Objective:

To determine the air velocity using Vane Anemometer across the given cross-sectional area.

Apparatus used:

Vane Anemometer, 1.5m Long Rod, Stopwatch etc.

Description Vane Anemometer: It is also known as propeller anemometer. The Vane Anemometer have its axis parallel to the direction of the wind and therefore horizontal. Low range vane anemometer will typically have eight vanes, jeweled bearings and give velocity reading in the range of 0.25-15 m/sec.

STEP  1 

Attach 1.5 m rod to anemometer and set it to zero by pressing the zero setting lever.

Wind direction

Note:

1.Hold the anemometer atleast 1.5m from the body so that it does not block the air passing through the body.
2.Allowing the anemometer to hang vertically and aligned with the axis of airway.

   

STEP  2 

Start the stopwatch and after 120 seconds press the clutch lever and stop the stopwatch simultaneously to take the reading.

Trial 1

Reading=_____.

Time=_____s.

Note:

1.When the outer needle complete one round, it is 100m and the right side circle needle will move to 1.
2.When the needle of right side circle complete one round, it is 1000m and needle in the left side circle will move to 1.

   

Wind direction

Observations:

Trial 1

Initial Reading(I) (m)	Final Reading(F) (m)	Distance (F-I) (m)	Time taken for traverse (T) (s)	Air Velocity V=D/T (m/sec)	Air Quantity Q=A*V (m3/s)
00

Area of cross section (A)=4.8m*3m = 14.4 m².

Air Velocity(v=D/T) (m/s) =       

✔

✘

Air Quantity(Q=A*V) (m³/s)=       

✔

✘

STEP  3 

Start the stopwatch and after 120 seconds press the clutch lever and stop the stopwatch simultaneously to take the reading.

Trial 2

Reading=_____.

Time=_____s.

Trial 2

Observations:

Initial Reading(I) (m)	Final Reading(F) (m)	Distance (F-I) (m)	Time taken for traverse (T) (s)	Air Velocity V=D/T (m/sec)	Air Quantity Q=A*V (m3/s)
00

Area of cross section (A)=4.8m*3m= 14.4 m².

Air Velocity(v=D/T) (m/s) =       

✔

✘

Air Quantity(Q=A*V) (m³/s)=       

✔

✘

STEP  4 

Start the stopwatch and after 120 seconds press the clutch lever and stop the stopwatch simultaneously to take the reading.

Trial 3

Reading=_____.

Time=_____s.

Observations:

Trial 3

Initial Reading(I) (m)	Final Reading(F) (m)	Distance (F-I) (m)	Time taken for traverse (T) (s)	Air Velocity V=D/T (m/sec)	Air Quantity Q=A*V (m3/s)
00

Area of cross section (A)=4.8m*3m = 14.4 m².

Air Velocity(v=D/T) (m/s) =       

✔

✘

Air Quantity(Q=A*V) (m³/s)=       

✔

✘

calculations:

Initial Reading(I) (m)	Final Reading(F) (m)	Distance (F-I) (m)	Time taken for traverse (T) (s)	Air Velocity V=D/T (m/sec)	Air Quantity Q=A*V (m3/s)	Average Air Velocity(m/s)	Average Air Quantity Q=A*V (m3/s)
00						1.8012	27.83
00
00

Method factor=0.85.

Actual velocity=       

Actual velocity=1.531 (m/s).

Formula Actual velocity=Method factor*Average velocity

✔

✘

Result:

1.The mean air velocity using anemometer=1.8012 m/s.

2.The mean air quantity using anemometer=27.83 m³/s.

Conclusion:

Actual velocity=1.531 m/s.