Absolute Low Speed Anemometer

Abstract

An absolute anemometer suitable for measurements in gases under a wide variety of conditions is described. The instrument, based on an idea first used by Kovasznay, utilizes the temperature fluctuations in the wake of a sinusoidally heated fine wire as tracer. A second hot‐wire detects the fluctuations, and the phase change between two successive positions of this wire can be used to determine the free stream velocity. The technique is shown to have good spatial resolution and an accuracy better than 2% in the velocity range 40–400 cm/sec. Sources of error and various experimental conditions are discussed in detail.