Advanced blade systems for open rotors
Open rotor technologies offer the potential for significant reductions in fuel burn and carbon dioxide emissions relative to turbofan engines of equivalent thrust. Such engines operate the propeller blades without a surrounding nacelle, thus enabling ultrahigh bypass ratios to be achieved. A second row of propeller blades rotating in the opposite direction can add to the propulsive efficiency. However, a major technical challenge of counter-rotating propellers is the complexity of blade pitch control. The blade pitch modulates aircraft power and speed and is a vital component for reliable blade operation. The EU-funded project OREAT II (Open rotor engines advanced technologies II) recognised that a proper pitch-change mechanism (PCM) system is crucial for accurate control of the blade pitch and thus for frictionless operation of the counter-rotating open rotor (CROR) engine. Project members successfully delivered a PCM for the Sustainable and Green Engine (SAGE) demonstrator SAGE 2 propellers at technology readiness level 5. Prototype testing was performed in a newly developed representative test facility. The test facility included a hydraulics system with separate configurations of low and high pressures and temperatures, a test cell room with a modular test plate, an electric drive system, and control and data acquisition. OREAT II made an important contribution to the development of a safe and reliable CROR concept by paving the way to reduction of risk associated with its critical PCM.
Keywords
Open rotor, blade pitch, OREAT II, pitch-change mechanism, counter-rotating open rotor
