淹没射流流场演化过程研究

发布时间：2018-02-11 11:10

本文关键词： 淹没射流大涡模拟流场结构压力演化涡旋运动　出处：《工程科学与技术》2017年S1期 　论文类型：期刊论文

【摘要】：射流在工程领域具有非常广泛的用途,为得到射流流场的演化过程,深入研究射流的运动机理,采用大涡模拟方法(LES)对淹没射流紊动流场进行数值模拟,采用有限体积法(FVM)和PISO算法进行方程离散和数值计算,得到了淹没射流的瞬态流场。分析压力场的演化过程发现,压力场等值线呈一簇簇同心圆,沿射流轴线方向和垂直射流轴线方向圆心高压和圆心低压交错分布;随着射流的进行,同心圆随射流下移并伴有变形、分裂、融合等现象。在淹没射流区和冲击射流区前部分,同心圆圆心的压力上下波动并呈上升趋势;在附壁射流区,同心圆圆心的压力较为平稳,进行较低频率、小幅度的波动。分析速度场的演化过程发现,在射流的进行中,射流主体左右摆动,轴线处存在高速流体团脱落现象。射流主体上固定点的速度和压力大小有显著的负相关关系。分析涡量场的演化过程发现,两个涡量束呈分段化中间大两端小的"藕"形分布,并随时间进行随机摆动。通过涡量场与压力场的对比看出,涡旋的摆动造成了射流主体的摆动,涡旋的存在导致了压力场圆心低压和圆心高压交错分布。淹没射流流场具有很强的紊动性和随机性,对射流流场演化过程和水力特性内在关系的研究得出了一些规律性的结论,但如射流摆动的定量分析等仍有许多内容有待研究。
[Abstract]:Jet is widely used in engineering field. In order to obtain the evolution process of jet flow field, the large eddy simulation method is used to simulate the turbulent flow field of submerged jet. The transient flow field of submerged jet is obtained by using finite volume method (FVM) and PISO algorithm. By analyzing the evolution process of pressure field, it is found that the contour of pressure field is a cluster of concentric circles. Along the axis of the jet and the direction of the axis of the vertical jet, the high pressure and the low pressure of the center of the circle are staggered; with the jet, the concentric circle moves down with the jet and is accompanied by the phenomena of deformation, splitting, fusion, etc. In the front part of the submerged jet zone and the impinging jet zone, The pressure of concentric circle center fluctuates up and down, and the pressure of concentric circle center fluctuates in a relatively low frequency and a small amplitude in the zone of wall jet. The evolution of velocity field shows that, in the process of jet flow, the pressure of concentric circle center is stable, and the pressure of concentric circle center fluctuates by small amplitude. The velocity and pressure of the fixed point on the jet body are inversely correlated with the velocity of the jet body, and the evolution process of the vorticity field is found by analyzing the evolution process of vorticity field. The two vortex beams are distributed in the shape of "lotus root" with small ends and large ends in the middle, and swing randomly with time. By comparing the vorticity field with the pressure field, it can be seen that the wobble of the vortex causes the wobble of the main body of the jet. The existence of vortices leads to the low pressure and interlaced distribution of high pressure in the center of the pressure field. The submerged jet flow field has strong turbulence and randomness. Some regular conclusions have been drawn on the inherent relationship between the evolution process of the jet flow field and the hydraulic characteristics. However, there are still many contents to be studied, such as quantitative analysis of jet wobble.
【作者单位】：四川大学水力学与山区河流开发保护国家重点实验室;四川大学水利水电学院;
【基金】：国家自然科学基金资助项目(51009102) 青年基金资助项目(51179133)
【分类号】：O358

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