Chapter 6 Steady closed-conduit flow A 6. 1 Exponential pipe-friction formulas 6.2 Single pipes 6.3 Hydraulic and energy grade lines 6. 4 The siphon 65Pⅰ pes in series 6.6 Pipes in parallel 6.7 Networks of pipes
Chapter 6 Steady closed-conduit flow • 6.1 Exponential pipe-friction formulas • 6.2 Single pipes • 6.3 Hydraulic and energy grade lines • 6.4 The siphon • 6.5 Pipes in series • 6.6 Pipes in parallel • 6.7 Networks of pipes
Purpose of calculation for steady pipe-flow To get the pump head To get the conveyance flow Design the diameter of pipes Analysis the pressure change
Purpose of calculation for steady pipe-flow • To get the pump head • To get the conveyance flow • Design the diameter of pipes • Analysis the pressure change
6.1 Exponential pipe friction formulas Industrial pipe-friction RO formulas commonly used: L Dm In which R=10675/Cn n=1.852,m=48704 Extremely smooth, straight pipes;asbestos-cement 130 Very smooth pipes; concrete; new cast iron 120 Wood stave: new welded steel c= 110 Vitrified clay new riveted steel 100 Cast iron after years of use 95 Riveted steel after years of use 60to80 Old pipes in bad condition
6.1 Exponential pipefriction formulas n f m h RQ L D = Industrial pipe-friction formulas commonly used: 10.675/ n R C = n m = = 1.852, 4.8704 In which 140 130 120 110 100 95 60 80 c to = Extremely smooth, straight pipes; asbestos-cement Very smooth pipes; concrete; new cast iron Wood stave; new welded steel Vitrified clay; new riveted steel Cast iron after years of use Riveted steel after years of use Old pipes in bad condition
o K In which K--- the flow modulus, and is different with the shape size and the roughness of the section So--- resistivity, with the dimension [T2/L6] K=ACVR=v8/82Td25 64 81 k- cd gd
2 2 f 2 0 Q h l S Q l K = = In which: K --- the flow modulus, and is different with the shape, size and the roughness of the section. S0 --- resistivity, with the dimension [T2/L6]. 2.5 0 2 2 2 5 2 5 / 8 1 64 8 K AC R g d S k C d g d = = = = =
v21.2m/s, So=0.001735/d urbulent fl <1.2m/s,S=(1+ 0.867030.001478 53 Transition flow
5.3 0 0.3 0 5.3 1.2m/s, 0.001735/ 0.867 0.001478 1.2m/s, (1 ) v S d v S v d = = + Wholly turbulent flow Transition flow