并联式TBCC发动机排气系统性能数值模拟

Numerical Study of the Over-Under TBCC Exhaust System

关键词:  涡轮基组合循环  排气系统  飞行包线  推力系数  升力  俯仰力矩 

Key words:  TBCC  Exhaust system  Flight envelope  Thrust coefficient  Lift  Pitch moment

摘要:

针对一个并联式涡轮基组合循环(Turbine Based Combined Cycle, TBCC)发动机排气系统的气动方案,对其在整个飞行包线范围内典型工作点上的流场进行了数值模拟研究,获得了飞行包线范围内排气系统相应的推力系数、升力、俯仰力矩随飞行马赫数的变化关系。计算结果显示,在整个飞行包线范围内,排气系统的轴向推力系数随着飞行马赫数先减小后增大,在跨声速飞行时降到最低 Ma=0.9,涡喷不加力时为0.562,加力时0.662),在设计点附近达到最大;升力和俯仰力矩性能在亚声速及跨声速飞行时较差,在超声速飞行时随着飞行马赫数增加逐渐好转。表明排气系统在跨声速飞行范围内工作时应采取措施以改善其性能。 

Abstract:

According to the representative working condition of a TBCC engine, an Over-under TBCC exhaust system with twin throats was designed by the MOC(Method of Characteristic), and the flowfield under the different flying conditions of the flight envelope from Ma=0~4, was numerically studied by the CFD software Fluent. The thrust coefficient, lift and the pitch moment were obtained and analyzed.The results show that during the whole flight envelope, the thrust coefficient of the exhaust system decreases at first from the take off to the transonic region, where it reaches its minimum (it is only 0.562for Ma=0.9without afterburning, and is 0.662at the same flight Mach number with afterburning). The lift and the pitch moment are relatively poor at the subsonic and transonic zone, and they would get better with increasing flight Mach number. Therefore, it is necessary to take some measures to improve the aerodynamic performance of the over-under TBCC exhaust system at low flight Mach number.