High Pressure Compressor Stabilization by Controlled Pulsed Injection

Steady tip injection with re-circulated air as a reliable method for high pressure compressor stabilization has the disadvantage to reduce the efficiency due to the usage of already compressed air. Therefore, the minimization of recirculation air and/or a large extension of the stable operation range is mandatory. The paper describes an alternative approach by using an active compressor stability control system with modulating valves. The system was tested at a high pressure compressor. It recognized evolving stall cells reliable. The achieved available stable throttling range of the compressor (in terms of mass flow) was more than doubled by active controlled injection compared to steady tip injection at 90% aerodynamic speed. The other way round, depending on the tip flow structure and the aerodynamic speed injection mass flow saving up to 50% at a similar surge margin compared to steady injection was achieved.