Flow Coefficient of Area-Type Flowmeter

Flow coefficient measured by an area-type flowmeter can be represented as a function of the Reynolds number through a series of experiments. From the experimental results obtained in this study, it was clarified that the characteristic curve can be divied into three ranges, that is, the viscous flow range, the intermediate flow range and the nonviscous flow range depending on the value of the Reynolds number.At first, in the viscous flow range, laminar flow theory can be adoped suitably to the flow at the clearance between the taper-tube and float. Secondary, in the intermediate flow range, the values of the two sorts of coefficient, that is, one is that for geometry of the clearance between the taper-tube and the float and the other is that for the distribution of flow rate, were obtained as a function of the Reynolds number experimentally.And then, it was observed that the float with sharp edge was useful for the measurement of viscous flow.Furthermore, the nonviscous flow range seems to be a special case of the intermediate flow range because the nonviscous flow range corresponds to the case of an extremely, large Reynolds number in the intermediate flow range.From the discussions on the value of α done above, the following experimental equations were derived.Those equations are well representing the experimental results with a high degree of approximation.α=α0(Re/Re0)1/2for the viscous flow rangeα=α0(1-K/√Re)(-1N/√Re)for the intermediate flow rangewhere α; flow coefficientα0; flow coefficient of nonviscous flow rangeRe, Reθ; Roynalds number (Re0 is obtained through the experiment)K; coefficient of rate distribution depending on Reynold numberN; coefficient geometrical condition depending on Reynolds number