111mhhgzVpgzVpll ++++=++αραρ)2/()/(or)2/(and)2/()/(222VDLfVKhVDLfhem⋅⋅⋅=⋅⋅=llz,VFWorkrr⋅=z)Re51.27.3/log(0.21fDef⋅+⋅−=(Colebrook equation)ContractionExpansionA1A2A1A2Area ratio, ARContraction loss coefficient, KcExpansion loss coefficient, KeθΔhθΔhTubeTubeAR=A2/A1AR=A1/A2
> 答案:?