Experimental investigation of high-pressure steam induced stall of a transonic rotor

Abstract

Steam leakage from the catapult system of U.S. Navy aircraft carriers can stall the compressors of modern jet aircraft if ingested during takeoff. This phenomenon, known as "pop stall", is of particular concern to the U.S. Navy as their current fleet of F404 engines age, the newer F414 engine comes online, and the F-35C variant of the Joint Strike Fighter begins service. The age of the F404 engine, the untested steam performance of the two stage fan in the F414 engine, and the low, serpentine intake of the F-35C make these engines and aircraft susceptible to steam-induced stall during takeoff. This study examines the high pressure steam-induced stall of a transonic rotor at both subsonic and transonic speeds. Steam stall was induced at 70%, 90% and 95% of rated rotor speed and the performance map of the rotor was re-established for 70%, 90%, 95%, and 100% of rated speed. The stall margin of the rotor and the presence of a stall precursor during both normal and steam ingested operation was investigated. In addition, the inlet nozzle mass flow measurements of the rig were tested against measurements in the inlet bellmouth to determine the feasibility of a shorter intake to introduce more inlet distortion into the flow.