Computational Investigation of Cold Flow in a Dump Combustor With Tapered Exit

This paper reports the results of a numerical study of the cold flow field in a dump combustor with a tapered exit. The numerical model was benchmarked against the data available in the literature. The flow field inside the combustor was investigated by numerical visualization of different regions in the flow field, and the effect of the combustor length was studied. It was seen that the presence of shear layer between the potential core and the recirculation region, as well as the pressure and velocity variation inside the combustor, alters the recirculation region and hence the flow field. It was also observed that the extent of the recirculation region increases, while the shear layer becomes thinner as the length of the chamber decreases. The effect of the variation in the flow Reynolds number and the inlet turbulence intensity on the flow field of a low aspect ratio (2.3) dump combustor was studied in detail. It was observed that the extent of recirculating flow increases with a decrease in the Reynolds number, and the increase in turbulence intensity results in higher turbulence energy generation in the shear layer. The pressure recovery was found less, but the recirculation was stronger in the low aspect ratio combustor. The results of this study can help optimize the combustor chamber to achieve better mixing of fuel with air and stabilization of the flame.