PIV Experimental Research And Numerical Simulation On Annular Helical Flow

The phenomenon of helical flow of Power-Law Fluid in concentric and eccentric annulus is the most common in the drilling process, and the flow of drilling fluid in annulus is turbulent or laminar. Turbulent is the most complex form in the motion of viscous liquid, except a small number of highly viscous and low speed fluid flow, the flow problem is almost turbulent flow in oil industry. In recent years, with the development of computational fluid dynamics and the measuring technique of fluid field, numerical simulation and PIV technology are spread and applied in the research fields of flow field characteristics. So the developing of numerical simulation and PIV experimental research on power-law fluid in annulus is of certain theoretic and engineering significance.In this paper, the physical models of concentric and eccentric annulus are set up in three dimensional Cartesian coordinate system in gambit of FLUENT. In the process of numerical simulation, finite volume method is used to discretise the governing equantions and the SIMPLEST algorithm is employed to solve the disctretised equations, moreover, the k-εcalculating turbulence model is used and the method of wall functions is used near wall, and the model parameters setting is in accordance with PIV experiment, then the numerical simulation calculation of annular flow field is carried out.Through post-processing of the data by using Tecplot and Origin software, the velocity contour, velocity vector, streamline and the distribution of the axial velocity of the flow field in concentric and eccentric annulus are obtained. Then, fluid viscosity and eccentricity on the axial velocity are analyzed in detail. The streamline shows that there is a secondary flow in the turbulent helical flow field of eccentric annulus, and the effects of eccentricity, fluid viscosity, rotation speed and direction of rotation on the secondary flow are deeply analyzed.The turbulent helical flow field of newtonian fluid and power-law fluid in concentric and eccentric annulus is simulated successfully by FLUENT software and PIV test for the first time in this paper. The numerical simulation result is basically accord with the PIV experimental result, which indicates that the numerical simulation of annular flow field by FLUENT is viable, and validates the reliability of the numerical simulation. Thus, it gives a theoretical basis and guidance for the further study on turbulent flow in annulus, and it can promote the development and application of FLUENT software in the simulation of annulus flow.