Question

Using the Kline-McClinktock Method

17. A certain obstruction-type flow-meter (orifice, venture, nozzle), shown in the figure, is used to measure the flow of air at low velocities. The relation describing the flow rate is m = c A 20(21 – P2)]"?, where C = empirical-discharge coefficient A = flow area Pị and P2 = the upstream and downstream pressures, respectively T1 = upstream temperature R= gas constant for air Calculate both the uncertainty and percentage uncertainty in the mass flow rate for the following conditions: C = 0.96 +0.005 (from calibration data) P1 = 25 psia + 0.5 psia Ti = 70 °F +2 °F Ap = pi - P2 = 1.4 psia + 0.005 psia (measured directly) A = 1.0 in? + 0.001 in? b e directis;

Answer 1

C=0.961 0.005 = 25 $312 10:5p5ia Ti = 0f 207 Ap = (P-fa) = 1-4 psia to.co5psia 4 = 100 I 0.colin Y? (= empirical-discharge mee? coefficient za papi (pi-Ba A =fice rate m = D.q6v2.0.2135 h Pi&B= the upstream and downstream pressure - respectively 1.57X70 m = 0.0545 kq1s! ? = upshermo tropeia trece P = gasconstant for air. Unaitannity of flow of air - Y Am 276-5 0-0545 21 25 An = 0.0025kgls flow rate m = 0.0545 I 0:0025 kg/s