New shape hub vortex diffusion propeller cap, approximately 3% energy-saving effect.
The hub vortex generated at the rear end of the cap due to the circumferential flow originating from the propeller's trailing edge causes energy loss. In an effort to diffuse the hub vortex and recover the loss, over 500 different cap shapes were tested and designed, ultimately showing the most effectiveness with a cap shape equipped with multiple wings, which became the prototype for the ECO-Cap.
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basic information
Verification by Pressure Distribution The pressure distribution at the rear end of the cap usually experiences significant resistance due to negative pressure in standard caps; however, in the eco-cap, thrust is generated due to positive pressure, resulting in increased propulsion compared to standard caps. In model tests, the efficiency improved by approximately 1 to 1.3%, depending on the propeller shape (number of blades, pitch, boss diameter). It was attached to a gold cap body. By using FRP material, we successfully minimized the mass difference compared to the standard cap. As a result of actual ship installation on existing vessels, an improvement of approximately 2.8% in fuel consumption was observed compared to before the eco-cap was installed.
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Applications/Examples of results
It is adopted for various types of vessels for international and domestic shipping. It is not limited to fixed pitch propellers but is also used for variable pitch propellers. Additionally, there are proven results of retrofitting from conventional caps, and ease of implementation is also a key point for energy-saving improvements.
Company information
Nakashima Propeller Co., Ltd. has been producing ship propellers that meet our customers' demands. We have developed this made-to-order production technology and philosophy, cultivated through propeller manufacturing, and expanded it into various fields such as healthcare, daily life, and the environment. Moving forward, we aim to tackle the challenge of accurately responding to each of our customers' diverse needs, continuously pursuing new possibilities and shaping the infinite potential that lies beyond.