Performance Improvement of Ship Propulsion Equipment Driven by Injecting Moist Air

The authors proposed the method of performance improvement by injecting moist air as the new propulsion system. The authors investigated on the effect by injecting dry air into the nozzle in former papers but there was the limit because the average fluid density decreased in the nozzle by air. In this study, the method of injecting moist air was investigated to obtain more thrust. Steam of the moist air injected into the nozzle condensed and the average density of fluid increased. By the increase of the density, the thrust increased about 20% comparing with the result of using only dry air and the propulsion efficiency was improved. There are some sources of exhausted heat such as engines and boilers in actual ships and obtaining the steam is relatively easy to make use of them. Our propulsion method is applicable for practical use and desirable for the energy efficiency.