周期性边界条件下二维射流冲击钛镍形状记忆合金传热的数值和实验研究

射流是一种有效的强化传热方式,随着微机械的快速发展近年来受到了广泛的关注.该文用实验和数值计算的方法研究了周期性边界条件下射流冲击形状记忆合金表面的温度场瞬态分布规律.主要分析了射流速度、喷距以及射流周期对驻点以及附壁射流区温度分布规律的影响.结果表明,射流速度越大、喷距越小、射流周期越长,形状记忆合金温度的波动范围也就越大,而且其表面温度在交变的冷热射流作用下也呈现一个明显的周期性变化规律.对比发现,表面温度波动范围完全超过了形状记忆合金的滞后温差.实验与数值计算结果吻合较好,研究结果对于以形状记忆合金作为热驱动元件的设计具有一定的指导意义.

EXPERIMENT AND NUMERICAL SIMULATIONS ON HEAT TRANSFER OF LIQUID-JET IMPINGING TINI SMA AT PERIODIC BOUNDARY CONDITION

Liquid-jet impinging is an effective heat transfer,which has drawn considerable attention in recent years,especially with the development of the micro-machine.In this paper transient temperature fields on the surface of shape memory alloy(SMA)are numerically and experimentally investigated by periodical liquid-jet impinging.The effects of exit velocity,nozzle-to-surface spacing and jet periods on the temperature distributions at the stagnation point and local area are mainly analyzed.Results show that the difference of temperature on the surface of SMA increases with the increasing of exit velocity,jet periods and with the decreasing of the nozzle-to-surface spacing,and the surface temperature also has an obvious periodic fluctuation under the periodic boundary condition.By comparison,the temperature wave amplitude is found much higher than the temperature hysteresis of the SMA,quite good agreements are found between model results and experimental data.The results of this paper have a guiding significance for the design of SMA as thermal driving element.