Deck 7: Internal Flows

Question 1

The wind speed of the air flowing over a 16-cm-diameter outside mirror is significantly higher than the speed of a vehicle. If the pressure on the front of the mirror is assumed to be
Stagnation pressure and the pressure on the rear is assumed to be atmospheric, the power
Needed to move the mirror, if the air velocity around the mirror is 30 m/s, is nearest:

A) 0.44 hp
B) 0.39 hp
C) 0.34 hp
D) 0.29 hp

Answer 1

0.44 hp

Question 2

A laminar flow is desired from a tank with a well-rounded entrance to a 6-mm-diameter pipe that drains the tank. A container catches 20 L of 20°C water in 4 minutes. Determine the
Reynolds number so one can decide if the flow is laminar.

A) 972
B) 1220
C) 1770
D) 1920

Answer 2

1770

Question 3

Oil flows through the Alaska pipe line on a clear, sunny day. The flow in the pipe can best be classified as:

A) Uniform
B) Developed
C) Two-dimensional
D) Cylindrical

Answer 3

Developed

Question 4

Select the flow which must be classified a viscous flow, a flow in which effects of viscosity cannot be neglected:
(A) Flow through a pipe contraction
(B) Flow through a rocket's nozzle
(C) Flow around an airfoil
(D) Flow in the entrance region of a pipe

Question 5

4 m/s. It's a nice sunny day in Arizona near Phoenix in the summertime. Is the flow laminar or turbulent?

A) Laminar
B) Turbulent
C) It can alternate between being laminar and turbulent
D) Insufficient information to decide

Question 6

Air at 30 $$30 ^ { \circ } \mathrm { C }$$ C and 200 kPa is flowing in a 30-cm-diameter pipe and difference between the inside of the bend and the outside of the
Bend is approximately:
Passes through the bend shown. An estimate of the pressure

A) 110 Pa
B) 140 Pa
C) 180 Pa
D) 240 Pa