Study on dynamical characteristics of cooling fluid in engine piston

Abstract

The cooling of engine piston is very important, and the fluid vibration characteristics of its internal cooling oil is the key to affect the heat transfer efficiency. In order to effectively ensure that the piston temperature will not be overloaded and avoid the reduction of sealing performance, a two-phase flow model in the piston cooling chamber is established in the paper. The flow field and heat transfer characteristics of the cooling oil are simulated by finite element method using FLUENT. In terms of model selection, VOF multiphase flow calculation and SST k-ω model are selected as turbulence model. The setting of boundary conditions combines the piston stroke characteristics of the hydraulic cylinder, so as to obtain accurate inlet parameters, and obtain the oil liquid phase proportion distribution, oil velocity field and the change law of convective heat transfer coefficient under different piston positions. The results show that the instantaneous ratio of cooling oil is closely related to the speed, and increasing the oil speed is an important means to improve the heat transfer performance. The multiphase flow model has high reliability, and there is no obvious difference between the average convective heat transfer coefficient obtained by the near-wall model method and the wall function method.