匀加速流中圆柱起动流动的研究

The Study of the Starting Flow Around a Uniformly Accelerated Circular Cylinder

本文用氢泡流动显示和数值计算求解N—S方程的方法详细研究了匀加速来流中圆柱起动流动。匀加速起动的圆柱绕流和突然起动的圆柱绕流的流动结果相似,在中低Re_α数时出现“α—现象”;在高Re_α时出现“β—现象”,但只有一个二次涡。起动涡形成初期,内部基本上是层流,起动涡形成后期,内部流动转变为湍流。用多种布置铂丝的方法,测量了流场的速度分布,计算结果和实验结果进行了比较,二者基本一致。

The starting flow around a uniformly accelerated circular cylinder is investigated by flow visualization technique and solving N - S equations numerically. The results of the starting flow is similar with that around impulsively started cylinder. At lower Re numbers the α -phenomenon is revealed; the β-phenomenon appears at higher Re numbers, but with only one secondary vortex. At the early stage of the starting vortex formation, the flow is laminar i at the later stage, the flow transforms into turbulent flow. The velocity distrbution in the flow field is measured with the multiwires installment. The calculational results are compared with the results of experiment, and both are agreement with each other.