Abstract

A control system for preventing a compressor stall in a gas turbine engine includes means for sensing an aerodynamic signal indicative of an impending stall condition. The weak stages of the compressor amplify an upstream disturbance originating in the low pressure compressor or fan, resulting in a discrete frequency disturbance, which is an effective stall precursor. The control system also includes means, responsive to the sensed signal, for processing the signal by isolating the relevant frequencies of the sensed signal, calculating the magnitude of the relevant portions of the sensed signal, comparing the sensed signal to a predetermined threshold indicative of a healthy compressor, and for providing a processed signal indicative of an impending stall condition. The control system further includes means, responsive to the processed signal, for providing an output to initiate corrective action to prevent the impending stall condition. The engine's electronic control system, in response to the output signal, increases the stall margin by either adjusting the compressor variable vanes or modulating the compressor bleed.