NUMERICAL SIMULATION OF POLLUTANT EMISSION OF A TURBOJET ENGINE WITH WATER INJECTION

Numerical simulation of a turbojet engine with water injection from the compressor inlet has been executed to evaluate the effect of wet compression on the pollutant emission in this paper. Water injection technique has shown the advantage of reducing the compression work and increasing the power output, and can also reduce the gas temperature in the combustion chamber and turbine which can help to reduce the thermal fatigue of the hot parts and extend their service life. Previous studies have indicated that there is a great relationship between pollutant emission of NOx and the combustion temperature, so the decrease of combustion temperature can reduce the amount of pollutant production of aircrafts especially near the airport because of the takeoff and landing of the aircrafts. And this potential of meeting the increasingly stringent pollutant emission target of water injection technique has aroused great interest of the world major engine manufacturers and research institutions. Compared with cases of no water injection, the results of this study show that the inlet temperature of combustion chamber drops obviously because of water injection, the average NO concentration in combustion chamber decreases greatly, but the concentration of CO increases significantly. Analysis of the results shows that based on fuel consumption of per unit mass the relation between the NO production in combustion chamber and the mass water evaporation varies according to the exponential law and CO production in water injection cases is similar to the cases without water injection.