Prediction Of Hydrodynamic Performance On Propeller By Surface Panel Method Based On Velocity

In recent years,with the flourishing development of navigation,people have higher demands of propellers.Using theory numerical calculation method to predict the hydrodynamic performance on propeller accurately can avoid many problems such as vibration and cavitation which caused by faulty design.Predicting the hydrodynamic performance on propeller by theory numerical calculation method has the advantages of economy,rapidity and convenience.But the results still have a definite disparity compared with experimental data.So many scholars home and abroad work hard on how to make an accurate prediction for the hydrodynamic performance on propeller.The surface panel method distributes source(sink) on the real body surface, which allows us to make reasonable consideration of the influence of the body thickness.We can get the pressure distribution approaching the real condition. The surface panel method can make more precise representation of the geometry of complex objects,and deal with the influence of cavitation on the surface of propeller,hub and duct more easily.The main idea of surface panel method based on velocity is that the velocity caused by body surface is substituted by the surface distribution of source(sink),then solving the strength of singularities by the body conditions that the normal velocity should be zero.In this thesis,an improved surface panel method based on velocity which satisfies easily the Kutta condition is employed. The surface of propeller and hub are discreted by a number of small hyperboloidal quadrilateral panels with constant source distribution. The camber surface and trailing vortex surface are also represented by a number of small hyperboloidal quadrilateral panels with vortex distribution.We consider that the velocity normal to the camber surface at trailing edge (T.E.) is zero as the Kutta condition in the steady condition.We calculate the induced velocity of field point caused by the singularity in every panel. The strength of the singularities are obtained by boundary conditions in the surface of propeller,hub and camber simultaneously,then the pressure distribution are obtained by Bernoulli equation and the thrust,the torque acting on propeller blades are calculated by pressure integration on the propeller blades.As application of this method,the DTMB4119 propeller's pressure distribution and velocity distribution on the blades in steady flow are solved,however,the results of which are not reasonable because of bad disposal of numerical problems.In spite of the bad results,this paper presents an idea of displaying singularities on both the blades,hub and camber surface simultaneously. This research is useful in enhancing the prediction precision of the propeller by using surface panel method.