壁面振动致气缸套空蚀现象模拟

为研究气缸套受活塞敲击而产生的壁面振动对气缸套振动壁面附近冷却水流场的空蚀影响情况,通过使用计算流体力学(CFD)方法,基于AVL-Fire流体计算软件提供的欧拉多相流空化模型,结合动网格技术建立近振动壁面处流场区域的多相流流场空化模型,将气缸套出现空蚀的振动壁面处的振动特性及其附近冷却水的流场特性进行耦合分析,得到了壁面衰减振动条件下流场的空化特性.对比在壁面振动条件下的流场空化云图,结果表明:气缸套壁面振动是气缸套空蚀的主要因素,受振动壁面影响而产生的空化气泡将在狭隙后圆弧壁面处聚集并溃灭,造成此处的空蚀较为严重,这与气缸套穴蚀部位的试验统计结果一致.通过对比同样壁面振动条件下入口流速不同时流场的空化云图,发现流场处于较大流速状态下,更容易产生空化区域.

Simulating cavitation erosion of cylinder liner caused by wall vibration

To study the cylinder wall vibration cased by the knocking piston to cylinder liner cavitation which is near the cooling water flow field by wall vibration, using computational fluid dynamics(CFD)method, based on Eulerian multiphase cavitation models provided by AVL-Fire computational fluid software, combined with the dynamic mesh technology to build multiphase cavitation models in the flow field region near the wall, the cylinder wall vibration characteristics of the cavitation erosion of cylinder liner are analyzed, coupled with the flow field characteristics, getting cavitation characteristics of flow field under the condition of cylinder wall vibration attenuation. From the cavitation field picture, we can come to the conclusion that the cylinder wall surface vibration is the decisive factor of the cylinder liner cavitation. The cavitation bubbles caused by the vibration effected to wall will be aggregated on the narrow gap arc wall and collapsed, causing more serious cavitation near here. The simulation results are in agreement with the experimental results of the cylinder linering.Compared with cavitation erosion characteristics at different inlet velocity under the cyclinder wall vibration, the flow field produces cavitation area easily at the large flow velocity.