用一复式U形压差计测量水流过管路中A、B两点的压力差。指示液为汞,两U形管之间充满水,已知h1=1.2m,h2=0.4m,h4=1.4m,h3=0.25m,试计算A、B两点的压力差。(mu )_(e)=dfrac ({P)_(2)-(P)_(1)}(Pg)+dfrac (1)(2g)(({v)_(2)}^2-({mu )_(1)}^2)+Delta z(mu )_(e)=dfrac ({P)_(2)-(P)_(1)}(Pg)+dfrac (1)(2g)(({v)_(2)}^2-({mu )_(1)}^2)+Delta z=27.07m(mu )_(e)=dfrac ({P)_(2)-(P)_(1)}(Pg)+dfrac (1)(2g)(({v)_(2)}^2-({mu )_(1)}^2)+Delta z(mu )_(e)=dfrac ({P)_(2)-(P)_(1)}(Pg)+dfrac (1)(2g)(({v)_(2)}^2-({mu )_(1)}^2)+Delta z37.在一化工生产车间,要求用离心泵将冷却水从贮水池经换热器送到一敞口高位槽中。已知高位槽中液面比贮水池中液面高出10m,管路总长为400m(包括所有局部阻力的当量长度)。管内径为75mm,换热器的压头损失为(mu )_(e)=dfrac ({P)_(2)-(P)_(1)}(Pg)+dfrac (1)(2g)(({v)_(2)}^2-({mu )_(1)}^2)+Delta z,摩擦系数可取为0.03。此离心泵在转速为2900rpm时的性能如下表所示:Q/(m3/s)0.0010.0020.0030.0040.0050.0060.0070.008H/m2625.524.5232118.515.5128.5试求:(1)管路特性方程;(2)泵工作点的流量与压头。

用一复式U形压差计测量水流过管路中A、B两点的压力差。指示液为汞,两U形管之间充满水,已知h1=1.2m,h2=0.4m,h4=1.4m,h3=0.25m,试计算A、B两点的压力差。

=27.07m

37.在一化工生产车间,要求用离心泵将冷却水从贮水池经换热器送到一敞口高位槽中。已知高位槽中液面比贮水池中液面高出10m,管路总长为400m(包括所有局部阻力的当量长度)。管内径为75mm,换热器的压头损失为,摩擦系数可取为0.03。此离心泵在转速为2900rpm时的性能如下表所示:

Q/(m3/s)

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

H/m

26

25.5

24.5

23

21

18.5

15.5

12

8.5

试求:(1)管路特性方程;

(2)泵工作点的流量与压头。