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
为了改善串联式TBCC (Turbine based combined cycle)排气系统在低压比状态下的工作性能,对有无辅助活门的两种串联式TBCC组合喷管开展了数值模拟,并对含辅助活门的串联式组合喷管进行了实验研究,来探究辅助活门对串联式组合喷管气动性...为了改善串联式TBCC (Turbine based combined cycle)排气系统在低压比状态下的工作性能,对有无辅助活门的两种串联式TBCC组合喷管开展了数值模拟,并对含辅助活门的串联式组合喷管进行了实验研究,来探究辅助活门对串联式组合喷管气动性能的影响。结果表明:辅助活门结构能够减少主流喷管外壁面的流动分离区范围和内流总压损失,有效地提高了组合喷管内推力。含辅助活门型组合喷管能够引射环境气流,减少引射喷管壁面的回流区范围与底部阻力,从而减少推力损失,提升组合喷管整体性能。提高次流压比或降低主流压比,主流喷管出口处欠膨胀程度降低,声速线往下游方向移动,主流流量减少。提高主流压比或者次流压比都能使辅助活门引射环境气流量增加。辅助活门进气通道距离会影响次流射流与引射喷管的相对位置,距离过小或过大都会造成引射环境气流量减少。展开更多
This letter proposes a novel hybrid component and configuration model for combined-cycle gas turbines(CCGTs) participating in independent system operator(ISO) markets. The proposed model overcomes the inaccuracy issue...This letter proposes a novel hybrid component and configuration model for combined-cycle gas turbines(CCGTs) participating in independent system operator(ISO) markets. The proposed model overcomes the inaccuracy issues in the current configuration-based model while retaining its simple and flexible bidding framework of configuration-based models. The physical limitations—such as minimum online/offline time and ramping rates—are modeled for each component separately, and the cost is calculated with the bidding curves from the configuration modes. This hybrid mode can represent the current dominant bidding model in the unit commitment problem of ISOs while treating the individual components in CCGTs accurately. The commitment status of the individual components is mapped to the unique configuration mode of the CCGTs. The transitions from one configuration mode to another are also modeled. No additional binary variables are added, and numerical case studies demonstrate the effectiveness of this model for CCGT units in the unit commitment problem.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.
文摘为了改善串联式TBCC (Turbine based combined cycle)排气系统在低压比状态下的工作性能,对有无辅助活门的两种串联式TBCC组合喷管开展了数值模拟,并对含辅助活门的串联式组合喷管进行了实验研究,来探究辅助活门对串联式组合喷管气动性能的影响。结果表明:辅助活门结构能够减少主流喷管外壁面的流动分离区范围和内流总压损失,有效地提高了组合喷管内推力。含辅助活门型组合喷管能够引射环境气流,减少引射喷管壁面的回流区范围与底部阻力,从而减少推力损失,提升组合喷管整体性能。提高次流压比或降低主流压比,主流喷管出口处欠膨胀程度降低,声速线往下游方向移动,主流流量减少。提高主流压比或者次流压比都能使辅助活门引射环境气流量增加。辅助活门进气通道距离会影响次流射流与引射喷管的相对位置,距离过小或过大都会造成引射环境气流量减少。
基金supported by the U.S.Department of Energy under Contract No.DE-AC36-08GO28308 with Alliance for Sustainable Energy,LLC,the Manager and Operator of the National Renewable Energy LaboratoryU.S.Department of Energy Office of Energy Efficiency and Renewable Energy Wind Energy Technologies Office
文摘This letter proposes a novel hybrid component and configuration model for combined-cycle gas turbines(CCGTs) participating in independent system operator(ISO) markets. The proposed model overcomes the inaccuracy issues in the current configuration-based model while retaining its simple and flexible bidding framework of configuration-based models. The physical limitations—such as minimum online/offline time and ramping rates—are modeled for each component separately, and the cost is calculated with the bidding curves from the configuration modes. This hybrid mode can represent the current dominant bidding model in the unit commitment problem of ISOs while treating the individual components in CCGTs accurately. The commitment status of the individual components is mapped to the unique configuration mode of the CCGTs. The transitions from one configuration mode to another are also modeled. No additional binary variables are added, and numerical case studies demonstrate the effectiveness of this model for CCGT units in the unit commitment problem.
