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| Multi-phase Numerical Simulation of Propeller Turbulent Cavitation Inception Flow |
| YANG Qiong-Fang-a, WANG Yong-Sheng-a, ZHANG Zhi-Hong-b |
| (a. College of Naval Architecture and Marine Power; b. College of Science, Naval University of Engineering, Wuhan 430033, China) |
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Abstract Both of the modified SST turbulence model and BSL Reynolds stress model were used to predict the tip vortex trajectories of E779A propeller under noncavitation and cavitation inception conditions. The vortex core’s minimum pressure coefficient, turbulent kinetic energy, axial velocity component and vortex size distribution related to the trajectory were analyzed at the same time, and the flow physics of tip vortex was presented from the flow field with tip vortex crimp beginning and streamtube formation. The improved Sauer cavitation model accounting for the effects of noncondensable gas’s mass and volume fraction and the bubble initial radius on cavitation inception and the effect of turbulence on phasechange pressure threshold was adopted along with validation of the cavity pattern and area of E779A propeller under lightly, moderately and heavily cavitation levels. The cavitation inception index was determined by the rule of “when σ>σi, the pressure coefficient of the blade tip section is relative unaltered”. The minimum pressure in vortex core on perpendicular cross plane was used to locate the vortex center, and vortex core bound was determined by the peak of turbulent eddy frequency. The results show that a slightly longer tip vortex trajectory appears with the BSL RSM model than the modified SST model as well as a litter bigger local tip vortex cavitation extension and more reasonable turbulent kinetic energy distribution, while the minimum pressure coefficient and axial velocity in blade tip region are smaller. On the other hand, the tip vortex trajectories captured by the two models almost superpose along with nearly the same tip vortex trajectories, minimum pressure coefficient and axial velocity distribution between noncavitation and cavitation inception condition of the two models respectively, which proves that the determination of cavitation inception by the rule is reasonable, and the adopted modified numerical models are appropriate to simulate the tip vortex trajectory.
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Received: 20 August 2011
Published: 31 August 2012
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