Flow rate measurement method and apparatus

摘要

[TECHNICAL PROBLEM] To provide a method and apparatus capable of accurately measuring a flow rate using Gaussian quadrature even under a small number of measurement points. [SOLUTION TO THE TECHNICAL PROBLEM] An average for the y-coordinate of values of normal-directional component with respect to the cross-section represented by v z0 (x, y) among an estimated flow velocities in a flow passage cross-section is used as V z0 (x), and a weighting function of Gaussian quadrature is set to V z0 (x)L(x), where L(x) = y max (x) - y min (x). Further, an average for y of values of normal-directional component with respect to the cross-section of an actual flow velocity represented by v z (x, y) is used as V z (x), and an integrand is set to V z (x)/V z0 (x). These values are used to determine an approximate value of a flow rate according to Gaussian quadrature. In addition, a method of virtually offsetting zero-point of the flow velocity distribution to apparently avoid a problem such as reverse flow is provided.