Deck 10: Flow in Open Channels

Question 1

Air moves through the duct shown. The for include:
Work-rate term (A) $\dot { W } _ { S }$ and $\dot { W } _ { I }$
(B) $\dot { W } _ { S }$ and $\int p \hat { \mathbf { n } } \cdot \mathbf { V } d A$
(C) $\dot { W } _ { S }$ and $\int p \hat { \mathbf { n } } \cdot \mathbf { V } d A$ and $\dot { W } _ { \text {sheur } }$
(D) $\dot { W } _ { S }$ and $\dot { W } _ { \text {shear } }$ s that must be accounted

Answer 1

C
$\dot { W } _ { S }$ and $\int p \hat { \mathbf { n } } \cdot \mathbf { V } d A$ and $\dot { W } _ { \text {shear } }$
$\text {The belt inputs energy in the form of \(\dot { W } _ { \text {shear } }\). The fan inputs energy as \(\dot { W } _ { S }\). And, }$$\text {there would be a pressure difference between the inlet and outlet requiring flow }$$\text {work, i.e., \(\int p \hat { \mathbf { n } } \cdot \mathbf { V } d A\)}$

Question 2

In the setup shown, if water is flowing, the

A) 820 kPa
B) 940 kPa

Answer 2

940 kPa

Question 3

$\text {The hydroturbine shown accepts water at \(4 \mathrm { MPa }\) and}$$\text { exits to the atmosphere. If the flow rate is \(2 \mathrm {~m} ^ { 3 } / \mathrm { s }\), the}$ $\text {maximum power output is nearest:}$
(A) $80 \mathrm { MW }$
(B) $70 \mathrm { MW }$
(C) $60 \mathrm { MW }$
(D) $50 \mathrm { MW }$ pressure gage should read:

A) 640 kPa
B) 760 kPa

Answer 3

640 kPa

Question 4

The owner of a cabin that is located on a small stream is thinking of placing a dam across the stream to create a possible drop of 120 cm. The stream is measured to have approximate
Dimensions of 180 cm by 10 cm and a leaf on the water's surface is observed to travel 10 m in
8 s) If an 80% efficient turbine is used, how much power can the owner expect to generate?

A) 1 kW
B) 2 kW
C) 3 kW
D) 4 kW