A method for subsonic cruise specific fuel consumption of a low-bypass-ratio turbofan engine

Abstract

The application belongs to the field of aircraft design and is a method for subsonic cruise state fuel consumption of a small-bypass-ratio turbofan engine. The method comprises the following steps: obtaining initial performance record results of the whole machine in a subsonic cruise state, analyzing and judging whether the working state of the small-bypass-ratio turbofan engine is in an optimal state, and optimizing a preliminary design of a cruise fuel consumption debugging scheme to determine a preliminary adjustment scheme of an optimal fan guide vane angle a1 and a preliminary adjustment scheme of an optimal compressor guide vane angle a2; further adjusting a nozzle throat area A8 and a nozzle outlet area A9 to different areas to determine an optimal nozzle throat area A8 and an optimal nozzle outlet area A9; and finally judging installation fuel consumption under the condition of the whole aircraft to obtain an optimal installation fuel consumption state when the installation fuel consumption is optimal. The method systematically and normatively proposes a debugging step for optimizing subsonic cruise state fuel consumption, which can effectively reduce engine installation fuel consumption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aircraft design, and particularly relates to a method for subsonic cruise state fuel consumption of a small-bypass-ratio turbofan engine. BACKGROUND

[0002] With the improvement of aircraft performance, the demand of aircraft on aero-engine is higher and higher. Under the condition of constant inlet air flow and weight, the aircraft requires high un-augmented thrust at high altitude and low fuel consumption at subsonic cruise state, which brings great difficulty to the design of the engine.

[0003] The greater the required un-augmented thrust at high altitude under the condition of constant inlet air flow and weight, the higher the turbine inlet temperature or the smaller the bypass ratio needs to be selected. Due to the limitation of high-temperature resistance of turbine materials and cooling technology of turbine blades, the turbine inlet temperature in the air cannot be too high, so the design scheme of small bypass ratio is usually selected to improve the un-augmented thrust at high altitude.

[0004] Under the design scheme of small bypass ratio, the problem of high fuel consumption at subsonic cruise state is brought, which affects the realization of important indicators such as aircraft loiter time and range, so it is necessary to reduce the fuel consumption at subsonic cruise as much as possible.

[0005] How to effectively optimize the subsonic cruise state fuel consumption of a high-performance small-bypass-ratio turbofan engine is a problem to be solved. SUMMARY

[0006] The purpose of the present application is to provide a method for subsonic cruise state fuel consumption of a small-bypass-ratio turbofan engine, to solve the problem of high fuel consumption of small-bypass-ratio under the existing design scheme in the prior art.

[0007] The technical solution of the present application is: a method for subsonic cruise state fuel consumption of a small-bypass-ratio turbofan engine, comprising:

[0008] Performing initial cruise performance test of the whole machine and component test of the small-bypass-ratio turbofan engine, obtaining analysis results by analyzing and judging whether the working state of the small-bypass-ratio turbofan engine is in the best state according to the initial performance recording results of the whole machine at subsonic cruise state and the component test results, and according to the initial performance recording results of the whole machine at subsonic cruise state;

[0009] According to the analysis results and the component test results, performing preliminary design of an optimized cruise fuel consumption debugging scheme, and determining a preliminary adjustment scheme of the best fan guide vane angle a1 and a preliminary adjustment scheme of the best compressor guide vane angle a2 according to the optimized cruise fuel consumption debugging scheme;

[0010] According to the best fan guide vane angle a1 preliminary adjustment scheme and the best compressor guide vane angle a2 preliminary adjustment scheme, the nozzle throat area A8 is adjusted to different areas, and the best nozzle throat area A8 is determined;

[0011] After the best nozzle throat area A8 is determined, the nozzle exit area A9 is adjusted to different areas, and the best nozzle exit area A9 is determined;

[0012] The best nozzle throat area A8 and the best nozzle exit area A9 are input into the whole aircraft, and the best nozzle throat area A8 and the best nozzle exit area A9 under the whole aircraft are determined according to the actual situation.

[0013] Preferably, the best fan guide vane angle a1 is obtained by selecting the node of closing the fan guide vane angle by 5°, 3° and opening by 5°, 3° respectively, and then obtaining the specific fuel consumption under different performance recording nodes, and selecting the fan guide vane angle a1 adjustment scheme with the lowest subsonic cruise specific fuel consumption as the best fan guide vane angle a1.

[0014] Preferably, the best compressor guide vane angle a2 is obtained by selecting the node of closing the compressor guide vane angle by 5°, 3° and opening by 5°, 3° respectively, and then obtaining the specific fuel consumption under different performance recording nodes, and selecting the compressor guide vane angle a2 adjustment scheme with the lowest subsonic cruise specific fuel consumption as the best compressor guide vane angle a2.

[0015] Preferably, the best nozzle throat area A8 is obtained by selecting the node of enlarging the nozzle throat area A8 by 5%, 10%, 15%, 20%, 25% respectively, and then obtaining the specific fuel consumption under different performance recording nodes, and selecting the nozzle throat area A8 with the lowest subsonic cruise specific fuel consumption as the best nozzle throat area A8.

[0016] Preferably, the best nozzle exit area A9 is obtained by selecting the node of closing the nozzle exit area A9 by 5%, 10%, 15%, 20% and simultaneously selecting the node of enlarging the nozzle exit area A9 by 5%, 10%, 15%, 20%, and then obtaining the specific fuel consumption under different performance recording nodes, and selecting the nozzle exit area A9 with the lowest subsonic cruise specific fuel consumption as the best nozzle exit area A9.

[0017] Preferably, when the installation specific fuel consumption is not the best, the best nozzle throat area A8 and the best nozzle exit area A9 are re-determined on the basis of the best fan guide vane angle a1 preliminary adjustment scheme and the best compressor guide vane angle a2 preliminary adjustment scheme, and are re-input into the whole aircraft, and the installation specific fuel consumption is re-judged until the installation specific fuel consumption of the whole aircraft reaches the best.

[0018] The method for small-bypass-ratio turbofan engine subsonic cruise state fuel consumption of the application, by selecting the initial performance recording results of the whole machine subsonic cruise state, analyzes and judges whether the working state of the small-bypass-ratio turbofan engine is in the best state, and optimizes the preliminary design of the cruise fuel consumption debugging scheme, determines the best fan guide vane angle a1 preliminary adjustment scheme and the best compressor guide vane angle a2 preliminary adjustment scheme; thereby further adjusting the nozzle throat area A8 and the nozzle exit area A9 to different areas to determine the best nozzle throat area A8 and the best nozzle exit area A9; finally, the installation fuel consumption under the condition of the whole aircraft is judged, and the installation best fuel consumption state is obtained when the installation fuel consumption is the best. The debugging steps for optimizing the subsonic cruise state fuel consumption are systematically and normatively proposed, which can effectively reduce the engine installation fuel consumption. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions provided by the application, the following will briefly introduce the drawings. Obviously, the drawings described below are only some embodiments of the application.

[0020] Figure 1 It is a whole process schematic diagram of the application;

[0021] Figure 2 It is a schematic diagram of the influence of the subsonic cruise state A8 amplification on the nozzle thrust coefficient of the application;

[0022] Figure 3 It is a schematic diagram of the influence of the subsonic cruise state A8 amplification on the engine air flow of the application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0024] A method for small-bypass-ratio turbofan engine subsonic cruise state fuel consumption, as shown in Figure 1 The method comprises the following steps:

[0025] Step S100, since the absolute values of subsonic cruise state thrust and fuel flow are relatively small, the measurement error is relatively large in high-altitude simulation test. In order to eliminate the large fuel consumption deviation caused by the measurement error of engine thrust and fuel flow in different test times, an initial performance recording of subsonic cruise state is usually carried out before the subsonic cruise state fuel consumption debugging, which lays a foundation for the subsequent debugging effect judgment.

[0026] The initial performance test of the whole machine and the component test of the small-bypass-ratio turbofan engine are performed. According to the initial performance recording result of the whole machine in the subsonic cruise state and the component test result, the working state of the small-bypass-ratio turbofan engine is analyzed and judged according to the initial performance recording result of the whole machine in the subsonic cruise state, whether the fan, the compressor, the high-pressure turbine and the low-pressure turbine work in the highest efficiency region, whether the turbine rear casing or the intermediate casing works in the best total pressure recovery coefficient region, and whether the nozzle works in the highest thrust coefficient state, so as to provide support for the subsequent cruise specific fuel consumption optimization, and thus the analysis result is obtained.

[0027] In step S200, according to the analysis result and the component test result, the preliminary design of the optimization cruise specific fuel consumption debugging scheme is performed, and the optimal fan vane angle a1 preliminary adjustment scheme and the optimal compressor vane angle a2 preliminary adjustment scheme are determined according to the optimization cruise specific fuel consumption debugging scheme.

[0028] According to the cruise specific fuel consumption debugging scheme, not only the optimal fan vane angle a1 preliminary adjustment scheme and the optimal compressor vane angle a2 can be determined, but also other vane angles can be determined, so that the optimal angles of other vanes can be obtained for synchronous judgment.

[0029] Preferably, the optimal fan vane angle a1 is obtained by respectively selecting the small fan vane angles 5° and 3° and respectively opening the small fan vane angles by 5° and 3° in the node for performance recording, and then obtaining the specific fuel consumption under different performance recording nodes, and selecting the fan vane angle a1 adjustment scheme with the lowest subsonic cruise specific fuel consumption as the optimal fan vane angle a1.

[0030] The optimal compressor vane angle a2 is obtained by respectively selecting the small compressor vane angles 5° and 3° and respectively opening the small compressor vane angles by 5° and 3° in the node for performance recording, and then obtaining the specific fuel consumption under different performance recording nodes, and selecting the compressor vane angle a2 adjustment scheme with the lowest subsonic cruise specific fuel consumption as the optimal compressor vane angle a2.

[0031] In step S300, in order to ensure the air-to-ground thrust requirement of the high-performance small-bypass-ratio engine, the upper limit of the adjustment range of the nozzle exit area A9 is usually large. Due to the mechanism limitation, the lower limit of the adjustment range of the nozzle exit area A9 is also large. Therefore, under the normal working condition, the nozzle of the subsonic cruise state is usually over-expanded, and the thrust coefficient deviates from the optimal thrust coefficient region (see Figure 2 ). At the same time, due to the requirements of stealth and thrust vectoring, the working environment and sealing structure of the nozzle are complex, and the theoretical analysis result usually deviates from the actual state. Therefore, when the debugging scheme of the nozzle throat area A8 and the nozzle exit area A9 is determined, a large adjustment range needs to be formulated.

[0032] From the perspective of installation specific fuel consumption, enlarging the nozzle throat area A8 increases the engine air flow (see Figure 3 ), the cruise state aircraft overflow resistance is reduced, and the nozzle exit area A9 enlarges the aircraft afterbody resistance is reduced, so when determining the A8, A9 adjustment scheme, the installation specific fuel consumption is also considered. Specifically:

[0033] According to the optimal fan guide vane angle a1 preliminary adjustment scheme and the optimal compressor guide vane angle a2 preliminary adjustment scheme, the nozzle throat area A8 is adjusted to different areas, and the optimal nozzle throat area A8 is determined.

[0034] Preferably, the optimal nozzle throat area A8 is obtained by respectively selecting the 5%, 10%, 15%, 20%, and 25% enlarged nozzle throat area A8 in the node, and then obtaining the specific fuel consumption under different performance recording nodes, and selecting the nozzle throat area A8 with the lowest subsonic cruise specific fuel consumption as the optimal nozzle throat area A8.

[0035] Step S400, after determining the optimal nozzle throat area A8, adjust the nozzle exit area A9 to different areas, and determine the optimal nozzle exit area A9.

[0036] Preferably, the optimal nozzle exit area A9 is obtained by respectively selecting the 5%, 10%, 15%, and 20% reduced nozzle exit area A9 in the node, and then considering the subsequent installation specific fuel consumption optimization, the 5%, 10%, 15%, and 20% enlarged nozzle exit area A9 is also required to be performance recorded, and then the specific fuel consumption under different performance recording nodes is obtained, and the nozzle exit area A9 with the lowest subsonic cruise specific fuel consumption is selected as the optimal nozzle exit area A9.

[0037] Step S500, input the optimal nozzle throat area A8 and the optimal nozzle exit area A9 into the aircraft whole machine, judge whether the installation specific fuel consumption is optimal, if yes, determine the optimal nozzle throat area A8 and the optimal nozzle exit area A9 of the aircraft whole machine.

[0038] The above series of adjustments obtain a relatively optimal subsonic cruise specific fuel consumption of the engine, but make the installation specific fuel consumption the lowest, which is a comprehensive consideration of the specific fuel consumption of the engine itself and the aircraft resistance, so after obtaining a series of adjustment parameters, the related parameters are provided to the aircraft department to carry out integrated design of the engine and the aircraft, and finally determine the optimal A8, A9 area (from the analysis, the a1, a2 angle adjustment usually does not affect the aircraft resistance parameter), so that the state specific fuel consumption is the lowest.

[0039] Preferably, when the installation specific fuel consumption is not optimal, then on the basis of the optimal fan vane angle a1 preliminary adjustment scheme and the optimal compressor vane angle a2 preliminary adjustment scheme, the optimal nozzle throat area A8 and the optimal nozzle exit area A9 are re-determined, such as the enlarged nozzle throat area A8 86%, 11%, 16%, 21%, 26% in the selected node is taken for performance recording, and is introduced into the aircraft again, and the installation specific fuel consumption is judged again, until the installation specific fuel consumption of the aircraft reaches the optimum.

[0040] The application selects the initial performance recording results of the whole machine subsonic cruise state, analyzes and judges whether the small-bypass-ratio turbofan engine working state is in the optimal state, optimizes the cruise specific fuel consumption debugging scheme preliminary design, determines the optimal fan vane angle a1 preliminary adjustment scheme and the optimal compressor vane angle a2 preliminary adjustment scheme; thereby further adjusting the nozzle throat area A8 and the nozzle exit area A9 to different areas, determining the optimal nozzle throat area A8 and the optimal nozzle exit area A9; finally, the installation specific fuel consumption of the aircraft under the whole machine condition is judged, and the optimal installation specific fuel consumption state is obtained when the installation specific fuel consumption is optimal.

[0041] Has the following advantages:

[0042] 1) The system, specification optimizes the debugging steps of the subsonic cruise state specific fuel consumption, including the specific fuel consumption optimization of the engine itself and the steps of the installation specific fuel consumption optimization of the engine-aircraft integrated design, perfects and supplements the debugging steps.

[0043] 2) Breaks the conventional debugging method and range, on the basis of theoretical analysis, test verification and engine-aircraft integrated design, with the help of advanced control system, the method of optimizing the subsonic cruise state specific fuel consumption by greatly adjusting the nozzle throat area A8 and greatly reducing the nozzle exit area A9 is proposed and realized. From the verification results, this method can effectively reduce the engine installation specific fuel consumption.

[0044] Finally, it should be noted that: the drawings of the disclosed embodiments 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;

[0045] 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. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for improving the fuel consumption rate of a low-bypass turbofan engine during subsonic cruise, characterized in that... include: Conduct initial cruise performance tests of the entire engine and tests of each component of the low-bypass turbofan engine. Based on the initial performance records of the entire engine in subsonic cruise state and the test results of each component, analyze and determine whether the low-bypass turbofan engine is in its optimal operating state and obtain the analysis results. Based on the analysis results and the test results of each component, a preliminary design of the cruise fuel consumption rate debugging scheme is carried out. Based on the optimized cruise fuel consumption rate debugging scheme, the preliminary adjustment schemes for the optimal fan guide vane angle a1 and the optimal compressor guide vane angle a2 are determined. Based on the preliminary adjustment schemes for the optimal fan guide vane angle a1 and the optimal compressor guide vane angle a2, the nozzle throat area A8 is adjusted to different areas, and the optimal nozzle throat area A8 is determined. After determining the optimal nozzle throat area A8, adjust the nozzle exit area A9 to different areas, and then determine the optimal nozzle exit area A9. Input the optimal nozzle throat area A8 and the optimal nozzle exit area A9 into the entire aircraft and determine whether the installed fuel consumption rate is optimal. If so, determine the optimal nozzle throat area A8 and the optimal nozzle exit area A9 for the entire aircraft.

2. The method for reducing fuel consumption rate of a low-bypass turbofan engine in subsonic cruise mode as described in claim 1, characterized in that: The optimal fan guide vane angle a1 is determined by selecting nodes to reduce the fan guide vane angle by 5° and 3° and increase it by 5° and 3° respectively for performance evaluation. Then, the fuel consumption rate under different performance evaluation nodes is obtained, and the fan guide vane angle a1 adjustment scheme with the lowest fuel consumption rate during subsonic cruise is selected as the optimal fan guide vane angle a1.

3. The method for reducing fuel consumption rate of a low-bypass turbofan engine in subsonic cruise mode as described in claim 1, characterized in that: The optimal compressor guide vane angle a2 is determined by selecting nodes to reduce the compressor guide vane angle by 5° and 3° and increase it by 5° and 3° respectively for performance evaluation. Then, the fuel consumption rate under different performance evaluation nodes is obtained, and the compressor guide vane angle a2 adjustment scheme with the lowest subsonic cruise fuel consumption rate is selected as the optimal compressor guide vane angle a2.

4. The method for reducing fuel consumption rate of a low-bypass turbofan engine in subsonic cruise mode as described in claim 1, characterized in that: The optimal nozzle throat area A8 is determined by selecting nodes at 5%, 10%, 15%, 20%, and 25% for performance evaluation, and then obtaining the fuel consumption rate under different performance evaluation nodes. The nozzle throat area A8 with the lowest subsonic cruise fuel consumption rate is selected as the optimal nozzle throat area A8.

5. The method for reducing fuel consumption rate of a low-bypass turbofan engine in subsonic cruise mode as described in claim 1, characterized in that: The optimal nozzle exit area A9 is determined by selecting nodes with reduced nozzle exit areas A95%, 10%, 15%, and 20% for performance evaluation, and simultaneously selecting nodes with increased nozzle exit areas A95%, 10%, 15%, and 20% for performance evaluation. Then, the fuel consumption rate under different performance evaluation nodes is obtained, and the nozzle exit area A9 with the lowest fuel consumption rate during subsonic cruise is selected as the optimal nozzle exit area A9.

6. The method for reducing fuel consumption rate of a low-bypass turbofan engine in subsonic cruise mode as described in claim 1, characterized in that: When the installation fuel consumption rate is not optimal, based on the preliminary adjustment schemes for the optimal fan guide vane angle a1 and the optimal compressor guide vane angle a2, the optimal nozzle throat area A8 and the optimal nozzle exit area A9 are re-determined and then imported back into the aircraft to re-judge the installation fuel consumption rate until the installation fuel consumption rate of the entire aircraft reaches the optimal level.

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