基于冷气预冷技术的高马赫数涡轮发动机建模与仿真研究

Modeling and Simulation Study of High Mach Gas Turbine Engine with Cooled Cooling Air Technology

关键词:  高马赫数  变循环涡扇发动机  冷气预冷  建模方法  叶片温度  性能仿真

Key words:  High Mach number  Variable cycle turbofan engine  Cooled cooling air  Modeling method  Blade temperature  Performance simulation

摘要:

针对高马赫数涡轮发动机存在的涡轮部件热防护问题，以基于冷气预冷 （CCA） 技术的变循环涡扇发动机为例，通过建立燃油的热物性库、电动燃油泵和空气-燃油换热器的计算模型，改进燃烧室和涡轮的计算模型，发展了可控制涡轮叶片温度的变引气量整机性能计算模型。结果表明，在Ma3，20.9km的设计点，采用CCA技术能够将涡轮引气温度降低181K，相对引气量降低22.04%，并使推力和比冲分别提高2.03%，0.66%；在Ma3的节流状态下，控制涡轮叶片温度的发动机推力随转速降低而减小得更快，但是使空气-燃油换热器空气侧的温降最高达到240K，且总压损失明显降低；沿飞行轨迹，控制涡轮叶片温度的发动机在飞行马赫数大于1.8具有更大的推力，在飞行马赫数小于1.8具有更高的比冲。空气-燃油换热器在发动机最大热负荷状态的性能设计是影响引气温降和涡轮引气回流裕度的关键。

Abstract:

For the thermal protection of turbine components of high-speed gas turbine engines， a variable cycle turbofan （VCTF） engine with cooled cooling air （CCA） technology is taken as an example. This paper establishes the library of fuel thermal physical properties， the simulation model of electric fuel pump and the air-fuel heat exchanger， and improves the burner and turbine simulation model. The engine performance simulation model with variable bleeding air flow that can control the turbine blade temperature was developed. The simulation results show that at the design point of Mach 3 and altitude 20km， introducing the CCA technology can reduce the temperature of turbine cooling air by 181K， reduce the relative bleeding air flow by 22.04%， and increase net thrust and specific impulse by 2.03% and 0.66%， respectively. During the throttling state of Mach 3， the thrust of the engine with turbine blade temperature control decreases faster with the decrease of the rotational speed， but the temperature drop on the air side of the air-fuel heat exchanger is up to 240K， and the total pressure loss is further reduced. Along the flight trajectory， introducing turbine blade temperature control can improve the engine thrust when the flight Mach number is greater than 1.8 and improve specific impulse when the flight Mach number is smaller than 1.8. The performance design of the air-fuel heat exchanger at the maximum heat load of the engine is the key to determining the bleeding air temperature drop and the backflow margin of turbine bleeding air.