Early stall warning technique for axial-flow compressors

This paper proposes a unique stall risk 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 single-stage low-speed 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.