Harmonic Pick-Up: Preliminary Mathematical Model for Interpretation
We devised a simple preliminary model simulating the geometry of a heat exchanger in order to interpret the measurements obtained with the pick-up. The exchanger is assumed to be a cylindrical fracture with radius Rf and thickness e, crossed in the centre by a boring with radius Rp, perpendicular to plane of the fracture. The transfer function between the flow at entry of fracture and the pressure measured at the same point depends biunivocally on the parameters e, Rp and Rf, and characterizes the fracture. We have drawn up a set of transfer functions, referred to as the spectral signatures. Identification of the parameters in situ is carried out by comparison of the experimental signature with this set of functions.
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