Combustion instability and emission characteristics of spray flame under flue gas jet

In this paper, dry flue gas was injected into the combustion chamber in a jet pattern that collided diagonally to control the combustion instability of ethanol spray flame. The effects of jet flow rate, jet height, and jet temperature were experimentally studied. The results show that the closer the jet point is to the flame root, the better the control effect on the pressure oscillations is. And as the jet flow rate grows, the pressure damping also increases, reaching a maximum of 68.7 %. However, the CO emissions also reached the maximum level of 5020.8 mg/m3. Moreover, it is observed that the oscillation frequencies tend to shift to a higher frequency at a significant jet flow rate. The flame will also transition from a high-fat type to a compact type, forming a lowtemperature zone at the tail. 80 celcius is the optimal jet temperature, which is conducive to flame and sound field decoupling. At this temperature, the pressure oscillations can not only be well suppressed, but also the emissions of CO and NOx are at relatively low levels. The flue gas jet provides a solution to the combustion instability of liquid fuels, expanding its practical application.