Study of combustion characteristics of coflowing gas and liquid fuel stream

One of the most important parameters combustion engineer looks for is the flame stability in combustion chamber. In this work, a trial was made to get a stable flame by using liquid fuel injected in gaseous fuel combustion, since liquid fuel combustion is more stable than gaseous fuel combustion. A test rig is designed and constructed to carry out the experiments. Two sets of experiments were carried out to investigate the effect of changing the injection location at constant percentage of liquid fuel (kerosene) of 20\% and the effect of changing the percentage of the injected liquid fuel while the injection location was maintained at X-inj/D = 0.377. It was found that the injection of liquid fuel leads to an increase in the maximum positive axial velocity and reduces the absolute value of the maximum negative velocity (recirculation zone). Also, a stable temperature distribution is noticed at an axial distance X/D approximate to 2.15 which is less than that of gaseous fuel combustion (LPG, X/D approximate to 2.91). The changing of injection location leads to a reduction in gas temperatures for X-inj/D = 0.189, then increasing to reach a maximum values (which approximately the same values for combustion of LPG fuel alone) at X-inj/D = 0.377. Any further increase in the injection location leads to a reduction in gas temperature especially at the upstream sections of the combustion chamber. It was found that a stable flame is found to be existed in all percentage of the liquid fuel injected.