Numerical Simulation On Aerodynamic Performance Of The Pumping Of Windsurfing

By use of the numerical simulation and experimental method to sail in steady and unsteady state, the aerodynamic performance of sail in women’s level of Olympic Games was studied. The result of the research guided by the Fluid Mechanics and Computational Fluid Dynamics could supervise the athletes to pump sails based on the external condition.Through the numerical calculation on the literature material SAIL1on the steady state, the research first put STAR-CCM+software into use. The calculation results and the test results were fit for the practice that verify the calculation method used in the literature material and the applicability of the STAR-CCM+software. The calculation area of NP sail was a sail with hemline chord length8times to the front, left, right and16times to the back of the benchmark shaping in a cuboid area. It adopted the method of hexahedron core grid that called Trimmed Mesh(Hexahedral) to divide the calculation area and its internal sail. According to the requirement in the actual windsurfer competition, the minimum wind conditions of2m/s and3m/s were elected as the inlet boundary conditions to the steady state of numerical simulation in NP sail. The calculation and comparison were done on NP sail with regard to different wind speed, lift coefficient and coefficient under different angle of attack. It also analyzed the distribution of pressure, the distribution of streamline and the changes of the distribution of velocity in different angle of attack in NP sail.The Unsteady Numerical Simulation of NP sail was based on the pumping state of the athletes, was simplified the needing model study into three mode of motion:1、 the turning direction of the sail around the sail surface;2、the turning direction of the sail around the sail surface string;3、the turning direction of the sail vibrate along the vertical direction. In order to effectively reduce the grid deformation area, to avoid excessive amount of calculation, at the same time, to guarantee the accuracy of numerical calculation, a new area in the internal constructs was built in the unsteady state calculation area. The Unsteady Numerical Simulation was under the direction of rotation movement in different flow to the angle of attack in the NP sail, the data was concluded and analyzed from different angle of attack in the sail through the lift coefficient, drag coefficient and lift-drag ratio of the pumping.According to the maximum lift coefficient and lift-drag ratio in the direction of pumping in the NP sail, the NP sail with amplitude and frequency variation of air power under different movement mode was simulated, thenthe different conditions under the pumping of lift coefficient, drag coefficient and lift/drag ratio were obtained. Based on the simulation results, the change of distribution of surface pressure around the sail surface string and the sail surface were then investigated. The relationship of amplitude and the frequency in different state of the aerodynamic performance in NP sail were then analysed and discussed. The research data showed that pumping can effectively improve the aerodynamic performance through the direction of sail surface in higher frequency shaking was good.This paper carried out a systematic windsurfer sail in aerodynamic performance study that provided a theoretical foundation for the scientific training of windsurfer sail. Some of the research result was applied to the training and the competition of the national windsurfer team for the run-up to the2008Beijing Olympic Games. Fortunately, it made a contribution to the first Olympic gold medal for the windsurfer project in our country. This thesis research worked only on the preliminary numerical simulation of the simple movement mode in pumping of sailboard whereas the subsequent actual movement of pumping should be on the list for the in-depth study.