摩擦損失係数
5 F B ) {\displaystyle X_{4}=R(0.032-3F_{A}+0.5F_{B})} F A = Y 3 − 2 {\displaystyle F_{A}=Y_{3}^{-2}} F B = F A ( 2 − 0.00514215 Y 2 Y 3 ) {\displaystyle F_{B}=F_{A}\left(2-{\frac {0.00514215}{Y_{2}Y_{3}}}\right)} Y 2 = ε 3.7 D + 5.74 R e 0.9 {\displaystyle Y_{2}={\frac {\varepsilon }{3.7D}}+{\frac {5.74}{Re^{0.9}}}} Y 3 = − 0.86859 ln  ( ε 3.7 D + 5.74 4000 0.9 ) {\displaystyle Y_{3}=-0.86859\ln \left({\frac {\varepsilon }{3.7D}}+{\frac {5.74}{4000^{0.9}}}\right)}
f = 0.25 [ log 10  ( ε 3.7 D + 5.74 R e 0.9 ) ] − 2 {\displaystyle f=0.25\left[\log _{10}\left({\frac {\varepsilon }{3.7D}}+{\frac {5.74}{Re^{0.9}}}\right)\right]^{-2}}