Study of a Simple Linearization Technique of p-n-Junction-Type Anemometric Flow Sensor

A p-n-junction-type flow sensor is used to measure the mass flow rate of a fluid through a pipeline by using anemometric principle. In this transducer, the cooling effect of a flowing fluid on the forward resistance of a constant-current or a constant-voltage p-n junction diode is utilized to sense the mass flow rate of the fluid flowing in contact with the diode surface. However, the main drawback of the sensor is that its flow characteristic is nonlinear. In this paper, a very simple linearization technique of a p-n-junction-type anemometric flow sensor has been proposed. The theoretical characteristic equation of this sensor has been derived. A prototype unit has been developed and fabricated, and its performance characteristic has been experimentally determined. The experimental results are reported in this paper. From these experimental data, a very good linear characteristic of the proposed flow sensor has been observed.