Metallurgical and Fluid Dynamic Results of a 2000-Hour Endurance Test on a Two-Stage, 200-Horsepower Turbine in Wet Potassium Vapor Free

In a potassium Rankine-cycle technology program concerned with the life and performance of turbines in wet potassium vapor, a two-stage turbine has been designed, built, and performance tested in potassium vapor up to a temperature of 1580 F. Subsequently, a 2000-hr endurance test was completed at 1500 F with the objectives of determining the relative erosion resistance of refractory blading materials, the degradation in turbine performance with erosion, if any, and the contamination effects on selected refractory alloys in a Type 316 stainless steel facility. Performance was unaffected in 2000 hr of testing. Although minor liquid-metal corrosion of turbine blades was noted, no impact erosion occurred on turbine components. Some evidence of mechanical damage by liquid-drop impact or by cavitation was observed in test-specimen inserts behind the second stage. The 2000-hr test indicated the adequacy of a Type 316 stainless steel potassium turbine test facility for development testing of space power turbines with molybdenum alloy components.