Performance Study of Wind Friction Reduction Attachments for Van Using Computational Fluid Dynamics

Subodh Kumar Ghimire.et.al Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 6, Issue 9,(Part-5) September.2016, pp.33-38
www.ijera.com 33|P a g e
Performance Study of Wind Friction Reduction Attachments
for Van Using Computational Fluid Dynamics
Subodh Kumar Ghimire,a*
, David Gyawali,b
D. Krishna Mohan Rajuc
,
a
PG Scholar (CAD/CAM), SVCET, Chittoor, A.P., India
b
G Scholar (Mechanical), SVCET, Chittoor, A.P., India
c
Vice-Principal (Academic), SVCET, Chittoor, A.P., India
ABSTRACT
Road transport is the key factor as it is the major method to connect places through land. Along with wide use of
internal combustion engines for this purpose comes the massive consumption of fossil fuels by vehicles. Most of
the research today is toward making efficient machines. This paper mainly deals with providing attachments to
existing models of vehicle to make it more efficient. An assessment of the impact of aerodynamic drag and its
relationship to energy consumption presented. A few models are designed and analysed for reducing drag with
the help of Attachments. Solid works is used to model and ANSYS Fluent is used for CFD analysis.
The results of Cd of various configuration is analysed, 0.427 being the Cd for conventional Van is reduced to
0.234 for van with front and rear attachment.
Keywords: Computational Fluid Dynamics, Drag, Aerodynamics, Collapsible Attachments, Coefficient of Drag,
ANSYS Fluent
I. INTRODUCTION
Main purpose of vehicle is the safe,
comfortable, quick and efficient transportation of
passengers and belongings. In growing economy
vehicle plays a vital role in its growth. In today’s
vehicle we can clearly view the optimization in
various energy consuming sections, in same story
we can also account for partial aerodynamics for a
significant fuel economy.
The layout of current commercial vehicle
design is governed primarily by their functional
requirements. They still have a lots of areas for
proper improvements and optimization. It can also
be seen that attention given to aerodynamic profile
of a vehicle is conventional. By opening a new
door of dynamically shape changing vehicle, we
can explorer deep into it with significant outcomes.
The collapsible aerodynamic design is mainly a
dynamic solution for different modes of a vehicle.
It provides a window of opportunity for the vehicle
to have normal ride in city drive mode, and to have
highly efficient drive with attachments in
highways.
For the purpose of analysis, Vehicle body
with and without attachments are modelled in
Solidworks-14. The model thus prepared is directly
applicable in ANSYS Fluent.Variant of Curved
profile attachment is considered in simulation.
Mainly there are 3 modifications and its
combination for different calculation viz., pointed
ends, truncated end and flat top
II. LITERATURE REVIEW
R. B. Sharma, Ram Bansal (2013)
generated a generic model of typical passenger car,
wind tunnel and applied boundary condition in
ANSYS workbench, there after model was
simulated and tested to gain baseline. Another
model with tail-plate was also subjected to same
configuration resulting the change in value of Cd
and thus provided evidence that tail plate can
improve aerodynamics and fuel economy of the
vehicle. (Sharma & Bansal, 2013)
Damjanović, Darko et al., (2010) Used
Ansys Fluent to simulate and analyze conceptual
car for aerodynamic improvement. Car was
designed using Autodesk 3ds Max 2010. Designed
car was derived from freeform sketches through
imagination. Final digital images were generated
through Mental Ray rendering. External surface of
the car was only modeled, and by the use of
ANSYS FLUENT, 2D analysis of the side contour
of the vehicle was done, further correction of
exterior geometry was done in order to improve the
design of vehicle in terms of reducing aerodynamic
drag and air resistance. (Damjanović, 2010)
Chainani. A, Perera. N (2008) analysed
the present state of art for racing vehicles. This
study of air flow over the body shows that drag
force unfavourably disturbs the accelerative motion
of the car and there is an alteration in the pressure
among the air flowing overhead and underneath the
vehicle. This produces the vertical forces.
Aerodynamic forces executing upon a car
prominently reduces its effectiveness. If the car is
redesigned to enhance these forces it could always
generate better results. The paper deliberates
various methods that have been castoff to
restructure and optimise the aerodynamics of a
radio control race car. (Chainani & Perera, 2008)
RESEARCH ARTICLE OPEN ACCESS
OPEN ACCESS

Kevin R. Cooper, Jason Leuschen (2005).
Prepared 1:10 scale model of truck and tested in
2mx3m wind tunnel and a full scale tests on a
Navistar 9200 Day Cab along with 40- foot trailer
in the 9mx9m wind tunnel. These tests were
targeted to develop the desired attachment devices
for trucks. The outputs demonstrated highly
effective fuel savings from a combination of a long
cab extenders, trailer boat-tails, and that increased
fuel economy as much as the contemporary
aerodynamic cab packages. (Cooper & Leuschen,
2005)
S. Roy and P. Srinivasan (2000)
Conducted full functioning research on
aerodynamics of heavy trucks and high sided
vehicles in significant interest of reducing accidents
due to wind loading and to improve fuel efficiency.
Realizing the limitations and drawbacks of
conventional wind tunnel, Computational analysis
for the same purpose is carried out for axial and
cross flow wind loading to obtain airflow
characteristics around the trucklike three
dimensional bluff body. Results provides
associated drag for the trucklike geometry
including the effects of rear-view mirror. Research
also suggest that modifying the External geometry
has significant effects on Fuel economy of the
vehicle. (Roy & Srinivasan, 2000)
Wolf-Heinrich Hucho (1993) analysed
various parts and compared them to catagorise
different standard lookalike shapes of vehicles and
forwarded the coefficient of drag value. This
resulted into the ability of general prediction of
coefficient of drag to a vehicular shape in real case
situation. Report also forward the possible
theoretical shapes of vehicle and their respective
value of coefficient of drag. Research also analysed
the different standard flow pattern seen in generally
obtained corners, edge and shapes around the
vehicle and was able to propose ideas to remove
such drag sources from the vehicle surfaces.
(Hucho, 1993)
Randall L. Peterson (1981) disclosed that
use of boatlike attachment on the box like vehicle
results into an average of 31 percentage of
reduction in aerodynamic drag, which is
significant. Research also showed that there is
slight increment in drag when boattail apex is cut
out, thus it also suggested that boat tail can retain
its aerodynamic effects without tip and thus
reduces the overall length of vehicle with
attachment. Hence truncated boattail attachment is
efficient as well as effective to use. (Peterson,
1981)
III. III.CFD ANALYSIS OF DIFFERENT
MODELS
1. Model A
This is baseline for vehicular calculation.
Simple vehicle design is used without attachments
for this computation. This will provide the scenario
of present state of art. Model A is the main vehicle
design with a vast area of improvement, we’ll only
be manipulating the vehicle body drag. Thus the
model which we have doesn’t have provision for
windows and other accessories vents.
Figure 1: Detailed diagram of Model A
Figure 2 : Velocity Contour of Model A
Figure 3 : Particle path line of Model A
Coefficient of Drag (Cd) :0.42716
Coefficient of Lift (Cl) :-0.10387
2. Model B
This model possess front and back
attachment with flat top. For the ease in driving we
have omitted the wind shield part from the
attachment thus driver can have single layer of
transparent material to view from.
Figure 4 : Detailed diagram of Model B

Figure 5 : Velocity Contour of Model B
Figure 6 : Particle path line of Model B
Coefficient of Drag (Cd) : 0.33316
3. Model C
This model possess front attachment with
curved top and back attachment with pointed end.
We have selected the top portion of attachment to
be curved s that we can have smooth transition
between wind shield and the attachment body. It is
also essential for the driver to view portion of road
top in a range while driving.
Figure 7 : Detailed diagram of Model C
Figure 8 : Velocity contour of Model C
Figure 9 : Particle path line of Model C
4. Model D
This model possess front and back
attachment with all four side curved. The advantage
of having this profile is that the air is pushed away
from vehicle in all directions. Pointed tip of vehicle
provides a better view of the road for driver thus
might have advantage over other designs.
Figure 10 : Detailed diagram of Model D
Figure 11 : Velocity Contour of Model D
Figure 12 : Particlepath line of Model D
5. Model E
The latter portion of the attachment
doesn’t have much effect on the wake. Thus we can
omit the latter segment of the vehicle. This
truncation of the attachment provides with
advantage of reduction in length of attachment with
better curvature.
Figure 13 : Detailed diagram of Model E

Figure 14 : Velocity contour of Model E
Figure 15 : Particle path line of Model E
6. Model F
This model possess front attachment with
curved top and the rear attachment is truncated. It
might not have the best performance but it sure
have advantage in mechanism development of the
attachments that can be further taken into future
scope of the research presented.
Figure 16 : Detailed diagram of Model F
Figure 17 : Velocity Contour of Model F
Figure 18 : Particle path line of Model F
Models in above simulation are provided
with inflation layer instead of mapped mesh to
accommodate the complex design. Inflation layer
of 6 steps are used that can provide boundary effect
for the air layer around the vehicle design.
Comparative study of all the models shows that for
the models with lower value of Cd, there is less
amount of wake behind the vehicle. It is also seen
that those models also have less dispersion of air
molecules around it. It signifies that the energy loss
from vehicle to surrounding air just to propel
forward. From the velocity contour it is visible that
the effect of wake have high impact on the drag.
From the results it is seen that efforts have been
made while designing the attachment to keep
coefficient of lift unchanged or least changed. This
indicates the vertical forces in vehicle is same as it
was before implementing the attachments.
Value of Cp is always high at the front
face of the vehicle. The value changes around
vehicle and is zero at the end of vehicle. Sudden
changes in value of Cp signifies the irregularities in
the surface of vehicle. This is mainly seen in the
connection point of attachment and vehicle
.
Geometry Coefficient of Drag (Cd) Coefficient of lift (Cl)
Model A 0.42716 -0.10387
Model B 0.33316 -0.085285
Model C 0.26155 -0.1181
Model D 0.24377 -0.082539
Model E 0.23028 -0.066855
Model F 0.24884 -0.091885
IV. ANALYTICAL CALCULATION
For the measurement of performance of
attachment drag loss for the design is major factor.
Drag is influenced by factors like shape, viscosity,
boundary layer separation, compressibility,texture,
lift (for induced drag), and so on. All these factors

can be applied into single
factorcoefficient of drag (Cd). Thus overall Drag
Energy loss is given as half of product of density
(ρ), the reference area (A),coefficient of drag (Cd)
and velocity (v) squared.
D=0.5 x ρ x A x Cd x v2
Equation 1: Drag loss
Drag loss (kW)
Velocity(ms-1
) 8.33 22.22 36.11
Model Coefficient of Drag
A 0.43 0.62 11.79 50.60
B 0.33 0.48 9.16 39.29
C 0.26 0.38 7.22 30.99
D 0.24 0.35 6.73 28.89
E 0.23 0.33 6.36 27.29
F 0.25 0.36 6.87 29.49
Rolling friction loss is another factor influencing
engine power requirement. Rolling resistance is
defined as the force required to maintain the
forward movement of a loaded pneumatic tire in a
straight line at a constant speed.
The rolling resistance can be expressed as product
of coefficient of rolling friction (μ), normal
reaction of body (R) and velocity (v)
Fr = μ x R x v
Equation 2: Rolling Friction Loss
Rolling Friction loss (kW)
Velocity(ms-1
) 8.33 22.22 36.11
All Model 1.70 4.53 7.37
For Computation of Mileage we use
output as Total energy requirement and as an input
we evaluate from the calorific value of fuel used.
Evaluation is done using following relation
whereCalorific value of fuel (Cv) and engine
efficiency (ƞ) Total energy loss (E) and velocity (v)
𝑀𝑖𝑙𝑒𝑎𝑔𝑒 =
𝐶𝑣∗ƞ
𝐸
∗ 𝑣
1000
Equation 3: Mileage computation
Mileage (kmpl) Velocity(ms-1
)
Model Coefficient of Drag 8.33 22.22 36.11
A 0.43 10.8 12.2 4.65
B 0.33 11.5 14.6 5.8
C 0.26 12.1 17.0 7.0
D 0.24 12.2 17.8 7.4
E 0.23 12.4 18.4 7.8
F 0.25 12.2 17.5 7.3
Economical interpretation of this achievement can
be done for a vehicle travelling 240km per day. For
this only the baseline model and the model with
least value of millage is considered.
V. CONCLUSION
In this paper presented to reduce the wind
friction losses, collapsible wind friction reduction
attachments are designed. These attachments are
provided at front and back of vehicle body. This
provided a smooth aerodynamically streamlined
body for existing vehicle design. This
aerodynamically improved model have highly
reduces wind friction and is responsible for the
reduction of coefficient of drag from 0.472 to
0.230.
Addition of attachment makes the driving
efficient, it doesn’t have any alteration in rolling
friction loss but the impact of attachment and this
reduced coefficient of drag causes huge difference
Fuel Economy
Diesel Cost 64.27 Rs/Liter
Distance travelled 240 per day
Vehicle Model A E
Coefficient of Drag (Cd) 0.427 0.230
Mileage (kmpl) 12.24 18.402
Fuel Consumption (l) 19.599 13.041
Cost (Rs.) 1259.66 838.183
Consumption Per Month 587.985 391.247
Cost Per Month (Rs.) 37789.8 25145.5
SAVINGS
Fuel saved per day 6.55 Litre
Cost saved per day 421.47 Rupees
Fuel saved per month 196.73 Litre
Cost saved per month 12644.34 Rupees

in wind friction loss. To propel a vehicle at the
speed of 80 Kmph, value of energy loss changes
from 16.232 kW to 10.801 kW
The reduced coefficient of Wind Friction
reduces the drag of vehicle at front and rare,
resulting into increase in speed of the vehicle with
same load conditions. This increase of speed helps
to cover some extra distance with same
consumption of fuel over the range of travel, hence
better mileage is obtained. Numerically Mileage is
increased form 12.240 KMPL to 18.402KMPL.
Thus we can confirm that with reduced drag
coefficient the performance of vehicle is increased
by 41.72%. Direct result of this on a vehicle
running 240Km per day is saving of
Rs. 12644.34 per month (under standard
conditions)
REFERENCES
[1]. Chainani, A., & Perera, N. (2008). CFD
Investigation of Airflow on a Model Radio
Control Race Car. World Congress on
Engineering 2008 Vol II, 22-26.
[2]. Cooper, K. R., & Leuschen, J. (2005).
Model and Full-Scale Wind Tunnel Tests
of Second-Generation Aerodynamic Fuel
Saving Devices for Tractor-Trailers.
Ottawa,Canada: SAE International.
[3]. Damjanović, D. (2010). car design as a
new conceptual solution and cfdanalysis in
purpose of improving aerodynamics.
Brod, Croatia: Josip Juraj Strossmayer
University of Osijek.
[4]. Gemba, K. (2007). Shape effects on drag.
Long Beach,California: Department of
Aerospace Engineering, California State
University.
[5]. Hucho, W.-H. (1993). Aerodynamics of
road vehicles. Michigan: General Motors
Research and Environmental Staff.
[6]. Lanfrit, M. (2005). Best practice
guidelines for handling Automotive
External Aerodynamics with FLUENT.
Darmstadt, Germany: Fluent Deutschland
GmbH.
[7]. Peterson, R. L. (1981). Drag reduction
obtained by the addition if a boattail to a
box shaped vehicle. California: Dryden
Flight research Center.
[8]. Roy, S., & Srinivasan, P. (2000). External
Flow Analysis of a Truck for Drag
Reduction. Society of Automotive
Engineers, Inc.
[9]. Sharma, R. B., & Bansal, R. (2013). CFD
Simulation for Flow over Passenger Car
Using Tail Plates for Aerodynamic Drag
Reduction. IOSR Journal of Mechanical
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35.

Performance Study of Wind Friction Reduction Attachments for Van Using Computational Fluid Dynamics

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Performance Study of Wind Friction Reduction Attachments for Van Using Computational Fluid Dynamics