An Experimental Study on a Ducted Propeller

Abstract

As an application of the equations (2)-(8) which express the flow around a symmetric ducted propeller in the uniform wake and were already reported by one of the authors, an empirical formula expressing thrust and torque of a symmetric ducted propeller in the uniform wake is obtained based on the above stated equations. The procedures used here are as follows. 1) Open tests on seven models of symmetric ducted propellers are carried out at our circulating water channal. 2) Based on the above stated equations, seven sets of geometrical parameters, γP_0, l_0, m_0, n_0, which represent the above seven models of ducted propellers, are obtained by means of the least square method. 3) It is assumed that hydrodynamic parameters, γP_0', l_0', m_0', n'_0, representing a symmetric ducted propeller in the uniform wake are expressed by unknown constants, advance constant of propeller, J, and γP_0, l_0, m_0, n_0 as equation (9). 4) Seven sets of unknown constants in equation (9) are determined by a regression analysis using the equations (1)-(9), seven sets of γP_0, l_0, m_0, n_0 and open test results on seven ducted propeller models. 5) Using seven sets of constants obtained by the above stated method and equations (1)-(9), an empirical formula expressing thrust and torque of a symmetric ducted propeller in the uniform wake is constructed.