An airflow sensor based on unsteady pressure measurement

An airflow sensor based on pressure measurement is proposed. This technique employes one-dimensional flow equations in finite differential forms. The equations were applied to a cell located at the inlet of a circular pipe. The pressure was atmospheric at the pipe inlet and the pressure at the cell boundary Delta-x apart from the pipe inlet was measured. The velocity was therefore calculated instantaneously by the flow equations from the measured pressure. This technique has the following features: non-intrusiveness, automatic reverse flow detection, independence of initial conditions, and minimum pressure loss. The technique also can be extended to a compressible flow. (Author)