A method for evaluating the inlet Mach number and total static pressure of a primary combustion chamber

Abstract

The application belongs to the technical field of aero-engines, and particularly relates to a method for evaluating a Mach number and total static pressure at an inlet of a main combustion chamber, comprising the following steps: S1: arranging a test rake at a windward surface of a support plate of a pre-expander of the main combustion chamber, and measuring and obtaining total pressure P31 and total temperature T31 of a support plate section; S2: obtaining known physical parameters of an outlet section of a high-pressure compressor, including a flow area A3 and an air mass flow W3 at the inlet of the main combustion chamber; S3: based on the total pressure P31 and the total temperature T31 of the support plate section and the parameters A3 and W3 of the outlet section of the compressor, a Mach number Ma3 of the outlet section of the compressor is obtained by iteratively solving a gas dynamics relationship; and S4: based on the obtained Mach number Ma3, total pressure P3 and static pressure Ps3 of the outlet section of the compressor are calculated.

Description

Technical Field

[0001] This application belongs to the field of aero-engine technology, and specifically relates to a method for evaluating the Mach number and total static pressure at the main combustion chamber inlet. Background Technology

[0002] In aero-engines, the physical parameters of the high-pressure compressor outlet section (section 3) are crucial for both the design and actual operation of the main combustion chamber, serving as key boundary conditions. These parameters primarily include flow rate, total pressure, static pressure, total temperature, and static temperature. Current methods for testing total pressure and total temperature typically require the placement of probes to impede the flow and collect samples.

[0003] High-pressure compressors have a small outlet cross-sectional area, high flow velocity, and high pressure. Therefore, the placement of total pressure and total temperature test rakes can significantly interfere with the flow. In other words, the testing process itself has already affected the test object and may cause the test results to be distorted. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a method for evaluating the Mach number and total static pressure at the main combustion chamber inlet, characterized by comprising: Step S1: Arranging a test rake at the windward side of the support plate of the diffuser in front of the main combustion chamber of the aero-engine, and measuring the total pressure P of the support plate cross-section. 31 and total temperature T 31 ;

[0005] Step S2: Obtain the known physical parameters of the high-pressure compressor outlet section, including the flow area A3 and the main combustion chamber inlet air mass flow rate W3;

[0006] Step S3: Based on the total pressure P of the support plate section 31 Total temperature T 31 The Mach number Ma3 of the compressor outlet section is obtained by iteratively solving the gas dynamics equations together with the compressor outlet section parameters A3 and W3.

[0007] Step S4: Based on the obtained Mach number Ma3, calculate the total pressure P3 and static pressure Ps3 at the compressor outlet section.

[0008] Preferably, in step S3, the gas dynamics relationship includes:

[0009] The relationship between compressor outlet flow rate and Mach number is as follows:

[0010] ;

[0011] The total pressure relationship between the compressor outlet section and the support plate section is as follows:

[0012] ;

[0013] in, and These are characteristic parameters obtained through diffuser component testing or flow simulation calculations;

[0014] in, The total temperature at the compressor outlet section is approximately equal to the total temperature value measured by the test rake at the support plate section. Let be the compressor outlet cross-sectional flow function expressed in terms of Mach number; These are constants related to the physical properties of gases.

[0015] Preferably, in step S3, the iterative solution includes: setting an intermediate variable X = 5 + Ma3², and performing calculations based on the following iterative formula:

[0016] ;

[0017] After convergence through iterative calculation, the Mach number Ma3 is obtained by inverse solving the X value.

[0018] Preferably, in step S4, the static pressure at the compressor outlet section is... Calculated using the following formula: .

[0019] Preferably, the method further includes step S5: calculating the static temperature Ts3 of the compressor outlet section based on the obtained Mach number Ma3 and total temperature T3, using the following formula: .

[0020] A computer-readable storage medium storing a computer program, which, when executed by a processor, is configured to perform the aforementioned method for evaluating the main combustion chamber inlet Mach number and total static pressure.

[0021] This application obtains the flow parameters at the cross-section of the diffuser support plate in front of the main combustion chamber by arranging total pressure and total temperature test rakes at the windward side of the support plate, and then inversely calculates the flow parameters at the high-pressure compressor outlet cross-section by combining the total pressure and total temperature change relationship between the high-pressure compressor outlet cross-section and the support plate cross-section. Attached Figure Description

[0022] Figure 1 This is a schematic diagram showing the positions of the high-pressure compressor outlet section and the diffuser support plate section;

[0023] Figure 2 This is a schematic diagram of the calculation process for Mach number and total pressure at three cross sections. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, a method for evaluating the Mach number and total static pressure at the main combustion chamber inlet is presented. For structural strength considerations, the pre-diffuser of an aero-engine's full-annular combustion chamber typically requires multiple support plates arranged circumferentially. These support plates are parallel to the incoming flow direction, and their thickness direction obstructs the incoming flow to some extent. By arranging total pressure and total temperature test rakes directly opposite these support plates to the incoming flow, the interference of the test rakes on the flow can be combined with the interference of the pre-diffuser support plates on the flow, thus minimizing the impact of the test behavior on the flow. The axial distance between the pre-diffuser support plate section (section 31) and the high-pressure compressor outlet section (section 3) is very short, with only a small-amplitude flow channel expansion between the two sections. Since both are cold-end components, the total temperature difference between the two sections can be considered very small. The total pressure loss caused by the flow channel expansion between the two sections can be evaluated through component testing or flow simulation.

[0026] 1. Basic Relationship

[0027] The figure below shows the location of the high-pressure compressor outlet section (section 3) and the front diffuser support plate section (section 31). These two sections are the two key sections involved in this method.

[0028] The basic physical relationships used in this method are listed below:

[0029] 1) Relationship between total pressure loss at sections 3 to 31 and the Mach number characteristics at the main combustion chamber inlet:

[0030] (1)

[0031] in, Total pressure at section 3 (to be determined); The Mach number for section 3 (to be determined) is the Mach number at the inlet of the main combustion chamber. The total pressure test value (known quantity) of the diffuser support plate section; and These are characteristic parameters obtained through diffuser component testing or flow simulation calculations.

[0032] 2) Flow rate relationship for 3 sections:

[0033] (2)

[0034] in, The mass flow rate of the main combustion chamber inlet air is calculated by the difference between the compressor inlet flow rate and the compressor bleed air flow rate to the turbine. The geometric flow area at the outlet of the last stage stator of the compressor; The total temperature of section 3 is approximately equal to the total temperature value measured by the test rake of section 31. The flow function for three sections is expressed in terms of Mach number; For air, the constants related to the physical properties of gases are... .

[0035] 3) The flow function expressed in Mach number:

[0036] (3)

[0037] in, These are constants related to the structure of gas molecules, for air .

[0038] 4) The relationship between total static pressure and Mach number at section 3 (can be used to calculate static pressure, not for simultaneous solutions):

[0039] (4)

[0040] in, It is a static pressure at a 3-section.

[0041] 5) The relationship between the total static temperature and Mach number of section 3 (can be used to calculate static temperature, not for simultaneous equations):

[0042] (5)

[0043] 2. Calculation process

[0044] The Mach number of the three sections can be solved using the above basic relationships (1-3). and the total pressure of the 3 sections The calculation process is as follows.

[0045] According to the calculation process, and Given two unknowns, we can obtain the equations (1-3) simultaneously to find the answer regarding... The iterative solution formula (which already includes air physical parameters) and Substitute):

[0046] (6)

[0047] For the above iterative formula, the convergence of conventional iterative methods is not ideal, and it is recommended to introduce unknowns.

[0048] (7)

[0049] Then iterative equation (6) can be transformed into

[0050] (8)

[0051] Solve Afterwards, Substituting back into relation (1) or (2), we can calculate... .

[0052] In addition, Substituting into equations (4) and (5), the static pressure at the three sections can be calculated respectively. and still temperature .

[0053] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for evaluating the Mach number and total static pressure at the main combustion chamber inlet, characterized in that, include: Step S1: Arrange a test rake at the windward side of the support plate of the diffuser in front of the main combustion chamber of the aero-engine, and measure the total pressure P of the support plate section. 31 and total temperature T 31 ; Step S2: Obtain the known physical parameters of the high-pressure compressor outlet section, including the flow area A3 and the main combustion chamber inlet air mass flow rate W3; Step S3: Based on the total pressure P of the support plate section 31 Total temperature T 31 The Mach number Ma3 of the compressor outlet section is obtained by iteratively solving the gas dynamics equations together with the compressor outlet section parameters A3 and W3. Step S4: Based on the obtained Mach number Ma3, calculate the total pressure P3 and static pressure Ps3 at the compressor outlet section.

2. The method for evaluating the Mach number and total static pressure at the main combustion chamber inlet as described in claim 1, characterized in that, In step S3, the gas dynamics relationship includes: The relationship between compressor outlet flow rate and Mach number is as follows: ； The total pressure relationship between the compressor outlet section and the support plate section is as follows: ； in, and These are characteristic parameters obtained through diffuser component testing or flow simulation calculations; in, The total temperature at the compressor outlet section is approximately equal to the total temperature value measured by the test rake at the support plate section. Let be the compressor outlet cross-sectional flow function expressed in terms of Mach number; These are constants related to the physical properties of gases.

3. The method for evaluating the Mach number and total static pressure at the main combustion chamber inlet as described in claim 1, characterized in that, In step S3, the iterative solution includes: setting an intermediate variable X = 5 + Ma3², and performing calculations based on the following iterative formula: ； After convergence through iterative calculation, the Mach number Ma3 is obtained by inverse solving the X value.

4. The method for evaluating the Mach number and total static pressure at the main combustion chamber inlet as described in claim 1, characterized in that, In step S4, the static pressure at the compressor outlet section Calculated using the following formula: .

5. The method for evaluating the Mach number and total static pressure at the main combustion chamber inlet as described in claim 1, characterized in that, The method further includes step S5: based on the obtained Mach number Ma3 and total temperature T3, calculate the static temperature Ts3 of the compressor outlet section, using the following formula: .

6. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it is configured to perform the method for evaluating the main combustion chamber inlet Mach number and total static pressure as described in any one of claims 1 to 5.

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