Abstract: A control system and method for utilizing the rotational speed of the high-speed spool in a multi-spool turbofan engine to stabilize changes in engine operation which affect the thrust output of the engine. Signals representing the actual rotational speed of the high-speed spool, the actual value of the selected engine pressures which provide an accurate measure of engine thrust, and a commanded value of the selected engine pressures are processed; and an error signal is provided in response to these three signals which is a function of all three signals. The error signal is then used to control the rate of fuel flow to the engine which, in turn, controls engine thrust. In one embodiment the error signal is a function of the rotational speed of the high-speed spool and the actual and commanded values of engine pressure ratio, and in another embodiment the error signal is a function of the rotational speed of the high-speed spool and the actual and commanded values of integrated engine pressure ratio.

Abstract: A real-time gas turbine engine monitoring system is disclosed which includes a digital processor that utilizes a set of scalar coefficients and the current value of various engine operating parameters to predict the current value of a set of engine performance parameters. The actual values of these performance parameters are monitored and compared with the predicted values to supply deviation or error signals to monitoring logic which provides an indication of faults within the digital processor, within the sensor units which provide the actual values of the monitored performance parameters and within the gas turbine engine. In addition, the deviation signals are utilized within the digital processor unit to determine a time dependent quadratic estimate of the temporal characteristics of each monitored engine parameter. Signals representative of this quadratic estimate are supplied to trending logic that provides prognostic information.

Abstract: A fan spool stabilization loop which improves the stability of the low speed or fan spool in a two spool turbofan engine. In a preferred embodiment, the actual rate of rotation of the high speed spool is compared with the desired rate of rotation determined by integrating the difference between the desired rate of rotation of the fan spool and the actual rate of rotation. The difference therebetween controls the flow of fuel to the turbofan engine. In an alternate preferred embodiment of the invention, the rate of change of rotation of the high speed spool is added to the actual rate of rotation of the fan spool and the result is compared with the desired rate of rotation of the fan spool. The difference therebetween is utilized to control the flow of fuel to the turbofan engine.

Abstract: A fan spool stabilization loop which improves the stability of the low speed or fan spool in a two spool turbofan engine. In a preferred embodiment, the actual rate of rotation of the high speed spool is compared with the desired rate of rotation determined by integrating the difference between the desired rate of rotation of the fan spool and the actual rate of rotation. The difference therebetween controls the flow of fuel to the turbofan engine. In an alternate preferred embodiment of the invention, the rate of change of rotation of the high speed spool is added to the actual rate of rotation of the fan spool and the result is compared with the desired rate of rotation of the fan spool. The difference therebetween is utilized to control the flow of fuel to the turbofan engine.