ABSTRACT
This chapter discusses some of the popularly employed techniques and devices for flow measurements. Mass and volume flow measurements become essential in many applications of practical interest. The principle involved in flow measurement may cover a wide variety of areas incorporating steady and unsteady flow of liquids, gases, two-phase media, and laminar and turbulent flows. Most of the displacement meters are basically positive-displacement meters, used for volume flow measurements. Indirect methods determine the flow rate from the measurement of quantities other than the flow rate. Some of the popularly used devices for indirect measurement of mass flow are the variable-head meter, drag-body meter, pitot tube, variable-area meter, mass flow meter, and hot-wire anemometer. All meters which measure the pressure drop across a restriction in a pipeline are variable-head meters. The stagnation pressure and temperatures can be measured easily, therefore the sonic nozzle is considered to be a convenient device for measuring gas flow rates.
