Mechanical Engineering Principles

FLUID FLOW 257

12. Write down the formula for the pressure
    due to a wind acting perpendicularly on
    a tall slender building.

Exercise 118 Multi-choice questions on
the measurement of fluid
flow (Answers on page 285)

1. The term’flow rate’ usually refers to:

(a) mass flow rate

(b) velocity of flow

(c) volumetric flow rate

2. The most suitable method for measuring
   the velocity of high-speed gas flow in a
   duct is:

(a) venturimeter

(b) orifice plate

(c) Pitot-static tube

(d) float and tapered-tube meter

3. Which of the following statements is
   false?
   When a fluid moves through a restriction
   in a pipe, the fluid
   (a) accelerates and the pressure
   increases
   (b) decelerates and the pressure
   decreases
   (c) decelerates and the pressure
   increases
   (d) accelerates and the pressure
   decreases


4. With an orifice plate in a pipeline the
   vena contracta is situated:

(a) downstream at the position of min-

imum cross-sectional area of flow

(b) upstream at the position of mini-

mum cross-sectional area of flow

(c) downstream at the position of max-

imum cross-sectional area of flow

(d) upstream at the position of maxi-

mum cross-sectional area of flow

In questions 5 to 14, select the most

appropriate device for the particular re-

quirements from the following list:

(a) orifice plate

(b) turbine flowmeter

(c) flow nozzle

(d) pitometer

(e) venturimeter

(f) cup anemometer

(g) electromagnetic flowmeter

(h) pitot-static tube

(i) float and tapered-tube meter

(j) hot-wire anemometer

(k) deflecting vane flowmeter

5. Easy to install, reasonably inexpensive,
   for high-velocity flows.


6. To measure the flow rate of gas, incor-
   porating a Wheatstone bridge circuit.


7. Very low flow rate of corrosive liquid in
   a chemical process.


8. To detect leakages from water mains.


9. To determine the flow rate of liquid
   metals without impeding its flow.


10. To measure the velocity of wind.


11. Constant flow rate, large bore pipe, in
    the general process industry.


12. To make a preliminary test of flow rate
    in order to specify permanent flow mea-
    suring equipment.


13. To determine the flow rate of fluid very
    accurately with low pressure loss.


14. To measure the flow rate of air in a
    ventilating duct.


15. For a certain wind velocity, what frac-
    tion of the pressure would act on a tall
    slender building in comparison with a
    very wide surface?

(a) 0.01 (b) 0 (c) 0.5 (d) 0.99

16. For a wind speed of 190 km/h, what
    fraction (approximate) of atmospheric
    pressure will this be, when blowing per-
    pendicularly to a very wide surface?

(a) 2.5 (b) 0.5 (c) 1/30 (d) 0