A method for correcting experimental data of flow distribution in main combustion chamber of aircraft engine

Abstract

The present application provides a method for correcting test data of flow distribution of a main combustion chamber of an aircraft engine, comprising: dividing the air circulation holes of the main combustion chamber into a first part of holes including flame tube head holes and a second part of holes including flame tube cooling holes and air induction holes, setting a first pressure measuring point on the front side of the first part of holes, setting a second pressure measuring point on the front side of the second part of holes, and setting a third pressure measuring point at the outlet of the main combustion chamber; constructing a relationship formula including an influence ratio and the first to third pressure measuring points and the pressure difference of the main combustion chamber, assigning a value to the influence ratio to obtain the pressure difference, and calculating the effective opening area under different blocked holes corresponding to the influence ratio according to the flow formula and the Bernoulli equation; adjusting the influence ratio so that the difference between the sum of the effective opening areas under different blocked holes and the effective opening area under non-blocked holes meets the threshold requirement, and at this time, the influence ratio and the effective opening area under the corresponding blocked hole meet the requirement.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft engine testing, and in particular, relates to a method for correcting test data of flow distribution in a main combustion chamber of an aircraft engine. Background Art

[0002] The main combustion chamber of a gas turbine engine is one of the main components of the core engine of a gas turbine engine. Flow distribution is one of the most basic and critical issues in the design and development of the combustion chamber. Flow distribution will affect the combustion performance and use of the combustion chamber, such as ignition, flame stability, combustion efficiency, total pressure loss, wall cooling, outlet temperature distribution and exhaust pollution. If the appropriate air flow distribution is obtained and there is an appropriate amount of cooling air uniformly along the circumference, then only a good basic fuel spray is needed to cooperate with it to achieve a good comprehensive design index of the combustion chamber.

[0003] At present, the way to obtain flow distribution generally adopts the flow distribution test method. The flow distribution test is mainly based on the plugging method, including the accumulation plugging method, the plugging method (also known as the "measure who plug who" method) and the isolated plugging method (also known as the flow characteristic curve method). The flow distribution test of a certain type of engine combustion chamber was compared using the flow resistance method, the accumulation plugging method and the plugging method. The results show that the plugging method is a relatively good method. It makes the flow state in the entire combustion chamber closer to the actual situation, and the air flow is large and easier to measure. Therefore, it is more accurate than the flow resistance method and more convenient and reliable than the accumulation plugging method. However, there is also a certain method error in measuring flow distribution using the plugging method. For the swirler whose air intake direction is the same as the mainstream at the head of the flame tube, the method error of the plugging method is small; for the main combustion holes, mixing holes and film cooling holes whose air intake direction has a large angle with the mainstream, the method error is large. The reasons for the error are: first, the plugging method does not truly simulate the flow conditions of the measured holes and ignores the influence of different flow coefficients between different hole rows; second, under different plugging conditions, the change of the flow field inside the combustion chamber is the direct cause of the method error.

[0004] In view of the defects of the plugging method, it is urgent to find a convenient, reliable and low-error test method or data processing method to make up for these defects. Summary of the invention

[0005] The purpose of the present application is to provide a method for correcting test data of flow distribution in the main combustion chamber of an aircraft engine, so as to solve or alleviate at least one problem in the background technology.

[0006] The technical solution of the present application is: a method for correcting test data of flow distribution in the main combustion chamber of an aircraft engine, the method comprising:

[0007] The air circulation holes of the main combustion chamber are divided into a first part of holes including flame tube head holes and a second part of holes including flame tube cooling holes and air induction holes, a first pressure measuring point is set at the front side of the first part of holes, a second pressure measuring point is set at the front side of the second part of holes, and a third pressure measuring point is set at the outlet of the main combustion chamber;

[0008] Construct a relationship formula including the influence ratio and the pressure difference between the first pressure measuring point, the second pressure measuring point, the third pressure measuring point and the main combustion chamber, obtain the pressure difference by assigning a value to the influence ratio, and calculate the effective opening area under different plugging holes corresponding to the influence ratio according to the flow formula and the Bernoulli equation;

[0009] By adjusting the influence ratio, the difference between the sum of the effective opening areas under different hole blockages and the effective opening area under no hole blockage meets the threshold requirement. At this time, the influence ratio and the corresponding effective opening area under hole blockage meet the requirement.

[0010] Further, the flame cooling holes and air entrainment holes include: inner ring cooling holes on the inner ring flame tube and inner ring air entrainment holes corresponding to the rear side of the inner ring cooling holes, and outer ring cooling holes on the outer ring flame tube and outer ring air entrainment holes corresponding to the rear side of the outer ring cooling holes;

[0011] The second pressure measuring points include an inner ring second pressure measuring point on the front side of the inner ring cooling hole and an outer ring second pressure measuring point on the front side of the outer ring cooling hole.

[0012] Furthermore, the relationship is:

[0013] ΔP=α*Pt31+1 / 2*(Ps32_o+Ps32_i)*(1-α)-Ps4

[0014] In the formula, ΔP is the pressure difference, α is the influence ratio, Pt31 is the total pressure at the diffuser outlet corresponding to the first pressure measuring point, Ps32_o is the static pressure in front of the outer ring flame tube cooling hole corresponding to the second pressure measuring point of the outer ring, Ps32_i is the static pressure in front of the inner ring flame tube cooling hole corresponding to the second pressure measuring point of the inner ring, and Ps4 is the static pressure at the main combustion chamber outlet corresponding to the third pressure measuring point.

[0015] Furthermore, the value range of the influence ratio α is (0, 1).

[0016] Furthermore, the pressure difference and the effective opening area under different hole blocking conditions satisfy:

[0017]

[0018] Where W is the flow rate, ACd is the effective opening area, ρ is the fluid density, and ΔP is the pressure difference.

[0019] Furthermore, the relationship between the difference between the sum of the effective opening areas under different blocking conditions and the effective opening area under no blocking conditions and the threshold value is: |ACd-ACd'|<δ

[0020] Where ACd is the sum of the effective opening areas under different hole plugging conditions. AC i is the effective opening area at the lower end of different hole blocking, i = 1, 2, 3...n; ACd' is the effective opening area without hole blocking; Δ is the threshold.

[0021] Furthermore, the threshold δ is not greater than 5%.

[0022] The method of the present application effectively overcomes the defects existing in the flow distribution test of the main combustion chamber of an aircraft engine when using the plugging method, improves the authenticity and accuracy of the data, and provides effective test data support for the design of the main combustion chamber of an aircraft engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0024] Figure 1 This is a schematic diagram of the layout of the pressure measurement points in the main combustion chamber in this application.

[0025] Figure 2 This is a flow chart of the data correction method of this application.

[0026] Reference numerals

[0027] 10-Main combustion chamber structure

[0028] 1-Inner Receiver

[0029] 2-Outer Receiver

[0030] 3-Flame tube head

[0031] 4-Outer ring cooling holes

[0032] 5-Outer ring flame tube

[0033] 6-Inner ring flame tube

[0034] 7-Inner ring cooling hole

[0035] 8-Outer ring air hole

[0036] 9-Inner ring air hole DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0038] The method for correcting the flow distribution test data of the main combustion chamber of an aircraft engine provided in this application is based on the measurement of the traditional plugging method, and the correction method includes:

[0039] 1. Determine the location of the inlet pressure measurement point

[0040] like Figure 1 The figure shows a typical schematic diagram of a main combustion chamber structure 10. The flame tube structure composed of a flame tube outer ring 5 and a flame tube inner ring 6 is located in the space surrounded by an inner casing 1 and an outer casing 2. The front end of the flame tube structure is a flame tube head 3. The flame tube head 3 is a main flow part of the flame tube structure. On the wall structures of the flame tube outer ring 5 and the flame tube inner ring 6, there are multiple circles of outer ring cooling holes 4 and inner ring cooling holes 7 arranged along the axial direction. The outer ring cooling holes 4 and the inner ring cooling holes 7 can be respectively bleed from the outer ring air bleed holes 8 and the inner ring air bleed holes 9 at the tail of the main combustion chamber.

[0041] Considering that the calculation method of the effective area of ​​the opening using the pressure difference before and after the hole is more accurate, the flow holes of the main combustion chamber are divided into two parts in this application. The first part is the holes at the head of the flame tube, and the second part is the cooling holes on the wall of the flame tube and the air bleed holes at the rear side of the flame tube. According to the classification of the flow holes, the pressure measuring points in front of the two parts of the holes are respectively selected in front of the most forward holes in each part of the holes, that is, in front of the holes at the head of the flame tube and in front of the inner and outer ring cooling holes. Since the flow channel pressure difference of the inner ring flame tube 6 and the outer ring flame tube 5 is relatively large, in this application, pressure measuring points are respectively set in front of the most forward cooling holes of the inner ring air bleed hole 8 and the outer ring air bleed hole 7. See the locations of the pressure measuring points for details. Figure 2 As shown, the pressure measuring point in front of the flame tube head hole is Pt31, and the total pressure at the diffuser outlet can be measured through the measuring point Pt31. The pressure measuring points in front of the outer ring cooling hole 4 and the inner ring cooling hole 7, which are the most forward of the outer ring air inlet holes 8 and the inner ring air inlet holes 9, are Ps32_o and Ps32_i, respectively. The static pressure in front of the outer ring flame tube cooling hole and the static pressure in front of the inner ring flame tube cooling hole can be measured respectively through the measuring points Ps32_o and Ps32_i. The outlet pressure measuring point of the flame tube structure is Ps4, and the static pressure at the main combustion chamber outlet can be measured through the measuring point Ps4.

[0042] 2. Construct a relational expression including the impact ratio and iterative calculation

[0043] According to the flow formula and Bernoulli equation, In the formula, W is the flow rate, ACd is the effective opening area, ρ is the fluid density, and ΔP is the pressure difference. From the above formula, we can see that the calculation of the pressure difference ΔP directly affects the solution of the sum of the effective opening areas ACd.

[0044] Table 1 shows the proportion of effective opening area at various locations solved by the conventional data processing method ΔP=Pt31-Ps4 in a flow distribution test of the main combustion chamber of a certain type of engine in one embodiment of the present application. It can be seen from the solution results of Table 1 that the sum of the proportions of the openings in each part is not equal to 1, and the data processing error is as high as 24%.

[0045] Table 1 Example of the proportion and error of the effective opening area at each location solved by ΔP = Pt31-Ps4

[0046]

[0047] For the entire combustion chamber, after some holes in the combustion chamber are blocked, especially those with larger areas such as the flame tube head, the redistribution of airflow causes the redistribution of pressure loss. Therefore, when a large area of ​​the combustion chamber is blocked, especially the holes in the flame tube head, the pressure difference is solved by ΔP=Pt31-Ps4 to calculate the effective opening area ACd', which will have a large error. At this time, it is more appropriate to use ΔP=Ps32-Ps4 to solve.

[0048] In this application, the influence ratio α of Pt31 is initially assigned, and the pressure difference before and after the plugging is iteratively solved. The final influence ratio α is calculated by the effective opening area ACd at each plugging hole. i The sum is equal to the effective area when the hole is fully opened.

[0049] like Figure 2 As shown, the method of the present application also includes: firstly constructing a relationship between the influence proportion α and the diffuser outlet total pressure Pt31 and the static pressures before the inner and outer ring flame tube cooling holes Ps32_o, Ps32_i and the main combustion chamber outlet static pressure Ps4:

[0050] ΔP=α*Pt31+1 / 2*(Ps32_o+Ps32_i)*(1-α)-Ps4

[0051] In the formula, ΔP is the pressure difference, α is the influence ratio, Pt31 is the total pressure at the diffuser outlet, Ps32_o is the static pressure in front of the cooling hole of the outer ring flame tube, Ps32_i is the static pressure in front of the cooling hole of the inner ring flame tube, and Ps4 is the static pressure at the main combustion chamber outlet.

[0052] Afterwards, the influence ratio α in the relationship is preliminarily assigned a value in the range of 0 to 1, thereby obtaining the pressure difference △P, and the effective opening area ACd under different plugging conditions is calculated based on the pressure difference △P, the flow formula, and the Bernoulli equation. i (i=1,2,3…n, i represents the flow hole);

[0053] Determine the sum of the effective opening areas ACd under different plugging conditions When the difference between the two meets the requirement (|ACd-ACd'|<δ, δ is the threshold value, which can be determined according to the actual situation, and the threshold value δ usually does not exceed 5%), the influence proportion α at this time meets the requirement, and the effective opening area ACd under each blocked hole at this time is i That is, the requirements are met; when the difference between the two does not meet the requirements, adjust the influence proportion α for iterative calculation until the above requirements are met.

[0054] Taking the flow distribution test of the main combustion chamber of a certain engine in Table 1 as an example, when the influence ratio α is calculated to be 0.3842, the ratio of the effective opening area of ​​each hole and the calculation error correction effect are shown in Table 3. It can be seen from Table 3 that the method of the present application can greatly reduce the error of data processing.

[0055] Table 3 Calculation error after pressure difference correction

[0056] Blocking hole position Data processing error (%) Inner ring air hole 2.9 Outer ring air hole 1.8 Outer ring flame tube cooling holes - Inner ring flame tube cooling holes - Flame tube head 2.0 total 0.6

[0057] The method of the present application effectively overcomes the defects existing in the flow distribution test of the main combustion chamber of an aircraft engine when using the plugging method, improves the authenticity and accuracy of the data, and provides effective test data support for the design of the main combustion chamber of an aircraft engine.

[0058] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for correcting test data of flow distribution in the main combustion chamber of an aircraft engine, characterized in that: The method comprises: The air circulation holes of the main combustion chamber are divided into a first part of holes including flame tube head holes and a second part of holes including flame tube cooling holes and air induction holes, a first pressure measuring point is set at the front side of the first part of holes, a second pressure measuring point is set at the front side of the second part of holes, and a third pressure measuring point is set at the outlet of the main combustion chamber; Construct a relationship formula including the influence ratio and the pressure difference between the first pressure measuring point, the second pressure measuring point and the third pressure measuring point and the main combustion chamber ΔP=α*Pt31+1 / 2*(Ps32_o+Ps32_i)*(1-α)-Ps4, where ΔP is the pressure difference, α is the influence ratio, Pt31 is the total pressure at the diffuser outlet corresponding to the first pressure measuring point, Ps32_o is the static pressure in front of the outer ring flame tube cooling hole corresponding to the outer ring second pressure measuring point, Ps32_i is the static pressure in front of the inner ring flame tube cooling hole corresponding to the inner ring second pressure measuring point, and Ps4 is the static pressure at the main combustion chamber outlet corresponding to the third pressure measuring point. The pressure difference is obtained by assigning a value to the influence ratio, and the effective opening area under different plugging holes corresponding to the influence ratio is calculated according to the flow formula and the Bernoulli equation, which satisfies Where W is the flow rate, ACd is the effective opening area, ρ is the fluid density, and ΔP is the pressure difference; By adjusting the influence ratio, the difference between the sum of the effective opening areas under different hole blockages and the effective opening area under no hole blockage meets the threshold requirement. At this time, the influence ratio and the corresponding effective opening area under hole blockage meet the requirement.

2. The method for correcting test data of flow distribution in the main combustion chamber of an aircraft engine according to claim 1, characterized in that: The flame tube cooling holes and air bleed holes include: inner ring cooling holes on the inner ring flame tube and inner ring air bleed holes corresponding to the rear side of the inner ring cooling holes, and outer ring cooling holes on the outer ring flame tube and outer ring air bleed holes corresponding to the rear side of the outer ring cooling holes; The second pressure measuring points include an inner ring second pressure measuring point on the front side of the inner ring cooling hole and an outer ring second pressure measuring point on the front side of the outer ring cooling hole.

3. The method for correcting test data of flow distribution in the main combustion chamber of an aircraft engine according to claim 2, characterized in that: The value range of the influence ratio α is (0, 1).

4. The method for correcting test data of flow distribution in the main combustion chamber of an aircraft engine according to any one of claims 1 to 3, characterized in that: The relationship between the difference between the sum of the effective opening areas under different blocking conditions and the effective opening area under no blocking and the threshold is: |ACd-ACd'|<δ Where ACd is the sum of the effective opening areas under different hole plugging conditions. AC i is the effective opening area at the lower end of different hole blocking, i = 1, 2, 3...n; ACd' is the effective opening area without hole blocking; Δ is the threshold.

5. The method for correcting test data of flow distribution in the main combustion chamber of an aircraft engine according to claim 3, characterized in that: The threshold δ is not greater than 5%.

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