空-油换热器对变循环航空发动机总体性能的影响研究

Overall Performance Evaluation of Variable Cycle Aero-Engine Based on Air-Fuel Heat Exchanger

关键词:  变循环发动机  空-油换热器  涡轮冷却  仿真模型  总体性能分析

Key words:  Variable cycle engine  Air-fuel heat exchanger  Turbine cooling  Simulation model  Overall performance analysis

摘要:

为解决变循环涡扇发动机涡轮前温度和涡轮冷却气体温度升高使得涡轮冷却效果降低的问题，以航空燃料作为冷源降低涡轮冷却气体温度，将空-油换热器应用在变循环发动机中，建立了变循环发动机的性能仿真模型。同时引入空油换热的冷却性能计算模型，评估采用超临界航空煤油作为冷却介质后，考虑航空煤油超临界喷射、燃烧、涡轮冷却、冷却空气流量、耗油率等参数及相关性能的影响，构建了以超临界航空煤油为纽带的燃烧/冷却热耦合的能量交互分析方法。利用所建立的变循环发动机仿真模型，开展了起飞、快速爬升、超声速巡航、超声速加力和最大推力5种典型飞行状态的总体性能计算，通过比对是否使用空-油换热器对涡轮静叶冷却的计算结果，分析了各个状态下空油换热对变循环发动机总体性能的影响。结果表明：在起飞状态时，采用空-油换热器可以较明显提升发动机总体性能，降低单位燃油消耗率1.86%和提升推力0.95%。因此，通过空-油换热器对变循环航空发动机涡轮冷却气体进行冷却可以有效提高发动机不同状态的性能水平。

Abstract:

In order to solve the problem of reducing the cooling effect of the turbine due to the increase of the temperature of the turbine inlet and the temperature of the cooling gas of the variable cycle turbofan engines， aviation fuel is used as a coolant to reduce the temperature of turbine cooling gas. The air-fuel heat exchanger was applied to the variable cycle engine and the performance simulation model of the engine was established. After introducing a cooling performance calculation model for air-fuel heat exchanger and using supercritical aviation kerosene as the coolant， the effects of parameters such as kerosene supercritical injection， combustion， turbine cooling， cooling air flow， and specific fuel consumption were evaluated. Using the energy interaction analysis method of combustion heat coupled cooling of supercritical kerosene， the overall performance calculations of five typical flight conditions， including take-off， fast climb， supersonic cruise， supersonic afterburner and maximum thrust， were carried out. By comparing the calculation results of turbine vane cooling with or without an air-fuel heat exchanger， the influence of air-fuel heat exchange on the overall performance of the variable cycle engine under various flight conditions was analyzed. It is shown that during take-off the specific fuel consumption decreases by 1.86%， the thrust increases by 0.95%， and the performance improvement is the most obvious. The use of air-fuel heat exchanger to cool the engine turbine cooling air can effectively improve the performance level of the variable cycle engine in different flight conditions.