Open-Water Thrust and Torque Predictions of a Ducted Propeller System With a Panel Method
Author Baltazar, J., Falc√£o de Campos, J.A.C. and Bosschers, J.
Title Open-Water Thrust and Torque Predictions of a Ducted Propeller System With a Panel Method
Conference/Journal SMP 2nd International Symposium on Marine Propulsors, Hamburg, Germany
Paper no. WB2-4
Month June
Year 2011

Abstract
This paper discusses several modelling aspects which are important for the performance predictions of a ducted propulsor with a low-order Panel Method. The aspects discussed are the alignment of the wake geometry, the influence of the duct boundary layer on the wake pitch and the influence of a transpiration velocity through the gap. The analysis is carried out for propeller Ka4-70 operating without and inside a modified duct 19A, in which the rounded trailing edge is replaced by a sharp trailing edge. Experimental data for the thrust and torque are used to validate the numerical results. The pitch of the tip vortex is found to have a strong influence on the propeller and duct loads. A good agreement with the measurements is achieved when the wake alignment is corrected for the presence of the duct boundary layer.

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