Question

A certain part of cast iron piping of a water distribution system involves a parallel section. both parallel pipes have a diameter of 30 cm, and the flow is fully turbulent. one of the branches (pipe

a.is 1500 m long, while the other branch (pipe
b.is 2650 m long. if the flow rate through pipe a is 0.4 m3/s, determine the flow rate through pipe
b. disregard minor losses and assume the water temperature to be 15°c. is the flow turbulent or laminar

Answer 1

Flow rate through pipe a is 0.4 m3/s Parallel pipes have a diameter D = 30 cm => r = 15 cm = 0.15 m Length of Pipe a = 1000m Length of Pipe b = 2650m Temparature = 15 degrees Va = V / A = (0.4m3/s) / (3.14 (0.15m)^2) = 5.66 m/s h = (f(LV^2)) / D2g (fa(LaVa^2)) / Da2g = (fb(LbVb^2)) / Da2g and Da = Db; fa = fb LaVa^2 = LbVb^2 => La/Lb = Vb^2/Va^2 Vd^2 = Va^2(La/Lb) => Vb = Va(La/Lb)^(1/2) Vb = 5.66 (1000/2650)^(1/2) => 5.66 x 0.6143 = 3.4769 m/s Vb = 3.4769 m/s V = AVb = 3.14(0.15)^2 x 3.4769 m/s = 0.245 m^3/s