Early stall warning technique for axial flow compressors

This paper proposes a unique stall warning index based on pressure signals by high response transducers on the casing wall at the rotor leading edge location. The aim of the research is to explore the possibility of reducing current excessive stall margin requirement for compressor design based on the worst case scenario. The index is generated by computing correlation degradation of pressure time histories of current and one revolution before over each blade pitch. Tests conducted on a research compressor exhibits that the correlation diminishes significantly with proximity to stall and the proposed technique might have the capability of generating a stall warning signal sufficiently in advance of spike inception. Extensive experiments on a research compressor show that the degree of the index degradation depends on various factors such as flow coefficient, tip clearance and rotor blade incidence. In order to obtain a reliable stall warning signal in practical use, these effects must be carefully examined.