Land Rover Discovery Mark 3
Drag Reduction
JJ.Kennedy
Research into the installation and optimisation of front
turning vanes and drag reduction technology applied to the
Land Rover Discovery MK3 vehicle
Mid-term report
Project Abstract
Previous industry based research has been carried out on the drag reduction of the
Land Rover discovery MK3 at Jaguar-Ford based on CFD models.
It has been noted at Jaguar that the cumulative drag coefficient for the open cooling
case is lower than that for the closed cooling case, until the cooling flow re-emerges
into the bulk flow.
This indicates that the energy loss incurred from passing through the vehicles heat
exchangers is less than that of the loss incurred by the fluid negotiating a path around
the large bluff front section.
The Drag on a body is determined greatly on the identity of the boundary layer, more
specifically whether the boundary layer is laminar, or turbulent.
Increasing the length of time that the boundary layer stays laminar and attached to the
vehicle, greatly increases the aerodynamic performance of said vehicle. The points
of separation (and also re-attachment) of this boundary layer are very important, and
factors that induce a premature separation will be examined in this research.
The object of this research is to examine any beneficial effect caused by the addition
of turning vanes, internal or external; and also further research into energising the
separated shear layer passing over the wheel-arch, which is currently scooping the reattachment boundary layer and acting as an air-brake.
Such aerodynamic improvements will reduce the drag penalty associated with the
bluff front fender and wheel/wheel-arch system.
Front turning vanes have given a CD.A (drag) reduction in Jaguar simulations, and it
is the object of this project to discover the most efficient vane/body gap and vane size
with respect to drag reduction and car aesthetics.
It is also the aim of the project to utilise the given University resources e.g. Wind
tunnel; Point LASER scanning device; dedicated CAD / CFD software, to obtain;
design; and verify data, both empirical and simulated.
JJ.Kennedy
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Drag Reduction
JJ.Kennedy
Table of contents
Project Abstract .............................................................................................................. 1
Gantt chart Tasks ........................................................................................................... 4
Progress and achievements ............................................................................................ 5
Laser scanning and Geometry creation .......................................................................... 7
Creating an accurate fluent simulation of the current Discovery ................................ 12
Working Fluent CFD models ....................................................................................... 15
Engineering Drawings and Lab set-up in the wind tunnel ........................................... 22
Initial designs and report conclusion ........................................................................... 26
Appendix ...................................................................................................................... 28
General arrangement Drawing ................................................................................. 28
Fairing stand Drawing.............................................................................................. 28
Aerodynamic drag balance stand Drawing .............................................................. 28
Model / Balance connector Drawing ....................................................................... 28
Table of figures
Figure 1 - Gantt chart to aid and map project completion ............................................. 5
Figure 2 - initial mesh of Land Rover Discovery .......................................................... 6
Figure 3 - Catia V5 winglet ........................................................................................... 7
Figure 4 - Gambit meshed winglet................................................................................. 7
Figure 5 - Simplified Discovery (velocity) .................................................................... 7
Figure 6 - Simplified discovery (pressure) .................................................................... 7
Figure 7 - Konica Minolta V1-910 LASER scanner ..................................................... 8
Figure 8 - Konica Minolta test scan point data .............................................................. 8
Figure 9 - Discovery Scan process using the PET ......................................................... 9
Figure 10 - Initial Geomagic point cloud triangulation (before surface creation) ....... 10
Figure 11 - Highly detailed point cloud recovered from Konica Minolta scanning and
stitching using the PET ................................................................................................ 10
Figure 12 - Rear view .................................................................................................. 10
Figure 13 - Initial NURBS surface creation in Geomagic ........................................... 10
Figure 14 - Initial Catia V5 surface creation attempt .................................................. 11
Figure 15 - Catia V5 auto-surface NURBS patch creation .......................................... 11
Figure 16 - Gambit image before meshing .................................................................. 12
Figure 17 - Gambit image after meshing ..................................................................... 12
Figure 18 - Pressure plot of discovery (full chassis).................................................... 13
Figure 19 - Full chassis and body work plot showing areas of very low pressure ...... 13
Figure 20 - Catia V5 image of Discovery MK3, the wheels and chassis are separate
volumes ........................................................................................................................ 14
Figure 21 - Actual Size Discovery MK 3 .................................................................... 14
Figure 22 - 1/6th scale CAD Model Discovery ........................................................... 15
Figure 23 - The half model, before meshing................................................................ 16
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Figure 24 - Half model after tri mesh was applied (3mm) .......................................... 16
Figure 25 - Graph estimating surface mesh reference length, Lanfrit (2005) ............. 17
Figure 26 - Edge mesh grading system ........................................................................ 18
Figure 27 - fully meshed (TGRID tet.) vehicle and control volume ........................... 18
Figure 28 - Discovery pressure plot ............................................................................. 19
Figure 29 - Pressure plot, side view ............................................................................. 19
Figure 30 - Velocity plot .............................................................................................. 19
Figure 31 - Velocity plot, side view............................................................................. 19
Figure 32 - Engineering drawings, see appendix for detailed prints ........................... 22
Figure 33 - Catia V5 'clash detection' .......................................................................... 23
Figure 34 - Wind tunnel Lab set-up ............................................................................. 24
Figure 35 - Lab set-up without wheels or board .......................................................... 24
Figure 36 - turning vane concept design ...................................................................... 26
Table of Tables & Equations
Table 1 - Gantt chart dates ............................................................................................. 4
Table 2 - Fluent force plot on 1/6th scale (half model) run ......................................... 20
Table 3 - Object shapes the respective Drag coefficients ............................................ 21
Equation 1 - drag Force equation, and details.............................................................. 21
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Drag Reduction
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Gantt chart Tasks
Table 1 - Gantt chart dates
Project management - GANTT CHART
Tasks
1 Literature Review
2 Gambit Proficiency
3 Fluent Proficiency
4 Create valid Geometry
5 Create accurate fluent simulation of current Discovery
6 Create Engineering + lab set-up drawings (for wind tunnel test
rig)
7 Test rig manufacture
8 CAD design generation (turning vanes; shapes; distances;
angles)
9 Rapid prototyping of CAD designs for wind tunnel test (TBC)
10 Fluent analysis of CAD generated designs
11 Wind tunnel lab set-up/dry runs
12 Wind tunnel design tests
13 Extra wind tunnel time allocation
14 Thesis write-up
Start date
10/10/2008
10/10/2008
15/11/2008
15/10/2008
05/12/2008
Duration
(days)
150
48
74
64
57
End date
09/03/2009
27/11/2008
28/01/2009
18/12/2008
31/01/2009
01/12/2008
07/01/2009
18
31
19/12/2008
07/02/2009
06/01/2009
27/02/2009
01/03/2009
25/03/2009
01/04/2009
01/05/2009
10/05/2009
83
61
61
6
31
15
113
30/03/2009
29/04/2009
01/05/2009
31/03/2009
02/05/2009
16/05/2009
31/08/2009
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Drag Reduction
JJ.Kennedy
29/09/2008
18/11/2008
07/01/2009
26/02/2009
17/04/2009
06/06/2009
26/07/2009
1 Literature Review
2 Gambit Proficiency
3 Fluent Proficiency
4 Create valid Geometry
5 Create accurate fluent simulation of current Discovery
6 Create Engineering + lab set-up draw ings (for w ind tunnel test rig)
7 Test rig manufacture
8 CAD design generation (turning vanes; shapes; distances; angles)
9 Rapid prototyping of CAD designs for w ind tunnel test (TBC)
10 Fluent analysis of CAD generated designs
11 Wind tunnel lab set-up/dry runs
12 Wind tunnel design tests
13 Extra w ind tunnel time allocation
14 Thesis w rite-up
Figure 1 - Gantt chart to aid and map project completion
Progress and achievements
The Gantt chart on the previous page was used to realise the tasks and objectives that
need to be completed in order to conduct this research project.
Aspects of the project such as the literature review are ongoing and technical data
from papers and books will aid my aerodynamic understanding and lead to better
engineered design solutions during the ‘CAD design generation’ stage.
The Gambit and fluent proficiency bars on the Gantt chart indicate my own individual
‘up-time’ with regard to these CFD software packages, and my increasing familiarity
and expertise. Currently I feel very proficient in the use of gambit in a 3D
environment both in terms of solid manipulation and meshing (shell+ solid).
Fluent proficiency is ongoing, due to difficulties with creating a valid wind tunnel
environment in gambit at the initial stages; I have not run as many full analyses yet to
allow me to feel 100% proficient.
K-epsilon turbulence and fluent calculation of the CD and also moving mesh analysis
are areas yet to be looked at in detail by me, although these are areas that Andy has
been looking into at a higher detail, my up-time for this area should not prove a
problem.
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Drag Reduction
JJ.Kennedy
Valid geometry creation for CFD analysis and CAD design / redesign has been a
major part of the project so far, from kick off to the Christmas break.
Figure 2 - initial mesh of Land Rover Discovery
Gambit Quad shell mesh of Land Rover Discovery
(disco geometry used depicting half –model, provided by Land Rover)
Note that mesh is refined around the front and back areas of vehicle.
From project kick-off the above Discovery geometry was provided, I initially spent
time constructing an accurate quad shell mesh. Despite a considerable amount of
geometry simplification, both Andy and I found the small nurbs patches produced too
irregular in shape to produce an accurate mesh with a level of element skew low
enough to allow volume meshing of the surrounding wind tunnel simulation.
During this time I was also experimenting with design software and exporting
differing file types to gambit, to test compatibility and design iteration, mesh and
CFD solve speed. I found that the Catia v5 design programme could export complex
designed geometry to gambit and mesh with ease, once saved in a ‘.model’ (Catia V4)
format.
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Drag Reduction
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Figure 3 - Catia V5 winglet
Catia V5 surface model, saved down as V4
.model and exported successfully to gambit.
Figure 4 - Gambit meshed winglet
Winglet concept read into gambit and meshed
using Catia V4 data
After concluding that the geometry provide was not suitable for the needs of the
project, the task of creating our own geometry, or requesting similar geometry was the
next priority.
In the interim Dr Matt Stickland provided both Andy and I a very much simplified
CAD model of a land rover, this provided me with some exercise material for use
with fluent. And also some realistic data this may prove useful, if the more accurate
geometry does not provide the appropriate results.
Figure 5 - Simplified Discovery (velocity)
Air fluid velocity plot; simulated wind tunnel
air velocity (on entry) of 30m/s, Highest
velocity 43.4 m/s in deep red zones (midplane shown).
Figure 6 - Simplified discovery (pressure)
Static pressure in Pa of simplified land
Rover, 617 Pa at maximum drag positions.
Laser scanning and Geometry creation
It was determined that the best way to achieve accurate geometry with regard to the
1/6th scale wind tunnel model’s angles and surface detail was to laser scan the model.
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Drag Reduction
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Using the university’s Konica Minolta laser scanner to create a point cloud that could
then be read into Catia V5, or Pro/Engineer; this could then be transferred (as a
.model file as illustrated earlier) to gambit and then fluent, and also successfully redesigned in Catia V5, and re-exported to gambit and solved in fluent.
This would lead to a successful concurrent engineering process with regard to the
simulation aspect of this project, and the usage of leading industrial standard design
and validation software.
Also, using a highly accurate 3D CAD model reflecting the dimensions of the model
used in the wind tunnel will hopefully lead to better result correlation.
This usage of the laser scanner leaves the possibility open for rapid prototyping of
wind tunnel designs; this is mentioned at point 9 of the Gantt chart, and further
research is needed to confirm this prototype manufacturing process capability.
If it is possible to create highly accurate 1/6th scale aerodynamically modified (as per
CAD re-design dictates) wind tunnel models, then this may prove very useful, both in
terms of time saving and data correlation.
Figure 7 - Konica Minolta V1-910 LASER
scanner
Figure 8 - Konica Minolta test scan point data
with three interchangeable lenses,
providing a flexible scanning area
Point cloud data from model sports car (initial test data).
This initial scan was a quick stitching process of two
independent scans from different angles, using the PET
(Polygon Editing Tool) software.
The laser scanning process was very much a learning curve, the Konica Minolta laser
scanner was a new purchase by the university, and Andy and I spent a lot of time
becoming familiar with the process and also refining our scanning technique.
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Drag Reduction
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A 1/6th scale model of the Land Rover discovery mark 3 was purchased to perform
wind tunnel tests on, it was agreed that this was the most accurate model to scan into
the computer, so perpetrations where made to the body work and chassis to allow for
accurate laser reflection and appropriate surface creation.
This meant removing the wheel system (this would be scanned separately at a later
date), and spray painting the body work with a light coloured matt finish model spray
paint.
The original colour and finish of the model Discovery would have been completely
useless, (black, reflective), due to the laser scan method any surface that absorbs all
light (e.g. black) and any surface that reflects light will yield poor, if any captured
data.
The spray painting was conducted using appropriate masks and safety precautions in
an external area using environmentally friendly model paint.
Once all reflective areas of the vehicle (and wheels) were scanned work was carried
out to secure the chassis to the body work using masking tape to cover gaps left in the
chassis by the removal of the wheels. The masking tape was also used to line the
inside of the wheel arches and remove the unwanted detail on the underside of the
chassis; the tape was picked up well by the scanner.
Figure 9 - Discovery Scan process using the PET
The above image shows an initial group of Discovery body work scans grouped
together, before the tape was applied. In the later more accurate scans had a taped
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chassis and also the model was placed on a black reflective film, to cut out unwanted
‘noise’ data from the table/stand.
The final scan contained ~60 scans of the body work and chassis and ~15 scans of one
wheel that was later added to the CAD model.
Figure 10 - Initial Geomagic point cloud triangulation (before
surface creation)
Figure 11 - Highly detailed point cloud recovered from Konica
Minolta scanning and stitching using the PET
Figure 12 - Rear view
Figure 13 - Initial NURBS surface creation in Geomagic
The polygon editing tool was used to create the point cloud shown above via a
stitching process of the scans. Each scan was taken at ~20 º intervals turning the car
through 360º (using the bottom of the chassis as a datum); the same process was
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Drag Reduction
JJ.Kennedy
repeated through pitch and yaw, using the same datum. This method produced a lot
of images, but the repeated data on the previous scan allowed for accurate
supplemental scan stitching, and eventually a highly detailed point cloud.
Once the valid scan information had been collected using the Konica Minolta scanner,
the data had been cleaned of unwanted ‘noise’ data, and stitched together using the
PET, the point cloud data was then exported as an ‘.igs’ file to ‘Geomagic’.
The point cloud data is all very well and good, but completely useless without
‘NURBS’ surfaces, NURBS are what all CAD programmes work on (including
Gambit and Fluent CFD programmes).
NURBS stands for; Non-Uniform Rational Bézier-Spline, NURBS in a 2D surface
meaning, create curves with respect to control points and lines defined by the
triangulation of the point cloud derived from the PET.
Problems arise when the data reaches high complexity, the more complex the surface
(i.e. the multiplicity) the knot vector has to increase and the number of NURB patches
has to increase.
Both Catia V5 and Geomagic have point cloud NURBS surface creation work
benches, but through investigation it was found that Geomagic was the dedicated
industry leading tool.
Figure 14 - Initial Catia V5 surface creation attempt
Figure 15 - Catia V5 auto-surface NURBS patch creation
This method created automatic NURBS patches;
Creating some difficult geometry.
GeoMagic also proved very useful for cleaning the data and smoothing rough/ uneven
areas on the body work. The hole filling tool fixed any areas that were not suitable
for creating a solid NURBS shell. The decimate triangles tool allowed the
triangulation to be simplified (decreasing the multiplicity of the knot vector) and thus
providing a simplified point cloud suitable for NURBS surfacing.
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The previous images show initial Catia V5 attempts to create a NURBS surface, and
also the manually aligned NURBS patches executed using Geomagic. The aim was
to refine the number of NURBS patches to allow for ease of meshing, but also retain
the surface detail in order to provide CFD results that will accurately correlate with
wind tunnel work.
Figure 16 - Gambit image before meshing
Figure 17 - Gambit image after meshing
The images above show the Catia V5 half-model, surfaced and meshed with CAD
created wheels. This model would potentially proved Ideal, due to the manageable
number of NURBS patches at the suitable mesh scheme; unfortunately it proved
impossible to align the cutting plane of the half-model with the control volume of the
simulation wind tunnel.
It was decided that a full vehicle model would have to be used, contained within the
control volume of the simulated wind tunnel in Gambit.
Creating an accurate fluent simulation of the current
Discovery
Task 5 on the Gantt chart, was to create a base simulation, as accurate as possible to
the CD currently obtained by Jaguar Land Rover, for the unmodified Discovery Mk 3.
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Figure 18 - Pressure plot of discovery (full chassis)
Full model fluent test of body work and chassis, without
wheels or ground modelled.
Static pressure plot, red areas showing maximum pressure.
Figure 19 - Full chassis and body work plot showing areas of very
low pressure
Wind tunnel size (i.e. control volume size, within Gambit) has been a topic for debate,
and has proved difficult to model to the dimensions forwarded by Dr Scanlon, without
a computer memory failure, due to element number. Other problems have also arisen
regarding the CD of the current working CFD model being that of 0.7 (Jaguar showing
a CD of 0.4).
This could be due to the max surface mesh element size of 20mm creating an angular
off geometry shape, or possibly the vehicle is at a slight angle to the direction of fluid
flow which would create a larger wetted surface area and thus a greater CD.
These are all possible situations, and work is on-going into creating an initial accurate
fluent analysis that will be an effective base for aerodynamic optimisation of front
turning vanes, and drag reducing processes.
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Figure 20 - Catia V5 image of Discovery MK3, the wheels and chassis are
separate volumes
Figure 21 - Actual Size Discovery MK 3
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Figure 22 - 1/6th scale CAD Model Discovery
The above images show the final Land Rover Discovery mark 3 CAD model
complete with scale and surface detail accurate wheels, in comparison with the full
size Discovery MK 3.
Working Fluent CFD models
All the Computer modelling done so far in the project is to aid the creation of a valid
CFD model in fluent. The CFD model produced in this project has to conform
accurately to the Land Rover Discovery Mk 3 actual geometry, but also be simplified
to the extent that it runs smoothly and accurately on the student edition of fluent.
It is common practice to create half-models for CFD runs, it was found that creating a
half model of the land rover discovery was simple, using the Boolean remove function
with respect to the control volume produced an accurate half model (shown below).
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Figure 23 - The half model, before meshing
Figure 24 - Half model after tri mesh was applied (3mm)
The finest mesh was used following wind tunnel mesh convention, with respect to
vehicle velocity (25m/s), shown in the graph below. The use of such a large control
volume necessitated mesh grading, the high CD.A values obtained before where the
result of too coarse a mesh, applied to a vehicle within a control volume that was
limiting surrounding airflow; thus causing back flow and recirculation.
TGrid tet-mesh was used to mesh the control volume after the surfaces of interest
were accurately meshed using the finest mesh in the study. The surrounding control
volume was graded using the edge mesh function; growth rate was closely monitored
and set at no greater than 20% to allow for a gradual size increase in the important
areas.
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Figure 25 - Graph estimating surface mesh reference length, Lanfrit (2005)
The graph above indicates mesh sizes with respect to flow velocities.
A mesh size of 3mm was selected for the vehicle surface, to decrease vehicle
angularity and increase the CFD accuracy.
This grading system was important as it proved impossible to create a uniform mesh
size that would be convergent with respect to accuracy of results time for analysis,
and adequate size of control volume. The student edition being limited to 4 million
elements, per analysis.
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Figure 26 - Edge mesh grading system
This image shows the edge mesh grading system used, it was important to eliminate
element skew from the meshed surfaces
Figure 27 - fully meshed (TGRID tet.) vehicle and control volume
The size of the domain for the external aerodynamic analysis of a vehicle should be at
least 3 vehicle lengths in front of the vehicle and 5 vehicle lengths behind. With
reference to data gathered on vehicle analysis the vehicle should not be greater (in
cross-sectional area) than 1 – 1.5% of the total control volume’s areas.
With this standard working data, the control volume pictured above was created
around the 1/6th scale model. The dimensions are as follows; length: 8m; height:
2.5m; breadth: 1.6m. The whole area can easily be scaled to actual size in fluent.
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In fluent, moving mesh was used to simulate the movement of the ground and the
rotation of the front and rear wheels. The air and ground velocity was set at 25m/s
and the rotation of the wheels was set at 333 Radians/s, this is due to the size of the
1/6th scale model.
Figure 28 - Discovery pressure plot
Static pressure plot of the discovery 1/6th scale
model, the deep red zones indicate a pressure high of
386 Pa
Figure 29 - Pressure plot, side view
low pressure zones can also be noted, at the bluff regions on the
wing and top section above and to the side of the windscreen
Figure 31 - Velocity plot, side view
Figure 30 - Velocity plot
These images show a velocity plot of the same fluent
run the standard air speed is 25m/s (shown in
yellowish hue) the wheels are also rotating at this
speed about a central axis.
The initial stagnation point can be seen quite clearly in front of
the front bumper and air dam in this plot. The drafting effect
can also be seen towards the rear; in some areas the air speed
drops to ~5m/s.
The run shown above was conducted using a ‘laminar’ viscous model; so far it has
proven difficult to obtain an accurate k-epsilon viscous model that converges in a
reasonable time frame. It may be prudent to utilise the department’s super computer
in order to conduct a fully turbulent model.
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Table 2 - Fluent force plot on 1/6th scale (half model) run
Force vector: (1 0 0)
pressure
viscous
total
pressure
viscous
total
zone name
force
force
force
coefficient
coefficient
coefficient
n
n
n
------------------------- -------------- --------------------------- ---------------------------------------car_front
1.7335379 0.033945862
1.7674838 0.0045284257 8.8674907e-05 0.0046171006
car_rear
2.1274292 0.0039919699
2.1314212 0.0055573663 1.0428003e-05 0.0055677943
front_wheel
0.57851338 0.011934292 0.59044768 0.0015112187 3.1175293e-05 0.001542394
rear_wheel
0.3120209 0.011335896
0.32335679 0.00081507502 2.9612138e-05 0.00084468715
wall
1.3913435
0.1206679
1.5120114 0.00363453
0.00031521411
0.0039497441
------------------------- -------------- -----------------------------------------------------------------net
6.1428449 0.18187592
6.3247208
0.016046616
0.00047510445
0.01652172
The force plot for the 1/6th scale model is shown above; the projected surface area of
the model discovery is 0.03996637m2 calculated by fluent.
From this information the CD can be calculated:
Multiplying the Total force and projected areas by 2 (to account for the second half of
the vehicle), this implies that:
12.648/CD = 0.5(1.225)(25)2(0.07993274)
→ 12.648/CD = 30.59925
→ 12.648 = 30.59925CD
i.e. 12.648/30.59925 = CD ≡ 0.4133
or CD = 0.42
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Equation 1 - drag Force equation, and details
Table 3 - Object shapes the respective Drag
coefficients
FD = the Force of drag (the total force N)
ρ = the mass density of the fluid, in this
case air at 15ºC (1.225 kg/m3)
u = the velocity, in this case the air
velocity at 25m/s
CD = Drag coefficient, dimensionless
constant required for correlation with
Jaguar CFD model
A = the projected area of the vehicle,
from front wetted area, calculated via
fluent
This current laminar viscosity model produces a CD comparable to the CD achieved
at Jaguar Land Rover. The CD of the above model is assumed to be higher than the
Jaguar model due to a lack of internal flows, but 0.42 is a good approximation to the
Jaguar result of 0.4.
As previously stated, the above study is a laminar viscous model, so far the more
stable and accepted method of simulating turbulence around vehicles and objects is
the k-Epsilon (k-ε) viscous model, and other models may prove better for the
streamlined sections of the Discovery.
Currently the residuals of k-ε models run have not converged appropriately, but
residual reduction is not the only indicator of study convergence. A truly converged
study is one that is no longer converging, i.e. not changing with successive iteration.
If the residuals continue to adapt and vary beyond the convergence criteria cut-off
zone, then the solution is effectively still changing.
The best indication of complete convergence is when the residuals flatten to a
traditional plot (i.e. residuals v. iteration).
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This point is referred to as, ‘convergence at the level of machine accuracy’, this
obviously takes time to reach, and as stated earlier in the report possibly may only be
achieved through using the Department’s super computer.
Engineering Drawings and Lab set-up in the wind
tunnel
Figure 32 - Engineering drawings, see appendix for detailed prints
The above engineering drawings were created after lab work and discussion regarding
wind tunnel measurement taking and the apparatus currently available.
The use of the wind tunnel balance was agreed on, but the balance was designed for
testing aeroplane prototypes, as a result it has fixing positions under each wing and
also the tail plane. This set up is obviously useless for vehicle testing, so a test-rig
had to be thought up, designed and drawn for manufacture.
As can be seen in the engineering drawings (appended to this report) I have designed
a system that utilises the tail plane fixing on the aerodynamic balance. This provides
a fixing for the aerodynamic fairing, which in turn houses the connector that bolts to a
bridge that sits above the cross bar on the balance. The other end of the connector
screws into wooden/nylon block bonded to the cavity currently occupied by the
battery case on the underside of the model’s chassis.
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The Lab set-up and test-rig is currently being manufactured; piece parts such as the
wooden/nylon block can be decided upon and manufactured ‘on the fly’ during task
11 on the Gantt chart ‘wind tunnel lab set-up/dry runs’.
Final adjustments and air speed test will also be conducted during this time, this time
will prove vital to accurate result taking during block 12, due to the air speed required
being close to the maximum speed capable in the wind tunnel.
It is important that the set up works correctly and is not hazardous to the operators, or
the wind tunnel itself.
Figure 33 - Catia V5 'clash detection'
Clash detection function can test to see if mating components and closely
fitting components have been assembled without clashing.
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Figure 34 - Wind tunnel Lab set-up
MDF simulation road pictured much smaller than the actual MDF board,
for clarity
Figure 35 - Lab set-up without wheels or board
Lab set-up again without MDF board, or the wheels, showing aerodynamic
fairing and set-up to actual size and orientation; see G.A. drawing for actual
dimensions and clearance distances.
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The creation of a product containing all of the wind tunnel test components, and the
use of the clash detection function in Catia V5 is a great visual aid, also with the
kinematics function the vehicles wheel can be made to spin. This provides assurance
that the set-up will fit and will work appropriately in the lab, before any material is
cut, or even ordered.
Torsion and or bending forces on the connector was deemed to be minimal, due to the
fact that the connector ideally is not tethered but moves with the aerodynamic
balance.
Bolt forces on the other hand need to be looked into as any forces generated will
collect around the fastening areas both on the vehicle and the bridge section, how ever
they are deemed to be minimal.
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Drag Reduction
JJ.Kennedy
Initial designs and report conclusion
Figure 36 - turning vane concept design
Design with three attaching winglets.
The above design is an initial realisation of the design intent, and an exercise in the
capability of the design programme to allow modification to the geometry.
The three winglets pictured are aerofoil shaped, on reflection it may provide more
drag than down-force generation, my current work is a small study into junction
shapes and the drag that results. I am currently looking at similar turning vane
designs, but with swept filleted fairing shaped winglets.
In conclusion to this report, so far budgeted time, with respect to the Gantt chart
discussed earlier has fallen within acceptable limits.
The project has yielded a certain amount of success so far, due to geometry creation
and rig manufacture initiations, which are both time consuming activities, and this is
detailed in the chart.
There is also a fair amount of work yet to be completed, and a CFD base analysis that
both Andy and I are fully happy with still eludes us. According to the Gantt chart,
design generation should be in an initial stage; this of course, is the main thrust of the
investigation. A range of designs dealing with turning vane drag reduction and also
wheel arch drag need to be completed to allow for the other tasks to be started.
Each Gantt chart block is quite liberal in size, and task 13, ‘Extra wind tunnel time
allocation’ may prove important as a finish up and debrief time before final thesis
write-up.
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Land Rover Discovery Mark 3
Drag Reduction
JJ.Kennedy
I feel that the first three months of this project have been productive, in terms of
computer package proficiency and aerodynamic learning and literature review.
The kick-off to early project stage has had an effective up-time with regard to work
done; problems during the project have been appropriately addressed and solutions
have been sought in an educated manner.
I believe these initial stages have built a solid foundation for the rest of the
investigation, and the real research and development into the drag reduction of the
Jaguar Land Rover Discovery mark 3 can begin in earnest from this point.
JJ.Kennedy
12/1/2009
27
Land Rover Discovery Mark 3
Drag Reduction
JJ.Kennedy
Appendix
General arrangement Drawing
Fairing stand Drawing
Aerodynamic drag balance stand Drawing
Model / Balance connector Drawing
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