A turbine based combined cycle(TBCC)propulsion system uses a turbine-based engine to accelerate the vehicle from takeoff to the mode transition flight condition,at which point,the propulsion system performs a“mode tr...A turbine based combined cycle(TBCC)propulsion system uses a turbine-based engine to accelerate the vehicle from takeoff to the mode transition flight condition,at which point,the propulsion system performs a“mode transition”from the turbine to ramjet engine.Smooth inlet mode transition is accomplished when flow is diverted from one flowpath to the other,without experiencing unstart or buzz.The smooth inlet mode transition is a complex unsteady process and it is one of the enabling technologies for combined cycle engine to become a functional reality.In order to unveil the unsteady process of inlet mode transition,the research of over/under TBCC inlet mode transition was conducted through a numerical simulation.It shows that during the mode transition the terminal shock oscillates in the inlet.During the process of inlet mode transition mass flow rate and Mach number of turbojet flowpath reduce with oscillation.While in ramjet flowpath the flow field is non-uniform at the beginning of inlet mode transition.The speed of mode transition and the operation states of the turbojet and ramjet engines will affect the motion of terminal shock.The result obtained in present paper can help us realize the unsteady flow characteristic during the mode transition and provide some suggestions for TBCC inlet mode transition based on the smooth transition of thrust.展开更多
For investigating the back pressure characteristics of turbine channel of an external-parallel turbine-based combined cycle(TBCC)inlet during the mode transition with the freestream air Mach number of 1.8,wind tunnel ...For investigating the back pressure characteristics of turbine channel of an external-parallel turbine-based combined cycle(TBCC)inlet during the mode transition with the freestream air Mach number of 1.8,wind tunnel tests and numerical simulations are carried out.The results show that the critical back pressure of the turbine channel decreases linearly with the decrease of the open degree of splitter plate.The turbine channel has self-starting capacity when the open degree of the turbine channel is 100%.The total pressure recovery coefficient increases with the increase of back pressure when turbine channel is at supercritical and critical state.The mass capture ratio,total pressure recovery coefficient and outlet pressure ratio decrease obviously when turbine channel is at subcritical state.Results of the research would provide scheme reference and technology storage for TBCC propulsion evolution.展开更多
针对推力状态控制时执行机构传感器发生故障影响发动机安全运行的问题,提出了一种非相似容错控制计划。该方法将燃油闭环/喷管开环和喷管闭环/燃油开环两种控制计划互为备份,并结合一种惯性切换逻辑,在执行机构传感器发生故障时切换控...针对推力状态控制时执行机构传感器发生故障影响发动机安全运行的问题,提出了一种非相似容错控制计划。该方法将燃油闭环/喷管开环和喷管闭环/燃油开环两种控制计划互为备份,并结合一种惯性切换逻辑,在执行机构传感器发生故障时切换控制计划以保障发动机的安全运行。面向串联式TBCC(Turbine Based Combined Cycle)发动机的冲压模态开展了仿真验证,结果表明,该容错控制计划能够实现发动机全包线范围内的推力状态容错控制,并且在传感器发生故障时能够平稳切换,推力波动小于1%,增强了控制系统的容错性。展开更多
基金The authors gratefully acknowledge the financial support received from the Aviation Foundation Project(Grant No.2012ZB52031)the Fundamental Research Funds for the Central Universities(Grant No.NJ20140021)for this project.
文摘A turbine based combined cycle(TBCC)propulsion system uses a turbine-based engine to accelerate the vehicle from takeoff to the mode transition flight condition,at which point,the propulsion system performs a“mode transition”from the turbine to ramjet engine.Smooth inlet mode transition is accomplished when flow is diverted from one flowpath to the other,without experiencing unstart or buzz.The smooth inlet mode transition is a complex unsteady process and it is one of the enabling technologies for combined cycle engine to become a functional reality.In order to unveil the unsteady process of inlet mode transition,the research of over/under TBCC inlet mode transition was conducted through a numerical simulation.It shows that during the mode transition the terminal shock oscillates in the inlet.During the process of inlet mode transition mass flow rate and Mach number of turbojet flowpath reduce with oscillation.While in ramjet flowpath the flow field is non-uniform at the beginning of inlet mode transition.The speed of mode transition and the operation states of the turbojet and ramjet engines will affect the motion of terminal shock.The result obtained in present paper can help us realize the unsteady flow characteristic during the mode transition and provide some suggestions for TBCC inlet mode transition based on the smooth transition of thrust.
文摘For investigating the back pressure characteristics of turbine channel of an external-parallel turbine-based combined cycle(TBCC)inlet during the mode transition with the freestream air Mach number of 1.8,wind tunnel tests and numerical simulations are carried out.The results show that the critical back pressure of the turbine channel decreases linearly with the decrease of the open degree of splitter plate.The turbine channel has self-starting capacity when the open degree of the turbine channel is 100%.The total pressure recovery coefficient increases with the increase of back pressure when turbine channel is at supercritical and critical state.The mass capture ratio,total pressure recovery coefficient and outlet pressure ratio decrease obviously when turbine channel is at subcritical state.Results of the research would provide scheme reference and technology storage for TBCC propulsion evolution.
文摘针对推力状态控制时执行机构传感器发生故障影响发动机安全运行的问题,提出了一种非相似容错控制计划。该方法将燃油闭环/喷管开环和喷管闭环/燃油开环两种控制计划互为备份,并结合一种惯性切换逻辑,在执行机构传感器发生故障时切换控制计划以保障发动机的安全运行。面向串联式TBCC(Turbine Based Combined Cycle)发动机的冲压模态开展了仿真验证,结果表明,该容错控制计划能够实现发动机全包线范围内的推力状态容错控制,并且在传感器发生故障时能够平稳切换,推力波动小于1%,增强了控制系统的容错性。
