Experimental Study on the Effect of Water Injection on a Micro Turbojet Engine

Due to increasing emissions in the 21st century, aviation  industry faces a rising pressure to reduce its contribution to air pollution. A possible way to mitigate such harmful  effects on the environment is to use water injection as a  thrust augmentation method which was developed in the  1960s. Since the emergence of modern engines, the need  for the performance-enhancing effect of water injection has become abandoned. However, considering its beneficial  impact on both emissions and engine structure, it can still  be used as an alternative nowadays as well. As a result of  the cooling effect of water injection, the service life of  engine components extends which could also lead to a  reduction in maintenance and operating costs. This paper  presents how water injection on TKT-1 experimental jet  engine affects performance and emissions. The  modifications implemented on the test bench enabled us to obtain a measure of the water injection operation with the  nozzle placed in the intake duct. Results reveal that such  method has no visible impact on the increase of thrust due  to the experimental environmental conditions and the  limitations of the system. Nevertheless, water injection  proved to be effective in reducing emissions. In addition to  the beneficial effect of lower gas temperature throughout  the turbine section of the engine, the emissions of NOx  gases also fall significantly (i.e. 30%) compared to dry  operation.