旋进射流冲击平板的传热实验研究

对旋进射流冲击平板时的传热进行了实验研究。通过在圆筒套管内设置一块孔板构成旋进射流喷嘴,得到了持续稳定的旋进射流。对旋进射流的流动特性作了研究,给出了旋进射流的频率与尺寸、Re的关系。用两种不同孔径的旋进射流冲击一块加热平板,并与普通的射流冲击传热作对比。结果表明,由于旋进射流与流体混合作用加剧而大大地降低了流速,使得强化传热的效果减弱,这种趋势在驻点附近尤为明显。

Experimental study on heat transfer of precessing jets impinging on flat plate

Heat transfer under precessing impinging jet was experimentally studied.A self-sustained uninterrupted precession motion was generated in a precessing jet nozzle consisting of a cylindrical tube added to an orifice.The precession frequency of the jet was identified from a power spectrum density analysis to the velocity data measured by a hot wire.The influences of the nozzle diameter and Reynolds number on precession frequency were studied.The heat transfer behavior of precessing jet impinging was compared with that of in-line impinging jet.The results indicate that heat transfer coefficients under precessing jet impinging decrease because the jet velocity is decreased by an ambient air entrainment.