Computational performance of a-100 kW low pressure turbine to recover gas turbine exhaust energy

Abstract

A low pressure turbine was designed to recover exhaust energy from internal combustion engine. The turbine is located downstream retrieved exhaust heat energy from combustion after flowing through the high-pressure turbine in the turbocharging system. The work output obtained from the exhaust energy is used to drive an electric generator with power output of 1.0kW. These was not done by commercial turbine as the low efficiency resulted when operated. The main purpose of this project is to develop a scaling model for low pressure turbine with power output up to 100kW. An existing low pressure turbine was used as a guideline to upscale the turbine. The scaling factor was obtained by comparing the baseline with the required power output. The turbine performance was analysed by using a commercial computational fluid dynamic software namely, ANSYS® CFX Version 17.0. The study found that the scaling factor, f of 10 can be used to produce a 100kW at passage. Thus, the geometrical parameter will be scaled accordingly. The rotational speed was reduced from 50,000 rpm to 5,000 rpm. The CFD analysis found the peak total-static efficiency (t-s) is 81% at the pressure ratio (PR) of 1.12 which has produced the turbine power of 119.88 kW. Despite the LPT swallowing capacity is increased from 0.05 kg/s to 5.0 kg/s, the LPT is limited by the operational choking PR which is 1.4. In conclusion, the computational analysis has shown that the scaling process is capable to produce a similar turbine characteristics between the baseline turbine and the upscale turbine.