光滑通道内格栅湍流特性实验

Experiment of grid-generated turbulent in a smooth channel

为了更好地模拟实际涡轮叶片内冷通道的流动换热,采用格栅对光滑通道内湍流度进行控制。并通过实验的方法对不同格栅尺寸激发的湍流度进行测量。实验中,在边长为80mm×80mm的方形通道中,放置了3种不同尺寸的格栅,利用热线风速仪,得到了通道雷诺数为5000～30000范围内的格栅后下游湍流特性。研究发现:流体通过该格栅后,气流在流经格栅后较短距离内就获得了4.5%的湍流度,同时湍流度沿程呈现衰减趋势,雷诺数对湍流度的影响较小。湍流积分时间尺度与雷诺数呈负相关的关系。

In order to simulate the flow and heat transfer in a turbine coolant channel,grids were used to control the turbulent intensity in a smooth channel.Different sizes of grids were used to generate different turbulence intensity.In the experiment,three different kinds of grids were put in a square smooth channel with the cross-section of 80 mm×80 mm.Hot-wire was used to measure the turbulence with Reynolds ranging from 5 000 to 30 000.The results showed that after flowing through the grids,the turbulent intensity can be up to4.5%,and decreased along the stream-wise directions.The effect of Reynolds numbers on turbulent intensity is not obvious in the current work.And the turbulent integral time scale has a positive relationship with Reynolds numbers.