Turbine CFD analysis of micro gas turbnine engine

Abstract

Modern large electric power plants use combined heat and power (CHP) cycle which includes the cogeneration of electrical power and useful heat at the same time, resulting in an increase in thermal efficiency. However, nowadays, governments tend to promote the distributed power generation and here comes the role of the Micro Gas Turbines (MGT), which are small power generators, that use the thermal power of the exhaust gases to heat water for usage and increase the total efficiency. This project will investigate the turbine performance of an axial MGT which is intended to produce to 2kW of electrical and 16 – 18 kW of thermal power. For that low power rates, usually radial turbines are used because of the enormous rotational speeds and the purpose here is to study if an axial turbine with that small dimensions can fulfil its purpose. The main analysis was done using the commercial Ansys – CFX solver with the Reynolds-Averaged Navier – Stokes (RANS) simulation. The turbulence model used here is the k-ω SST. The preliminary and validation simulations, to match the power output, the efficiency and the air mass flow rate was done by the build in Cranfield’s University software Turbomatch, mainly for the design point. The primary considerations were towards the relatively large design point pressure ratio and mass flow rate given the small turbine dimensions. The results showed that the turbine can deliver the required power but there are losses due to irregular flow characteristics (Figure 4.5), therefore, the geometry needs to be optimized.