Low Emission, Water-Tolerant Combustor for a Small, All-WeatherTurboshaft Gas Turbine Engine

An experimental program was conducted to select a combustion system design for the 500 shp Model 250-C28 turboshaft/turboprop engine. The primary goals were:

1. 1.
   Capability of complying with the Environmental Protection Agency (EPA) 1979 Class P2 turboprop engine emission standards.
2. 2.
   Capability of ingesting a 100 ml slug of water in 1/4 s without flameout.

The Model 250-C28 engine is an uprated version of the Model 250 (T63 military designation) production engine. The conventional Model 250 production combustor meets the EPA 1979 turboprop emission standards for NO_x and smoke, but unburned hydrocarbons (UHC) and CO exceed the standards. Also, the water ingestion requirement for the Model 250-C28 exceeded the capability of the current technology conventional combustor.

The emission and water ingestion goals of the program were met with a prechamber combustor design. Exhaust emissions measured during testing with a current production engine configuration met all of the EPA 1979 Class P2 turboprop engine emission standards. Engine water ingestion tests with the prototype prechamber combustor exceeded the program goal, and a tolerance level about four times that of the production Model 250 engine was demonstrated.

The favorable results from this investigation led directly to a Model 250-C28 prechamber combustor design that is currently undergoing development.