Research on Combustion Characteristics of a Jet Flame With Penetration of Side Micro-Jets

Abstract

Nowadays as clean energy gas is being got more widely utilization in the industrial fields, such as the industrial boilers and kilns. How to improve the combustion performance, including the high efficiency and low pollution emission of the gas flame, is becoming the hot topic for the combustion researchers. In this paper, an innovative jet flame with side micro-jets has been proposed and its effects on the flame structure and its performance have also been investigated. Due to the changes of the initial combustion conditions, mixing and aerodynamics which results from the perturbation of the side micro-jets, such a lifted jet flame have different flame structure compared with the common premixed flame. Results show that use of the micro-jets can control, to a certain extent, the flame structure, including the flame length, lift-off distance and blow-off limit. With the same fuel and air flow rate, the flame length with the side micro-jets will decrease about 5%–40% as the air volume ratio a increases from 58%–76%. Compared with the common diffusion flame, such a jet flame demonstrates to be easier to be momentum-dominated flame. The flame length with 2 micro-jets is about 5% less than with 6 micro-jets under the same fuel and air flow rate. With the same α, the fewer number of the controlled jets lead to the flame with relatively shorter length, not easier to be blown off and higher NOx emission. With certain fuel flow rate, the critical air volume ratio is largest for the flame with 3 micro-jets, which is more difficult to be blown off than the cases with 2, 4 or 6 micro-jets.