Frequency response of a thermocouple wire: Effects of axial conduction
Abstract
Theoretical expressions are derived for the steadystate frequency response of a thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a uniform thermocouple wire and a nonuniform wire with unequal material properties and wire diameters across the junction. For the case of a uniform wire, the amplitude ratio and phase angle compare favorably with the series solution of Scadron and Warshawsky (1952) except near the ends of the wire. For the case of a nonuniform wire, the amplitude ratio at low frequency omega yields 0 agrees with the results of Scadron and Warshawsky for a steadystate temperature distribution. Moreover, the frequency response for a nonuniform wire in the limit of infinite length l yields infinity is shown to reduce to a simple expression that is analogous to the classic first order solution for a thermocouple wire with uniform properties.
 Publication:

National Aeronautics and Space Administration Report
 Pub Date:
 September 1990
 Bibcode:
 1990nasa.reptS....F
 Keywords:

 Conductive Heat Transfer;
 Temperature Distribution;
 Temperature Effects;
 Thermal Conductivity;
 Thermocouples;
 Wire;
 Boundary Conditions;
 Low Frequencies;
 Nonuniformity;
 Phase Shift;
 Steady State;
 Instrumentation and Photography