單項選擇題

如圖所示突然放大有壓管流,放大前細管直徑d1=100mm,放大后粗管直徑d2=200mm,若放大后斷面平均流速v2=1m/s,則局部水頭損失hm為:()

A.0.613m
B.0.556m
C.0.459m
D.0.343m