前台阶流场的传热实验研究

本文尝试用瞬态实验方法, 在卢德威格风洞实验台上, 对小台阶高度 (H=4.0mm)的前台阶二维流场进行传热实验研究, 测定了当雷诺数为 11800至32200时的流场内热流通量和努谢尔特数的变化规律以及努谢尔特数随雷诺数变化的准则关系式。实验结果是令人满意的。 

EXPERIMENTAL STUDY OF HEAT TRANSFER IN TURBULENT SEPARATED FLOW OVER A FORWARD-FACING STEP

An experimental study of heat transfer in turbulent separated flow over a forward facing step is reported in this paper.The present work deals with a quite small forward facing step model (step height H=4.0mm),therefore a special technique that can change the relative locations of heat flux gauge from the step is applied successfully. The investigation is focused on two recirculation zones.Measurements of heat transfer are performed in Ludwieg Wind Tunnel by the transient technique,which demonstrates a new method of experimental research in this field.Within the range of Reynolds number 11800 to 32200,the distribution of wall heat flux and the distribution of Nusselt number are obtained.Those distributions show that the heat transfer coefficient increases to the first maximum value near the step in the front recirculation zone and the second maximum occurs at the reattachment point in the downstream recirculation zone where this point is fixed roughly at X/H=2.5 for the five different Reynolds numbers.The second maximum is larger than the first for same Reynolds number.At last a correlative equation between Reynolds and Nusselt numbers is presented.