液压锥阀气穴现象两相流仿真及实验

Simulation and experimentof cavitation phenomenon two-phase flow of hydraulic cone valve

摘要:

为研究液压锥阀存在的气穴问题,基于流体力学理论及阀芯受力分析,计算出径向偏移量的大小,在考虑阀芯发生径向偏移的情况下,借助UG软件建立不同工况下的内流场三维模型,通过ICEM-CFD软件划分网格模型,基于FLUENT软件对锥阀内流场的气穴现象进行液-气两相流仿真,获得径向偏移、半锥角、开口度、背压4个影响因素下的气穴分布及强度的变化规律. 搭建可视化的液压锥阀气穴现象实验台,借助高像素的相机拍摄各工况下阀口位置的气穴图像,对仿真结果进行实验验证. 结果表明:仿真结果与实验结果相吻合,径向偏移使气穴集中分布在上锥面一侧的流场. 半锥角为45°时,阀芯的锥阀气穴强度变化平缓,同时半锥角为45°时,开口度为0.4 mm时气穴的强度最明显,随着开口度增大,气穴现象的气团强度逐渐减弱. 综合通流能力、气穴强度,半锥角为45°是一个较优的阀芯半锥角度,同时,增大开口度和背压具有抑制气穴发生的作用.

Abstract:

In order to investigate the cavitation phenomenon of the hydraulic cone valve, the magnitude of radial offset was calculated by the fluid mechanic theory and the radial force analysis of the fluid on the valve core. The solid models of the internal flow field were established by UG. The mesh was divided by using ICEM-CFD software. The numerical simulation of the two-phase flow was performed on the cavitation of the flow field inside the cone valve based on FLUENT. The variation on cavitation was obtained under four factors, such as radial offset, half cone angle, opening degree and back pressure. A visible experiment of the cone valve cavitation was built. A high pixel camera was used to capture the cavitation image of each valve position. According to the experiment results, the simulation results were verified. The results show that the radial offset causes the cavitation position accumulated in the valve cavity on the side of the upper cone. In addition, the strength of the cavitation changes slowly with the half cone angle of 45°. At the same time, when the half cone angle is 45°, and the opening degree is 0.4mm, the strength of cavitation is the most obvious. With the increase of the opening degree, the strength of air mass in the cavitation phenomenon gradually weakens. Combined with the flow capacity and cavitation strength, the half cone angle of 45° is suitable for cone valve. Furthermore, the increasing of the opening degree and back pressure in a reasonable range can effectively suppress cavitation.