Stable attached partial cavitation in separated flows can transition to cloud shedding, and the mechanism of transition has been attributed to the presence of a re-entrant liquid jet. Our findings have revealed the pr...Stable attached partial cavitation in separated flows can transition to cloud shedding, and the mechanism of transition has been attributed to the presence of a re-entrant liquid jet. Our findings have revealed the presence of propagating bubbly shock waves as an alternative dominant mechanism of shedding when the compressibility of the bubbly mixture is appreciable. In the present paper, we discuss dynamics associated with these bubbly shock waves, interaction of shock waves with obstacles in their path, and means to manipulate their properties to control the shedding process by non-condensable gas injection.展开更多
Cavitating bubbly flows can form in separated flows and shear layers leading to local regions high vapor void fraction,and these flows often exhibit periodic shedding of vaporous clouds.Historically,the presence of a ...Cavitating bubbly flows can form in separated flows and shear layers leading to local regions high vapor void fraction,and these flows often exhibit periodic shedding of vaporous clouds.Historically,the presence of a liquid re-entrant flow,driven by the kinematics of liquid flow stagnation,has been identified as an important mechanism leading to cavity shedding.However,high local vapor void fractions can also result in a reduced mixture speed of sound and a possible supersonic flow.Our recent findings on different geometries indicate that propagating bubbly shocks in these flows are a primary mechanism of flow instability.In this study,we discuss the effect of compressibility on four geometries,mainly in the generation of propagating bubbly shocks that can influence the cavitation shedding dynamics.In order to elucidate the differences and similarities of the observed cavitation dynamics,and the influence of compressibility,we report observations from a backward facing step,backward facing wedge,NACA0015 hydrofoil,and a bluff body with a wedge cross section.展开更多
基金supported by the Office of Naval Research(Grant No.N00014-14-1-0292)under program manager Dr.Ki-Han Kim
文摘Stable attached partial cavitation in separated flows can transition to cloud shedding, and the mechanism of transition has been attributed to the presence of a re-entrant liquid jet. Our findings have revealed the presence of propagating bubbly shock waves as an alternative dominant mechanism of shedding when the compressibility of the bubbly mixture is appreciable. In the present paper, we discuss dynamics associated with these bubbly shock waves, interaction of shock waves with obstacles in their path, and means to manipulate their properties to control the shedding process by non-condensable gas injection.
基金This work was supported by the Office of Naval Research(Grant No.N00014-18-1-2699),under program manager Dr.Ki-Han Kim.
文摘Cavitating bubbly flows can form in separated flows and shear layers leading to local regions high vapor void fraction,and these flows often exhibit periodic shedding of vaporous clouds.Historically,the presence of a liquid re-entrant flow,driven by the kinematics of liquid flow stagnation,has been identified as an important mechanism leading to cavity shedding.However,high local vapor void fractions can also result in a reduced mixture speed of sound and a possible supersonic flow.Our recent findings on different geometries indicate that propagating bubbly shocks in these flows are a primary mechanism of flow instability.In this study,we discuss the effect of compressibility on four geometries,mainly in the generation of propagating bubbly shocks that can influence the cavitation shedding dynamics.In order to elucidate the differences and similarities of the observed cavitation dynamics,and the influence of compressibility,we report observations from a backward facing step,backward facing wedge,NACA0015 hydrofoil,and a bluff body with a wedge cross section.
