水平液─固流中颗粒抑制湍流的行为和条件

THE BEHAVIOR AND CRITERION OF TURBULENCE SUPPRESSION EFFECT OF THE PARTICLES IN A HORIZONTAL LIQUID SOLID FLOW

用激光多普勒分相测量方法，考察了水平含颗粒水流的主流区，亚毫米颗粒对水流湍流有抑制行为，湍流削弱程度与颗粒浓度、流动发展长度、水流雷诺数等因素有关．按照不出现尾涡脱落和至少能响应一部分大尺度涡的运动这两个基本条件，分析了湍流抑制与有关参量的依赖性．结果表明，流动尺度和颗粒尺寸之比，对于颗粒消耗而不增生湍流起着最主要的作用．在一定的水流雷诺数下，只要这一比值很大。

By using two phase measuring technique of LDV, the suppression effects of sub millimeter particles to the water turbulence in mainstream zone of a horizontal pipe flow have been experimentally studied. This includes the investigation of the dependences of turbulence reduction on the parameters of particle size, flow development length, water flow Reynolds number, etc. According to the basic conditions that the appearance of vortex shedding phenomenon should be excluded and that the particles should respond to the movement of large scale vortex, the dependences of suppression criterion on some flow parameters have been analysed. It is demonstrated that, the ratio of flow scale to particle size plays a most important role in the reduction of turbulence intensity can be reduced or not by the particles, but other parameters such as the ratio of two phase densities, the Reynolds number of water flow and especially the dimensionless gravity are also exerting their influences onto the criterion.