Considerações de projeto para anemômetros a fio quente baseado em estruturas realimentadas.

Abstract

Anemometers based on the measurement principle of the fluid velocity using heat transfer and heated electrically thermo-resistive sensor are called Hot wire anemometer. They can be classified as an measurement electrical instrument because the sensor used has one of its electrical parameter modified in presence of the fluid velocity variation. In order to obtain a fluid velocity from a electric parameter one use the electrical equivalence principle in the measurement structures. Among measurement structures that use such a principle, it was investigated the called Constant Temperature Anemometer - CTA. This dissertation consists of establishing a methodology to be used in design of fluid velocity measurement systems based on feedback structures using PWM excitation, beyond procedures for sensor characterization, circuits of fluid temperature compensation and a data acquisition system. Based on the methodology presented in this dissertation, it was developed a CTA with PWM excitation which measures air velocity.