Duraisamy P

Sr. Development Engineer

CFD analysis of ceiling fan

by

Lucas TVS Limited

22nd July 2016

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Company profile

Established 1962, JV - Lucas UK and TVS

Wholly owned since 2001

7 plants in India

Main plant in Chennai - 2600 employees

Complete Product development capability 75% of revenue from products

developed In-house

TS16949 and OHSAS 18001 certified company

Deming grand prize in 2012 for excellence in applying the principles of

TQM

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Products

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CFD analysis of ceiling fan

Objective of case study

To perform flow simulation of ceiling fan.

Analyse the fluid flow and predicted results.

Establish correlation with experimental data.

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Geometry Nomenclature and Spec

Top canopy

Downrod

Blade

Blade flange

Specifications

Fan sweep 1200 mm

No of blade 3

Blade thickness 1.2 mm

Fan speed 350 RPM

Range of speed 280-350 RPM

Rotation CCW from floor

Evaluate flow rate as per IS 374 -1979 specification.

Determine mechanical input power

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IS 374-1979 spec - test chamber

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Virtual flow chamber

4.2

5 m

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Virtual chamber surfaces

Floor

Bottom opening

Outer wall

Roof

Top opening

Test chamber wall

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Diaphragm - Top opening and Rot domain

Enlarged View

Top opening recommanded diameter is 1.1 to 1.2 times of fan sweep diameter.

Fan - Rotating domain

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Surface and Volume mesh

Mesh - Cut section view

Surface Mesh

Boundary layer mesh created over blade surfaces. Conical mesh created to capture flow under fan region.

Surface mesh created in HM.Surface mesh can constrcut volume.

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Input details and Boundary conditions

Material properties: Input speed:

Density of air 1.2 kg/m3

Viscosity of air 1.8 e-5 Ns/m2

Boundary Condition:

• Wall BC to all the outer walls.

• No BC to rot domain surfaces.

• Pressure point is created in domain

to initiate simulation.

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Velocity measurement points

Test chamber wall

Probe points at four semi diagonalsbegins at 40 mm from centre and 80 mm incremental in all diagonals.

The measurement plane located 1.5 m below plane of fan blades.

Mesurement points are shown below which are used to read value of velocity.

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Solution convergence - AcuProbe

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Stream lines

Air entering into top opening and fan moves air with higher velocity.

Air comes out through bottom opening from chamber and circulated.

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Velocity contour

X Z plane - velocity contour

Z axis component velocity contour shown below

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Velocity contour cont..

X Y plane - velocity contour

0.01 m 0.5 m

1 m 1.5 m

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CFD results

Steady state analysis performed.Velocity evaluated at discrete points of four semi diagonals.Geometry position - A blade oriented to Y axis.

0 Deg

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CFD results - Three different initial positions

Accumulated air flow rate : 242 CMMTorque required to develop flow : 0.75 Nm @ 350 rpm

0 Deg30 Deg

60 Deg

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Test results

Velocity profile along four semi - diagonals are shown below.

Accumulated air flow rate : 231 CMMTorque : 0.74 Nm @ 350 rpm

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Comparision

S No Parameters Test results CFD results Remarks

1Flow domain

size

IS 374 - 1979

followed

IS 374 - 1979

followed

Thickness of chamber neglected

2Speed

RPM350 350

Input for simulation

3Flow rate

CMM231 242 5% variation

4 Torque

Nm0.74 0.75 2% variation

5Power

W27 W 27.5 2% variation

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AcuSolve could predict the flow parameters for given input speed of ceiling fan

by

1. Flow rate >95 % accuracy.

2. Torque >95% accuracy

Conclusion

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Benefits summary

Flow simulation method has been established to evaluate airflow rate and mechanical input power of fan as per IS 374 - 1979 specification.

This methodology proposed to optimize fan blade design in order to improve efficiency.

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I would like to acknowlegde

1. The excellent support provided - M/s DesignTech sys Ltd

2. Lucas TVS providing the permission to present fan simulation work in ATC 2016

Acknowledgements/Credits