Investigation Of A Potential Based Surface Panel Method For Prediction Of Propeller Performances

The design and performance calculation of marine propellers have increasingly become fundamental goals for both researchers and designers in the field of fluid mechanics. As the theoretical methods have better flexibility and adaptability for marine propeller design and performance calculation compared with conventional methods, it is significant to predict the hydrodynamic performance accurately in order to avoid vibration and noise brought by poor design, increase propeller efficiency and improve propeller performance. Therefore, how to make an accurate prediction of the hydrodynamic performance for marine propeller is a promising topic. In present paper, the investigation for theoretical methods including lifting surface method and surface panel method is carried out and special attention is paid to the potential-based low order panel method, which is used to predict the hydrodynamic performance and pressure distribution of marine propeller. A new grid arrangement with the local flow characteristics taken into consideration is proposed and a new trailing wake model is applied compared with existing ones.The trailing wake model is one of the most important issues in the process of propeller design and numerical calculation, and it has great effect on the precision of prediction results to some extent. However, the complexity of the problem retards the determination of the wake geometry accurately. For this reason, an improvement of wake model is made for the numerical procedure by using vortex lattice method. In the transition wake region, wake vortex is determined by aligning the vortex line with streamline. New numerical methods are adopted to reduce the numerical calculations and wake vortex radii are determined on the basis of continuity equation of in-compressible fluid to avoid the divergence of the tip vortex radius. New wake vortex model provides new numerical methods for the propeller design and propeller off-design analysis.When the low order surface panel method is used to solve the direct problem of propeller, both the propeller blades and hub are approximated by a number of hyperbolical quadrilateral panels with constant source and dipole distribution, while the trailing wake surface is represented by hyperbolical quadrilateral panels with only constant dipoles on them. Special emphasis has been considered to meet Kutta condition, which is used to ensure pressure equivalency on the panels at trailing edges and the cross flow component is taken into account for its significant effect on three dimensional problems. The influence coefficients are...