Abstract:
A method for measuring the differential emissivity between two sites on the surface of a body and the temperature of the two sites. The method includes a plurality of measurements of the infrared radiation arising from each of the two sites under a number of different conditions. Some of the measurements include irradiation by external infrared radiation at a known wavelength and intensity. The infrared radiation arising from each of the sites may include emitted radiation, reflected ambient radiation, and reflected external radiation. Additionally, the temperature determined using the method described can be used to calibrate infrared imaging devices used to inspect the entire body.
Abstract:
Apparatus and method for monitoring vibration levels in rotatable machinery (52). In one embodiment, a system (50) includes a source (66) for generating coherent radiation (70) and a first partially transmissive, partially reflective device (90) positioned to receive radiation (70) from the source (66) and transmit a part of the radiation there through. A second partially transmissive, partially reflective device (100) is mounted to the machinery (52), positioned to reflect a first signal (72) and transmit radiation (70) transmitted by the first device (90). A third device 104) is mounted to the machinery (52) and positioned to reflect radiation transmitted through the second device to provide a second signal (78). Circuitry (82, 86) is configured to generate an electrical signal based on a combination of the first and second signals (72, 78), and processing circuitry (114) provides a value indicative of vibration amplitude occurring in the machinery (52) based on the combination of the first and second signals. An embodiment of an associated method includes providing a first radiation signal (70) of a first frequency, deriving second and third radiation signals (78A, 78B) each having a time-varying Doppler shifting frequency relative to the first signal, and providing a value indicative of vibration amplitude occurring in the machinery (52) based on a combination of the second and third signals.
Abstract:
A method of measuring vibration in a bladed rotor structure with a vibration monitor. The vibration monitor includes a sensor for sensing passage of the sensor targets on radially outer portions of the blade structure, and the sensor generates signals corresponding to target passing events. An excitation structure is provided including at least one air jet for providing an excitation force to the blade structure. The blade structure is rotated about an axis of rotation and the air jet is driven in a circular path about the axis of rotation at a different rotational speed to apply a non-synchronous excitation force to the blade structure.
Abstract:
A method and apparatus for monitoring vibrations in a blade structure of a turbine including generating signals from a probe located adjacent to a radial outer edge of the blade structure to provide signals corresponding to vibrations at predetermined locations along the tips of the blades. A leading edge of a blade tip is detected during a blade tracking operation, and a known location along the length of the blade tips is monitored during a vibration measurement operation. The measurement operation may be performed simultaneously with the tracking operation to provide measurements as the axial location of the blades change during transitional modes of operation of the turbine.
Abstract:
A method of matching sensors in a multi-probe blade vibration monitor for a turbine. The method includes providing at least two probes mounted in a casing of the turbine adjacent to a rotating blade structure of the turbine. Targets are provided on radially outer portions of the blade structure. Each of the probes includes a sensor generating signals corresponding to target passing events, and a set of synchronous harmonics of the rotational speed of the rotor are produced for each sensor. The position of the sensors is adjusted such that the sets of harmonics of the sensors are substantially matched, indicating that the positions of the sensors are matched.
Abstract:
In some instances, ice can form on the surface of a compressor airfoil. If the ice dislodges, it can impact and damage other compressor components. Aspects of the invention relate to systems for detecting the presence of ice or water on a compressor vane during engine operation. A ceramic insulating coating can be deposited on a portion of the surface of the vane. A heater and a thermocouple can be provided near the outermost surface of the coating such that the thermocouple can sense heat from the heater. The heater and the thermocouple can be provided within the coating. The presence of water film and/or ice on the coating surface can be detected by taking a thermocouple measurement following a heater pulse. The presence of a water film or ice results in a delay in the temperature rise detected by the thermocouple.
Abstract:
In some instances, ice can form on the surface of a compressor airfoil. If the ice dislodges, it can impact and damage other compressor components. Aspects of the invention relate to systems for detecting the presence of ice or water on a compressor vane during engine operation. A ceramic insulating coating can be deposited on a portion of the surface of the vane. A heater and a thermocouple can be provided near the outermost surface of the coating such that the thermocouple can sense heat from the heater. The heater and the thermocouple can be provided within the coating. The presence of water film and/or ice on the coating surface can be detected by taking a thermocouple measurement following a heater pulse. The presence of a water film or ice results in a delay in the temperature rise detected by the thermocouple.
Abstract:
Aspects of the invention relate to a system for assessing the condition of a thermal barrier coating on a turbine vane during engine operation. According to embodiments of the invention, one or more wires can be passed along the airfoil portion of the vane. The wires can extend over, within, or beneath the thermal coating. An electrical current can be passed along the wires, and electrical resistance can be measured across the wires. Thus, if a portion of the thermal coating becomes damaged, then the wires located in that area may break. A disconnect in the wires can lead to an increase in resistance across the wires, which can alert an operator to a problem. Some assessment systems can provide a general indication of the magnitude of damage and whether the damage is spreading.
Abstract:
Non-synchronous vibrations in blades on a rotating wheel, such as a turbine wheel, are measured using Fourier analysis adjusted to correct for uneven sampling produced by a pair of probes spaced from each other about the wheel by a probe angle (PA) other than 180.degree.. The Fourier transform matrix is phase shifted by an amount which is a function of the PA which is other than 180.degree., and the harmonic in which the mode of non-synchronous vibration is expected to be found. A scaling factor in the form of an inverse correction factor is applied to the frequency spectra produced by the phase shifted Fourier transform matrix to generate an output representative of the frequency and amplitude of the true excitation frequency which can be presented on a display.
Abstract:
The present invention provides a valve control apparatus which can be programmed to deliver a desired flow of gas. A valve 22 is connected to a stepper motor 28 which is controlled by a computer 32 to open or close the valve in steps within a gas flow line 24 to deliver a desired rate of flow. A flowmeter 30 is provided along the gas flow line 24 for measuring the flow and inputting this flow to the computer 32. The computer 32 calculates rate of flow information obtained from the flowmeter 30 and controls the stepper motor 28 to open or close the valve 22 as necessary in accordance with the received rate of flow information and a desired rate of flow preprogrammed into the computer 32. As a result, a precise desired rate of flow can be obtained. Also, position indicators 34 may be added to the valve 22 to indicate when the valve 22 is completely open or completely closed. The valve 22 may be provided with a return spring 36 to automatically close the valve 22 in the event of a power loss. The computer 32 may be programmed to detect a significant increase in the rate of gas flow being closing the valve 22 accordingly. Additionally, a pressure switch 38 may be provided along the gas flow line 24 to cause the valve 22 to close upon a pressure change. Finally, temperature 40 and pressure 42 sensors may be added along the gas flow line so that the computer 32 can calculate and maintain a specific mass flow of gas.