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RISS 인기검색어
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- 저자 : Guanghao Chen (검색결과 2 건)
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Guanghao Chen,Guoyu Wang,Biao Huang,Changli Hu,Taotao Liu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.3
We investigated the influence of interphase interaction on unsteady sheet/cloud cavitating flows around a 2D hydrofoil numerically. Inthe computations, the homogeneous (without the consideration of interphase interaction) and inhomogeneous (with the consideration ofinterphase interaction) multiphase flow models are used, respectively. The inhomogeneous model assumes that both phases co-exist atevery point in the flow field and each phase is governed by its own set of conservation laws. The exchanges of mass, interphase dragforce and momentum transfer induced by interphase mass transfer are treated explicitly as transfer terms. The results show that the distributionsof interphase drag force and momentum transfer induced by mass transfer are highly related with the velocity difference of twophases and interphase mass transfer rate, respectively. Without the consideration of interphase interaction, the over-prediction of turbulenteddy viscosity in the rear of attached cavity causes the reentrant jet to lose its momentum and becomes too weak to cut across thecavity sheet. However, when considering the interphase interaction, the predicted turbulent kinetic energy in the rear of attached cavitycan be reduced considerably; thus, turbulent eddy viscosity drops significantly in this region, and the reentrant jet becomes much stronger,so typical cloud cavitation shedding occurs. Compared with those predicted without the consideration of interphase interaction, a betteragreement with experimental results concerning the time evolution of cavity shape, time-averaged lift/drag coefficient, frequency andmean u-velocity profiles is obtained with the consideration of interphase interaction.
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Three-dimensional unsteady cavitating flows around an axisymmetric body with a blunt headform
Changli Hu,Guoyu Wang,Guanghao Chen,Biao Huang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.3
We investigated the three-dimensional characteristics in the unsteady cavitating flow over an axisymmetric body with a blunt headform. A high-speed video camera was used to visualize the cavitating flow structures. A modified PANS (Partially-averaged Navier-Stokes) turbulence model coupled with Kubota cavitation model was used to simulate the time-evolution process of the unsteady cavitatingflows. The finite-time Lyapunov exponent (FTLE) and Lagrangian coherent structures (LCS) methods are applied to investigate thethree-dimensional flow patterns. The results show that the numerical method is capable of simulating the unsteady cavitating flow forcapturing the attached cavity with maximum-length, the cavity break-off and U-type shedding, in accordance with the qualitative featuresobserved in the experiment. Three-dimensional characteristics are extremely impressive in the unsteady cavitating flows. The re-entrantflows originate from different circumferential positions at the closure region of the attached cavity, and move upstream at differentspeeds. Moreover, substantial circumferential motions in the unsteady cavitating flow are found based on Lagrangian trajectories, and itis reasonably deduced that the U-type shedding cavity is primarily induced by the effect of re-entrant flow motions consisting of movingupstream and circumferential flows as well.
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