Effect of bubble size on cylinder head boiling heat transfer

In Eulerian multiphase flow model to simulate the gas-liquid two-phase flow boiling heat transfer, the bubble size of discrete phase is often treated as the constant. However, bubbles exist in different shapes and sizes, and bubble size is vital important to the simulation results. Using ANSYS Workbench as the simulation platform, and by considering the effects of different bubble sizes in the computational fluid dynamics module CFX, the gas-liquid two-phase flow boiling heat transfer model was applied in the fluid-solid coupling heat transfer system, which consists of cylinder head and cooling water jacket. Gasliquid two-phase flow field distribution in cooling water jacket and cylinder head temperature distribution was obtained and validated by the experimental data. Results show that, in the case of bubble size=1 mm, simulation results agree well with the experimental data. Gas-liquid two-phase flow boiling heat transfer can effectively reduce the peak temperature of cylinder head flame-face in the nose region of exhaust port and decreases heat load at this position.