boundary conditions are: total inlet pressure, outlet flow rate, blade speed, and adiabatic no-slip wall. When setting the high-temperature operating conditions in the preprocessing, the selection of boundary conditions should meet the actual operating boundary conditions, including the actual operating total inlet pressure, outlet flow rate, and blade speed.

[0054] Step S11: Based on the isentropic expansion process theory and similarity criteria, calculate the expansion isentropic correlation under different working conditions. Combine the simulated turbine rotor characteristic curve under medium temperature conditions to obtain the predicted value of total pressure expansion ratio and the predicted value of total isentropic efficiency under high temperature conditions.

[0055] The expansion isentropic correlation includes expansion ratio correlation, isentropic efficiency correlation, and Mach number correlation.

[0056] Specifically, the calculation methods for the expansion ratio correlation include:

[0057] Based on the consistency of the equivalent speed and equivalent flow rate under high-temperature and medium-temperature operating conditions, constraints are established using the aerodynamic similarity criterion, and the correlation of load coefficients under different inlet temperatures is calculated.

[0058] In other words, under the same working fluid, the velocity triangles of the same turbine under high-temperature and medium-temperature conditions are similar. Furthermore, when the equivalent speed, equivalent flow rate, and Reynolds number are fixed for both conditions, the internal flow channels are also similar, meaning the load factors for both conditions are equal, ensuring aerodynamic similarity of the flow channels. The load factor is expressed as:

[0059] (1)

[0060] in, This refers to the stagnation enthalpy drop of the turbine rotor from inlet to outlet. For turbine rotor blade speed, This refers to the load factor.

[0061] For an ideal gas undergoing isentropic expansion in a turbine rotor, based on the specific heat ratio and total isentropic efficiency of the working fluid under different inlet temperatures, the stagnation enthalpy drop during the isentropic expansion process is calculated, as follows:

[0062] (2)

[0063] in, This refers to the stagnation enthalpy drop of the turbine rotor from inlet to outlet. The total isentropic efficiency of the turbine rotor. The specific heat capacity at constant pressure of the working fluid. The total temperature at the turbine rotor inlet. The specific heat ratio of the working fluid. The total pressure expansion ratio of the turbine rotor is expressed as:

[0064] (3)

[0065] in, This refers to the total pressure at the turbine rotor inlet. Total pressure at the turbine rotor outlet;

[0066] Turbine rotor blade speed Represented as:

[0067] (4)

[0068] in, The diameter of the blade. To convert the rotational speed, Let be the gas constant of the working fluid. The total temperature at the turbine rotor inlet. The specific heat ratio of the working fluid;

[0069] According to equation (1), when the same turbine uses the same working fluid but has different inlet temperatures, and the equivalent flow rate, equivalent speed, and Reynolds number are equal under different inlet temperature conditions, the load factor is also equal. Therefore, the inlet temperature of the turbine rotor can be calculated. Operating conditions and inlet temperature The correlation for the expansion ratio under the operating conditions is:

[0070] (5)

[0071] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions.

[0072] Furthermore, the method for calculating the isentropic efficiency correlation includes:

[0073] Based on the enthalpy drop during adiabatic expansion and the second law of thermodynamics, the associated parameters are calculated as follows:

[0074] The formula for calculating the adiabatic expansion efficiency of a subsonic turbine rotor is expressed as:

[0075] (6)

[0076] in, For adiabatic expansion efficiency, , These are the stagnation enthalpies at the turbine rotor inlet and outlet, respectively. The isentropic stagnation enthalpy at the turbine rotor outlet. The turbine rotor outlet temperature, The entropy difference between the inlet and outlet of the turbine rotor;

[0077] Assuming the working fluid is an ideal gas with a constant relative stagnation enthalpy Through the turbine rotor, we can derive from the second law of thermodynamics:

[0078] (7)

[0079] (8)

[0080] in, The relative total temperature at the turbine rotor inlet. The entropy difference between the inlet and outlet of the turbine rotor. The total pressure drop at the inlet and outlet of the turbine rotor. The relative total density of the working fluid at the turbine rotor inlet is given. , These are the relative total pressures at the turbine rotor inlet and outlet, respectively.

[0081] Furthermore, the associated parameters are calculated using the ideal gas law. Based on equation (7) and the associated parameters, the entropy difference between the turbine rotor inlet and outlet is calculated and expressed as follows:

[0082] (9)

[0083] in, The entropy difference between the inlet and outlet of the turbine rotor. The working gas constant is... The inlet static pressure of the turbine rotor. , These are the relative total pressures at the turbine rotor inlet and outlet, respectively. For associated parameters;

[0084] Substituting equation (9) into equation (6), we get:

[0085] (10)

[0086] in, For adiabatic expansion efficiency, The specific heat ratio of the working fluid. The inlet static pressure of the turbine rotor. The relative total pressure at the turbine rotor inlet. , These are the total temperatures at the turbine rotor inlet and outlet, respectively. For associated parameters;

[0087] The isentropic expansion process can be represented as:

[0088] (11)

[0089] (12)

[0090] in, , These are the total temperatures at the turbine rotor inlet and outlet, respectively. , These are the total inlet pressure and total outlet pressure of the turbine rotor, respectively. The relative total pressure at the turbine rotor inlet. The specific heat ratio of the working fluid. This refers to the relative Mach number at the turbine rotor inlet.

[0091] Based on the above, equation (10) is:

[0092] (13)

[0093] in, The total isentropic efficiency of the turbine rotor. The specific heat ratio of the working fluid. This refers to the relative Mach number at the turbine rotor inlet. This is the total pressure expansion ratio of the turbine rotor. For associated parameters;

[0094] Equivalent to:

[0095] (14)

[0096] When the same turbine uses the same working fluid but has different inlet temperatures, and the equivalent flow rate, equivalent speed, and Reynolds number are equal at different inlet temperatures, the two different inlet temperatures... Operating conditions and inlet temperature The initial correlation of the isentropic efficiency under the operating condition is expressed as:

[0097] (15)

[0098] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The associated parameters of the working conditions , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The relative Mach number of the inlet under operating conditions;

[0099] The losses within the turbine rotor flow channel are mainly due to dynamic viscosity. The average velocity of the fluid in the turbine rotor channel ,density , Ye Gao String length The decision is as follows:

[0100] According to dimensional analysis:

[0101] , (16)

[0102] in, The pressure drop of the turbine rotor from inlet to outlet;

[0103] According to The theorem states that:

[0104] (17)

[0105] in, For the velocity of the fluid, It is the Reynolds number.

[0106] Conclusion:

[0107] (18)

[0108] Based on the consistency of the reduced rotational speed and reduced flow rate under high-temperature and medium-temperature operating conditions, constraints are established using the flow similarity criterion to analyze the loss correlation. That is, when the same turbine operates with the same working fluid but different inlet temperatures and at the same Reynolds number, the loss coefficient will vary. Since it is a single-valued function of the Reynolds number, the operating conditions under different inlet temperatures... If they are equal, then The relationship is:

[0109] (19)

[0110] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The associated parameters of the working conditions , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The density of the working fluid under the operating conditions, , The inlet temperature of the turbine rotor is respectively The density of the working fluid at the inlet and outlet under the operating conditions. , The inlet temperature of the turbine rotor is respectively The density of the working fluid at the inlet and outlet under the operating conditions. This represents the average of the squares of the relative velocities of the fluid within the turbine rotor flow channel. , The inlet temperature of the turbine rotor is respectively The inlet and outlet fluid velocities under the operating conditions. , The inlet temperature of the turbine rotor is respectively The inlet and outlet fluid velocities under the operating conditions;

[0111] According to the continuity equation and Equation (19) can be expressed as:

[0112] (20)

[0113] in, , The inlet temperature of the turbine rotor is respectively The working fluid density at the inlet and outlet of the working condition. , The inlet temperature of the turbine rotor is respectively The import and export circulation area under the working conditions. , The inlet temperature of the turbine rotor is respectively The inlet and outlet fluid velocities under the operating conditions. , The inlet temperature of the turbine rotor is respectively The total pressure at the inlet and outlet of the operating conditions. For the inlet temperature of the turbine rotor The specific heat ratio of the working fluid under the operating conditions;

[0114] Based on the correlation parameters and loss correlation, the isentropic efficiency correlation under different inlet temperatures is calculated. Substituting equation (20) into equation (15), the isentropic efficiency correlation is obtained as follows:

[0115] ,(twenty one)

[0116] Wherein, the isentropic efficiency correlation is the inlet temperature of the turbine rotor. Operating conditions and inlet temperature The correlation between the total isentropic efficiency under the operating conditions.

[0117] Next, the method for calculating the Mach number correlation includes:

[0118] Based on the fitted relationship between air specific heat ratio and temperature, the specific heat ratio of the working fluid under different inlet temperatures is obtained. The calculation steps of the Mach number correlation include:

[0119] From the dimensionless mass flow rate and the reduced flow rate, we can see that:

[0120] ,(twenty two)

[0121] ,(twenty three)

[0122] in, The mass flow rate of the working fluid in the turbine rotor is denoted as . The specific heat capacity at constant pressure of the working fluid for the turbine rotor. The relative total temperature of the working fluid in the turbine rotor. The flow area of ​​the turbine rotor. The relative total pressure of the working fluid in the turbine rotor. The relative Mach number of the turbine rotor. The specific heat ratio of the working fluid in the turbine rotor. For the mass flow similarity parameters of the turbine rotor, The total temperature at the turbine rotor inlet. This refers to the total pressure at the turbine rotor inlet.

[0123] Equation (22) can be derived as:

[0124] ,(twenty four)

[0125] in, These are the mass flow similarity parameters for the turbine rotor under relatively stationary conditions. The specific heat capacity at constant pressure of the working fluid for the turbine rotor. The flow area of ​​the turbine rotor. The specific heat ratio of the working fluid in the turbine rotor. The relative Mach number of the turbine rotor;

[0126] Based on the consistency of the reduced rotational speed and reduced flow rate under high-temperature and medium-temperature operating conditions, constraints are established using the flow field similarity criterion to obtain the correlation of the relative stagnation parameters. According to similarity theory, when the same turbine uses the same working fluid but has different inlet temperatures, and operates under the conditions of equal reduced flow rate, reduced rotational speed, and Reynolds number, the velocity triangles and flow fields under different inlet temperature conditions are similar. Therefore, the mass flow rate similarity parameters based on the relative stagnation parameters are consistent, i.e.:

[0127] (25)

[0128] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The mass flow similarity parameters under the relative stagnation state of the working condition;

[0129] Based on the correlation of the relative stagnation parameter and the specific heat ratio of the working fluid under different inlet temperatures, the Mach number correlation under different inlet temperatures is calculated and expressed as follows:

[0130] (26)

[0131] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat capacity of the working fluid under constant pressure under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The inlet relative Mach number under operating conditions, the Mach number correlation is the inlet temperature of the turbine rotor. Operating conditions and inlet temperature The correlation between the import relative Mach number under the operating conditions.

[0132] Furthermore, based on the fitting formula for the specific heat ratio of air versus temperature, the steps for obtaining the specific heat ratio of the working fluid under different inlet temperatures include:

[0133] By fitting the specific heat ratio of air as a working fluid in the temperature range of 300K-1800K using the Logisitic function model of nonlinear curve fitting in Origin, the fitting relationship between the specific heat ratio of air and temperature can be obtained, as follows:

[0134] (27)

[0135] in, The specific heat ratio of the working fluid to air. This refers to the air temperature.

[0136] like Figure 2 It can be seen that the fitted curve is highly consistent with the real data, and its relative error is controlled between -0.04% and 0.16%, which meets the accuracy requirements. Therefore, equation (27) can be used to express the fitting relationship between the specific heat ratio of air and the temperature.

[0137] It should be noted that, based on the isentropic expansion theory and similarity criteria (when the equivalent rotational speed / flow rate / Reynolds number is the same, the load coefficient is equal, the loss coefficient is equal, and the relative stagnation parameter is equal), combined with the ideal gas law and thermodynamic formulas, the expansion isentropic correlation is calculated. On the basis of flow similarity, process similarity, and aerodynamic similarity, a preliminary performance mapping relationship between medium-temperature experiments and high-temperature actual performance is established, overcoming the performance differences caused by temperature differences, providing a benchmark prediction value for subsequent corrections, clarifying the error distribution, and guiding the correction direction.

[0138] That is, based on the theory of isentropic expansion process and similarity criteria, the expansion isentropic correlation between medium-temperature and high-temperature operating conditions is calculated, the coupling effect of temperature on the specific heat ratio of the working fluid and the relative Mach number at the inlet is quantified, the performance mapping relationship between medium-temperature experiments and high-temperature actual conditions is established, and cross-temperature performance prediction is realized, providing accurate mathematical basis for the preliminary prediction of high-temperature operating conditions.

[0139] In this embodiment, as Figure 3 It can be seen that the prediction effect of the total pressure expansion ratio is significant under the high temperature condition of 1800K, and the error of the predicted value of the total pressure expansion ratio is less than 0.5% for most conditions.

[0140] like Figure 4 It can be seen that the error between the predicted and simulated values ​​of the total isentropic efficiency is large, and the prediction effect is not good, but the overall prediction error is low and needs to be corrected.

[0141] Step S12: Based on the simulated turbine rotor characteristic curve under high temperature conditions, compare it with the predicted value of total pressure expansion ratio and the predicted value of total isentropic efficiency, and correct the expansion isentropic correlation.

[0142] Specifically, the specific heat ratio of the working fluid under medium-temperature and high-temperature conditions is obtained by fitting the relationship between the specific heat ratio of air and temperature, i.e., equation (27).

[0143] According to the Mach number correlation, i.e. equation (26), the predicted inlet relative Mach number for high-temperature conditions is obtained.

[0144] The predicted parameters calculated above are solved by combining the expansion ratio correlation (5) and the isentropic efficiency correlation (21) to obtain the predicted total pressure expansion ratio and the predicted total isentropic efficiency under high temperature conditions.

[0145] Based on the relevant parameters obtained from the simulated turbine rotor characteristic curves under high-temperature conditions, and compared with the predicted values ​​of total pressure expansion ratio and total isentropic efficiency, the expansion isentropic correlation is corrected. The calculation formula is as follows:

[0146] (28)

[0147] in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The relative Mach number of the import under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions. To correct the index.

[0148] Specifically, the expansion ratio correlation (5), Mach number correlation (26), and air specific heat ratio fitting relationship with temperature (27) are used in equation (28) to replace the total pressure expansion ratio and inlet relative Mach number under high temperature conditions. This ensures that the total-to-total isentropic efficiency correlation with correction index only contains the parameters under medium temperature conditions and the total-to-total isentropic efficiency under high temperature conditions. This replaces the effect of the specific heat ratio of the working fluid and the inlet relative Mach number being fixed values ​​under high temperature conditions. That is, due to temperature changes, the specific heat ratio of the working fluid decreases, and the change in sound velocity leads to a change in the inlet relative Mach number. Only the medium temperature parameters and the total-to-total isentropic efficiency are retained. This breaks through the limitations of traditional methods that assume the specific heat ratio of the working fluid to be constant, and provides accurate compensation.

[0149] Furthermore, when selecting the correction index, the correction index corresponding to the converted flow rate with a large prediction error in the initial forecast should be considered. For the working fluid, the correction index... This will effectively improve the overall prediction accuracy.

[0150] In this embodiment, as Figure 5 It can be seen that the prediction effect of the corrected total pressure expansion ratio is consistent with the original prediction effect, with no significant improvement. The prediction error for most working conditions is less than 0.5%.

[0151] like Figure 6 As can be seen, the prediction effect of the corrected isentropic efficiency is significantly improved. The corrected performance parameter correlation can more accurately predict the performance of the turbine rotor under actual operating conditions.

[0152] It should be noted that priority should be given to selecting the corrected index for the reduced flow rate solution with large initial prediction errors (such as high flow rate conditions, where the change in the specific heat ratio of the working fluid has a more significant impact on the relative Mach number at the inlet) to achieve directional error compensation, avoid local accuracy loss caused by global average correction, and focus on the operating point with the most significant performance deviation (such as extreme flow rate conditions).

[0153] Step S13: Based on the boundary conditions of the medium-temperature operating condition, an experiment is conducted on the turbine rotor under test to obtain the experimental turbine rotor characteristics. Combined with the corrected expansion isentropic correlation, the turbine rotor characteristic curve is obtained.

[0154] Specifically, based on the boundary conditions of the medium-temperature operating condition, experiments were conducted on the turbine rotor under test to obtain the characteristics of the experimental turbine rotor.

[0155] Based on the fitting formula of air specific heat ratio with temperature, the specific heat ratio of the working fluid under different inlet temperatures is obtained.

[0156] By inputting the specific heat ratio of the working fluid and the experimental turbine rotor characteristics under different inlet temperatures into the Mach number correlation, the relative inlet Mach number under different inlet temperatures is obtained.

[0157] By inputting the relative Mach number of the inlet and the specific heat ratio of the working fluid under different inlet temperatures, as well as the experimental turbine rotor characteristics, into the expansion ratio correlation and the corrected isentropic efficiency correlation, the turbine rotor characteristic curves are obtained.

[0158] By testing the turbine rotor under test, we can obtain real experimental data on boundary conditions, make up for the ideal assumptions of numerical simulation, such as working fluid purity and actual boundary disturbances, and verify the reliability of numerical simulation results, providing actual working condition inputs for the correction formula.

[0159] Furthermore, by forming a closed loop through similarity construction, preliminary prediction, error correction, and experimental verification, the impact of temperature differences on the specific heat ratio of the working fluid and the change in the relative Mach number at the inlet on turbine performance is gradually resolved, ultimately achieving accurate performance prediction from medium-temperature experiments to high-temperature actual operating conditions.

[0160] Compared with existing technologies, the temperature-corrected turbine rotor performance experimental method shown in this embodiment constructs an isentropic expansion correlation between medium-temperature and high-temperature operating conditions based on the isentropic expansion process theory and similarity criteria. This overcomes the limitation that the specific heat ratio of the working fluid is constant in traditional methods, quantifies the coupled influence of temperature on the specific heat ratio and inlet relative Mach number of the working fluid, and calculates and establishes a mathematical framework for performance mapping across temperature domains (medium-temperature → high-temperature). This enables cross-temperature domain performance prediction and provides accurate mathematical basis for preliminary prediction of high-temperature operating conditions. Furthermore, by inverting correction coefficients through numerical simulation data, the cumulative deviation of the nonlinear change in the specific heat ratio of the working fluid is compensated, improving the prediction accuracy across wide temperature domains. This solves the technical problem in existing technologies where the temperature difference between traditional medium-temperature and high-temperature operating conditions changes the specific heat ratio of the working fluid, affecting the accuracy of high-temperature operating condition predictions.

[0161] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0162] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0163] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A temperature-corrected experimental method for turbine rotor performance, characterized in that, The method includes: A physical model of the turbine rotor under test is performed and meshed to obtain a mesh file. The operating condition type and corresponding boundary conditions are set for the mesh file, and the simulated turbine rotor characteristic curves under different operating conditions are simulated. The simulated turbine rotor characteristic curves include the simulated total pressure expansion ratio characteristic curve and the simulated total-to-total isentropic efficiency characteristic curve. The operating condition type includes high temperature condition and medium temperature condition. The boundary conditions of the high temperature condition are the actual operating conditions, and the boundary conditions of the medium temperature condition are to keep the reduced speed and reduced flow rate consistent with those of the high temperature condition. Based on the theory of isentropic expansion process and similarity criteria, expansion isentropic correlations under different operating conditions are calculated. Combined with the simulated turbine rotor characteristic curves under medium-temperature conditions, predicted values ​​for the total pressure expansion ratio and total-to-total isentropic efficiency under high-temperature conditions are obtained. The expansion isentropic correlations include expansion ratio correlations, isentropic efficiency correlations, and Mach number correlations. The calculation method for the Mach number correlation includes: Based on the fitted relationship between air specific heat ratio and temperature, the specific heat ratio of the working fluid under different inlet temperatures was obtained. Dimensionless mass flow rate and reduced flow rate, based on the consistency of reduced rotational speed and reduced flow rate under high-temperature and medium-temperature conditions, are constrained using flow field similarity criteria to obtain the correlation of relative stagnation parameters. Based on the correlation of the relative stagnation parameter and the specific heat ratio of the working fluid under different inlet temperatures, the Mach number correlation under different inlet temperatures is calculated and expressed as follows: ， in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat capacity of the working fluid under constant pressure under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The relative Mach number of the inlet under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions; Based on the simulated turbine rotor characteristic curve under high temperature conditions, the expansion isentropic correlation is corrected by comparing it with the predicted values ​​of total pressure expansion ratio and total isentropic efficiency. Based on the boundary conditions of the medium-temperature operating condition, an experiment was conducted on the turbine rotor under test to obtain the characteristics of the experimental turbine rotor. Combined with the corrected expansion isentropic correlation, the characteristic curve of the turbine rotor was obtained.

2. The experimental method for turbine rotor performance based on temperature correction according to claim 1, characterized in that, The calculation method for the expansion ratio correlation includes: Based on the consistency of the equivalent speed and equivalent flow rate under high temperature and medium temperature conditions, constraints are established using the aerodynamic similarity criterion, and the correlation of load coefficients under different inlet temperatures is calculated. Based on the specific heat ratio and total isentropic efficiency of the working fluid under different inlet temperatures, the stagnation enthalpy drop during the isentropic expansion process under different inlet temperatures is calculated. Based on the load factor correlation and the stagnation enthalpy drop, the expansion ratio correlation under different inlet temperatures is calculated and expressed as: ， in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions.

3. The experimental method for turbine rotor performance based on temperature correction according to claim 2, characterized in that, The calculation method for the isentropic efficiency correlation includes: Based on the enthalpy drop during adiabatic expansion and the second law of thermodynamics, the correlation parameters were calculated. Based on the consistency of the equivalent rotational speed and equivalent flow rate under high-temperature and medium-temperature conditions, constraints are established using the flow similarity criterion to analyze the correlation of losses. Based on the correlation parameters and loss correlation, the isentropic efficiency correlation under different inlet temperatures is calculated and expressed as: ， in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The relative Mach number of the import under operating conditions.

4. The experimental method for turbine rotor performance based on temperature correction according to claim 3, characterized in that, Based on the simulated turbine rotor characteristic curve under high-temperature conditions, and compared with the predicted values ​​of total pressure expansion ratio and total isentropic efficiency, the expansion isentropic correlation is corrected. The calculation formula is as follows: ， in, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The overall isentropic efficiency under the operating conditions. , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The total pressure expansion ratio under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The relative Mach number of the inlet under the operating conditions, , The inlet temperature of the turbine rotor is respectively Operating conditions and inlet temperature The specific heat ratio of the working fluid under the operating conditions. To correct the index.

5. The experimental method for turbine rotor performance based on temperature correction according to claim 4, characterized in that, Based on the boundary conditions under intermediate temperature conditions, experiments were conducted on the turbine rotor under test to obtain its characteristics. The turbine rotor characteristic curves were then derived by combining the corrected expansion isentropic correlation. The specific steps include: Based on the boundary conditions of the medium-temperature working condition, an experiment was conducted on the turbine rotor under test to obtain the experimental turbine rotor characteristics. Based on the fitting formula of air specific heat ratio with temperature, the specific heat ratio of the working fluid under different inlet temperatures is obtained. By inputting the specific heat ratio of the working fluid and the experimental turbine rotor characteristics under different inlet temperatures into the Mach number correlation, the relative inlet Mach number under different inlet temperatures is obtained. By inputting the relative Mach number of the inlet and the specific heat ratio of the working fluid under different inlet temperatures, as well as the experimental turbine rotor characteristics, into the expansion ratio correlation and the corrected isentropic efficiency correlation, the turbine rotor characteristic curves are obtained.

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