Patent ID: 9494491
Filing Date: 2016-11-15
CPC Classification: G01H,G01M,G06F

Claim Text:
1. A method of determining blade tip timing measurement uncertainty comprising: a) irregularly spacing a reference set of stationary probes around at least a portion of a circumference of a casing in a rotor assembly so that vibrations at different excitation frequencies are captured, wherein a minimum number of the stationary probes is two plus twice a number of simultaneous excitation modes of blades that are mounted to the rotor assembly; b) measuring time of arrival of each of the blades at each of the stationary probes; c) deriving a reference blade tip parameter from the measurements and a position of each of the stationary, probes; d) calculating a reference condition number from the position of each of the stationary probes and each targeted engine order; e) calculating a reference mean condition number from the reference condition numbers; f) defining an integer subset x and determining all combinations of x stationary probes; g) for each combination, calculating a condition number from the position of each probe of the reference set of stationary probes and each targeted engine order; h) for each combination, calculating a combination mean condition number from the combination condition numbers; i) ordering the combination means from step h) relative to the reference mean and selecting a predetermined number of combinations; j) deriving a blade tip parameter from the measurements and the position of each probe of the selected combination; k) calculating uncertainty of the blade tip parameter for each selected combination as a percentage of the reference blade tip parameter; and (l) tracking and outputting the uncertainty of the blade tip parameter to determine deterioration of the rotor assembly.