دراسة تأثير أبعاد وشكل المحددات على أداء التزليق الهوائي على سفينة الصب JBC بدون وجود الرفاص باستخدام CFD

Abstract

In this work, the effect of the effect of shape and dimensions of guiding barriers on the sufficiency of air lubrication on the resistance of the JBC bulk carrier ship was studied. The CFD technique was used to achieve this purpose, where the URANS (Unsteady RANS Averaged Navier Stocks Equation) equations and the k-ω SST turbulence model available in Ansys program were used to solve the Navier-Stokes equations. The JBC bulk carrier was chosen to conduct this study, due to the availability of a large number of experimental results for this ship, which helps to verify the quality of the obtained numerical results. Initially, the calculations were performed on the ship without any additions in order to validate both the grid and the numerical settings. The comparison between the results showed a good agreement with the experimental results. Then, Air Barriers were added on the bottom and sides of the parallel body of the ship with two different Air Barriers heights, the first height was 0.25 cm on the model, corresponding to an actual height of 10 cm on the real ship and the second one was 1.25 cm on the model corresponding to an actual height of 50 cm on the real ship. The Air Barriers were added in several ways, first they were added in parallel, then they were added in the form of ⸧ , and then the air injector body was added which was a half-cylinder with a radius of 0.25 cm, the first part of which is a flow stopper and the second part is the air injector. The effect of these additions on the resistance of the ship without air injection was studied, and the Air Barriers with the form of ⸧ and the height of 1.25 cm were the worst as they caused an increase in resistance by 15.92% without injector body, and by 16.21% with the injector body. Then air was injected to the case of parallel Air Barriers and the resistance was reduced by 31.59% which is considered very good in the marine field because it greatly reduces the amount of fuel consumption and thus the air pollution resulting from it.