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Lynnworth, L. C.

Publications and source records attributed to Lynnworth, L. C..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Ultrasound propagation measurements and applications

This paper reviews three systems designed for accurately measuring the propagation of ultrasonic pulses. The three systems are presented in order of velocity-measuring precision: + or - 100 ns, + or - 1 ns, + or - 0.2 ns. Also included is a brief discussion of phase and group velocities, with reference to dispersive, highly attenuating materials. Measurement of attenuation by pulse-echo buffer rod techniques is described briefly. These techniques and instruments have been used to measure sound velocity and attenuation in a variety of materials and shapes, over a wide temperature range.

Lynnworth, L. C.↗
NASA NTRS1976

Magnetostrictive ultrasonic probes

The principles underlying the design and use of magnetostrictive ultrasonic probes is illustrated by oscillograms and sketches. Attention is given to such concepts as magnetostrictive transduction, broadband pulse shaping, guided wave propagation, wave impedance, reflection, transmission, and attenuation coefficients, coupling methods, and impulse-induced resonance. A number of applications of such probes are discussed including the measurement of elastic moduli, temperature, and acoustic emission and resonance studies.

Lynnworth, L. C.↗
NASA NTRS1973

Ultrasonic measurement of elastic moduli in slender specimens using extensional and torsional wave pulses.

The pulse-echo method using extensional and torsional waves is described relative to determining elastic properties and other characteristics of specimens which are slender acoustically. Several applications are reviewed, including: glass fibers of diameter 16 to 42 microns; glass rods of diameter about 1 mm, tested to 700 C; iron-base alloys of diameter 3.2 mm, tested from nearly -200 up to +200 C; titanium specimens of rectangular cross section, 1.5 by 3 mm; and tantalum-base alloys of diameter 6.4 mm, tested up to 1400 C. Limitations are pointed out regarding dispersive materials and geometry.

Lynnworth, L. C.↗
NASA NTRS1973

Nonintrusive dynamic flowmeter

Description of some of the design and performance characteristics of an ultrasonic dynamic flowmeter which combines nonintrusiveness, fast response, high accuracy, and high resolution and is intended for use with cryogenic liquids and water. The flowmeter measures to 1% accuracy the dynamic as well as the steady flow velocity averaged over the pipe area.

Pedersen, N. E.↗
NASA NTRS1972

Prototype ultrasonic instrument for quantitative testing

A prototype ultrasonic instrument has been designed and developed for quantitative testing. The complete delivered instrument consists of a pulser/receiver which plugs into a standard oscilloscope, an rf power amplifier, a standard decade oscillator, and a set of broadband transducers for typical use at 1, 2, 5 and 10 MHz. The system provides for its own calibration, and on the oscilloscope, presents a quantitative (digital) indication of time base and sensitivity scale factors and some measurement data.

Lynnworth, L. C.↗
NASA NTRS1972

Ultrasonic thermometry using pulse techniques.

Ultrasonic pulse techniques have been developed which, when applied to inert gases, provide temperature measurements up to 8000 K. The response time can be less than 1 msec. This is a significant feature in studying shock-heated or combusting gases. Using a momentary contact coupling technique, temperature has been measured inside steel from 300 to 1500 K. Thin-wire sensors have been used above 2000 K in nuclear and industrial applications where conditions preclude the use of thermocouples, resistance devices, or optical pyrometers. At 2500 K, temperature sensitivity of 0.1% is obtained in Re wire sensors 5 cm long by timing five round trips with an electronic instrument that resolves the time interval between selected echoes to 0.1 microsec. Sensors have been operated at rotational speeds over 2000 rpm and in noisy environments. Temperature profiling of up to ten regions using only a single guided path or beam has also been accomplished.

Lynnworth, L. C.↗
NASA NTRS1968

Ultrasonic temperature measuring device

Pulse echo ultrasonic system automatically determines the temperature in the core of a nuclear rocket engine by measuring the transit time of an acoustic pulse in a wire sensor. The measurement is based on the fact that the speed of sound in the sensor material is a function of temperature.

Carnevale, E. H.↗