Experimental investigation on a diffusion jet flame performance using a developed flame holder supplied with air from a concentric pipe

Abstract

In this study, a diffusion jet flame consisting of a newly developed flame holder with three coaxial pipes to transfer air and fuel to the combustion zone, is investigated experimentally to simulate the ramjet effect. The flame holder is a double cone with three fuel ports on the top cone to improve the mixing of fuel and air. The inner pipe transfer fuel and is connected to the flame holder (which serves as a fuel injection point) and the middle pipe transfer primary air and the outer pipe transfer secondary air to the combustion zone (to investigate the impact of removing still air from around the flame as in ramjet applications). The flame holder and the primary air exit were at fixed positions (Datum Z4= 0) while the secondary air exit position changed many times below and above the datum line. The results showed that the secondary air exit location had an effect on the flame temperature distribution, flame shape, flame length, and flame width. The optimum position of the secondary air pipe was found above the datum line at Z5 = 7.5 mm, where the flame temperature and length are considered relatively high compared to other secondary air pipe positions.