Pyroelectric anemometry: Theory of operation

A thermal model is developed to describe the electrical response of a new thermal flow sensor, the pyroelectric anemometer (PA), as a function of the laminar flow rate. For low Reynolds numbers (Re), i.e., Re less than or equal to Re-c, the PA response is proportional to Re. For Re > Re-c, the PA response is proportional to root Re. The critical Reynolds number, Re-c, is a function of the gas's thermophysical properties, the thermal excitation frequency, and the spacing of the measuring electrodes relative to the central heater strip. The theoretical predictions are compared with experimental observations. The Reynolds numbers examined in this study range from 0.01 to 10(4). To provide a more critical test of the model, no 'adjustable' parameters are introduced into the theory. The deviations between the theory and experiment can be accounted for by the limitations of the idealized theoretical treatment of the problem.