The Principles, Theory and Testing of a Flow Meter Insensitive to Velocity-Profile Distortions

An introduction is given to what is believed to be a novel form of low pressure-loss flow meter capable of integrating the mass, or volumetric, flow rate across a metering station within a duct or pipe. The principle of the flow meter, which incorporates a hydraulic integrator whose output is directly proportional to the mass, or volumetric, flow rate is described and associated essential theoretical analysis is presented. The design of a prototype flow meter is also described and reference is made to the method of construction employed. The results of tests carried out with the flow meter, and those of comparative tests using a conventional pitot-traverse technique, are reported. It was concluded that flow measurements made using the prototype meter agreed favorably with results obtained by pitot-traverse throughout the operating range of the flow rig. Tests are also described, which were carried out independently of the flow meter tests to establish the minimum length of straight ducting required up-stream of the meter between the meter and various types of fittings. This work indicates that the straight length requirements of the proposed flow meter are about 1/8 those of conventional orifice, nozzle or venturi meters.