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如图示常温水由高位槽以1.5m/s流速流向低位槽,管路中装有板流量计和一个截止阀, 已知管道为φ57 ́3.5mm的钢管,直管与局部阻力的当量长度____总和为 60m,截止阀在某一开度时的局部阻力系数ζ为7.5。设系统为稳定湍流,管路摩擦系数l为0.026。 求:(1)管路中的质量流量及两槽液面的位差△Z; (2)阀门前后的压强差及汞柱压差计的读数R 2 。 若将阀门关小,使流速减为原来的0.8倍,设系统仍为稳定湍流,l近似不变。问: (3)截止阀的阻力系数ζ变为多少? (4)阀门前的压强Pa如何变化?为什么? 20分 ____ 1-1.2-2截面列伯努利方程 5分 ____阀前后: ∵Dp = ____gR即 8.438 ́10 3 = ____ ́10 3 ́9.81R 2 ∴R 2 = 0.06826 m=6mm 5分 ____ 1-1.2-2截面列伯努利方程 当u ¢ = 0.8u = 0.8 ́1.5 = 1.2 m/s ∴ 5分 ____因高位槽水位不变,流量减小,阀前管路阻力减小,必引起a点压强p a 增大。 5分
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【单选题】How does your father call your mother's father?
A.
Brother.
B.
Uncle.
C.
Father-in-law.
D.
Brother-in-law.
【简答题】Your mother's father is your ____.
【单选题】—Is your mother's father your ______ ? —Yes, he is. [ ]
A.
aunt
B.
uncle
C.
grandfather
D.
grandmother
【简答题】Complete the following sentences. Your husband's father is your __. Your mother's new husband is your ___. Your wife's mother is your ___. Your husband is dead.You are_____. You have an ex-wife.You ar...
【简答题】听音，补全句子。 1. My mother's father is very ____________. 2. How many people in your family wear ____________? 3. Look at this ____________. 4. ____________ live in Australia. 5. How far is it from China t...
【单选题】Which of these is NOT a term for your father or mother's father??
A.
Grandfather
B.
Grandpa
C.
Granddad
D.
Granny
【简答题】Your mother's sister's daughter should(应该)call your father .
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