Analyzing air flow through Sqaure duct

1. Measurement of Velocity
Profile in a Square Duct
ME 400
Jafar Samarah
Motasem Abu Shanap

2. Introduction
Aim of the experiments is to obtain the velocity
profile in square duct at different location along x-
axis.
Velocity Profile Measuring Devices.
Pressure Measuring Devices.
Pitot Static Tube.
Pressure Transducers.

3. Principles
Viscous flow
Laminar, Transition and Turbulent flow
Reynolds Number
Hydraulic diameter
Entrance length

4. Viscous Flow
Viscosity is a measure of the resistance of a fluid
which is being deformed by shear stress.
Dynamic viscosity.
Kinematic viscosity .

5. Flow Regimes
Laminar Flow, Re<2300.
Transition Flow, 2300<Re<4000.
Turbulent Flow, Re>4000.

6. Reynolds Number

7. Hydraulic Diameter

8. Entrance Length
It is the length required to reach the fully developed
flow.

9. Governing Equations
Conservation of Mass
Conservation of Momentum
Navier stokes equation
Euler's Equation
Bernoulli's equation

10. Conservation of Mass

11. Navier Stokes Equation

12. Euler's Equation

13. Bernoulli's Equation

14. Experimental Setup
Square Cross Section (20X20cm) and 2 m long duct.
Fan.
Glass piece on the side of the duct.
Nozzle.
Pitot Static Device.
Signal Reading Device with Pressure Transducers.
Straighteners.

15. Experimental Setup

16. Experimental Results
We Obtained The Velocity Profiles at The Locations Shown in The Figures

17. Figure 4.3 shows the velocity profile for the duct channel along x-axis with
variation of y-axis, without straws at fixed z=0 cm. For each location we
took 5 readings of velocity, and then we took the average velocity ⊽.
⊽
[m/s]
m/s cm,Vm=
m/s cm,Vm=
m/s cm,Vm=
m/s cm,Vm=
y-axis (cm)

18. ⊽/ _
200cm,Vm=5.479m/s
190cm,Vm=5.333m/s
160cm,Vm=5.453m/s
140cm,Vm=5.529m/s
/( _
)

19. Figure 4.5 shows the velocity profile for the duct channel along x-axis with
variation of z-axis, without straws and fixed height y=0cm.
For each location we took 5 readings of velocity, and then we took the
average ⊽.
⊽
[m/s]
m/s cm,Vm= x=
m/s cm,Vm= x=
m/s cm,Vm= x=
z-axis (cm)

20. ⊽/
_
m/s cm,Vm= x=
m/s cm,Vm= x=
m/s cm,Vm= x=
/( _ )

21. Figure 4.7,Comparing the results at
x=180 cm, for y & z axis
⊽
[m/s]
cm, z axis x=
cm,y axis x=
z axis (cm)
y axis (cm)

22. Conclusion
Vibration of the duct due to the fan rotation.
Irregularity of the duct shape.
Extra friction due to the flange connection.
Eccentricity of the fan eye.
Vibration of Pitot static tube due to the air flow.
The Frame of the glass which gives extra friction.

23. Questions