Transient thermal response of SMA actuator under gas-jet impingement

Transient thermal response of shape memory alloy actuator under gas-jet impingement has been investigated numerically and experimentally. Two-dimensional incompressible and unsteady flow (both hydrodynamically and thermally) is solved using the standard k–ɛ turbulence model and energy conservation equation. The solid region is simulated by coupling the fluid with moving and static boundary condition at the fluid–solid interface, respectively. Much attention was focused on the effects of jet velocity and periods on temperature fields and shape deformation of the SMA actuator. Results show that the temperature of the actuator for static boundary condition is slightly higher than for moving boundary condition and the difference increases along the flow direction. The difference of temperature and the shape deformation on the surface of SMA increase with the increasing of exit velocity and jet periods. The numerical simulation and the experiment have been performed with the following parameters: 16 ≤ vinvin ≤ 40 m/s, L/D = 5, 2≤ T ≤12 s. An experimental apparatus about periodic jet impingement is set up to study the transient thermal response and heat transfer between the jet gas and the SMA actuator. The effect of the jet period and velocity on the transient thermal response was investigated in detail. The results of the numerical simulation are shown in good agreement with the experimental data.