ABSTRACT
This chapter deals with the fundamental principles of hot-wire anemometry as applied to the study of turbulence and unsteady laminar flows in wind streams. The vital component in a hot-wire anemometer system is the hot-wire filament. The hot-wire filament may be regarded as an infinitely long, straight cylinder in cross flow. The wires used in cross-wire probes should have the same diameter, length, and resistance. In practice, making such probes is difficult and requires a lot of caution and experience. The constant current hot-wire anemometer may also be employed for measuring fluid temperature. Platinum-rhodium alloy wire is also used instead of pure platinum to give extra tensile strength to the hot-wire element. The turbulent fluctuations are usually measured by suitable configuration of the hot-wire probe. The hot-wire anemometer will prove to be an extremely useful instrument to get an insight into the turbulence characteristics, if properly made standard probes are used.
