Projeto de um anemômetro térmico baseado em Termistor NTC com modelo linearizado por realimentação

Abstract

The velocity or volumetric flow measurement of laminar or turbulent flow flows meet various engineering applications. Thus, scientific research for the development of architectures and measurement techniques for these magnitudes is of great relevance and is constantly expanding. Among the existing architectures for anemometric applications in an indistinct flow regime, thermal denotes several advantages such as large bandwidth, spatial resolution and low cost. This is basically a thermistor connected to one of the arms of a modified Whetstone bridge. Although it has a simple configuration, it has some limitations imposed by the non-linear relation between the temperature and the signal applied to the sensor. In addition, it contributes as a limitation the physical parameters of the operational amplifier that composes the architecture. Therefore, it is proposed the design and implementation of a thermal anemometer architecture with voltage feedback linearization, using a thermoresistive sensor of the NTC type. This technique allows to obtain a linear relation between the temperature and the quantity used as input. Comparisons between the classic anemometer and the one advocated in this work are also promoted. The validation of the proposed architecture is conducted through simulations, as well as experimental comparison with classic and commercial instrument.