Design and Test of a Small Turbine at 2500F with Transpiration Cooled Blading 690035

With the increasing need for high performance, small gas turbine engines in the 500–1000 hp class, there is a requirement for use of high turbine inlet temperature in the range of 2500 F. Engines designed at these temperatures will supply more than twice the horsepower available in present day noncooled engines. Reliable operation of the turbine component at gas temperatures that exceed the melting temperature of the materials, however, requires selection and application of an efficient and practical blade cooling method. This paper presents the design of a transpiration air cooled, single stage, high work, axial flow, small turbine suitable for 2500 F turbine inlet temperature and capable of driving an 8:1 pressure ratio 4 lb/sec compressor. The manufacturing techniques associated with incorporating transpiration cooling into the small blading and the electron beam welding of these blades to the disc to form an integrally welded rotor assembly are also discussed. The results of the experimental testing of cascade and full stage component of this small turbine design at gas temperatures to 2500 F are presented.