Abstract

In this paper, research that was carried out to optimise an
initial variable guide vane schedule of a high-pressure ratio,
multistage axial compressor is reported. The research was
carried out on an extensively instrumented scaled compressor
rig. The compressor rig tests carried out employing the initial
schedule identified regions in the low speed area of the
compressor map that developed rotating stall. Rotating stall
regions that caused undesirable non-synchronous vibration of
rotor blades were identified. The variable guide vane schedule
optimisation carried out balancing the aerodynamic, aeromechanical
and blade dynamic characteristics gave the ‘Silent
Start’ variable guide vane schedule, that prevented the
development of rotating stall in the start regime and removed the
non-synchronous vibration. Aerodynamic performance and
aero-mechanical characteristics of the compressor when
operated with the initial schedule and the optimised ‘Silent Start’
schedule are compared. The compressor with the ‘Silent Start’
variable guide vane schedule when used on a twin shaft engine
reduced the start time to minimum load by a factor of four and
significantly improved the operability of the engine compared to
when the initial schedule was used.