Compensação da temperatura do fluido em anemômetros a fio quente.

Abstract

A hot-wire anemometer sensor is influenced not only by the fluid velocity, but also by the fluid temperature 7). Hence, for accurate fluid velocity measurement, compensation must be provided for the effect of fluid temperature variations. In the literature, configurations described for compensating the effect of variations in fluid temperature T/ in hot-wire anemometers, usually employ two sensors. The constant temperature hot-wire anemometer is the most widely used. This anemometer configuration has the shortest response time, which allows its use in instantaneous velocity measurements in transient and turbulent fluid flows. The present work, analyses existing methods of compensating for fluid temperature variations and investigates the possibility of compensation with a single sensor, for a constant temperature anemometer. A mathematical model was developed to simulate the constant temperature hot wire anemometers. This model includes the dynamic response limitations of the sensor and operational amplifier. Another important aspect covered in this work is the study of the influence of the amplifier input offset voltage on fluid velocity measurements and proposals for its compensation.