Numerical Experimental Research On The Vortex Shedding Characters Of A Three-dimensional Circle Cylinder

In the harbor, coast and offshore engineering, many pivotal components have the circular cylinder shape such as the offshore platform and the drill pipe, the conduit vitta in the seabed, the bridge pier and so on. The phenomenon which the three-dimensional circular cylinder destroyed by vortex-induced vibration often happens in steady flow. Many scholars abroad take the primary research, but the numerical simulation and the experimental research are very few on this problem at home. According to this, the research of the vortex shedding form of the flow around the three-dimensional circular cylinder and the forces acted on the circular cylinder is valuable.Using the CFD software CFX and indopting the LES model, this paper simulated the flow around the three-dimensional circular cylinder at different Reynolds numbers (Re=5.6×10~3, 2.8×10~4, 1.1×10~5 and 1.1×10~6) and researched the vortex shedding form and the hydrodynamic forces acting on the circular cylinder. The research work is summarized as follows:1) The fliud field sizes of the flow around the three-dimensional circular cylinder numerical simulation were chosen. The advantages and disadvantages in different softwares and the problems which should be emphasized in the process of mesh were expatiated. The software CFX was indopted to do the simulations of this paper.2) Analyzed the vortex shedding form, vortex shedding angles, the vortex tube and every points' fluctuationg pressure coefficient in the wake flow of the five sections in the spanwise of different Reynolds numbers so that we can see the three-dimensional effects.3) Discussed the static and the fluctuating pressure coefficients distribution along the circumferential direction in different sections of the circular cylinder at different Reynolds numbers.4) Researched the lift coefficient and drag coefficient period time of curves, the static and the fluctuating drag coefficient and the fluctuating lift coefficient in different sections of the circular cylinder at different Reynolds numbers.5) Under the help of power spectrual density, analyzed the power spectrual of the the fluctuating drag, the fluctuating lift, the velocity and the pressure of the three-dimensional circular cylinder, calcute the Strouhal numbers of each section in the spanwise at different Reynolds numbers.