Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Review of Scientific Instruments
62 (1991), S. 208-213
ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
The use of a surface acoustic wave (SAW) device for measuring rate of gas flow is described. A delay-line stabilized SAW oscillator is heated above the ambient by using a novel approach in which radio frequency (rf) energy is converted to heat via acoustic dissipation. This "self-heating'' arrangement eliminates the need for a separate heater and associated circuitry. Convective cooling caused by gas flow results in a change in the substrate temperature and thereby the oscillator frequency. The frequency of a 75-MHz oscillator fabricated on a 128° rotated Y-cut, X-propagating lithium niobate substrate is found to vary by more than 55 kHz for variation in flow rate from 0 to 500 cm3/min. A dual-oscillator configuration is implemented to provide temperature compensation and a convenient low-frequency output corresponding to flow rate. Adequate flow-sensing response is achieved with only modest (15 mW) oscillator loop power.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1142307
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