Mathematical model of the hovercraft lift system

Abstract

BACKGROUND: Currently, hovercrafts are used worldwide thanks to their amphibian capabilities and mobility at water and slightly prepared areas with low supporting properties. Whereas, in practice, hovercrafts have two main systems ensuring motion, lift and traction which can be combined (operating from a common source of mechanical energy) as well as separated. This paper considers a hovercraft with separated lift and traction systems. The lift system of this hovercraft consist of piston diesel internal combustion engine (ICE), hydrostatic transmission, axial fans, feeding channel and an air-cushion plenum. The considered variant is chosen because hydrostatic transmission has a number of sufficient advantages in comparison with mechanical transmission with universal shafts and pulley drives, widely used at present time. The paper considers the open plenum lift system. AIM: Development of the combined mathematical model of the hovercraft lift system consisting of piston diesel ICE, hydrostatic transmission and a fan supplying air into the air-cushion plenum. METHODS: Using the MATLAB/Simulink environment, the engine power adjustment at hovercraft motion on various ground surfaces is studied with regard to increasing the efficiency of the fan and the whole system. Analytical scheme of the system is given, acceptable transient characteristics are obtained. Efficiency and range of optimal operation of the Sauer-Danfoss pump and hydraulic motor are estimated. The process of hovercraft adjustment from the established mode to a new state when motion condition change is considered. RESULTS: According to the simulation results, there is influence of the income control signal (adjustment parameter of engine operation modes) and disturbance signal (pressure change coefficient that defines properties of ground surface) on parameters describing the hovercraft motion. CONCLUSION: The developed mathematical model helps to choose and evaluate adjustment parameters of engine operation modes at hovercraft motion on various ground surfaces, to analyze and to improve the system energy efficiency.