Abstract: A method of monitoring the condition of a thermal barrier coating on a turbine blade or vane during operation of the turbine is provided. The method includes providing a means for receiving acoustic output of the blade or vane during operation of the turbine and monitoring the acoustic output over time, to determine the condition of the thermal barrier coating on the blade or vane. The acoustic output arises from a force on the blade or vane, such as that due to impact of particles, a pulse of gas pressure or constant gas flow. An apparatus employing the above method for monitoring the condition of the thermal barrier coating during operation of the turbine, is also provided.

Abstract: A pressure sensor (52) for a harsh environment such as the combustion chamber (58) of a gas turbine engine (50). The pressure sensor includes an acoustic waveguide (60) having a sensing portion (66) exposed to the combustion gas in the combustion chamber. Modulations in an acoustic signal passing through the acoustic waveguide are sensed and correlated to pressure fluctuations in the combustion gas. The sensing portion of the waveguide includes a core acoustic waveguide element (42) covered by a coating material (44). The coating material not only protects the core from the harsh environment, but it also improves the efficiency of the transfer of energy from the combustion gas into the waveguide because it provides a stepped transition from the acoustic impedance of the gas to the acoustic impedance of the core material. The protective coating may have a plurality of layers (46, 48) and/or it may include a graded material (78, 80) having an acoustic impedance value that varies across its depth.

Abstract: A method and apparatus for monitoring the condition of the thermal barrier coating on turbine blades and vanes is provided. The coating is monitored with ultraviolet sensors which can detect ultraviolet radiation emitted from electrical discharges and glow coronas at the surface of the blades and vanes. Such electrical glow discharges and coronas are the result of friction electricity found at the surface of blades and vanes, and are also due to the high pressure, temperature and velocity conditions within the turbine. As the thermal barrier coating deteriorates, the electrical discharges and glow coronas and associated UV emissions decrease in magnitude or have other characteristic changes, thus permitting monitoring of the corona to detect changes in the coating over time.

Abstract: A pressure sensor (52) for a harsh environment such as the combustion chamber (58) of a gas turbine engine (50). The pressure sensor includes an acoustic waveguide (60) having a sensing portion (66) exposed to the combustion gas in the combustion chamber. Modulations in an acoustic signal passing through the acoustic waveguide are sensed and correlated to pressure fluctuations in the combustion gas. The sensing portion of the waveguide includes a core acoustic waveguide element (42) covered by a coating material (44). The coating material not only protects the core from the harsh environment, but it also improves the efficiency of the transfer of energy from the combustion gas into the waveguide because it provides a stepped transition from the acoustic impedance of the gas to the acoustic impedance of the core material. The protective coating may have a plurality of layers (46, 48) and/or it may include a graded material (78, 80) having an acoustic impedance value that varies across its depth.

Abstract: A foreign object impact sensor for use with combustion turbines utilizes a passive acoustic waveguide within the turbine to receive acoustic signals from foreign object impact. The magnitude of these signals is displayed and or stored using a lighted display or other suitable indicating device. The information is also recorded and stored, so that a spectrum signature can be obtained from Fourier analysis.

Abstract: A method and apparatus for monitoring the condition of the thermal barrier coating on turbine blades and vanes is provided. The coating is monitored with ultraviolet sensors which can detect ultraviolet radiation emitted from electrical discharges and glow coronas at the surface of the blades and vanes. Such electrical glow discharges and coronas are the result of friction electricity found at the surface of blades and vanes, and are also due to the high pressure, temperature and velocity conditions within the turbine. As the thermal barrier coating deteriorates, the electrical discharges and glow coronas and associated UV emissions decrease in magnitude or have other characteristic changes, thus permitting monitoring of the corona to detect changes in the coating over time.

Abstract: A method of monitoring the condition of a thermal barrier coating on a turbine blade or vane during operation of the turbine is provided. The method includes providing a means for receiving acoustic output of the blade or vane during operation of the turbine and monitoring the acoustic output over time, to determine the condition of the thermal barrier coating on the blade or vane. The acoustic output arises from a force on the blade or vane, such as that due to impact of particles, a pulse of gas pressure or constant gas flow. An apparatus employing the above method for monitoring the condition of the thermal barrier coating during operation of the turbine, is also provided.

Abstract: A foreign object impact sensor for use with combustion turbines utilizes a passive acoustic waveguide within the turbine to receive acoustic signals from foreign object impact. The magnitude of these signals is displayed and or stored using a lighted display or other suitable indicating device. The information is also recorded and stored, so that a spectrum signature can be obtained from Fourier analysis.

Abstract: A non-reflecting, wave-absorbing structure absorbs sound, radio and radiation wave. The non-reflecting, wave-absorbing structure combines an outer non-reflecting wave structure and a wave-absorbing portion. The outer non-reflecting wave structure allows for the transmission of the wave therethrough without appreciable reflection and the wave-absorbing material absorbs substantially all of the transmitted wave. In the case the wave to be absorbed in a sound wave, the wave-absorbing material is preferably an epoxy in a chemical state of gelatinization which is prevented from reaching a state of cure.

Abstract: A device is disclosed which allows an object to be tuned to an incoming sound wave magnitude and wavelength, such that the sound wave will alternatively be passed therethrough without detectable reflection or be completely reflected. The apparatus is intended to be mounted within a hollow object and adjust the perceived distance between the exterior walls of that object to mimic a single thick wall. A signal processing means is supplied which detects the sound wave magnitude and wavelength impinging on the wall facing the sound wave source. The wavelength is passed to the signal processing means, which transmits a complimentary signal to the second wall of the hollow object. The complimentary signal allows the hollow object to resonate as a whole as if it were a solid of a thickness much different from its actual thickness, allowing the sound wave to pass undisturbed therethrough or be reflected therefrom.

Abstract: A method in which ionization associated with fine wire or solid electrode systems causes mist droplets to charge and collect on electrode surfaces or at a region of highest electrical stress. The method includes manipulating droplet clouds to reach high stress regions. This process achieves improved electrical strength by depositing a mist in optimum locations before voltage applications.

Abstract: System and method for detecting arcing faults in a dynamoelectric machine by monitoring the neutral lead of the machine for a radio frequency voltage produced by arcing, providing a warning signal in response to a change in the radio frequency voltage, and providing a shutdown signal in response to a radio frequency voltage greater than a predetermined level. An RF voltage coupler is capacitively coupled ot the neutrla lead, and a radio frequency monitor connected to the voltage coupler detects peaks in the RF voltage.

Abstract: System and method of detecting arcing faults in dynamoelectric machines by monitoring the voltage on the neutral grounding lead to detect RF voltages produced by arcing in the machine. The voltage is monitored by an RF voltage coupler and an RF monitor having a high impedance input amplifier. In one embodiment, the voltage coupler is clamped onto the neutral lead, and in another it is connected electrically in series with it.

Abstract: Disclosed is a method of monitoring physical and chemical changes in a host material which passes from a liquid state to a solid state. A waveguide is embedded in the host material while it is in the liquid or uncured state, the waveguide extending outside of the host material. A sound wave is sent through the waveguide and is monitored after it has passed through the host material. An article is also disclosed of a container having a liquid sealing exit means for waveguide, a waveguide which passes through the liquid sealing exit means into the container, a solidifiable liquid in the container at a level above the liquid sealing exit means, means outside the container for sending an acoustic wave through the waveguide into the container, and means outside the container for monitoring the acoustic wave after it has passed through said waveguide into the container.

Abstract: Disclosed is an apparatus which is resistant to electrical breakdown consisting of a chamber containing electrodes separated by dielectric gas supersaturated with the vapor from a dielectric liquid.

Abstract: A vapor-cooled power transformer characterized by a transformer within a sealed housing, and means for applying ultrasonic vibrations to a dielectric liquid within the housing in order to vaporize the fluid and to apply it to the exposed surfaces of the transformer.

Abstract: A dielectric fluid composition with high electrical strength characterized by a gas mixed with the vapor from a first fluid having a high vapor pressure at a low temperature and the vapor from a second fluid having a low vapor pressure at a low temperature to effect a mixture having a higher electrical strength than any component thereof over a temperature range from about -20.degree. C. to -40.degree. C. to about +120.degree. C. to +140.degree. C., with the vapor pressure of the mixture at the highest temperature being about one to two atmospheres. Also, the mixing of low and high cost liquids to obtain a low cost liquid with a vapor with an electrical strength equivalent or better than the best vapor over a wide temperature range.

Abstract: A dielectric fluid composition with high electrical strength characterized by a first fluid selected from the group consisting of electronegative gases, such as SF.sub.6, CCl.sub.2 F.sub.2, C.sub.2 F.sub.6, CF.sub.3 Cl, and CF.sub.4, and mixtures thereof; or from another group consisting of electropositive gases, such as N.sub.2 and CO.sub.2, and mixtures thereof; or from mixtures of the two groups; and a second fluid from a group of atomized liquids, which may be chlorinated liquid, such as, C.sub.2 Cl.sub.4 (tetrachloroethylene); and fluorocarbon liquids, such as, C.sub.8 F.sub.16 O (perfluorodibutyl ether), and mixtures thereof.

Abstract: Apparatus for detecting and locating corona discharges within the tank of an electrical apparatus. Acoustic waveguides are disposed within a tank of an electrical apparatus, with each having one end situated in proximity with a portion of the electrical apparatus to transmit acoustic emissions from the source of a corona or partial discharge to acoustic sensors located at remote locations.

Abstract: Apparatus for detecting and locating corona discharges within electrical apparatus. A continuous acoustic waveguide is disposed within the tank in proximity with the electrical apparatus and has first and second ends respectively coupled to first and second acoustic sensors. Acoustic emissions from a source of corona discharge within the electrical apparatus impinge upon the surface of the acoustic waveguide and are transmitted from any point thereon to the ends of the waveguide.