Abstract
In this paper, cylinder nozzles for low Reynolds mumber flow are dealt. The form of the device is very simple and only a circular sectional flow conduit is interposed among pipes as a restriction.
It is evident that the device confers a benefit upon measurement of small size pipe flow. As the first step of the research, the relations among the restriction diameter d, nozzle length l, and flow coefficient α, are found in the case of air flow. As the result of this experiment, it is shown that the flow coefficients of the cylinder nozzle which has the length l as long as 2 or 3 times the diameter d, remains constant for wide range of Reynolds number.
According to those results, an optimum relation between l and d is decided as l/d=3 and the flow coefficients are determined. These experiments are made with air and carbon-dioxide flow under the condition of the pipe diameter is 20.0mm, diameter ratio β is 0.200, 0.400, 0.600, 0.700, or 0.800, and the range of Reynolds number is about 2·103∼10·103. The experimental arrangements are shown in detail and the measurement accuracies of each instrument are discussed. Pressure distribution along the wall of cylinder nozzle and both the upstream and the downstream of the pipe are also measured.
