TORQUING TURBOS: Integrated driveline solutions for helicopter turboshaft engine trials

摘要

The testing of modern helicopter turboshaft engines occurs across a wide spectrum, from initial and ongoing engine development, to production pass-off by the OEM through maintenance, repair and overhaul by both military and civil operators. Helicopter turbines generally have either a relatively low output speed, typically 6-8,000rpm, or a high speed of around 15-25,000rpm. In all cases, power absorption is by means of a dynamometer and, increasingly, to allow for full transient testing, via a high-inertia flywheel to simulate the aircraft's rotor. The most common type of dyno is a water brake, but opinion is divided between the merits of having a reduction gearbox and a more reliable low-speed unit, or a direct-drive high-speed brake. Recently, consideration has also been given to electric dynos, which recover the otherwise wasted energy from the turbine and avoid the complexity of a water-cooling plant, and might to some degree allow inertia simulation. Another solution is the Varoc air dyno - used extensively by the US Navy and Army - which can readily be used outdoors, without external services, even at military theater level.