Gas Turbine Prediffuser-Combustor Performance During Operation with Air- Water Mixture

In a continuing effort to establish performance changes due to water ingestion into an aircraft gas turbine engine and possible design improvements, an experimental investigation was performed with a model gas turbine prediffuser-combustor sector utilizing a number of mixture and flow conditions in a tunnel operating with a two-phase, air-liquid film-droplet mixture. For given entry conditions into the prediffuser which can be related to the exit conditions of the core compressor in a bypass engine, and, therefore, also to ingestion conditions at the engine face the two main issues are 1 the amount of water entering the primary zone of the combustor, and 2 the local reduction in temperature, flame-water interactions, and the vitiation caused by the vaporizing of water. Flow visualization and estimates of water flow and droplet size in the primary zone have been undertaken under cold flow conditions. The amount of water entering the primary zone has been found to be a complex function of 1 the air-water mixture conditions at entry to the prediffuser, and 2 the effects of gravity on the flowfield for given geometry of the prediffuser-combustor, and the flow split between the primary and the coolant streams in the combustor. Combustion tests have been carried out to establish the effects on performance, occurrence of flameout, and recoverability of combustor exit temperature by enhancement of one or both of the fuel equivalence ratio and the oxygen content of air. Water Ingestion, Hail Ingestion, Turbofan Engine, Combustor Performance