Transient analysis of thermo-sensitive cavitating flows over a hydrofoil in various angles of attack and temperatures

The present work aims to contrastively study the cavitation intensity, temperature drop, turbulence kinetic energy as well as the changed lift and drag forces for various free-stream temperatures and angle of attacks (T_∞=68.64-88.54K,AOA=3.5^o-12^o) in a thermo-sensitive cavitating flow. The simulation results indicate that the higher temperature and larger angle of attack intensify the cavitation thermal effect and increase the temperature drop jointly. The difference lies in the large angle of attack promotes the cavitation development, but the high temperature weakens the cavitation intensity and reduces the vapour volume. The influential mechanisms exist in the cavity evolution, vorticity, turbulence kinetic energy as well as angle of attack are revealed. The high-level turbulence kinetic energy occurs in the unstable flow regions, include the cavity tail, the separation zone on the suction surface and cavitation vorticity region. For the attached cavity, the larger angle of attack suppresses the turbulence kinetic energy due to the enhanced cavity adhesion on hydrofoil surface. The turbulence kinetic energy caused by cavity shedding and cavity collapse becomes more obvious at a smaller angle of attack. The study on the force evolution show that increased temperature and angle of attack weaken the fluctuation amplitudes of lift and drag forces and reduce the occurrence frequencies of peak values, and then the averages of lift and drag forces are increased. The temperature rise increases the average of lift force and reduces the average of drag force, which is characterized by a increase of lift-drag ratio. Meanwhile, the quantitative results include transition of shedding period and temperature drop in cavity thickness direction are also analysed.