Aerodynamic limits of gas turbine compressor during high air offtakes for minimum load extension

Abstract Renewable energy sources (RES) have become a favoured alternative to fossil fuel generation that has been driven by environmental concerns. Their intermittent nature meant gas turbines remained relevant support them as backup. Current grid operation requires operate at low power possible when their demand drops, and also ramp-up quickly from renewables declines. Air extraction turbine compressor can address the first requirement, this mechanism reduces load or of engine while storing air for further pressurised reinjection, related rate improvements. This study demonstrates aerodynamic implications limits behind last stage compressor, achieve minimum reduction. To this, zero-dimensional (0D) analytical model an design off-design conditions (air extraction) used determine boundary 3D Computational Fluid Dynamics (CFD) model. The multi-stage CFD shows high extractions are limited choke, flow separation, loss in pressure hub region OGV stator. As such, back was more affected than earlier stages. Based on these, limit is 18% (of discharge). showed similarity trends comparable with stand-alone however, optimistic latter. work shown capable airflow reduce further.