Numerical Simulation of Periodical Turbulent Shear Vortexes in a Submerged Water Jet
Numerical Simulation of Periodical Turbulent Shear Vortexes in a Submerged Water Jet
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通讯作者：
G. Peng;Hideto Ito;Shimizu Sheiji
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作者：
G. Peng;Hideto Ito;Shimizu Sheiji
为了提高水射流装置的性能，采用两相混合流法对浸没式喷嘴喷出的水射流进行数值分析。通过求解一组雷诺平均纳维斯托克斯方程计算伴随空化的水射流的非定常流动，并根据随局部压力变化的平均气泡半径的估计，用气体体积分数来评估空化的强度。在不同的空化数下处理空化和非空化水射流。结果表明，脉冲喷射射流头部产生环形起始涡，环形涡中心形成低压区。随着淹没射流的发展，射流外围依次产生剪切涡，一系列剪切涡周期性地向下游遮蔽。在剪切涡的作用下，射流外围压力交替变化，从而在涡核低压区依次发生空化。空化数减少到临界值。
With the purpose of improving the performance of water jet devices numericalanalysis of water jets issuing from asubmergednozzle is carried out by applying a two-phase mixture flow method. Unsteady flow of water jet accompanied by cavitation is calculated by solving a set of Reynolds Averaged NavierStokes equations and the intensity of cavitation is evaluated by the gas volume fraction based on an estimation of average bubbleradius varying with the local pressure.Cavitating and no-cavitationgwater jets are treated under different cavitation numbers. The results demonstrate thataring-like starting vortex is generatedat the head ofimpulsively injectedjet and a low-pressure region is formed at the center of the ringlike vortex.With developing of submerged jet shear vortexes are generated sequentially on the jet periphery and a sequence of shear vortexes shade downstream periodically.Under the effect of shear vortexes pressure varies alternatively on the jet periphery and thus cavitation takes place sequentiallyin the low-pressurearea ofvortex coresonce the cavitation number is decreased to a critical value.