Abstract
This study provides a comparison of propulsion performance, with a particular focus on efficiency, by varying rake distribution at the tips of propellers. Owing to increased attention to environmental pollution, there is a significant interest in reducing the energy efficiency design index (EEDI) and SOx emissions by improving the performance in the field of shipbuilding. The forward (Kappel) [1] and backward tip rake propellers have been widely used to improve efficiency, as well as to reduce fluctuating pressure from the tip vortex cavitation. As there is almost no parametric and design research on tip rake propellers, this systematic parametric study was conducted to identify the optimal configuration by the potential code. For this performance comparison the KP505 (KCS propeller) was chosen as the reference propeller as the tips of that propeller have no rake. The model test and computational fluid dynamics (CFD) calculation confirmed the result by comparing the open water performances for the three optimally selected propellers (forward, backward, KP505). The differences of efficiency obtained from the potential analysis and the model test exhibit similar tendencies, but the result for the CFD is different. The difference would be investigated by changing the grid system around the tip as well as the turbulence model in the CFD analysis. An analysis of self-propulsion and pressure fluctuation is also expected to be conducted in the near future.
Highlights
Interest in fossil energy depletion and global warming has increased in recent years.The International Maritime Organization (IMO) has been applying indicators for energy efficiency to ships constructed after 2013
The energy efficiency design index (EEDI) represents the amount of carbon dioxide emitted during the transportation of 1ton of cargo per mile
The Compound propulsion system can be classified as pre device, main device, and post device
Summary
Interest in fossil energy depletion and global warming has increased in recent years. Winglets reduce the induced drag by weakening the vortex at the wing, leading to greater efficiency (Ha, et al, 2014) [3] In other words, both propellers prevent the threedimensional vortex effect by reducing fluctuating pressure changes at the wing tips. Winglets induced drag by weakening theand vortex the have more widely used than the CLTs reduce due to the risk of cavitation in the corners alsoatloss wing,the leading to greater (Ha, et al, 2014) [3] In other words, both propellers prevent the with end plate drag atefficiency high speeds. Pressure fluctuation issuesthan fromthat theofpropeller should be andrake compared to have been more widely used than the CLTs due to the risk of cavitation in the corners and loss verify the performance of the tip rake propeller because it is more effectively used to reduce the aft withsurface the endpressure plate drag at high speeds.
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