GB719105A - Improvements in or relating to hot wire anemometers - Google Patents

Abstract

719,105. Hot-wire anemometers. NAPIER & SON, Ltd., D. March 17, 1953 [March 25, 1952], No. 7679152. Class 97(2) In a hot-wire anemometer comprising two electrically heated straight wires of which one, the detecting wire, is exposed to a gas stream of velocity equal or proportional to that under investigation and the second, the compensating wire, is affected by temperature changes of the stream but not substantially by its rate of flow, the two wires forming part of an electrical bridge circuit for detecting changes in the resistance of the wires, the wires are each extended between two supports one at least of which includes a resilient part arranged to tension the wire without appreciably stretching it. As shown, wires 5 and 5a are tensioned by Z-shaped resilient wires 4c between supports 4b, and are covered by protecting tubes 5b of fused silica, the wires being mounted in a housing oven at one end and with a large aperture 9 allowing free passage of gas over the detecting wire 5a, while the gas flow over the compensating wire 5 is reduced to a low rate by closing the wall 8 by the partition 10 and end wall 7b, except for apertures 8a and 10a respectively. In an alternative form, the wires are mounted side by side in the two halves of a housing partitioned down the centre.