Angular Characteristics of Resistance Asymmetry Coeffi cient in a Single-Wire Reverse Flow Sensor

Angular Characteristics of Resistance Asymmetry Coeffi cient in a Single-Wire Reverse Flow Sensor Author: J. Kielbasa  In this article the author discusses a single hot-wire probe for the detection of reverse fl ow velocity. The probe is modifi ed by introducing a third holder into which the middle section of the wire is inserted. Due to this modifi cation, voltage Uw is achieved within the whole wire and voltage Um is achieved in the middle section of the wire. The asymmetry coeffi cient k of the probe can be calculated from these voltage values. When the probe is placed in a fl ow, the coeffi cient k depends additionally on the angle α between the wire axis and the velocity vector, on the angle β between the rotation plane of the wire and the velocity vector, and on the velocity v. During the probe assembly there are always some inaccuracies that cause initial asymmetry of the resistance distribution in both sections of the heated wire. These are included in the probe asymmetry coeffi cient as the calculated average of all α angles.

 

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