The ingestion of water from the atmosphere into the inlet of a gas turbine engine may significantly influence the performance and operability of the engine. The objective of this paper is to assess the effect of water ingestion on engine performance and operability. The ingestion of atmospheric water is considered in two types; gaseous humidity ingestion and liquid water ingestion. The ingestion of gaseous humidity changes the property of working fluid. Gas constant and specific heat ratio are important properties that are changed by the ingestion of humidity in turbomachinery. The changes of these properties not only lead to the variation of the engine performances, but also degrade similarity when using turbomachinery test data. This degradation of similarity brings about incorrect evaluation of engine performance when the usual similarity plots are employed. The varying fluid properties due to varying humidity were considered in the aerodynamic calculation of the engine. And the turbomachinery characteristic map data were corrected to maintain the similarity. The ingestion of liquid water is rather hazard. Liquid water approaching into the burner causes flame temperature drop due to the latent heat. The flame temperature drop leads to burner efficiency drop, which causes more dropped flame temperature. In order to sustain required engine speed with temperature drop more fuel is required. And the ingestion of water causes a loss in surge margin because of increased fuel consumption. Note that the surge is critical to the compressor operability. In order to simulate the effect of liquid water ingestion the evaporation model was included in the burner analysis. And the burner efficiency correlated with water ingestion was also used.
