A method for numerical calculation of propeller hydrodynamics in unsteady inflow

Abstract

The hydrodynamic performance of a propeller in unsteady inflow was calculated using the surface panel method. The surfaces of blades and hub were discreted by a number of hyperboloidal quadrilateral panels with constant source and doublet distribution. Each panel’s comer coordinates were calculated by spline interpolation between the main parameter and the blade geometry of the propeller. The integral equation was derived using the Green Formula. The influence coefficient of the matrix was calculated by the Morino analytic formula. The tangential velocity distribution was calculated with the Yanagizawa method, and the pressure coefficient was calculated using the Bonuli equation. The pressure Kutta condition was satisfied at the trailing edge of the propeller blade using the Newton-Raphson iterative procedure, so as to make the pressure coefficients of the suction and pressure faces of the blade equal at the trailing edge. Calculated results for the propeller in steady inflow were taken as initialization values for the unsteady inflow calculation process. Calculations were carried out from the moment the propeller achieved steady rotation. At each time interval, a linear algebraic equation combined with Kutta condition was established on a key blade and solved numerically. Comparison between calculated results and experimental results indicates that this method is correct and effective.