Optimization On The Side-hull Configuration Of Trimaran Based On CFD Method

Nowdays, high speed is the developing direction of ship transportation. The high speed trimaran is growing rapidly because of its excellent performance. In order to cope with the increasing greenhouse effect, the International Maritime Organization (IMO) launched the new ship energy efficiency design index (EEDI) rules to control the emissions of carbon dioxide in the process of navigation of the ship. So, energy-saving optimization of trimaran is bound to become one of the focus in the shipbuilding field. Under this background, this paper make study on the side-hull configuration of trimaran optimization which based on CFD method. This paper find out the optimal side body configurations by compared the results of numerical calculation. This paper also analyse the high-speed trimaran’s energy efficiency design index (EEDI) changes before and after optimization.This article selects a semi-planning forward placed outrigger high-speed trimaran which has the test data. Firstly, this paper apply CFD commercial software for validation of this high-speed trimaran, compare of resistance, pitching etc. numerical calculation results with test values, The results show that, Fr> 0.27, the relative error of resistance is within 5%; Fr> 0.45, the relative error of pitching is within 5%; Because of the trimaran’s speed is very high, so, the CFD method is used for numerical simulation of the high-speed trimaran is feasible.Secondly, this paper use the orthogonal experiment method and the enumeration method for high-speed trimaran optimization. In the optimization of orthogonal test, select the vertical position、horizontal position and bow line of side-hull as three factors for change. Analysis optimization results show that, the vertical position and horizontal position of side-hull has greater influence on resistance and pitching of the high-speed trimaran, but the bow line of side-hull has small impact. So, in the second optimization, we only change horizontal and vertical position of side-hull, the enumeration method is adopted, the longitudinal of side-hull change 6 position, horizontal change 5 positions, then explore the resistance characteristics of the 30 points, find out the optimal side-hull configurations. this paper also make comparative analysis between the optimized trimaran resistance and the original value. Finally, according to the CCS "Rules for Green Ships", this paper calculate and compare the EEDI value of the high speed trimaran before and after optimization, prove that reduce the high speed trimaran EEDI is feasible by optimize the side-hull Configuration of trimaran.