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Discharge coefficients of square-edged orifices for measuring the flow of air
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1929
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Unsteady FlowEngineeringFlow ControlMeasurementAerospace EngineeringFluid MechanicsPipe FlowDischarge CoefficientsPressure VesselFlow PhysicAerodynamicsFlow Nozzles 570Gas-liquid FlowFlow NozzleFlow MeasurementSquare-edged OrificesHydraulics
1. Air at pressures between 1 and 13 atmospheres was passed through squareedged concentric orifices installed in long, straight pipes of 4, 6, and 8 inches nominal diameter, the three pipes being in series.At each orifice the temperature and static pressure were observed, and the fall of pressure through the orifice was measured between pairs of taps located in each of the three ways commonly adopted in commercial orifice meter practice.2. The rate of flow was measured by throttling the air nearly to atmospheric pressure and discharging it through a flow nozzle on the end of the line.The design, calibration, and peculiarities of behavior of the nozzles are described, and the theory of this method of measurement is discussed in two appendixes.Such nozzles appear to be very satisfactory for use as primary standards.3. The various quantities known as discharge coefficients and used in orifice meter computations are defined.4. The experimental results are represented by equations connecting the values of the discharge coefficients with the ratio of orifice to pipe diameter and with the ratio of downstream to upstream static pressure.Tables of numerical values of discharge coefficients are also given.5. The accuracy of the results and the limitations to their general applicability are discussed. CONTENTS PagoI. Introduction 562 II.General plan of the investigation 562 III.Orifice plates 563 IV.Compressors and test line 565 V. Orifice stations 566 VI.Apparatus for measuring the rate of discharge 567 VII.Measurement of the rate of discharge 568 VIII.Remarks on flow nozzles 570 IX.Discharge coefficients of orfices for liquids 571 X. Discharge coefficients of orifices for gases 578 XI. Outline of the methods of computation 581 XII.Location of the pressure taps 584 1. Pipe taps 584 2. Throattaps 585 3. Flange taps 585 XIII.Method of analyzing the results 586 XIV.Results for throat taps 588 XV.Comments on the results for throat taps 594 XVI.Results for flange taps