Investigation On Influence Of Tip Shape On Output Power And Aerodynamic Noise Of Wind Turbine

The influence on flow field and sound field by tip region of the wind turbine is alwaysthe research focus of domestic and foreign scholars.The region has great influence onmany aspects, such as the production and shedding of tip vortex, the radiation andpropagation of noise, the whole wake field and even the output power.This paper attemptedto combine Improved Delayed Detached Eddy Simulation(IDDES) method with thepermeable FW-H equation to analyze the influence on flow field and noise field bychanging blade tip.The flow field and sound field of horizontal axis wind turbine were simulated on thebasis of reading literature and learning basic theory. Physical models were established andmesh was selected by verification of mesh independence. IDDES was chosen as turbulencemodel and FW-H was selected as acoustic equation. The rotation of the rotor was realizedby using sliding mesh. The output power and propagation law of acoustic radiation wereanalyzed at various aspects such as tip speed ratio and wind speed. The result werecompared to the experiment; The static pressure time derivative around the rotor bladesand radiation noise frequency spectrum were analyzed under rated working condition. Theoutput power and propagation law of acoustic radiation of the ogee type tip shape and thethree slotted tip shape were simulated and compared with the actual tip shape. The size ofS-type tip vane was optimized by using orthogonal optimization method. The output powerand test point noise of25groups S-type tip vane were carried out bi-objective optimizationsimulation.The numerical simulation results displayed that output power increased at first thendecreased along with the increasing of the tip speed ratio. The results agreed basically withthe experimental results；The complete vortex distribution in wake field of wind turbinewas obtained. The production and propagation law of tip vortex and center vortex wereanalyzed；The max region of the value of the static pressure time derivative concentrateson the region of the tip of wind turbine rotor blade. The noise around the tip of the blade isthe highest；The fundamental of blade through frequency and frequency of tip vortexshedding were obtained by analyzing radiation noise frequency spectrum；The propagationlaw and extent of reduction of overall sound pressure levels in every direction away from the rotor were analyzed.Comparing with the actual tip shape, the output power of ogee type tip shape has aincreasing of4.23%；The overall sound pressure levels are lower than the actual tip shape.The overall sound pressure levels of the ogee type tip shape decrease faster in axial with arange of1dB to8dB.The amplitude reduction of overall sound pressure level for the ogeetype tip shape is larger than the actual tip shape along with the increasing of the radialdistance.The output power of rectangular groove tip shape and curved groove tip shape have aincreasing of-0.51%and1.25%compared with the actual tip shape；Boss of the decreasingeffect of overall sound pressure levels are superior to the actual tip shape. The rectangulargroove tip shape has the best decreasing effect with a range of1dB to13dB.The width B and radius-width ratio i are the most influential factors of output powerand test point noise and length to width ratio j is the least influential factor.The posteriorfield angle β merely has great influence on output power and arc design angle α just hasgreat influence on test point noise；The optimum dimension of S-type tip vane whichsatisfied simultaneously higher output power and lower noise on test point is34mm×0.65×1.15×39°×50°. The results of the numerical simulation were identical with theexperimental results...