Action of the Fluid in the Air-Micrometer : 2nd Report, Characteristics of Small-Diameter Nozzle and Orifice, No.2,In the Case of Compressibility Being Considered

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The discharge characteristics of nozzle or orifice for high-pressure type air-micrometer were investigated for pressure difference from 0.2 kg/cm^2 to 3.0 kg/cm^2 over a range of pressure ratio from 0.25 to 0.95. The experiment has revealed the following : 1. By plotting (c : discharge coefficient of incompressible fluid, ε : expansion factor) against the pressure ratio, using parameter l/d, a nearly linear relation is obtained. For rounded nozzle, cylindrical nozzle and knife-edged orifice, a change of flow regime occurs respectively at the pressure ratio of 0.53,0.55,and 0.63. 2. The values of cε at a position where the pressure ratio is equal to 1 agree with discharge coefficients of incompressible fluid over the so-called "limit of constancy"of Reynolds number. 3. Discharge coefficients of each type of nozzle and orifice were collected and one experimental formula is worked out for each. 4. Downstream pressure and temperature are recovered at a position respectively 5 times and 4 times the pipe diameter. 5. Recovery rate of pressure was nearly same as in 1 st Report.