This study aims to investigate the intricate dynamic characteristics of the high-speed duct during the over-under Turbine-Based Combined Cycle(TBCC)inlet mode transition process while operating in an off-design state ...This study aims to investigate the intricate dynamic characteristics of the high-speed duct during the over-under Turbine-Based Combined Cycle(TBCC)inlet mode transition process while operating in an off-design state under throttled conditions.A typical over-under TBCC inlet,designed for a working Mach number range of 0–6 with a transition Mach number of 3.5,is examined through experimental studies in a supersonic wind tunnel with a freestream Mach number of2.9.The investigation focuses on the complex oscillatory flow and unique hysteresis observed in the mode transition process of the high-speed duct under the mildly throttled condition,utilizing highspeed schlieren and dynamic pressure acquisition system.The findings reveal that the high-speed duct undergoes four distinct oscillation stages akin to those in a higher throttled state during the mode transition,albeit with smaller dominant frequency and energy.Moreover,an irregular alternating“big/little buzz”mode is observed in the early stage of the large oscillation stage.Notably,the mildly throttled state exhibits three intriguing hysteresis properties compared to the unthrottled and higher throttled states.Firstly,hysteresis is observed in the shock train motion stage in the duct before unstart,along with the corresponding inverse process.Subsequently,hysteresis is noted in the unstart and restart of the high-speed duct,with a smaller hysteresis interval than in the unthrottled state.Finally,the hysteresis characteristics of oscillation mode switching and the corresponding inverse process are explored.Based on the analysis,the first two hysteresis phenomena are associated with the formation and dissipation of the separation bubble.The significant adverse pressure gradient constrains the cross-sectional capacity of the channel,rendering the disappearance of the separation bubble more challenging.The hysteresis in oscillation mode switching is linked to not only the channel cross-sectional capacity but also the state of the incoming boundary layer.展开更多
采用拓展中心线、不同的流通截面面积变化规律和倒圆半径变化规律对内并联型TBCC（turbine based combined cycle engine）进气道涡轮通道扩张段进行了设计．通过数值模拟的手段，对涡轮通道扩张段设计参数的影响规律和涡轮模态下涡轮...采用拓展中心线、不同的流通截面面积变化规律和倒圆半径变化规律对内并联型TBCC（turbine based combined cycle engine）进气道涡轮通道扩张段进行了设计．通过数值模拟的手段，对涡轮通道扩张段设计参数的影响规律和涡轮模态下涡轮通道扩张段的气动特性进行了研究，并利用高速风洞试验结果对数值模拟方法进行了验证．研究结果表明：中心线控制点纵坐标在1．50～2．25、涡轮通道扩张段出口等直段长度与出口直径比值在0．3～0．7的范围内取值时，涡轮通道扩张段可获得较高的出口总压恢复系数和较小的出口总压畸变指数；采用前急后缓的流通截面面积和倒圆半径变化规律能使涡轮通道扩张段获得较小的出口总压畸变指数；随着飞行马赫数的增加，进气道和涡轮通道扩张段的流量系数先不断减小，在飞行马赫数为0．9附近达到最小，之后又逐渐增加，涡轮通道扩张段出口总压恢复系数不断升高，在飞行马赫数为0．7附近达到最大，之后又逐渐降低；涡轮模态下，涡轮通道扩张段出口总压畸变指数均小于0．5，能很好地满足涡轮发动机对进口流场的要求．展开更多
基金funded by the National Natural Science Foundation of China(Nos.12025202,U20A2070,12172175)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,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This study aims to investigate the intricate dynamic characteristics of the high-speed duct during the over-under Turbine-Based Combined Cycle(TBCC)inlet mode transition process while operating in an off-design state under throttled conditions.A typical over-under TBCC inlet,designed for a working Mach number range of 0–6 with a transition Mach number of 3.5,is examined through experimental studies in a supersonic wind tunnel with a freestream Mach number of2.9.The investigation focuses on the complex oscillatory flow and unique hysteresis observed in the mode transition process of the high-speed duct under the mildly throttled condition,utilizing highspeed schlieren and dynamic pressure acquisition system.The findings reveal that the high-speed duct undergoes four distinct oscillation stages akin to those in a higher throttled state during the mode transition,albeit with smaller dominant frequency and energy.Moreover,an irregular alternating“big/little buzz”mode is observed in the early stage of the large oscillation stage.Notably,the mildly throttled state exhibits three intriguing hysteresis properties compared to the unthrottled and higher throttled states.Firstly,hysteresis is observed in the shock train motion stage in the duct before unstart,along with the corresponding inverse process.Subsequently,hysteresis is noted in the unstart and restart of the high-speed duct,with a smaller hysteresis interval than in the unthrottled state.Finally,the hysteresis characteristics of oscillation mode switching and the corresponding inverse process are explored.Based on the analysis,the first two hysteresis phenomena are associated with the formation and dissipation of the separation bubble.The significant adverse pressure gradient constrains the cross-sectional capacity of the channel,rendering the disappearance of the separation bubble more challenging.The hysteresis in oscillation mode switching is linked to not only the channel cross-sectional capacity but also the state of the incoming boundary layer.
文摘采用拓展中心线、不同的流通截面面积变化规律和倒圆半径变化规律对内并联型TBCC（turbine based combined cycle engine）进气道涡轮通道扩张段进行了设计．通过数值模拟的手段，对涡轮通道扩张段设计参数的影响规律和涡轮模态下涡轮通道扩张段的气动特性进行了研究，并利用高速风洞试验结果对数值模拟方法进行了验证．研究结果表明：中心线控制点纵坐标在1．50～2．25、涡轮通道扩张段出口等直段长度与出口直径比值在0．3～0．7的范围内取值时，涡轮通道扩张段可获得较高的出口总压恢复系数和较小的出口总压畸变指数；采用前急后缓的流通截面面积和倒圆半径变化规律能使涡轮通道扩张段获得较小的出口总压畸变指数；随着飞行马赫数的增加，进气道和涡轮通道扩张段的流量系数先不断减小，在飞行马赫数为0．9附近达到最小，之后又逐渐增加，涡轮通道扩张段出口总压恢复系数不断升高，在飞行马赫数为0．7附近达到最大，之后又逐渐降低；涡轮模态下，涡轮通道扩张段出口总压畸变指数均小于0．5，能很好地满足涡轮发动机对进口流场的要求．
