Effect of air cushion on the resistance reduction of Multi-purpose Amphibious Vehicle (MAV) in calm and waves water

Abstract

In a recent year, shipping industry had been extensively developed as a countermeasure from economic growth of a country, rise of raw materials price as well as the regulations for CO2 emission from international shipping operation The combustion process of ship engine will emit the greenhouse gases which are carbon dioxide (Co2), Sulphur dioxide (Sox), Nitrogen dioxide (Nox), as well as particulate matter which contribute to greenhouse effect. A concern from the public on this situation had lead the academician and transportation industry to extensive developed and explored on fuel-efficient and energy concept ship. Multi Amphibious Vehicle (MAV) is a transport that able to navigate on land and water including under water. MAV have a blunt-shape bow where it produces a large bow wave forming and hydrodynamic resistance resulted increase on power consumption. A higher in resistance also resulted in a bow submerging and swamping on the MAV. So, the air cushion concept is introduced to reduce these problems. In this research, the resistance acting on Multi Amphibious Vehicle (MAV) hull navigated in calm and regular waves condition is investigated experimentally and numerically. A simplified MAV model for computing resistance of air cushion effect on regular head waves is established. Simulations were carried out in finite element analysis ANSYS CFX 15.0 in two different wave height conditions which were 0.5m and 0.75m to study on the MAV resistance and also its motion. The resistances and the motion of MAV model with and without the air cushion effect were compared in a graph of total resistance versus MAV speed. The maximum resistance reductions occur at forward speed 6kn with 0.2 l/s air flow rate injection for both wave height 0.5m and 0.75m at 10.89% and 8.65 %. It is noticeable that, air cushion effect also gives a slightly improvement on ship motion in heaving and pitching.