Ventilated cavitation could be applied to underwater vehicles to achieve a high drag-reduction ratio.The ventilated supercavity may experience deformation,fluctuation,and instability under the influence of the high-sp...Ventilated cavitation could be applied to underwater vehicles to achieve a high drag-reduction ratio.The ventilated supercavity may experience deformation,fluctuation,and instability under the influence of the high-speed jetting flow generated by the propulsion system.This study focuses on understanding the transient dynamics of a ventilated supercavity with jetting flow at the tail.Experiments are performed in an open water tunnel system with a high degassing rate.The evolution of the gas-liquid interface under different jetting flow rates is recorded in detail.A compressible multiphase model coupled with shear stress turbulence(SST)and surface capturing models is adopted herein to study the flow pattern in depth.As the jet velocity increases from subsonic to sonic speed,the flow field presents three different modes that could be identified as the transparent cavity(TC),transparent cavityjetting(TC-J),and deformed cavity-jetting(DC-J)modes.A new gas shedding scheme that couples twinvortex shedding with surface fluctuation shedding is observed in the TC mode.The variations in the internal flow structure and the local pressure vibration are discussed in detail.The transition of the flow pattern with dimensionless jetting momentum ratio and kinetic energy ratio is obtained.The obtained results could provide valuable insights into the control of the ventilated supercavity.展开更多
基金the National Natural Science Foundation of China(Grant Nos.52176164 and 51776221)the Research Project Foundation of National University of Defense Technology(Grant No.ZK18-02-07).
文摘Ventilated cavitation could be applied to underwater vehicles to achieve a high drag-reduction ratio.The ventilated supercavity may experience deformation,fluctuation,and instability under the influence of the high-speed jetting flow generated by the propulsion system.This study focuses on understanding the transient dynamics of a ventilated supercavity with jetting flow at the tail.Experiments are performed in an open water tunnel system with a high degassing rate.The evolution of the gas-liquid interface under different jetting flow rates is recorded in detail.A compressible multiphase model coupled with shear stress turbulence(SST)and surface capturing models is adopted herein to study the flow pattern in depth.As the jet velocity increases from subsonic to sonic speed,the flow field presents three different modes that could be identified as the transparent cavity(TC),transparent cavityjetting(TC-J),and deformed cavity-jetting(DC-J)modes.A new gas shedding scheme that couples twinvortex shedding with surface fluctuation shedding is observed in the TC mode.The variations in the internal flow structure and the local pressure vibration are discussed in detail.The transition of the flow pattern with dimensionless jetting momentum ratio and kinetic energy ratio is obtained.The obtained results could provide valuable insights into the control of the ventilated supercavity.
