Effects of fluid property variations on the response of hot-wire anemometers

The existence and magnitude of the influence of fluid property variations on the perturbation response of a constant-current hot-wire anemometer is investigated. Analysis and experiments indicate that unless the current injection technique is used for calibrating a constant-current hot-wire anemometer substantial errors will be introduced into the perturbation sensitivity calculation owing to omissions in the usually assumed form of the heat transfer relation for a hot wire.