Patent ID: 7559234
Filing Date: 2009-07-14
Classification: G01M

Abstract:
1. A method of monitoring dynamic pressure oscillations in a combustion process, comprising: providing a combustion system including a fuel injector equipped with an acoustic tuner in fluid communication with a fuel nozzle, the fuel nozzle in fluid communication with a combustion chamber and a variable fuel supply and a variable oxidant supply along with means for igniting the fuel and oxidant thereby initiating the combustion process producing hydrocarbon ions and electrons and an oscillating flame with dynamic pressure oscillations having both amplitudes and frequencies within the combustion chamber, a means for determining an equivalence ratio in the combustion chamber, and a means for determining a reference velocity, where the reference velocity is the velocity of oxidant entering the combustion chamber through the variable oxidant supply; providing an electrode in communication with the combustion chamber and hydrocarbon ions and/or electrons produced by the combustion process, where the electrode is connected to a control circuit such that the control circuit emits an electrode signal in response to an electrode current from the electrode in communication with hydrocarbon ions and electrons produced by the combustion process; calibrating the relationship between electrode signals and dynamic pressure oscillations to produce calibration data by which electrode signal, equivalence ratio, and reference velocity during the combustion process may be correlated to dynamic pressure oscillation in the combustion chamber, by, (a) determining a range of equivalence ratios and a range of reference velocities to be monitored during the combustion process, (b) defining a calibration map, where the calibration map is bound by the range of equivalence ratios along a first coordinate axis and the range of reference velocities along a second coordinate axis, (c) selecting a plurality of calibration points on the calibration map, where a calibration point is described by a specific equivalence ratio and a specific reference velocity, (d) providing a pressure transducer in communication with the combustion chamber and providing a pressure signal, (e) correlating the electrode signals and the pressure signals indicative of dynamic pressure oscillations for each calibration point by (f) interpolating between calibration points to produce the calibration data such that an observed electrode signal, an observed equivalence ratio, and an observed reference velocity during subsequent combustor operations may be correlated to an expected pressure signal, where the expected pressure signal is a value of the pressure signal predicted for the observed electrode signal, the observed equivalence ratio, and the observed reference velocity based on the calibration data; and monitoring the dynamic pressure oscillations in the combustion chamber during subsequent combustor operations by determining the observed electrode signal, the observed equivalence ratio, and the observed reference velocity, correlating the observed electrode signal, the observed equivalence ratio, and the observed reference velocity to the expected pressure signal using the calibration data, and using the expected pressure signal to indicate the dynamic pressure oscillation in the combustion chamber.