Download Homework #2

Homework #2
1. (5)A fluid is flowing with a mass flow rate in a smooth horizontal pipe of
length L and diameter D as the result of a pressure difference between the inlet
pressure and outlet pressure, which is 0.1bar.
If the pipe is replaced by one of
the diameter D/2 but the same length. The same fluid is to be pumped at the
same mass flow rate ,W.
(1) (2)Determine the pressure difference between the inlet and the outlet when
the flow is laminar.
(2) (3)Determine the pressure difference between the inlet and the outlet using
the Blasius equation when the flow is turbulent.
2. (5)Consider a flow channel of length 4m(for a hydraulic simulation of flow
through a PWR assembly) with no heat addition, and mass flow rate of 0.7 kg/s
at 300℃ and 15.5MPa. MIT people suggest the annular fuel(shown in the righthanded side in the below figure) in which the central channel exists to cool the
fuel. In the actual design process, the pressure drop in the external channel
should be the same as that in the internal channel.
Estimate the pressure drop throughout the internal channel of the annular flow
with its roughness of 0.0045cm and the very small radius of 0.337cm where the
mass flow rate is 0.122kg/s. Use the following Colebrook formula representing
the Moody diagram or the Moody diagram for wall friction coefficients
External
cooling
4.13
4.22
4.85 mm
Regular fuel
Internal
cooling
3.37
4.00
5.99
6.62 mm
Annular fuel proposed by MIT