为了研究不同燃料对火箭基组合循环(rocket based combined cycle,RBCC)发动机总体性能的影响,建立了RBCC发动机准一维总体性能仿真模型,分别研究了以液氧煤油、过氧化氢煤油、液氧甲烷和液氧液氢为燃料的RBCC发动机推力和比冲性能。结...为了研究不同燃料对火箭基组合循环(rocket based combined cycle,RBCC)发动机总体性能的影响,建立了RBCC发动机准一维总体性能仿真模型,分别研究了以液氧煤油、过氧化氢煤油、液氧甲烷和液氧液氢为燃料的RBCC发动机推力和比冲性能。结合飞/发一体化性能分析模型,研究了不同燃料发动机性能对完成飞行任务能力的影响。结果表明:氢燃料RBCC发动机引射模态推力是煤油燃料RBCC发动机的1.3倍;氢燃料RBCC动力飞行器巡航距离最远,为4 470 km;相同的飞行器参数下,过氧化氢煤油燃料RBCC动力飞行器机动性最大。本方法可为RBCC发动机总体性能方案设计和燃料选取提供参考。展开更多
The study presents an experimental exploration into the mode transition of an overunder TBCC(Turbine-Based Combined Cycle)inlet,with a specific emphasis on the flow characteristics at off-design transition Mach number...The study presents an experimental exploration into the mode transition of an overunder TBCC(Turbine-Based Combined Cycle)inlet,with a specific emphasis on the flow characteristics at off-design transition Mach number.A systematic investigation was undertaken into the mode transition characteristics in both unthrottled and throttled conditions within a highspeed duct,employing high speed Schlieren and dynamic pressure acquisition systems.The results show that the high-speed duct faced flow oscillations primarily dictated by the separation bubble near the duct entrance during the downward rotation of splitter,leading to the duct’s unstart under the unthrottled condition.During the splitter’s reverse rotation,a notable hysteresis of unstart/restart of the high-speed duct was observed.Conversely,hysteresis vanishes when the initial flowfield nears the critical state owing to downstream throttling.Moreover,the oscillatory diversity,a distinctive characteristic of the high-speed duct,was firstly observed during the mode transition induced by throttling.The flow evolution was divided into four stages:an initial instability stage characterized by low-frequency oscillations below 255 Hz induced by shock train self-excitation oscillation and high-frequency oscillations around 1367 Hz caused by the movement of separation bubble.This stage is succeeded by the“big buzz”phase,comprised of pressure accumulation/release within the overflow-free duct and shock motion outside the duct to retain dynamic flow balance.The dominant frequency escalated with the increase of the internal contraction ratio in the range of 280 Hz to 400 Hz.This was followed by a high-frequency oscillation stage around 453 Hz dominated by a large internal contraction ratio with low pulsating energy,accompanied by a continuous supersonic overflow.Lastly,as the splitter gradually intersected the boundary layer of the first-stage compression surface,the capture area and the turbulence intensity of the incoming flow underwent a sudden shift,leading to a more diverse flow oscillation within the duct,manifested as various forms of mixed buzz.展开更多
基金funded by the National Natural Science Foundation of China(Nos.12025202,U20A2070 and 12172175)the National Science and Technology Major Project,China(No.J2019-Ⅱ-0014-0035)+2 种基金the Postdoctoral Fellowship Program of CPSF,China(No.GZB20230970)the Science Center for Gas Turbine Project,China(Nos.P2022-C-Ⅱ-002-001 and P2022-A-Ⅱ-002-001)the Young Scientific and Technological Talents Project of Jiangsu Association for Science and Technology,China(No.TJ-2021-052).
文摘The study presents an experimental exploration into the mode transition of an overunder TBCC(Turbine-Based Combined Cycle)inlet,with a specific emphasis on the flow characteristics at off-design transition Mach number.A systematic investigation was undertaken into the mode transition characteristics in both unthrottled and throttled conditions within a highspeed duct,employing high speed Schlieren and dynamic pressure acquisition systems.The results show that the high-speed duct faced flow oscillations primarily dictated by the separation bubble near the duct entrance during the downward rotation of splitter,leading to the duct’s unstart under the unthrottled condition.During the splitter’s reverse rotation,a notable hysteresis of unstart/restart of the high-speed duct was observed.Conversely,hysteresis vanishes when the initial flowfield nears the critical state owing to downstream throttling.Moreover,the oscillatory diversity,a distinctive characteristic of the high-speed duct,was firstly observed during the mode transition induced by throttling.The flow evolution was divided into four stages:an initial instability stage characterized by low-frequency oscillations below 255 Hz induced by shock train self-excitation oscillation and high-frequency oscillations around 1367 Hz caused by the movement of separation bubble.This stage is succeeded by the“big buzz”phase,comprised of pressure accumulation/release within the overflow-free duct and shock motion outside the duct to retain dynamic flow balance.The dominant frequency escalated with the increase of the internal contraction ratio in the range of 280 Hz to 400 Hz.This was followed by a high-frequency oscillation stage around 453 Hz dominated by a large internal contraction ratio with low pulsating energy,accompanied by a continuous supersonic overflow.Lastly,as the splitter gradually intersected the boundary layer of the first-stage compression surface,the capture area and the turbulence intensity of the incoming flow underwent a sudden shift,leading to a more diverse flow oscillation within the duct,manifested as various forms of mixed buzz.
