Experimental study of start performance in civil turbofan engine

To optimize the starting procedures for a civil turbofan engine, an analysis of influencing factors during the subsequent two phases (accelerating from ignition success to idle, and maintaining steady state at idle) of the starting process was conducted. Research was conducted on adjusting starter air supply pressure, matching start fuel scheduling with variable geometry components, and exploring the stable operating boundary at idle. The results indicate that increasing the start fuel flow by 10% reduces the engine starting time by 6.30 s. Increasing the variable stator vane opening by 1.5° results in a 5.10% increase in compressor pressure ratio, a 4.99% rise in airflow, and a 9.25% improvement in rotor acceleration rate, and the starting time shorten by approximately 6.00 s. Additionally, coordinating the transient bleed valve at the compressor outlet to bleed air can effectively reduce the operating line of the high-pressure compressor, increase compressor surge margin, and resolve longstanding issues such as prolonged starting time, high risk of overheating and surge, and instability at idle. This research provides essential support for the airworthiness certification of turbofan engine starting capabilities.