The United States of America As Represented by the Administrator of the

The United States of America As Represented by the United States

John M Franke

Richard L Puster

An acoustic flame-out detection system that renders a large high pressure combustor 12 (FIG. 1) safe in the event of a flame-out and possible explosive reignition. A dynamic pressure transducer 22 is placed in the fuel line 16 and detects the stabilizing fuel pressure oscillations, caused by the combustion process. An electric circuit (FIG. 5) converts the signal from the combustion vortices, and transmitted to the fuel flow, to a series of pulses. A missing pulse detector 39 counts the pulses and continuously resets itself. If three consecutive pulses are missing, the circuit closes the fuel valve 20. With fuel denied, the combustor 12 is shut down or restarted under controlled conditions.

Fuel line based acoustic flame-out detection system

A laser velocimeter that determines the direction of movement of particles. A laser produces a transmitted beam that illuminates the volume under investigation. The backscattered light is divided into two equal intensity beams. A first part of a sample of the transmitted beam is mised with one of the two equal intensity beams and applied to a first photodetector. A second part of the sample is phase shifted by 90.degree., mixed with the other of the two equal intensity beams and applied to a second photodetector. The output of the first photodetector is phase shifted by -90.degree. and then multiplied with the output of the second photodetector to produce a signal indicative of direction of movement.

Direction sensitive laser velocimeter

A method and apparatus for inducing a Doppler frequency shift in a reference beam laser velocimeter light beam to simulate target velocity wherein the light beam is passed through a rotating refractive transparent block positioned between two reference points along the beam resulting in a continuous change in the light beam optical path length between the reference points according to a known function. The velocity indicated by the laser velocimeter is compared to the known simulated velocity function for velocimeter testing and calibration.

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Norfolk, VA, United States of America

John M Franke