光滑通道内格栅湍流特性实验

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。 

Experiment of grid-generated turbulent ina smooth channel

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 80mm×80mm. Hot-wire was used to measure the turbulence with Reynolds ranging from 5000 to 30000. The results showed that after flowing through the grids, the turbulent intensity can be up to 4.5%, 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.