CFD에 의한 선박폐열회수용 100kW급 구심터빈의 성능해석에 관한 연구

Abstract

The rising cost of energy and global warming in recent years have highlighted the need to develop advanced energy systems to increase efficiency and to reduce emissions. The availability of energy plays an important role in the development and prosperity of a nation. In recent years, waste heat recovery, renewable energy sources, cogeneration and combined cycle power generation systems are receiving a great deal of attention.

WHRS(Waste Heat Recovery System) generates electrical energy from a ship's exhaust gases. This could reduce the ship's fuel consumption and CO2 emissions.

A turbine is a rotary machine that extracts energy from a fluid flow and converts it into useful work. Axial flow turbines and radial inflow turbines are the two most common types of dynamic turbines. The radial inflow turbine stage is differentiated from an axial stage by having the fluid undergo a significant radius change in passing through the rotor. In other words, in the radial stage the fluid enters the rotor in the radial inward direction and leaves in the axial direction. The flow within the rotor passage is three dimensional and complex, hence the use of numerical methods such as computational fluid dynamics(CFD) is necessary. CFD is analysis of systems involving fluid flow, heat transfer and associated phenomena by means of computer-based simulation.

In this study, performance and internal flow of 100kW class radial inflow turbine were analysed. Three dimensional simulation was performed using commercial code of ANSYS CFX 12.1. The radial inflow turbine was comprised of vane nozzle with 18 blades and rotor with 13 blades. Performance analysis was made for the isentropic efficiency(total-static) and mechanical power covering a range of different massflow rate, turbine speed and area ratio of the scroll casing.