圖示一矩形斷面通風(fēng)管道,斷面尺寸為1.2m×0.6m,空氣密度ρ=1.20kg/m3,流速v=16.2m/s,沿程阻力系數(shù)λ=0.0145,流程長度L=12m的沿程壓強(qiáng)損失為()
A.31N/m2 B.28.14N/m2 C.34.25N/m2 D.45.51N/m2
某一圓形有壓油管的直徑為d=150mm,流速v=0.256m/s,長1km,雷諾數(shù)Re=1921,其沿程損失hf為()
A.74.25cm油柱 B.74.25mH2O C.95.26cm油柱 D.62.26m油柱
半圓形明渠如圖所示,半徑r=4m,其水力半徑R為()
A.4m B.3m C.2.5m D.2m