二维射流冲击形状记忆合金驱动器的瞬态传热

Two-dimensional Heat Transfer of Jet Impinging on Shape Memory Alloy Actuator

用数值和实验两种方法对射流冷却、加热形状记忆合金驱动器进行研究.控制方程采用守恒形式和标准二维不可压缩k-ε紊流模型,流体和固体的耦合边界上采用与形状记忆合金相关的动、静边界条件两种形式分别进行计算,并比较了两种边界条件下射流换热效果.分析了射流速度、射流周期对换热的影响,设计了一套交变射流的实验装置,并对射流加热和冷却形状记忆合金驱动器进行了实验研究.结果表明:静边界条件下形状记忆合金驱动器温度稍高于动边界条件;射流速度越大、射流周期越长,形状记忆合金温度和形变的波动范围也就越大;实验数据与数值计算的结果吻合较好.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.

The SMA （shape memory alloy） actuator heated and cooled by jet impingement was investigated numerically and experimentally. Two-dimenslonal incompressible and unsteady flow （both hydrodynamically and thermally） is solved using the standard k-ε turbulence model and energy conservation equation. The solid region is simulated by coupling the fluid with the moving and static boundary condition at the fluid-solid interface, respec- tively. The temperature of the actuator for the static boundary condition is a little higher than that for the moving boundary condition. The results show that the difference of temperature and the shape deformation on the surface of SMA increase with the increasing of exit velocity and jet periods. An experimental apparatus about periodic let impingement was set up to study the heat transfer of the jet gas and the SMA actuator. The model results are found to compare favorably with the experimental data.