自转螺旋扭带管内湍流特性研究

应用激光测速仪LDV(Laser Doppler Velocimeter)对自转塑料螺旋扭带管的湍流特性进行了实验研究。结果表明：与普通光管内流体的流动相比，自转塑料螺旋扭带管内流体的湍流特性发生了根本性的变化：流体在自转塑料螺旋扭带的带动下，呈螺旋流动，而且在近管壁环形区域内流体的轴向分速度明显比管中心区域的高，提高幅度为25％左右，轴向湍流度比无自转扭带的大，提高幅度为68％左右；切向分速度随半径的增大而增大，而且切向湍流度很大，比轴向湍流度大10倍左右。流体的这些湍流特性的测得为自转塑料螺旋扭带管内对流传热强化机理的深入理论研究提供了实验支持。

Investigation of Turbulent Characteristics in the Self-Rotating, Self-Cleaning Twisted-tape-inserted Tube

The turbulent characteristics of self-rotating self-cleaning plastic twisted-tape-inserted tube were studied experimentally by using a 2D frequency shifting Laser Doppler Velocimeter (LDV) System. The results show the behavior of fluid flow in the self-rotating self-cleaning plastic twisted-tape-inserted tube is different from that in the normal smooth tube. The twisted-tape makes flow field change ultimately. The fluid flow in self-rotating self-cleaning twisted-tape-inserted tube is in spiral motion following the self-rotating twisted tape. In the annular area near the tube wall the axial velocity is 25% or so higher than that of the central area of the tube, and the axial turbulence intensity is 68% or so stronger than that of the smooth tube. The fluid flow has distinct tangential motion, the tangential velocity increases as the radius increase; the tangential turbulence is very high, and the tangential turbulence intensity is 10 times than the axial turbulence. These turbulent characteristics of fluid flow for self-rotating self-cleaning twisted-tape- inserted tube will provide experimental support for the further theoretical research of convection heat transfer enhancement mechanism.