Analytical Determination of Effect of Water Injection on Power Output of Turbine-Propeller Engine

The effect of water injection on power output of a turbine-propeller engine incorporating a centrifugal compressor is determined by computing the wet compression process as polytropic and using currently available data on the effect of water injection at the compressor inlet to determine empirical constants related to the rate of evaporation. The analytical investigation includes compressor tip speeds of 1200, 1500, and 1800 feet per second at a turbine-inlet temperature of 2000 deg R. The calculations based on experimental data indicate that with the use of water injection the shaft power of the engine may be increased by more than 78 percent at a compressor tip speed of 1800 feet per second without increase in turbine-inlet temperature. The liquid consumption is increased 4.5 times in order to achieve this augmentation. If sufficient water is injected within the compressor to saturate the air at the compressor outlet, power augmentation as great as 200 percent is possible at a compressor tip speed of 1800 feet per second.