Unsteady flows in the last stator rows of axial compressor of gas turbine working in coal gasification combined cycle

Fatigue failure of the last three stator row vanes of the Alstom gas turbine axial compressor occurred in Vresova power plant. The plant uses syngas, produced by the brown coal gasification, as fuel. Experimental investigation of non-steady flow in the axial compressor was carried out by means of the static and total pressure probes. Flow pulsations, in the rear part of compressor, at a frequency of (380 - 400) Hz were found. This frequency is near the first natural frequency of the damaged stator vanes. The stalled flow on vane surfaces with vortex structure shedding off is responsible for the flow pulsation origin. The results of flow simulations in cascades of last three stator rows support such conclusion.