Modeling and Simulation of Axial Fan Using CFD

8/18/2019 Modeling and Simulation of Axial Fan Using CFD

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Abstract— Axial flow fans, while incapable of developing high pressures, they are well suitable for handling large volumes of air at

relatively low pressures. In general, they are low in cost and possessgood efficiency, and can have blades of airfoil shape. Axial flow fansshow good efficiencies, and can operate at high static pressures ifsuch operation is necessary. Our objective is to model and analyze

the flow through AXIAL FANS using CFD Software and drawinference from the obtained results, so as to get maximum efficiency.The performance of an axial fan was simulated using CFD and theeffect of variation of different parameters such as the blade number,noise level, velocity, temperature and pressure distribution on the

blade surface was studied. This paper aims to present a final 3D CAD

model of axial flow fan. Adapting this model to the availablecomponents in the market, the first optimization was done. After thisstep, CFX flow solver is used to do the necessary numerical analyses

on the aerodynamic performance of this model. This analysis resultsin a final optimization of the proposed 3D model which is presentedin this article.

Keywords — ANSYS CFX, Axial Fan, Computational FluidDynamics (CFD), Optimization.

I.I NTRODUCTION

HE axial flow fan is extensively used in many engineering

applications. This type of fan is used in a wide variety of

applications, ranging from small cooling fans for electronics tothe giant fans used in wind tunnels. Axial flow fans are

applied for air conditioning and industrial process

applications. Its adaptability has resulted in implementation

into large scale systems, from industrial dryers to automotive

engine cooling and in-cabin air recirculation systems [1], [2].

The extended use of axial flow fans for fluid movement and

heat transfer has resulted in detailed research into the

performance attributes of many designs. Numerical

investigations have been performed to quantify the

performance of axial fans and their flow characteristics [3].

Axial fans blow air along the axis of the fan, linearly, hence

their name. The axial-flow fans have blades that force air to

move parallel to the shaft about which the blades rotate [4].With the expressive computer capability and extensive

development in the simulation field, CFD have drawn

attention in recent years. With the help of CFD, the complex

3-D geometries of equipment can now be modeled with only

minor simplifications [5]. CFD models, if created correctly,

can account for the complex flows in equipment. CFD models

for axial fans have been used to evaluate the flow behavior

and characteristics. The models provide sufficiently accurate

predictions over a range of operating conditions, which are not

possible using other methods. In this paper, CFD was used to

Hemant Kumawat is a Mechanical Engineer, from VIT University,

Vellore, Tamil Nadu, India (2014) (phone: +917073195809; e-mail:[email protected]).

model the flow passing through an axial fan. The objective

was to determine ways to increase the efficiency.

Fig. 1 Axial fan assembly

Axial flow fans, while incapable of developing high

pressures, they are well suitable for handling large volumes of

air at relatively low pressures [6]. In general, they are low in

cost and possess good efficiency, and can have blades of

airfoil shape. The operating principle of axial-flow fans is

simply deflection of air. Flow can be decomposed into two

components: axial velocity and tangential or circumferential

velocity. Axial velocity is the desired velocity since it moves

air from/to the desired spaces and tangential velocity is an

energy loss in axial fans or it can be converted into static

pressure as in case of vane axial fans.

II. EXPERIMENTATION

The first step is to identify a typical axial flow fan that can

be reproduced as a 3-D CAD Solidworks® software

engineering drawing package (Fig. 2).

The 3-D models are then imported into the CFD software,

remodeled into different sections, and refined to generate a

finite volume meshing. This is a crucial step, where details of

the geometrical shape need to be defined precisely. The flow

domain is also created (Fig. 3), and the final meshing of all

components needs to be accurate. Any errors in the drawings

and flow area need to be corrected before continuing.

Modeling and Simulation of Axial Fan Using CFDHemant Kumawat

T

World Academy of Science, Engineering and Technology

International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering Vol:8, No:11, 2014

1899International Scholarly and Scientific Research & Innovation 8(11) 2014 scholar.waset.org/1999.8/10000214

I n t e r n a t i o n a l S c

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http://scholar.waset.org/1999.8/10000214http://scholar.waset.org/1999.8/10000214http://waset.org/publication/Modeling-and-Simulation-of-Axial-Fan-Using-CFD/10000214


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Fig. 2 Solidworks CAD model

Fig. 3 Computational domain

The second step is to import the files

preprocessor, which will solve the flow

flow fields boundary conditions are set. Tmass flow, outlet pressure, fluid properti

characterization, such as moving internal

solid walls. The next step is to set the si

3-D steady and turbulent problem (Fig. 4).

The simulation is preceded with the

the data, applying the basic theory of

balancing the mass continuity and mo

numerical form and thereafter pr

predictions of the flow variables. The pro

completed by defining the boundary

controls, and convergence monitors. Ass

ideal and dry air at standard atmosp

boundary conditions include fixed wall,

of fan

of fan

into the CFD code

equations. Here, the

hese include inlet aires, and flow domain

zone and stationary

ulation process as a

.

FD code processing

fluid mechanics by

entum equations in

oducing numerical

lem setup process is

conditions, solver

ming the flow to be

heric pressure, the

oving internal zone,

zero pressure at outlet, and

The residual values of all

during the iteration process.

monitored for convergence a

conditions are not satisfied.

output data and present tstreamline (Fig. 5) and conto

Fig. 4 Simul

Fig. 5 Velocit

III.

R ESULTS

On post-processing the

observations are present

temperature contour plots, a

Optimized design results

design for temperature cont

variable mass flow rate at inlet.

variables solved are monitored

his iteration process needs to be

d repeated if the numerical error

The final step is to analyze the

hem in the form of velocityr plots (Fig. 6).

ation parameters

streamline of fan

ND DISCUSSION

numerical CFD results, the

ed as velocity streamlines,

nd static pressure contour plots.

ere then compared with initial

our and velocity streamline and







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presented in the form of contour plots.

separately for initial and optimized design

Fig. 6 Pressure contour of

A. Initial Design

Initially designed fan is having 7

designed fan, results were compiled for ai

22 m/s and having the outlet pressure as

shows the turbulence kinetic energy con

designed fan.

Fig. 7 Turbulence K.E. contour of initia

Fig. 8 shows the pressure contour of in

fan. By observing the pressure contour,

negative to positive scale; hence, creatin

the outlet.

Fig. 9 shows the temperature contour

axial fan. Variation in temperature occ

temperature of air and frictional h

variation is not uniform on the blade su

figure. Color (showing temp contour) is

Sudden change in temperature on the blad

the formation of thermal cracks which ca

Moreover, the airfoil design of the blade

esults are compiled

s.

an

lades. For initially

r flowing at a rate of

atmospheric. Fig. 7

tour plot of initially

lly designed fan

itially designed axial

ressure ranges from

g a pressure zone at

of initially designed

rs because of room

ating. Temperature

rface as seen in the

drastically changing.

e surface will lead to

n damage the blade.

gets distorted due to

the high temperature meltin

Temperature of the output

goes down.

Fig. 8 Pressure conto

Fig. 9 Temperature con

Fig. 10 Velocity stream

. Blade life is highly decreased.

air is also increased. Efficiency

r of initially designed fan

our of initially designed fan

line of initially designed fan







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Fig. 10 shows the velocity streamlines

fan. By observing the plot, velocity

uniform over fan wheel which implie

uniform. Large variation in velocity ca

blade. As we can see from Fig. 10,

streamlines changes drastically as we moMoreover, there is a reduction in velocit

uniform flow will result in huge noise a

and will decrease the overall efficiency.

B. Optimized Design

Optimized designed fan is having 11 b

designed fan results were compiled

conditions as for the initially designed f

rate of 22 m/s and having the outlet pres

Fig. 8 illustrates the temperature co

designed fan.

Fig. 11 Temperature contour of optimiz

Fig. 11 shows the temperature co

designed axial fan. Variation in temperat

room temperature of air and frictional

variation is almost uniform on the blade s

same throughout the blade. This is evi

color pattern of temperature contour of

there is less chances of formation of

design of the fan blade remains uncha

working life of fan. Blade life is increaseoutput air is same or nearly same as i

increases.

Fig. 12 shows the velocity strea

designed fan. By observing the plot, vel

uniform which implies that flow is

variation in velocity across the blade is

streamlines is almost same across the bla

output. We get the desires output velocit

to the parameters given. As a result of u

lesser or negligible noise and all acoustic

and hence efficiency is increased.

of initially designed

streamlines are not

s that flow is not

be seen across the

the colour of the

ve across the blade.at outlet. This non

d acoustic problems

lades. For optimized

for same working

n - air flowing at a

sure as atmospheric.

tour of optimized

ed designed fan

tour of optimized

re occurs because of

eating. Temperature

urface or it is almost

dent form the same

lade. In this design

hermal cracks. The

ged throughout the

. Temperature of thenput air. Efficiency

lines of optimized

city streamlines are

uniform. Required

achieved. Color of

de, i.e., at input and

at output according

niform flow, we get

problems are solved

Fig. 12 Velocity streamli

IV.

CO

The results from the nu

insightful understanding of t

an axial fan with different

CFD analysis was performe

optimized designed axial fan

optimized design were then

axial fan. The key and impor

follows:

1) The CFD modeling sho

helpful in initiating fu

numerical study of the a

2)

CFD results were presstreamlines, which provi

air around the fan for dif

3)

The different parameter

noise, and turbulence,

performing CFD analysi

with an optimum numbe

compared to the fan wi

general, as a compromi

five to twelve blades a

optimized design is havi

ACKNO

The author thanks the ma

their support and permissio

expresses gratitude to all o

who contributed to the job d

of the operation to achieve th

R EF

[1]

S. Jain, and Y. Deshpande, “C

Air Flow Distribution,” in

and Technology, Vol : 6 2012-[2]

Mahajan Vandana N., ShekhAxial Flow Fan using Ansys,

Engineering Technology, E-IS

[3]

Prof. Jigar S. Patel Prof. Shai

Performance of Axial Fan Pe

ne of optimized designed fan

CLUSION

erical simulations provided an

e behavior of fluid flow around

umber of fan blades. Numerical

for both initially designed and

. The numerical CFD results for

compared with initially designed

ant outcomes of this study are as

n in this study proved to be very

rther and more comprehensive

ial fan.

ented in the form of velocityded actual flow characteristics of

ferent number of fan blades.

s like temperature, pressure, fan

were also considered while

s. The study revealed that a fan

r of fan blades performed well as

h less number of fan blades. In

se between efficiency and cost,

e good practical solutions. Our

g 11 blades.

LEDGEMENT

nagement of VIT University for

to publish this paper. He also

the faculties and lab assistants

esign, preparation, and execution

e results presented in this paper.

RENCES

D Modeling of a Radiator Axial Fan for

orld Academy of Science, Engineering

1-28.wat Sanjay P., “Analysis of Blades of” in

International Journal of Advanced

N 0976-3945.

lesh M. Patel, “Parameter Affecting the

rformance,” in International Journal of







e e r i n g V o l : 8 ,

N o : 1 1 ,




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Engineering Research & Technology (IJERT), Vol. 1 Issue 3, May -

2012 ISSN: 2278-0181.

[4]

Konrad Bamberger, Thomas Carolus, “Optimization of Axial Fans with

Highly Swept Blades with Respect to Losses and Noise Reduction,” in

University of Siegen, Paul-Bonatz-Strasse 9-11, 57223 Siegen, Germany.[5]

Park, J., “A Sound Method for Fan Modeling”, Fluent News, US,

Summer 2005.

[6]

A report on fan design by Moore, 800 s. Missouri avenue Marceline,Missouri.







e e r i n g V o l : 8 ,

N o : 1 1 ,


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Modeling and Simulation of Axial Fan Using CFD

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