A method for estimating the mass flow at the compressor inlet of an engine in an overall engine state

Abstract

The application belongs to the field of engine test, and is a method for evaluating the compressor inlet mass flow in the state of the whole engine. An iteration parameter is set, and according to the test measurement parameters and the design parameters, the engine mutual matching constraint relationship is used to obtain whether the performance evaluation key parameter that cannot be measured in the engine test process is the actual working parameter of the engine. Compared with the simulation calculation result, the real measurement parameter in the test process is added, the design parameter that is not much different from the test and the design is retained, and through the constraint relationship between the engine matching, the compressor inlet mass flow can be accurately obtained, and the performance of the whole engine and the performance of the compressor and the turbine under the state of the whole engine can be more accurately evaluated. The difference in performance of different engines caused by factors such as manufacturing and assembly will be reflected in the measurement parameters in the test process, and will finally be reflected in the evaluation result of the compressor inlet mass flow.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of engine test, and particularly relates to a method for evaluating compressor inlet mass flow under engine overall state. BACKGROUND

[0002] During the test of an aero-engine, the compressor inlet mass flow cannot be obtained by direct measurement due to the special structural features and working environment of the compressor inlet. However, the compressor inlet mass flow is a very important performance parameter, and is an indispensable parameter for evaluating the overall performance and the performance of the compressor and turbine under the overall state.

[0003] At present, the compressor inlet mass flow is obtained by calculation through a total performance simulation program. However, the compressor inlet mass flow obtained by calculation through the total performance simulation program is only a design value. The main shortcomings are as follows:

[0004] 1) Since some design parameters are greatly different from the test state, the compressor inlet mass flow is affected, so that the calculation result cannot truly reflect the test result, and a large error is generated for the evaluation result of the overall performance and the performance of the compressor and turbine under the overall state;

[0005] 2) For batch production engines, the performance difference between different engines caused by manufacturing, assembly and other factors cannot be identified.

[0006] Therefore, how to obtain an accurate compressor inlet mass flow is a problem to be solved. SUMMARY

[0007] The present application aims to provide a method for evaluating the compressor inlet mass flow under the overall state of an engine, so as to solve the problem that the compressor inlet mass flow obtained by calculation through a total performance simulation program is only a design value.

[0008] The technical scheme of the present application is: a method for evaluating the compressor inlet mass flow under the overall state of an engine, comprising:

[0009] performing engine test running test, collecting the compressor inlet total pressure P 25 , the compressor inlet total temperature T 25 , the physical rotating speed n2 of the compressor and the compressor outlet total pressure P3; obtaining the calculation formula of the compressor pressure ratio and the converted rotating speed, and then calculating the compressor pressure ratio π c and the converted rotating speed n 2R25 according to the compressor inlet total pressure P 25 , the compressor inlet total temperature T 25 , the physical rotating speed n2 of the compressor and the compressor outlet total pressure P3; and then obtaining the compressor inlet mass flow according to the compressor pressure ratio π c , the compressor converted rotating speed n2R25 By analyzing the theoretical characteristic diagram of the compressor, the initial value of the compressor's converted flow rate W is obtained. 25R，给定 ;

[0010] Based on the initial value of the compressor's converted flow rate W 25R，给定 The compressor outlet physical flow rate W3 and total enthalpy H3 are calculated using the corresponding first measurement parameters, first design parameters, and first physical parameters, combined with the compressor outlet physical flow rate and total enthalpy calculation formulas.

[0011] Based on the compressor outlet parameters physical flow rate W3 and total enthalpy H3, combined with the corresponding second measurement parameters, second design parameters and second physical parameters, and based on the principle of energy balance in the main combustion chamber, the combustion chamber outlet parameter T4 is calculated using the combustion chamber outlet parameter calculation formula.

[0012] Based on the combustion chamber outlet parameter T4 and the compressor pressure ratio π c Total temperature T at the compressor inlet 25 In addition to the corresponding third design parameters and third physical parameters, the compressor inlet equivalent flow rate W is calculated based on the principle of compressor and turbine flow balance and the compressor inlet equivalent flow rate calculation formula. 25R，评估 ;

[0013] Convert the compressor inlet flow rate W 25R，评估 Initial value of flow rate W converted with compressor 25R，给定 The comparison is performed to determine whether the difference between the two is less than the iteration error, which is set to 0.5%. If the difference is greater than 0.5%, the initial value of the compressor's converted flow rate is adjusted according to the difference ratio, and the iteration is repeated. If the difference is less than 0.5%, the iteration is stopped.

[0014] When the compressor inlet converted flow rate W 25R，评估 Initial value of flow rate W converted with compressor 25R，给定 When the iteration error requirement is met, the compressor inlet mass flow rate W is output according to the compressor inlet mass flow rate calculation formula. 25 .

[0015] Preferably, the first measurement parameters include the compressor inlet total pressure, compressor inlet total temperature, and compressor outlet total temperature; the first design parameters include the total bleed air flow rate W of the compressor's air system. Bleed The first physical parameter includes the specific heat of air, C. p The second measurement parameter includes the combustion chamber fuel mass flow rate W. f The second design parameter includes the combustion chamber combustion efficiency η. b Total bleed air flow rate W of the compressor section air system Bleed The second physical parameter includes the lower calorific value of the fuel (Hu) and the specific heat of air (C). p Specific heat of gas C pg; the third design parameter includes a combustion chamber total pressure recovery coefficient and a high pressure turbine guide vane throat area, and the third physical parameter includes a constant K used in flow calculation g .

[0016] Preferably, the compressor pressure ratio π c and the converted rotational speed n 2R25 The calculation formula is:

[0017] (1)

[0018] (2).

[0019] Preferably, the calculation formula of the compressor outlet parameter physical flow and total enthalpy is:

[0020] (3)

[0021] (4)

[0022] (5).

[0023] Preferably, the calculation formula of the combustion chamber outlet parameter T4 is:

[0024] (6).

[0025] Preferably, the calculation formula of the compressor inlet converted flow is:

[0026] (7).

[0027] Preferably, the calculation formula of the difference ratio is:

[0028] (8).

[0029] Preferably, the calculation formula of the compressor inlet mass flow is:

[0030] (9).

[0031] The method for evaluating the compressor inlet mass flow of the whole engine according to the present application increases the real measurement parameters in the test process compared with the simulation calculation results, retains the design parameters which are not much different from the test, and can accurately obtain the compressor inlet mass flow through the constraint relationship between the engine matching, and can more accurately evaluate the performance of the whole engine and the performance of the compressor and turbine under the state of the whole engine. Meanwhile, the difference between the compressor inlet mass flows of the batch production engines caused by manufacturing, assembly and other factors can be evaluated. The difference in performance of different engines caused by manufacturing, assembly and other factors will be reflected in the measurement parameters in the test process, and will finally be reflected in the evaluation results of the compressor inlet mass flow. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions provided by the present application, the following will briefly introduce the drawings. Obviously, the drawings described below are only some embodiments of the present application.

[0033] Figure 1 It is a schematic diagram of the overall process of the present application.

[0034] Figure 2 It is a compressor theoretical characteristic diagram of the present application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0036] A method for evaluating the compressor inlet mass flow of the whole engine, the compressor inlet mass flow cannot be obtained by direct measurement during the engine test due to the special structural characteristics and working environment of the compressor inlet. Based on this problem, the present application designs a compressor inlet mass flow evaluation scheme based on test measurement parameters, design parameters and engine matching constraint relationship, and the overall method is as follows:

[0037] Set an iteration parameter, use the engine mutual matching constraint relationship to obtain whether the performance evaluation key parameter which cannot be measured during the engine test is the actual working parameter of the engine according to the test measurement parameter and the design parameter, and output if yes, and continue iteration according to the step if not.

[0038] The parameters used in the method are shown in Table 1:

[0039] Table 1 Related parameter name, symbol, unit and category

[0040]

[0041] like Figure 1 As shown, the specific process is as follows:

[0042] Step S100: Conduct an engine test run and collect the compressor inlet total pressure P during the engine test run. 25 Total temperature T at the compressor inlet 25 The compressor's physical speed n2 and total compressor outlet pressure P3 are determined. The formulas for calculating the compressor pressure ratio and converted speed are obtained, and then the total compressor inlet pressure P is used as the basis for the calculation. 25 Total temperature T at the compressor inlet 25 The compressor pressure ratio π is obtained by calculating the compressor's physical speed n2 and the total compressor outlet pressure P3. c And converted speed n 2R25 The calculation formula is:

[0043] (1)

[0044] (2)

[0045] Then, based on the compressor pressure ratio π c Compressor conversion speed n 2R25 By analyzing the theoretical characteristic diagram of the compressor, the initial value of the compressor's converted flow rate W is obtained. 25R，给定 The theoretical characteristic diagram of the compressor is as follows: Figure 2 As shown, this was obtained by collecting and organizing engine test data.

[0046] Step S200: Obtain the compressor outlet parameters, physical flow rate, and total enthalpy calculation formula, based on the initial value W of the compressor's converted flow rate. 25R，给定 Using the corresponding first measured parameters, first design parameters, and first physical parameters, and combining them with the formulas for calculating the physical flow rate and total enthalpy of the compressor outlet parameters, the physical flow rate W3 and total enthalpy H3 of the compressor outlet parameters are calculated. The first measured parameters include the total pressure, total temperature at the compressor inlet, and total temperature at the compressor outlet. The first design parameters include the total bleed air flow rate W of the compressor's air system. Bleed The first physical parameter includes the specific heat of air, C. p The first measurement parameter, the first design parameter, and the first physical parameter are all obtained directly or by calculation through engine test runs. The calculation formulas are as follows:

[0047] (3)

[0048] (4)

[0049] (5)

[0050] Step S300, obtain a combustion chamber outlet parameter calculation formula, calculate the combustion chamber outlet parameter T4 according to the compressor outlet parameter physical flow W3 and total enthalpy H3, in combination with corresponding second measurement parameters, second design parameters and second physical parameters, based on the principle of energy balance of the main combustion chamber, and in combination with the combustion chamber outlet parameter calculation formula. The second measurement parameters include the combustion chamber fuel mass flow W f , the second design parameters include the combustion chamber combustion efficiency η b and the compressor part air system bleed air total flow W Bleed , and the second physical parameters include the fuel lower heating value Hu, the air specific heat C p and the gas specific heat C pg . The second measurement parameters, the second design parameters and the second physical parameters are directly or calculated obtained through the engine test, wherein the gas specific heat C pg is obtained through iterative calculation.

[0051] The specific combustion chamber outlet parameter T4 calculation formula is:

[0052] (6)

[0053] Step S400, obtain a compressor inlet conversion flow calculation formula, calculate the compressor inlet conversion flow W 25R，评估 according to the combustion chamber outlet parameter T4, the compressor pressure ratio π c , the compressor inlet total temperature T 25 and corresponding third design parameters and third physical parameters, based on the principle of compressor and turbine flow balance, in combination with the compressor inlet conversion flow calculation formula. The third design parameters include the combustion chamber total pressure recovery coefficient and the high-pressure turbine guide vane throat area, and the third physical parameters include the constant K g used in flow calculation. The third design parameters and the third physical parameters are directly or calculated obtained through the engine test. The compressor inlet conversion flow calculation formula is:

[0054] (7)

[0055] Step S500, compare the compressor inlet conversion flow W 25R，评估 with the compressor conversion flow initial value W 25R，给定 , judge whether the difference ratio is less than the iteration error, and the iteration error is set to 0.5%. If it is greater than 0.5%, adjust the compressor conversion flow initial value according to the difference ratio and repeat the iteration; if it is less than 0.5%, stop the iteration.

[0056] The difference ratio calculation formula is:

[0057] (8)

[0058] Step S600, obtain the compressor inlet mass flow calculation formula, when the compressor inlet equivalent flow W 25R，评估 With the compressor equivalent flow initial value W 25R，给定 When the iteration error requirement is met, the compressor inlet mass flow W is output according to the compressor inlet mass flow calculation formula. 25 .

[0059] The compressor inlet mass flow calculation formula is:

[0060] (9)

[0061] Through the above design, compared with the simulation calculation result, the real measurement parameters in the test process are increased, the design parameters that are not much different from the test are retained, and through the constraint relationship between the engine matching, the compressor inlet mass flow can be accurately obtained, and the performance of the whole machine and the performance of the compressor and turbine under the whole machine state can be more accurately evaluated. At the same time, the difference between the batch production engine compressor inlet mass flow caused by manufacturing, assembly and other factors can also be evaluated. The difference in performance of different engines caused by manufacturing, assembly and other factors will be reflected in the measurement parameters in the test process, and will finally be reflected in the evaluation result of the compressor inlet mass flow.

[0062] Finally, it should be noted that: the drawings of the disclosed embodiments of the application only involve the structures involved in the disclosed embodiments, other structures can refer to the usual design, and in the case of no conflict, the same embodiment and different embodiments of the application can be combined with each other;

[0063] Finally: the above only describes the preferred embodiments of the application and is not used to limit the application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A method of estimating mass flow at the inlet of a compressor in an engine overall state, characterized in that, Comprise: Conduct engine test runs and collect the compressor inlet total pressure P during the engine test runs. 25 Total temperature T at the compressor inlet 25 1. The compressor's physical speed n2 and total compressor outlet pressure P3; obtain the calculation formulas for the compressor pressure ratio and converted speed, and then calculate based on the compressor inlet total pressure P. 25 Total temperature T at the compressor inlet 25 The compressor pressure ratio π is obtained by calculating the compressor's physical speed n2 and the total compressor outlet pressure P3. c and converted speed n 2R25 Then, based on the compressor pressure ratio π c Compressor conversion speed n 2R25 By analyzing the theoretical characteristic diagram of the compressor, the initial value of the compressor's converted flow rate W is obtained. 25R，给定 ; According to the initial value of the compressor scaled flow W 25R，给定 and the corresponding first measured parameters, first design parameters and first physical parameters, the physical flow W3 and the total enthalpy H3 at the outlet of the compressor are calculated by combining the physical flow and total enthalpy calculation formulae of the outlet parameters of the compressor. According to the compressor outlet parameter physical flow W3 and total enthalpy H3, combined with the corresponding second measurement parameter, second design parameter and second physical parameter, based on the principle of main combustion chamber energy balance, combined with the combustion chamber outlet parameter calculation formula, the combustion chamber outlet parameter T4 is obtained; According to the combustion chamber outlet parameters T4, the compressor pressure ratio π c , the compressor inlet total temperature T 25 , and the corresponding third design parameters and third physical parameters, the compressor inlet equivalent flow rate W 25R，评估 is calculated based on the principle of compressor and turbine flow rate balance, combined with the compressor inlet equivalent flow rate calculation formula. The compressor inlet equivalent flow rate W 25R，评估 The compressor equivalent flow rate initial value W 25R，给定 The difference ratio is compared to determine whether it is less than the iteration error, which is set to 0.5%. If it is greater than 0.5%, the compressor equivalent flow rate initial value is adjusted according to the difference ratio, and the iteration is repeated. If less than 0.5%, stop iteration; When the iteration error meets the requirement, the compressor inlet mass flow W is output according to the compressor inlet mass flow calculation formula 25R，评估 When the iteration error meets the requirement, the compressor inlet mass flow W is output according to the compressor inlet mass flow calculation formula 25R，给定 When the iteration error meets the requirement, the compressor inlet mass flow W is output according to the compressor inlet mass flow calculation formula 25 ; The first measurement parameters include compressor inlet total pressure, compressor inlet total temperature and compressor outlet total temperature, the first design parameters include compressor part air system bleed air total flow W Bleed , the first physical parameters include air specific heat C p ; the second measurement parameters include combustion chamber fuel mass flow W f , the second design parameters include combustion chamber combustion efficiency η b and compressor part air system bleed air total flow W Bleed , the second physical parameters include fuel low heat value Hu, air specific heat C p and gas specific heat C pg ; the third design parameters include combustion chamber total pressure recovery coefficient σ b and high pressure turbine guide vane throat area A nb , the third physical parameters include flow calculation constant K g .

2. The method of estimating compressor inlet mass flow for an engine in an overall engine condition as recited in claim 1, wherein, The compressor pressure ratio π c And the conversion speed n 2R25 The calculation formula is: （1） （2） In the formula, T 25designpoint is the compressor design point inlet total temperature.

3. The method of estimating compressor inlet mass flow for an engine in an overall engine condition as recited in claim 1, wherein, The compressor outlet parameter physical flow and total enthalpy calculation formula is: （3） （4） （5） where T3 is the total temperature at the compressor exit, W 25 is the mass flow rate at the compressor inlet.

4. The method of estimating compressor inlet mass flow for an engine in an overall engine condition as recited in claim 1, wherein, The combustion chamber outlet parameter T4 calculation formula is: （6）。 5. The method of estimating compressor inlet mass flow for engine health assessment of claim 1, wherein: The compressor inlet conversion flow calculation formula is: （7）。 6. The method of estimating compressor inlet mass flow for an engine in an overall engine condition as recited in claim 1, wherein, The difference ratio calculation formula is: （8）。 7. The method of estimating compressor inlet mass flow for engine health assessment of claim 1, wherein: The compressor inlet mass flow calculation formula is: （9）。

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