Transient performance of fan engine with water ingestion

: In a continuing investigation on developing and applying codes for prediction of performance of a turbine jet engine and its components with water ingestion during flight operation, including power settings, and flight altitudes and speed changes, an attempt has been made to establish the effects of water ingestion through simulation of a generic high bypass ratio engine with a generic control. In view of the large effects arising in the air compression system and the prediffuser- combustor unit during water ingestion, attention has been focused on those effects and the resulting changes in engine performance. Under all conditions of operation, whether ingestion is steady or not, it has become evident that water ingestion causes a fan-compressor unit to operate in a time-dependent fashion with periodic features, particularly with respect to the state of water in the span and the film in the casing clearance space, at the exit of the machine. On the other hand, the aerodynamic performance of the unit may be considered as quasi-steady once the distribution of water has attained an equilibrium state with respect to its distribution and motion. For purposes of engine simulation, the performance maps for the generic fan-compressor unit have been generated based on the attainment of a quasi-steady state (meaning steady except for long-period variations in performance) during ingestion and operation over a wide enough range of rotational speeds.