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

19. 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 ⊽.

20. In figure 4.4, velocity profile Over y-Axis With Fixed Height z=0 cm, along x-
Axis without straws. Normalized by dividing each velocity by the mean
one, ⊽/Vm.

21. 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 ⊽.

22. Figure 4.6 shows the velocity profile for the duct channel along x-axis with
variation of z-axis, without straws and fixed height y=0cm. it is normalized
by dividing the velocity of each location by the mean velocity ⊽/Vm.

23. Figure 4.7,Comparing the results at
x=180 cm, for y & z axis

24. 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.

25. Questions
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