Pyroelectric anemometry: Frequency, geometry and gas dependence

A series of detailed experiments was conducted on two different types of pyroelectric anemometers: a two-electrode element, 3.8 mm X 3.8 mm X 200 mu m, and a six-electrode element, 7.8 mm X 3.8 mm X 200 mu m. An a.c. heating current provided a symmetric thermal signal to the electrodes and the differential response yielded an a.c. signal that depends on the flow of gas over the device. The behavior of the amplitude and phase of the differential response to frequency, gas composition, and geometry was measured. Aside from its value as a mass-flow sensor, the pyroelectric structure is a promising structure for more general studies of heat-transfer processes between fluids and solids.