A method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine

Abstract

The present invention discloses a method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine, comprising: analyzing detection requirements; cleaning the detected part; marking the detection position; checking the stability of the contraction and expansion state to ensure that there is no stuck problem in the throat of the tail nozzle to be tested; detecting the throat size of the tail nozzle to be tested in each state; calculating the throat area of ​​the tail nozzle to be tested in each state; establishing a calibration model for the throat area of ​​the tail nozzle to be tested, and using the calculated value S of the throat area of ​​the tail nozzle to be tested in each state based on the least squares method. i and control signal value V i , establish an area calibration model as needed and solve the fitting coefficient; based on the established area calibration model, test the calibration results; issue a calibration report and organize the test site.

Description

Technical Field

[0001] The invention belongs to the field of aviation engine measurement and detection, and in particular relates to a method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aviation engine. Background Art

[0002] Modern aircraft engines are developing towards high thrust-to-weight ratio, high compression ratio, high turbine front temperature and high maneuverability, especially represented by the new generation of variable cycle engines, and the engine thrust and lift have reached a new height. The tail nozzle is a key component for the generation of thrust and lift of aircraft engines. Its configuration characteristics are that it matches the flow path of the aircraft and is highly integrated with the fuselage. The magnitude and direction of the thrust generated by the tail nozzle have a decisive influence on the performance of the aircraft engine. Studies have shown that the geometric parameters of the tail nozzle, such as the initial expansion angle, total length, area expansion ratio, outer cover length, and outer cover inner wall expansion angle, have an important influence on the performance of the tail nozzle. Among them, the throat area of ​​the tail nozzle is directly related to the expansion degree of the airflow in the outer nozzle, thereby affecting the thrust coefficient, lift coefficient and pitch moment coefficient.

[0003] With the increasing requirements for aircraft maneuverability, more and more high-performance aircraft engines use adjustable tail nozzles to replace traditional fixed tail nozzles. The unique structure of the adjustable tail nozzle enables it to change the tail nozzle throat area according to the engine control signal, thereby realizing the regulation of engine thrust, lift and other performance under different speed conditions. However, in order to ensure accurate and reliable engine performance control, the adjustable tail nozzle throat area must be calibrated before the test to ensure that the control signal corresponds to the throat area one by one. In addition, during the engine development stage, the repeated assembly and disassembly of the mechanical structure will cause slight changes in the calibration parameters, and the tail nozzle throat area needs to be recalibrated before each whole machine test. Therefore, the calibration of the adjustable tail nozzle throat area of ​​aircraft engines is an essential link to ensure engine performance and the smooth conduct of the test.

[0004] Currently, adjustable tail nozzles are divided into two types: circular and rectangular. Among them, the circular tail nozzle is the most widely used. Its special alternating stacking structure of sealing plates and adjustment plates poses a great challenge to the calibration technology. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine. The method comprises the following steps: by marking the tail nozzle detection position, using an internal diameter micrometer or other measuring tools to measure the throat dimensions of the multi-states in a roughly small order according to different throat contraction and expansion states of the circular tail nozzle, selecting a suitable formula to calculate the throat area according to the situation, recording the engine control signal value at the same time, constructing a calibration model based on the least squares method, solving the calibration parameters, and checking the calibration results, so as to realize the accurate calibration of the adjustable circular tail nozzle area.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine comprises the following steps:

[0008] S1. Analyze the testing requirements and select the measuring tool according to the variation range of the nozzle throat diameter to be tested and the measurement accuracy requirements;

[0009] S2. Clean the tested part, and clean the oil stains on the surface of the sealing piece and the regulating piece of the tail nozzle throat to be tested;

[0010] S3. Mark the test position, and code and mark the sealing sheet and adjusting sheet of the nozzle throat to be tested. A pair of sealing sheets or adjusting sheets at the relative positions of the throat is a group. A total of m groups of sealing sheets and m groups of adjusting sheets are marked, and m ≥ 3;

[0011] S4. Check the stability of the contraction and expansion state. Use the oil source vehicle to control the contraction and expansion of the tail nozzle throat to check whether the contraction and expansion process is smooth and ensure that there is no jamming problem in the tail nozzle throat to be tested.

[0012] S5. Detect the throat size of the tail nozzle to be tested in each state, set the throat area of ​​the tail nozzle to be tested to be divided into N states from the largest to the smallest, N ≥ 5, and control the throat of the tail nozzle to be tested to be adjusted to different states i in order from large to small. Use the measuring tool to detect the distance between the two sealing sheets in each group of sealing sheets and record it as D i1 ,D i2 ,......,D im , and the distance between two adjustment plates in each group of adjustment plates and recorded as D' i1 ,D' i2 ,......,D' im , record the control signal value V in the corresponding state i ; The control signal value is the difference ratio and signal value of the angular displacement sensor;

[0013] S6. Calculate the nozzle throat area to be measured in each state;

[0014] S7. Establish a calibration model for the tail nozzle throat area to be measured, based on the least squares method, and use the calculated value S of the tail nozzle throat area to be measured in each state i and control signal value V i , establish the area calibration model as needed and solve the fitting coefficient;

[0015] S8. Based on the area calibration model established in step S7, the calibration results are verified. According to the methods in steps S5 and S6, the tail nozzle throat dimensions of the other M states are detected, M ≥ 3, and the M states do not overlap with the N states in step S5, and the observation values ​​S' of the M tail nozzle throat areas to be measured and the observation values ​​V' of the control signal are obtained. The maximum state and minimum state data are removed, and the control signal observation values ​​of the remaining M-2 states are substituted into the area calibration model to calculate the estimated values ​​of the M-2 tail nozzle throat areas to be measured. Compare the estimated value with the observed value V'. If the error meets the requirement, proceed to the next step. Otherwise, return to step S3 and recalibrate.

[0016] S9. Issue a calibration report and organize the test site.

[0017] Furthermore, in step S6, assuming that the nozzle throat to be tested is formed by splicing n sealing sheets and n adjusting sheets, the area of ​​the polygon is regarded as the superposition of the areas of 2n triangles, including n sealing sheet triangles and n adjusting sheet triangles. Therefore, the area of ​​the polygon under a certain state i is calculated as

[0018]

[0019] Where W is the width of the sealing sheet, θ is the angle between the sealing sheet and the adjusting sheet, and α is 1 / 2 of the triangle vertex angle of the sealing sheet. is the average distance between the sealing sheets, is the average distance between the adjustment plates.

[0020] Furthermore, in the area calibration model, the input is the control signal value V, and the output is the estimated value of the throat area Both should comply with:

[0021]

[0022] In the formula, is the estimated value of the fitting coefficient; according to the least squares method, the fitting coefficient is estimated by using the tail nozzle throat size and control signal value obtained in step S5.

[0023]

[0024] In the formula, S i 、V i are the observed values ​​of the nozzle throat area and control signal under each state, and N is the number of states.

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0026] The method of the present invention realizes the accurate calibration of the throat area of ​​the adjustable circular tail nozzle of the aircraft engine by marking the detection position, detecting the throat size of the tail nozzle to be tested in each state, calculating the throat area of ​​the tail nozzle to be tested, constructing the area calibration model and solving the parameters, and checking the calibration results. For the new generation of aircraft engines, the adjustable tail nozzle is a key component that determines its performance. The present invention proposes an effective method and a complete process for calibrating the throat area of ​​the adjustable circular tail nozzle, which comprehensively considers the actual situation of the engineering site, can effectively reduce the measurement uncertainty introduced by factors such as the subjective experience of the operator, the mechanical return error, and the difference in the calculation formula, and realizes the rapid and accurate calibration of the throat area of ​​the adjustable circular tail nozzle, improves the efficiency of the aircraft engine whole machine test, and lays the foundation for the final formation of the aircraft engine test specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of a method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine.

[0028] Figure 2 It is a schematic diagram of the detection position of the throat mark of the adjustable circular tail nozzle of the present invention.

[0029] Figure 3 It is a schematic diagram of calculating the throat area of ​​the adjustable circular tail nozzle of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] The present invention proposes a method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine. Figure 1 As shown, it mainly includes the following steps:

[0032] S1. Analyze the testing requirements and reasonably select measuring tools, such as internal diameter micrometer or other automatic measuring devices, according to the variation range of the nozzle throat diameter to be measured and the measurement accuracy requirements.

[0033] S2. Clean the measured parts, including the oil stains on the surface of the sealing piece and the adjusting piece of the tail nozzle throat to prevent the pollutants from affecting the measurement results.

[0034] S3. Mark the test position and code the sealing piece and adjusting piece of the tail nozzle throat to be tested, such as Figure 2 As shown, a pair of sealing plates or adjusting plates at relative positions of the throat is a group, and a total of 3 groups of sealing plates (1#, 2#, 3#) and 3 groups of adjusting plates (1'#, 2'#, 3'#) are marked.

[0035] S4. Check the stability of the contraction and expansion state. Control the contraction and expansion of the tail nozzle throat to be tested through the oil source vehicle to check whether the contraction and expansion process is smooth and ensure that there is no jamming problem in the tail nozzle throat to be tested.

[0036] S5. Detect the throat size of the tail nozzle to be tested in each state. The tail nozzle throat area is divided into N = 5 states from the largest to the smallest. In order to eliminate the return error and ensure the measurement accuracy, the tail nozzle must be strictly controlled to adjust to different states i, i≤N in order from large to small. Use the measuring tool to detect the distance between the two sealing pieces in each group of sealing pieces (denoted as D i1 ,D i2 ,D i3 ) and the distance between two adjustment plates in each group of adjustment plates (denoted as D' i1 ,D' i2 ,D' i3 ),like Figure 3 As shown, record the control signal value (usually the angular displacement sensor difference ratio and signal value) V in this state i .

[0037] S6. Calculate the throat area of ​​the tail nozzle to be tested in each state. For each state, it is important to note that although the tail nozzle throat is approximately circular, it is actually a polygon composed of several sealing sheets and adjustment sheets. Therefore, specific analysis is required:

[0038] like Figure 3 As shown in Fig. 1, assuming that the nozzle throat to be tested is formed by splicing 8 sealing sheets and 8 adjusting sheets, the area of ​​the polygon can be regarded as the superposition of 2×8 triangle areas (including 8 sealing sheet triangles and 8 adjusting sheet triangles), so the area of ​​the polygon under a certain state i can be calculated as

[0039]

[0040] Where W is the width of the sealing sheet, θ is the angle between the sealing sheet and the adjusting sheet, and α is 1 / 2 of the triangle vertex angle of the sealing sheet. is the average distance between the sealing sheets, is the average distance between the adjustment plates.

[0041] S7. Establish a calibration model for the tail nozzle throat area to be tested, based on the least squares method, and use the throat area calculation value S under each state i and control signal value V i , establish the area calibration model, the input is the control signal value V, and the output is the estimated value of the throat area Both should comply with:

[0042]

[0043] In the formula, is the estimated value of the fitting coefficient. According to the least squares method, using the throat size value and the control signal value detected in step S5, the fitting coefficient is estimated to be

[0044]

[0045] In the formula, S i 、V i are the observed values ​​of the tail nozzle throat area and control signal under each state.

[0046] S8. Check the calibration results. Based on the area calibration model established in step S7, check the calibration results. According to the methods in steps S5 and S6, test the throat dimensions of the other three states of the tail nozzle to be tested, obtain the observed values ​​S' of the three throat areas and the observed values ​​V' of the control signal, remove the data of the maximum state and the minimum state, substitute the observed value of the control signal of the remaining state into formula (2), and calculate the estimated value of the throat area. The estimated value Compare it with the observed value V'. If the error meets the requirements, proceed to the next step. Otherwise, return to step S3 and recalibrate.

[0047] S9. Issue a calibration report and organize the test site.

[0048] Finally, it should be pointed out that the above examples are only used to illustrate the calculation process of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above examples, a person skilled in the art should understand that the calculation process described in the above examples can still be modified, or some parameters can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding calculation method deviate from the spirit and scope of the calculation method of the present invention.

[0049] The present invention is not limited to the embodiments described above. The above description of the specific embodiments is intended to describe and illustrate the technical solution of the present invention. The above specific embodiments are merely illustrative and not restrictive. Without departing from the scope of the present invention and the scope of protection of the claims, a person of ordinary skill in the art can also make many forms of specific changes under the guidance of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine, characterized in that: The following steps are involved: S1. Analyze the testing requirements and select the measuring tool according to the variation range of the nozzle throat diameter to be tested and the measurement accuracy requirements; S2. Clean the tested part, and clean the oil stains on the surface of the sealing piece and the regulating piece of the tail nozzle throat to be tested; S3. Mark the test position, and code and mark the sealing sheet and adjusting sheet of the nozzle throat to be tested. A pair of sealing sheets or adjusting sheets at the relative positions of the throat is a group. A total of m groups of sealing sheets and m groups of adjusting sheets are marked, and m ≥ 3; S4. Check the stability of the contraction and expansion state. Use the oil source vehicle to control the contraction and expansion of the tail nozzle throat to check whether the contraction and expansion process is smooth and ensure that there is no jamming problem in the tail nozzle throat to be tested. S5. Detect the throat size of the tail nozzle to be tested in each state, set the throat area of ​​the tail nozzle to be tested to be divided into N states from the largest to the smallest, N ≥ 5, and control the throat of the tail nozzle to be tested to be adjusted to different states i in order from large to small. Use the measuring tool to detect the distance between the two sealing sheets in each group of sealing sheets and record it as D i1 ,D i2 ,......,D im , and the distance between two adjustment plates in each group of adjustment plates and recorded as D' i1 ,D' i2 ,......,D' im , record the control signal value V in the corresponding state i ; The control signal value is the difference ratio and signal value of the angular displacement sensor; S6. Calculate the nozzle throat area to be measured in each state; S7. Establish a calibration model for the tail nozzle throat area to be measured, based on the least squares method, and use the calculated value S of the tail nozzle throat area to be measured in each state i and control signal value V i , establish the area calibration model as needed and solve the fitting coefficient; S8. Based on the area calibration model established in step S7, the calibration results are verified. According to the methods in steps S5 and S6, the tail nozzle throat dimensions of the other M states are detected, M ≥ 3, and the M states do not overlap with the N states in step S5, and the observation values ​​S' of the M tail nozzle throat areas to be measured and the observation values ​​V' of the control signal are obtained. The maximum state and minimum state data are removed, and the control signal observation values ​​of the remaining M-2 states are substituted into the area calibration model to calculate the estimated values ​​of the M-2 tail nozzle throat areas to be measured. Compare the estimated value with the observed value V'. If the error meets the requirement, proceed to the next step. Otherwise, return to step S3 and recalibrate. S9. Issue a calibration report and organize the test site.

2. The method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine according to claim 1, characterized in that: In step S6, assuming that the nozzle throat to be tested is formed by splicing n sealing sheets and n adjusting sheets, the area of ​​the polygon is regarded as the superposition of the areas of 2n triangles, including n sealing sheet triangles and n adjusting sheet triangles. Therefore, the area of ​​the polygon under a certain state i is calculated as Where W is the width of the sealing sheet, θ is the angle between the sealing sheet and the adjusting sheet, and α is 1 / 2 of the triangle vertex angle of the sealing sheet. is the average distance between the sealing sheets, is the average distance between the adjustment plates.

3. The method for calibrating the throat area of ​​an adjustable circular tail nozzle of an aircraft engine according to claim 1, characterized in that: In the area calibration model, the input is the control signal value V, and the output is the estimated value of the throat area Both should comply with: In the formula, is the estimated value of the fitting coefficient; according to the least squares method, the fitting coefficient is estimated by using the tail nozzle throat size and control signal value obtained in step S5. In the formula, S i 、V i are the observed values ​​of the nozzle throat area and control signal under each state, and N is the number of states.

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