Positional effect of vortex generators on the combustion efficiency of the micro combustor fuelled with hydrogen/air mixture

Abstract

The focus of this study is to explore the effect of vortex generator placement in a planar hydrogen combustor. The optimization of vortex generator placement is crucial for improving combustion efficiency and reducing pollutant emissions in the exhaust by achieving higher combustion. A numerical simulation model was developed using ANSYS- Reynolds-averaged Navier Stokes to examine the effect of vortex generators. Vortex generators were placed at four different locations away from the inlet at distances of 0.25 m, 0.30 m, 0.40 m, and 0.60 m such as 0.25S, 0.3S, 0.4S, and 0.6S models, respectively. Parameters such as combustion temperature, mass fraction of H2, mass fraction of H2O, turbulence intensity, and heat of reactions (HOR) were determined. The flow was assumed to be turbulent and steady, with hydrogen and air used as the fuel mixture. Hydrogen was released from the nozzle at a pressure of 300 bar and the velocity of air was 10 m/s. The strategic placement of vortex generators near the air inlet has been shown to have a significant impact on combustion temperatures and mixing, resulting in notable improvements in H2O formation and peak HOR. Furthermore, the utilization of vortex generators has been observed to enhance velocity magnitude and HOR, with the 0.25S model demonstrating the highest HOR values. 0.25S model also exhibited elevated temperatures and turbulent kinetic energy, indicating its potential for achieving optimal combustion efficiency. However, it is crucial to optimize the design and placement of vortex generators to mitigate disturbances in fuel spray patterns and attain the desired performance levels. Overall, these findings strongly suggest that vortex generators represent a promising technology for enhancing combustion efficiency and reducing emissions in planar combustors.