Experimental investigation of an engine quick-start system with compact air supply for rotorcraft application

A quick-start system for turboshaft engines is an appropriate method to enhance safety and the flight operation range of a helicopter during intended single engine operation. Such a system was designed and successfully tested at the institute. However, the quick-start system used shop air of 13 bar(a) pressure for proof of concept. The shop air supply has to be replaced by an airworthy, compact and lightweight air supply system for feasible rotorcraft application. This comprises in first case general identification of adjustable system parameters by numerical studies and experimental tests in consideration of certain system constraints. Therewith, the ideal nozzle count is determined to 3 and the required nozzle entry pressure has to be about 19 bar(a). Based on these findings the final air supply system for rotorcraft application is designed and simulated with ESPSS. This system is built up at the engine testbed with some modifications for experimental testing. Gas generator acceleration tests as well as engine starting tests to idle speed are performed with the new system. A final engine start-up time of 2.8 s was achieved. Finally, further advice is given for feasibility.