Experimental Study of The Flow Field Over Simplified Superstructure of A Ship

Abstract

Highly complex flow pattern around the ship’s superstructure is not amenable to theoretical analysis and empirical calculation procedures. Wind tunnel tests on scale models are therefore a reliable tool to estimate and map the flow field as well as to study the exhaust smoke – superstructure interaction on ships. This paper presents the mapping of the flow field around a simplified topside configuration of a ship with two funnels. Scale model experimentation in wind tunnel with wind conditions scaled accordingly and injection of iso-thermal (unheated) exhaust flow from the funnels was undertaken to study the interaction between different configurations of funnels. The study included the mapping of the flow by velocity measurements using a 3-hole probe as well as the flow visualisation by smoke technique. 12 measurement planes were chosen so as to cover the most critical flow region around the superstructure. The mapping of the flow field for three different operating conditions in the wind tunnel through velocity measurements at the 12 planes with a total of 7560 discrete measurements has yielded experimental data, which can be treated as benchmark for future studies. The study provides an understanding the near-field behavior of merging plumes on ships. From a designer’s viewpoint the accuracy of this mapping of the flow structure is important because apart from providing an insight into the flow pattern, the results also constitute useful benchmark data that can directly be correlated to the results of the numerical simulation for validation of the CFD (Computational Fluid Dynamics) predictions.