Unsteady flow characteristics in an over-under TBCC inlet during mode transition under unthrottled and throttled conditions  

作　　者：Liang CHEN Yue ZHANG Hao ZHANG Huijun TAN Ziyun WANG Hang YU Hongchao XUE 

机构地区：[1]Jiangsu Province Key Laboratory of Aerospace Power Systems,College of Energy and Power Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China

出　　处：《Chinese Journal of Aeronautics》2024年第12期275-295,共21页中国航空学报（英文版）

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);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).

摘　　要：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

关 键 词：Over-under TBCC inlet Mode transition Off-design condition Unsteady flows HYSTERESIS 

分 类 号：V438[航空宇航科学与技术—航空宇航推进理论与工程]