Abstract: Apparatus, methods, and other embodiments associated with monitoring combustion dynamics in a gas turbine engine environment are described herein. In one embodiment of a system for monitoring combustion dynamics in a gas turbine engine environment, the system includes a transducer and an optical fiber. The transducer is positioned within the gas turbine engine environment, and the transducer includes a diaphragm, a window, and a Fabry-Perot gap. The diaphragm has a reflective surface, and the window has a partially reflective surface. The Fabry-Perot gap is formed between the reflective surface of the diaphragm and the partially reflective surface of the window. The optical fiber is positioned proximate to the window and directs light into the Fabry-Perot gap and receiving light reflected from the Fabry-Perot gap.

Abstract: Apparatus, methods, and other embodiments associated with measuring environmental parameters are described herein. In one embodiment, a transducer comprises a tube, an elongated member, a first reflective surface, a second reflective surface, and an optical fiber. The tube has a first end and a second end, and the elongated member also has a first end and a second end, with the first end of the elongated member secured to the tube. The second reflective surface is secured to the second end of said elongated member, and the first reflective surface is spaced apart from the second reflective surface and secured to the second end of the tube. The optical fiber is positioned to direct light towards the first and second reflective surfaces and to collect the reflected light from these two surfaces.

Abstract: The present invention is directed to a system for determining a fluid level in a vessel. The system comprises a first differential pressure transducer, a second differential pressure transducer, a pressure delivery system, and a fluid passage. The first differential pressure transducer includes a first side and a second side. The first side is selectively in fluid communication with a portion of the vessel above the fluid level. The second differential pressure transducer includes a third side and a fourth side. The third side is selectively in fluid communication with a portion of the vessel below the fluid level. The fluid passage is in fluid communication with the second side of the first transducer, the fourth side of the second transducer, and the pressure delivery mechanism.

Abstract: An apparatus to interrogate one or more fiber optic sensors to make high-resolution measurements at long distances between the sensor and the interrogator apparatus. The apparatus comprises a tunable light source, an optical switch for pulsing the light source, at least one sensor (e.g., a Fabry-Perot sensor) for reflecting the laser light, a fiber optic cable interconnecting the sensor with the light source, a coupler for directing the reflected light from the sensor to a detector in order to generate a digital output, and a control logic for tuning the laser light source based on the digital output from the detector. Use of a fiber Bragg grating temperature sensor is also contemplated.

Abstract: The present invention pertains to differential pressure transducers. In an embodiment of the invention, a differential pressure transducer includes a transducer housing, a diaphragm, a bellows, and a sensing assembly. The transducer housing, diaphragm, and bellows are coupled to form a pressure chamber. The pressure chamber is separated into two portions by the diaphragm, with each portion arranged to be filled with a process fluid. A pressure differential across the diaphragm causes displacement of the diaphragm. Such displacement is measured by the sensing assembly and used to calculate the pressure differential between the two process fluids.

Abstract: In a Fabry-Perot interferometer based sensor if insufficient light reflected from the sensor re-enters the fiber, the results from the Fabry-Perot interferometer-based sensor are compromised. Accordingly, a sensor assembly is provided that comprises an optical fiber having an optical axis, a lens in optical communication with the optical fiber, the lens having an optical axis and the lens capable of transmitting a beam of light, a reflective surface, the reflective surface spaced from the lens such that the beam of light transmitted from the lens is capable of reflecting from the reflective surface back to the lens, and an alignment device capable of aligning the beam of light transmitted from the lens substantially perpendicular with the reflective surface.

Abstract: A method and apparatus for monitoring one or more environmental parameters using interferometric sensor(s), a cross-correlator, a two-dimensional photosensitive array and optical focusing means are described. The method and apparatus allows for near simultaneous monitoring of the parameter(s) of interest.

Abstract: A method for monitoring changes in a gap which corresponds to changes in a particular environmental parameter using a tunable laser and interferometer at high frequency is disclosed. The laser light provided to the interferometer is swept through a small range of wavelengths. Light modulated by the interferometer is detected and a non-sinusoidal light intensity output curve is created, a reference point on the curve identified and subsequent sweep of the laser performed. The difference in time, wavelength, or frequency at the occurrence of the reference point between the two sweeps allows for measuring the relative changes in the gap and, as a result, the change in the environmental parameter.

Abstract: A differential pressure transducer which incorporates a Fabry-Perot sensor for direct quantitative measurements of the distance displaced by a piston abutting two pressure boundaries is described. The apparatus includes a piston with an annular protrusion which is fitted into a transducer housing having a peripheral groove that serves as a stop to prevent damage to the in overpressure situations. A method of measuring differential pressure using a Fabry-Perot sensor is also contemplated.

Abstract: A signal conditioner to measure the length of an interferometric gap in a Fabry-Perot sensor (interferometer). The invention includes a light source, a Fabry-Perot interferometer capable of spanning a range of gaps in response to physical changes in the environment, a second interferometer that is placed in series with the Fabry-Perot interferometer which does not filter any particular wavelengths of light but acts as an optical cross-correlator, a detector for converting the correlated light signal into electronic signals, and an electronic processor which controls system elements and generates a signal indicative of the length of the gap spanned by the Fabry-Perot sensor.

Abstract: Pressure transducers are used to measure pressure under high temperature, hostile environments, including in gas turbine combustors and internal combustion engines. The present a pressure transducer comprises a member having a first end and a second end, a diaphragm sealed within the member at the first end, a sensor sealed within the member at the first end and in operable communication with the diaphragm, a first plate having a plurality of apertures, the first plate being attached to the member at the second end, a second plate having a plurality of apertures, the second plate being attached to the tubular member at the second end and being spaced from the first plate, and wherein the apertures of the first plate are not aligned with the apertures of the second plate.

Abstract: A pressure measurement system and method are described. The system uses a tunable laser and a Fabry-Perot sensor with integrated transducer. A detector senses the light modulated by the Fabry-Perot sensor. A signal conditioner, which can be located up to 15 km away, then uses the detector signal to determine the displacement of the diaphragm, which is indicative of pressure exerted against the diaphragm. Use of a temperature sensor to generate a signal, fed to the signal conditioner, to compensate for temperature is also contemplated.

Abstract: A method and apparatus for quantitatively measuring the distance of an unknown variable gap is disclosed. Light is provided to two Fabry-Perot interferometers arranged in a series, one spanning the unknown gap and the other spanning a controllably variable gap. Means for verifying the positioning of the Fabry-Perot interferometer having the controllably variable gap work in conjunction with a signal processor, a correlation burst signal detector and means for conveying the light to the various system elements to perform a comparison of detector signals from the two interferometers and quantitatively establish the gap distance. The invention may also be varied to function on a time basis, include more than one source of light, possess filter means to distinguish between light sources and/or include one or more reference interferometers.