An Exploratory Study on the Working Principles of Energy Saving Devices (ESDs): PIV, CFD Investigations and ESD Design Guidelines

The Maritime Research Institute Netherlands (MARIN) has recently started a Joint Industry Project (JIP) called ESD-JILI, investigating the working principles of energy saving devices (ESDs). Within the framework of this JIP, three ESDs have been selected and thoroughly investigated. They are a Pre-Duct with an inner Stator (PDS), a Pre-Swirl Stator (PSS) with asymmetric blade design and Hub Fins (HFs). The investigations have been carried out by using dedicated force and moment sensors to measure all the components of the ESDs independently during the propulsion tests, by using Particle Image Velocimetry (PIV) to measure the flow before, in-plane and behind the propeller and the ESDs, and by using Smart Ship Model technology (Wijngaarden 2011) to simulate the full-scale wake field during the model tests to gain insights on scale effects of the ESDs. At the same time, computational fluid dynamics (CFD) calculations are also carried out in order to further deepen the understanding of the working principles of the selected ESDs, and to assist the ESDs designs under certain guidelines. Some of the results of the study have been published to the Greenship’2011 Conference (Dang et al 2011). The flow details around the propulsion system with the PDS, which were obtained by both PIV measurements and CFD calculations, and the energy balance of the ship-propulsion system with a PDS are further investigated and reported here. Based on the results of the studies, the principle guidelines for ESD designs for single screw merchant ships have been proposed.