Study Of The Loading Characteristic On The Wall By Near Wall High Speed Flow Based On CFD

The structure of target velocity boundary layer and temperature boundary layer, and the influences of flow field on laser loading are investigated using CFD methods with the specimen under the loading of flow from flow field simulation instruments.In simulation, an appropriate turbulent model is selected based on the comparison between simulation results using different models and test data.Simulation results show that the heat transferred by convection increase with the increase of target temperature. As a result, under a constant energy input, the growing heat loss makes the ascending rate of temperature slow down. Then the time of reaching melting point for target is prolonged. The influences of heat convection will be enlarged by lower thermal conductivity, making heat convection a key factor to be considered in the laser loading experiment. The increase in thickness of velocity boundary layer reduces flow velocity and the heat convection between flow and wall, which improves the heat loading efficiency of laser. The continuous loss of metal particles due to the loading of gas force makes the surface of targets rough, which favors the loading of laser because of the exposure of interior of the target. With the elapse of time, the pothole at the center of radiation caused by accumulated loss of material will appear. Lasting energy loading will finally melt through the target.