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Barranger, J. P.

Publications and source records attributed to Barranger, J. P..

18 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Ramp-integration technique for capacitance-type blade-tip clearance measurement

The analysis of a proposed new technique for capacitance type blade tip clearance measurement is presented. The capacitance between the blade tip and a mounted capacitance electrode within a guard ring forms one of the feedback elements of a high speed operational amplifier. The differential equation governing the operational amplifier circuit is formulated and solved for two types of inputs to the amplifier - a constant voltage and a ramp. The resultant solutions shows an output that contains a term that is proportional to the derivative of the product of the input voltage and the time constant of the feedback network. The blade tip clearance capacitance is obtained by subtracting the output of a balancing reference channel followed by integration. The proposed sampled data algorithm corrects the environmental effects and varying rotor speeds on-line, making the system suitable for turbine instrumentation. System requirements, block diagrams, and typical application are included.

Sarma, G. R.↗
NASA NTRS1984

Eddy current jet engine disk-crack monitor

A disk-crack monitor is described that is suitable for use on the ground or in flight. The system consists of an engine-mounted eddy current sensor, a series capacitance in each leg of the sensor circuit, and a capacitance-conductance bridge followed by an oscilloscope capable of advanced signal processing. It was applied to the detection of service-induced cracks in the first-stage turbine wheel of a helicopter engine. A 3.5 mm long radial fatigue crack plus smaller cracks, all located in the blade root region of the wheel, were detected during engine test stand operation at ground idle speed and temperature. The calculation of the value of series capacitance is also presented.

Barranger, J. P.↗
NASA NTRS1983

Precision optical angular position marker system for rotating machinery

An optical system is described which generates one or more markers of the angular shaft position of rotating machinery. The system consists of a light source, an optical cable, a machinery mounted lens assembly, a light detector, and a signal conditioner. Light reflected by targets on the rotor is converted to a digital output signal. The system is highly immune to extreme environments of vibration and temperature and achieved a 0.002 percent precision under operational test conditions.

Barranger, J. P.↗
NASA NTRS1980

Laser-optical blade tip clearance measurement system

The need for blade tip clearance instrumentation has been intensified recently by advances in technology of gas turbine engines. A new laser-optical measurement system has been developed to measure single blade tip clearances and average blade tip clearances between a rotor and its gas path seal in rotating component rigs and complete engines. The system is applicable to fan, compressor and turbine blade tip clearance measurements. The engine mounted probe is particularly suitable for operation in the extreme turbine environment. The measurement system consists of an optical subsystem, an electronic subsystem and a computing and graphic terminal. Bench tests and environmental tests were conducted to confirm operation at temperatures, pressures, and vibration levels typically encountered in an operating gas turbine engine.

Barranger, J. P.↗
NASA NTRS1979

Laser-optical blade tip clearance measurement system

A laser-optical measurement system was developed to measure single blade tip clearances and average blade tip clearances between a rotor and its gas path seal in rotating component rigs and complete engines. The system is applicable to fan, compressor and turbine blade tip clearance measurements. The engine mounted probe is particularly suitable for operation in the extreme turbine environment. The measurement system consists of an optical subsystem, an electronic subsystem and a computing and graphic terminal. Bench tests and environmental tests were conducted to confirm operation at temperatures, pressures, and vibration levels typically encountered in an operating gas turbine engine.

Barranger, J. P.↗
NASA NTRS1978

In-place recalibration technique applied to a capacitance-type system for measuring rotor blade tip clearance

The rotor blade tip clearance measurement system consists of a capacitance sensing probe with self contained tuning elements, a connecting coaxial cable, and remotely located electronics. Tests show that the accuracy of the system suffers from a strong dependence on probe tip temperature and humidity. A novel inplace recalibration technique was presented which partly overcomes this problem through a simple modification of the electronics that permits a scale factor correction. This technique, when applied to a commercial system significantly reduced errors under varying conditions of humidity and temperature. Equations were also found that characterize the important cable and probe design quantities.

Barranger, J. P.↗
NASA NTRS1977

Application of a flight-line disk crack detector to a small engine

A disk crack detector was developed and applied to a small military engine for use as a flight-line turbine crack monitor. The system consists of an eddy current type sensor and its cables within the engine, external connecting cables, and a remotely located electrical capacitance-conductance bridge and signal analyzer. As the turbine spins, the rotor is monitored by the sensor for radial surface cracks emanating from the interblade region of the rotor.

Barranger, J. P.↗
NASA NTRS1975

In-service turbine wheel crack monitor

System can be utilized in flight or at flight line. It monitors disk rim for surface cracks emanating from blade root interface. System consists of eddy-current sensor, mounted approximately 1 1/2 mm (1/16 in) away from face of disk, and remotely located electrical capacitance-conductance bridge and signal analyzer.

Barranger, J. P.↗
NASA NTRS1974

Study of a flight monitor for jet engine disk cracks using the critical length criterion of fracture mechanics

A disk crack detector is discussed which is intended to operate while in flight. The crack detector monitors the disk rim for radial surface cracks emanating from the blade root interface. An eddy current type sensor with a remotely located capacitance-resistance bridge and signal analyzer is able to detect reliably a simulated crack 1/8 in. long. The sensor was tested at rim velocities of 600 fps and at 1000 F. Fracture mechanics is used to calculate the critical crack length. Knowledge of the crack growth rate permits the calculation of the number of stress cycles remaining for the detected crack to grow to critical size. A plot is presented of the remaining life as a function of the critical crack length and the operating stress. It is shown that for a disk of Inconel 718 a through-the-thickness crack operating under a rim stress of 50 kpsi has a critical length of 0.7-in. and a remaining life of 130 flights.

Barranger, J. P.↗
NASA NTRS1973

Flight monitor for jet engine disk cracks and the use of critical length criterion of fracture mechanics

A disk crack detector is discussed which is intended to operate under flight conditions. It monitors the disk rim for surface cracks emanating from the blade root interface. An eddy current type sensor, with a remotely located capacitance/conductance bridge and signal analyzer, can reliably detect a simulated crack 3 mm long. The sensor was tested on a spinning turbine disk at 540 C. Tests indicate that the system is useful at disk rim velocities to 460 m/sec. By using fracture mechanics, it is shown for Inconel 718 th at a crack operating under a rim stress of 34 x ten to the 7th power N/sqm has a critical length of 18 mm.

Barranger, J. P.↗
NASA NTRS1972

High temperature permeameter for measuring magnetic properties

Instrument for measuring magnetic permeability of materials undergoing heat treatment as method for monitoring stress relief and tempering is described. Procedure is based on magnetic potentiometer principle with yoke compensating coils to cancel effects of reluctance of yoke and joint gaps. Instrument is heated with specimen being heat treated.

Barranger, J. P.↗
NASA NTRS1972

Permeameter for high-temperature magnetic measurements

A permeameter is described that measures the magnetizing force and the corresponding magnetic induction up to 1000 C. The two symmetrical yokes are made of an alloy of 9 percent iron, 91 percent cobalt. A coil surrounding the specimen supplies a magnetizing force of up to 100 oersteds. The instrument uses the magnetic potentiometer principle to cancel the effects of the reluctance of the yoke and the joint gaps. Very close agreement was obtained at room temperature when compared to an MH type permeameter. The effect of temperature on the normal induction curves for the yoke material is also presented.

Barranger, J. P.↗
NASA NTRS1966

Process yield Co-Fe alloys with superior high temperature magnetic properties

Cobalt-iron alloys containing from 7.0 to 9.3 percent iron prepared from ultrapure cobalt and iron have the highest Curie point of all known magnetically soft materials. Their high permeability, low hysteresis loss, good saturation induction, and square loop characteristics recommend them for use in power transformers and rotating machinery.

Barranger, J. P.↗