Effectiveness of water spray in infrared signature suppression of engine plumes

In modern military aircraft, reducing the Infrared (IR) signature is critical for stealth. However, the IR signature from the engine plume is particularly challenging to address due to its link with engine operation and its unique, non-continuous characteristics. In this study, a novel approach using a water spray cloud to attenuate the IR signature from the engine plume was proposed, and it is experimentally verified by employing a micro-turbine engine. Six water nozzles generated the water spray cloud, and IR signature reduction was quantitatively measured using an IR spectrometer. Variations in water injection pressure and observation angles were used as experimental conditions. The results revealed that the IR signature was reduced with higher water injection pressure, attributed to the increased thickness of the water spray cloud. The IR signature from the engine plume was effectively attenuated by the water spray cloud in overall, with a more pronounced effect observed at lower observation angles due to the extended path within the cloud. The potential of water spray clouds for enhancing the IR stealth of military aircraft is underscored by this research.