湍流渠道中几何减阻技术及其机理研究

Research on Geometrical Drag Reduction and Mechanism of Turbulent Channel

为了研究波浪壁面对渠道中湍流流动阻力的影响规律,将任意形状的波浪壁面表达为一阶傅里叶模式,选取流动方向单位长度渠道作为研究对象,对该模型进行单位化处理,推导了渠道减阻系数的计算方法,通过与 DNS 计算结果对比,验证了本文计算方法具有较好的准确性。通过 Fluent 流场分析软件计算得到不同的波数和幅值模型的压降损失,获得减阻系数随波数和幅值变化规律。选取不同的几何形状进行计算,并与一阶傅里叶模式下的结果进行对比,除具有内尖角壁面模型外,一阶傅里叶模式均可以进行较好的近似。该规律为建立减阻几何形状提供了一定参考。

In order to investigate the drag reduction of turbulent flow in a channel, and get its mechanism, the arbitrary geometry wave wall is expressed in first mode of Fourier expansions. Per unit length is selected along the direction of flow as the researching object, and the unit model of the channel is established. The calculating models of drag reduction factor are obtained. The results of some typically conditions got by the methods agree with DNS results very well, which verify the calculation precision of the method. The models with different kinds of amplitudes and wave number α have been calculated by fluent software. Different geometries have been selected to calculate their pressure drop, and compared with the results of first mode of Fourier expansions. The first mode of Fourier expansions can get a good agreement with arbitrary geometry except the geometry with inside sharp corners. The rules will provide some certain references for establishing geometrical drag reduction.