Problem No 6:
Liquid (temperature t=0 °C) flows from the lower reservoir to
the upper reservoir through the serially connected pipeline. The
lower reservoir is under the gage pressure pm, while the upper
reservoir is under the vacuum pressure pv. The diameters of the
pipes are d and D, lengths are 1 and L. Calculate difference of
elevations in the reservoirs h if surface roughness $\Delta_s$ =0.1 mm.
The coefficients of minor losses for entrance are $K_m$ =0.5, for
exit $K_m$ =1.0. Use Borda-Karnot relation for sudden expansion
$K_m$ = (1-$A_1$/$A_2$).
Liquid: ethylene glycol 80%
D, mm 55
d, mm 35
L, m 18
l, m 16
pmn, kPa 250
Pvk, kPa 17
Q, l/s 5
Pmn
又
4
d,l
D,L
Q
Fig.6
Pvk
又