Soft Sensing Technique For 3-D Roughness And Its Effect On Flow And Heat Transfer Characteristics

The influences of the roughness of heat exchange surface on transport properties of the fluid near wall are diverse, but it was lacking to associate quantitatively the 3-D roughness with the transport properties of surface so far, so the previous researches could not meet the demands of some application fields, such as the studies on the interfacial phenomena, the microscale heat transfer, the heat transfer enhancement, and the miniaturization of thermal and fluid machinery, and so on. Based on the traditional characterization method of 3-D roughness, this paper proposes making a new 3-D dimensionless roughness Rc , which is composed of the height parameter, the density parameter and the shape parameter of roughness elements. The contour curve of three dimensional roughness elements can be extracted by roughometer. Then the value of Rc can be easily obtained according to soft sensing algorithm designed specially. In this paper, similarity law of inner wall contained the parameter of Rc is established. The quantitative correlation between the parameter of Rc and heat transfer and momentum transfer are also set up by means of experiments. The analysis results show that it is easy than other parameters for the parameter of Rc to construct quantitative correlation with transport properties.In order to seek a reasonable processing method of 3-D roughness, research on the numerical simulation of the influence between turning processing and the parameter Rc are conducted. The results show that only by the precise of reasonable cutting depth and feed rate the value of Rc changes in a given range. The method proposed in this paper can offer a feasible approach of comprehensive optimum design of 3-D roughness and engineering application.