Experimental study of flow characteristics of enhanced biogas lean premixed nozzle of micro gas turbine by PIV

Distributed energy supply (DES) systems based on biogas micro gas turbines can effectively improve the energy consumption level in rural areas, and China paid more attention to the biogas DES system. In order to improve the combustion performance and fuel adaptability of biogas lean premixed nozzles, in this work, two enhanced lean premixed nozzles (EPN1 and EPN2) redesigned from the original premixed nozzle (OPN) of a 60 kW class micro gas turbine were tested. A single nozzle test bench was designed and built to investigate the main characteristics of flow field in the combustor and nozzles using two-dimensional planar Particle Image Velocimetry (PIV). Proper orthogonal decomposition (POD) was used to capture the coherent structures at the outlet of nozzles. The results show the maximum value of TKE for EPN1 is approximately 50.9% lower than that of OPN. The absolute value of vorticity in EPN1 increase from 49 s−1 to 255 s−1 along the mixing tube, and strong swirl enhances the mixing of fuel and air. The flow energy in EPN1 and EPN2 are more concentrated in 1-10 mode. There are less fluctuations and instabilities of the flow field at the outlet of EPN1. Therefore, the enhanced lean premixed nozzle (EPN1) has better flow characteristics.