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THESIS FOR THE DEGREE OF LICENTIATE OF
ENGINEERING
IN
MACHINE AND VEHICLE SYSTEMS
Investigation of Aerodynamic Resistance of
Rotating Wheels on Passenger Cars
by
A L E X E Y V D O V I N
Department of Apple! Me"#an"$
CHALMERS %NIVERSITY OF TECHNOLOGY
Got#enb&r'( S)e!en( *+,-
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Investigation of Aerodynamic Resistance of Rotating Wheels
on
Passenger CarsA L E X E Y V D O V I N
. ALEXEY VDOVIN( *+,-
THESIS FOR LICENTIATE OF ENGINEERING no *+,-/,-
ISSN ,01*23101
Department of Apple! Me"#an"$C#almer$ %n4er$ty of Te"#nolo'y
SE25,* 60 Got#enb&r'S)e!en
Telep#one 750 8+9-, ::* ,+++
;rnte! by C#almer$ Repro$er4"e
G
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Investigation of Aerodynamic Resistance of Rotating
Wheels on Passenger Cars
Ale=ey V!o4n
Department of Apple! Me"#an"$
C#almer$ %n4er$ty of Te"#nolo'y
Abstract
>t# t#e "&rrent "on!ton$ of r$n' f&el pr"e$ an! t#e
to&'#enn' of en4ronmental
le'$laton for CO*an! ot#er em$$on 'a$e$( 4e#"le
man&fa"t&rer$ aro&n! t#e )orl! are
loo?n' nto t#e )ay$ to ma?e t#er 4e#"le$ more ener'y eff"ent an!
t#erefore more
en4ronmentally fren!ly@ One of t#e )ay$ to a"#e4e t#$ 'oal $ to
mpro4e aero!ynam"
!e$'n of 4e#"le$ n or!er to !e"rea$e aero!ynam" re$$tan"e
for"e$@ T#e$e for"e$ are
e$pe"ally mportant for any 4e#"le$ "apable of 1+?m#o&r an!
#'#er( an! t#at $
ba$"ally any pa$$en'er or "ommer"al 4e#"le@
In t#$ t#e$$ t#e fo"&$ $ on pa$$en'er 4e#"le aero!ynam"$ an!
more $pe"f"ally on t#e
area of t#e )#eel$ an! )#eel#o&$e$@ T#ere #a4e been a
n&mber of $t&!e$ of t#e
aero!ynam" performan"e of t#$ area( )#"# #a4e $#o)n t#at )#eel$
an! )#eel2#o&$n'
flo)$ 'enerate a $'nf"ant part of t#e aero!ynam" !ra' on a
pa$$en'er "ar an! "an
relate to a$ m&"# a$ *1B of t@ T#e $t&!e$ al$o $#o) t#e
relat4e mportan"e of tyre an!
rm !e$'n n #a4n' better aero!ynam" "#ara"ter$t"$@
%$&ally )#en $pea?n' abo&t aero!ynam" re$$tan"e of
4e#"le$ one t#n?$ abo&t t#e
aero!ynam" !ra' for"e@ Certanly t $ t#e lar'e$t "ontrb&ton
to t#e o4erall re$$tan"e
t#at t#e 4e#"le #a$ to o4er"ome )#en mo4n' b&t t $ not t#e
only "ontrb&ton@ T#e
re$$tan"e moment a"tn' on t#e )#eel$ rotatn' n t#e ar( "ommonly
referre! a$
4entlaton re$$tan"e( play$ an mportant role a$ )ell@ T#$ moment
$ not a$ ea$y tomea$&re n a $tan!ar! aero!ynam" )n!2t&nnel
a$ aero!ynam" !ra' for"e( an! t#erefore
t $ &$&ally left &na""o&nte! for@
In t#$ t#e$$ a "lo$er loo? at 4entlaton re$$tan"e $ ta?en( an!
!fferent effe"t$
"ontrb&tn' to t#$ re$$tan"e moment are !$"&$$e!@ In
or!er to be able to mea$&re
4entlaton re$$tan"e 4aro&$ mo!f"aton$ to a normal
)n!2t&nnel $et2&p are pre$ente!@
T#e re$<$ an! analy$$ of one of t#e $t&!e$ n4e$t'atn'
4entlaton re$$tan"e( an! t$
!epen!en"y on rm !e$'n( are al$o '4en n t#$ t#e$$@ It $ $#o)n
t#at 4entlaton
re$$tan"e #a$ a $'nf"ant effe"t on total aero!ynam" performan"e
an! t $#o&l! be
ta?en nto a""o&nt )#en !e$'nn' a 4e#"le@
ey)or!$/ >#eel for"e$( )#eel aero!ynam"$( 4entlaton
re$$tan"e( aero!ynam"
moment( rm !e$'n
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Acknowledgements
T#$ )or? )o&l! not #a4e been po$$ble )t#o&t t#e
$&pport from a lar'e 'ro&p of
people@
Fr$t of all I )o&l! l?e to t#an? my $&per4$or an!
e=amner ;rofe$$or Lennart L
ot#er "ollea'&e$ at Apple! Me"#an"$ !epartment of C#almer$
%n4er$ty of
Te"#nolo'y@
I )o&l! e$pe"ally l?e to t#an? An!re) Da)?e$ for $#arn' #$
'reat e=pert$e n t#e area
of 4e#"le !e$'n an! proof2rea!n' t#e man&$"rpt of t#$
t#e$$@
F&rt#ermore( I am really 'ratef&l to t#e S)e!$# Ener'y
A'en"y for f&n!n' t#$ proe"t@
La$tly( b&t by no mean$ lea$t( I )o&l! l?e to t#an? my
!ear famly an! fren!$ for t#er"on$tant $&pport an!
en"o&ra'n' !&rn' my $t&!e$ at C#almer$@
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4
List of papers
T#$ t#e$$ "ontan$ t#e follo)n' paper$/
V!o4n A@( L
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4
Nomenclature
Symbols
A ;roe"te! front area m*
Dra' "oeff"ent 2
() Ventlaton !ra' "oeff"ent 2 Lft "oeff"ent 2 ;re$$&re
"oeff"ent 2 Ventlaton re$$tan"e "oeff"ent m-$
fr Rolln' re$$tan"e "oeff"ent 2
g Gra4tatonal a""eleraton m$*
Fa A""eleraton for"e N
Aero!ynam" !ra' for"e NFD Aero!ynam" !ra' for"e N
FG Dr4n' for"e !&e to 'ra4ty N
D$trb&te! nertal for"e$ !&e to rotaton of t#e ma$$e$
Nm-
Aero!ynam" lft for"e NFR Rolln' re$$tan"e for"e N
Tra"ton for"e N ;art of t#e tra"ton for"e( re$pon$ble for
4entlaton re$$tan"e N EP&4alent 4entlaton re$$tan"e for"e N
Fx Tra"t4e for"e N
_ =2"omponent of t#e eP&4alent me"#an"al for"e N_ 2"omponent
of t#e eP&4alent me"#an"al for"e Nm Ma$$ of 4e#"le ?'
Re$$tan"e moment !&e to nerta of t#e rotatn' part$ Nm_
EP&4alent me"#an"al moment aro&n! y2a=$ Nm Moment of rolln'
re$$tan"e Nm Ventlaton moment Nm Normal for"e n a "onta"t pat"# N
;o)er reP&re! to o4er"ome 4entlaton re$$tan"e >V
Ab$ol&te 4e#"le 4elo"ty m$
Ve#"le 4elo"ty relat4e to ar m$ Roa! n"lnaton !e'
! Coeff"ent n"l&!n' t#e nerta of rotatn' part$ 2 Ar !en$ty
?'m
-
" Rotatonal 4elo"ty ra!$
AbbreviationsCFD Comp&tatonal Fl&! Dynam"$
CoG Centre of Gra4ty
FVM Fnte Vol&me Met#o!
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=
Table of Contents
,@
Intro!&"ton
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,
,@,@ ;roe"t ba"?'ro&n!
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*
,@*@
;roe"t 'oal$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
-
*@ ;a$$en'er 4e#"le aero!ynam"$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
1
*@,@ Dr4n' re$$tan"e
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
1
*@*@ Aero!ynam" !ra' of pa$$en'er "ar$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
0
*@-@
>#eel an! )#eel#o&$e
aero!ynam"$@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
:
*@5@
Dfferent met#o!$ for a$$e$$n' aero!ynam"$ on pa$$en'er "ar$
@@@@@@@@@@@@@@@@@@@@@@ :
*@5@,
Comp&tatonal fl&! !ynam"$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
:
*@5@* Coa$t !o)n te$t$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
3
*@1@ >n! t&nnel te$t$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
3
*@1@, Sn'le belt $y$tem
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
3
*@1@* F4e2belt $y$tem
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
6
*@1@- Ot#er mo4n' 'ro&n! $y$tem$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,+
-@
For"e$ a"tn' on rotatn' )#eel$ an! 4entlaton re$$tan"e
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ ,-
-@,@
For"e$ "la$$f"aton
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,-
-@*@
Ventlaton re$$tan"e
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,1
-@*@, Ventlaton re$$tan"e or'n$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,1
-@*@* Ventlaton re$$tan"e mea$&rement$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ ,1
5@ E=permental $et2&p
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,:
5@,@ T#e )n! t&nnel $et2&p
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,:
5@*@ Mnm$n' lo$$e$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,3
5@-@
Te$t obe"t$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
,6
1@ Re$<$ an! !$"&$$on$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*,
1@,@ Intro!&"ton of 4entlaton !ra' "oeff"ent
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ *,
1@*@ Ventlaton re$$tan"e for )#eel$ )t# !fferent rm !e$'n$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@ **
1@*@, Ventlaton re$$tan"e
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
**
1@*@* Aero!ynam" !ra' for"e
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*-
1@*@- Total aero!ynam" re$$tan"e
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*5
1@-@ Alternat4e )ay to ntro!&"e 4entlaton re$$tan"e nto
!r4n' re$$tan"e
eP&aton
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*1
1@5@ E=ample of po)er "ompar$on
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*0
1@1@ Lmtaton$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*:
0@
Con"l&$on$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
*6
:@
F&t&re )or?
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
-,
3@
Referen"e$
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
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,
1. Introduction
No)a!ay$ t $ #ar! to ma'ne o&r l4e$ )t#o&t "on4enent
)ay$ of tran$portaton t#at
n"l&!e bot# p&bl" an! per$onal 4e#"le$@ A$ t#e #&man
pop&laton 'ro)$ t#e n&mber of
pa$$en'er 4e#"le$ n"rea$e$ a$ )ell@ In F'&re , one "an $ee
t#e 'lobal pro!&"ton of
pa$$en'er 4e#"le$ n"rea$n' from year to year@ T#ere )a$ an
ob4o&$ !rop n pro!&"tonn *++32*++6 !&e to e"onom" "r$$(
b&t $n"e *+,+ pro!&"ton "ontn&e! to 'ro) e4ery
year@
Figure 1. World passenger vehicle production in millions 1!
Ha4n' $o many ne) 4e#"le$ pro!&"e! t $ #ar! to 'nore
en4ronmental $$&e$a$$o"ate! )t# roa!24e#"le tran$portaton@ A$ a
re$< of t#e "omb&$ton pro"e$$
tra!tonal pa$$en'er 4e#"le$ pro!&"e em$$on$ an! mo$t
mportantly "arbon !o=!e
8CO*9( )#"# $ an mportant 'reen#o&$e 'a$@ It $ "on$!ere! to
be re$pon$ble for
ant#ropo'en" "lmate "#an'e n term$ of "a&$n' 'lobal )armn'@
E4en t#o&'# roa!
tran$portaton $ only a""o&ntable for ,1@6B of man2ma!e
CO*em$$on$ *( t#ere $ a
#&'e pre$$&re on 4e#"le man&fa"t&rer$ to
pro!&"e more en4ronmentally2fren!ly "ar$@
E&ropean %non le'$laton from *++6 $et$ tar'et$ for fleet
a4era'e CO* em$$on$ per
?lometre for e4ery man&fa"t&rer@ T#&$( by *+,1 only
,-+ 'ram$ of CO*per ?lometre
$#o&l! be pro!&"e! by an a4era'e 4e#"le -@ T#e tar'et
4al&e for *+*+ $ 61'?m@ T#e$e
are fleet a4era'e 4al&e$ meann' t#at #ea4er "ar$ are allo)e!
to #a4e #'#er em$$on$
t#an l'#ter "ar$( b&t an o4erall a4era'e $#o&l! not
e="ee! t#e lmt ben' $et@ T#e
man&fa"t&re( )#o $ faln' to meet t#e 'oal$( )ll #a4e to
pay a fee for ea"# "ar
re'$tere!@ T#e E&ropean %non $ not &nP&e n t$
"ampa'n for lo)er em$$on$/ %SA(
C#na( In!a( apan an! ot#er "o&ntre$ )orl!)!e are al$o
promotn' $mlar re'&laton$@
Sn"e t $ ob4o&$ t#at 4e#"le em$$on$ #a4e to be re!&"e!(
a&tomot4e man&fa"t&rer$
are loo?n' for )ay$ to a"#e4e t#$ 'oal@ One of t#em $ !e"rea$n'
f&el "on$&mpton
t#$ $ e$pe"ally ntere$tn' f one al$o ta?e$ 'ro)n' f&el pr"e$
nto "on$!eraton@
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*
In F'&re * ol pr"e !e4elopment for t#e la$t *+ year$ $
$#o)n@ A$ t "an be ob$er4e!
pr"e$ are 'ro)n'( t#ere )a$ a $'nf"ant !rop n *++32*++6 !&e
to pre4o&$ly
mentone! e"onom" "r$$ b&t no) t#e )orl! $ re"o4ern' an! ol $
be"omn' more
e=pen$4e e4ery year@ T#$ mean$ t#at by ma?n' a 4e#"le )t# lo)er
f&el "on$&mpton
one "an not only re!&"e em$$on$ b&t al$o ma?e t more
attra"t4e for t#e fnal "&$tomer
n term$ of money $pent on f&el@
Figure ". #il prices in development in $S dollars per barrel
%!
1.1. Project background
Sn"e en4ronmental le'$laton $ 'ettn' $tr"ter an! f&el pr"e$
are 'ro)n' t#ere $ a!eman! from bot# 'o4ernmental n$tt&ton$ an!
"&$tomer$ to re!&"e t#e f&el
"on$&mpton of pa$$en'er 4e#"le$@ T#ere are n&mero&$
)ay$ to a"#e4e t#$ 'oal/
ntro!&"ton of better tyre$ )t# lo)er rolln' re$$tan"e
mpro4n' !r4etran by
mnmn' lo$$e$ n !fferent $y$tem$ ntro!&"n' $&pplementary
ele"tr"al motor$ )t#
battere$( allo)n' part of t#e o&rney to be !r4en &$n'
ele"tr"al po)er $tore! et"@ K&t
one of t#e mo$t effe"t4e )ay$ to re!&"e t#e f&el
"on$&mpton $ by mpro4n'
aero!ynam" properte$ of t#e 4e#"le@ It $ e$pe"ally mportant n
t#e "a$e of #'#)ay
!r4n' $n"e aero!ynam" re$$tan"e $ a P&a!rat" f&n"ton of
4e#"le $pee!@ A 4e#"le
)t# better aero!ynam" properte$ )ll not only "on$&me le$$
f&el( t )ll al$o #a4e better
a""eleraton "apablte$( #'#er ma=m&m $pee! an! n"rea$e! !r4n'
ran'e( )#"# $
e$pe"ally mportant for #ybr! an! "ompletely ele"tr"al
4e#"le$@
De$'ner$ an! aero!ynam"$t$ are )or?n' #ar! fn!n' "omprom$e$ to
a"#e4e bot#
'oo! loo?n' an! aero!ynam"ally eff"ent $#ape$@ A lot of )or? #a$
alrea!y been !one
to t#e &pper bo!y of t#e 4e#"le$( b&t t#ere are ot#er
area$ t#at "an be ntere$tn' to be
n4e$t'ate!@ In F'&re - one "an $ee t#e appro=mate per"enta'e
of aero!ynam" lo$$e$
a$$o"ate! )t# part$ of t#e "ar 1@
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Figure &. Contributions to the aerodynamic drag from
different parts of a passenger car
A$ one "an $ee le$$ t#an 1+B of aero!ynam" !ra' for"e $
'enerate! by t#e &pper bo!y1@ >#eel$ an! )#eel2#o&$e$
"an 'enerate &p to one P&arter of t#e total !ra' 0( :@
Sn"e t#e &n!erbo!y an! )#eel2#o&$e$ to'et#er are
re$pon$ble for t#e lar'e$t part of t#e
aero!ynam" !ra' for"e t#e$e area$ are "on$!ere! to 'reat
potental for mpro4ement@
Aero!ynam" en'neer$ )or? #ar! to &n!er$tan! t#e p#enomena
a$$o"ate! )t# t#e area$
n P&e$ton an! 4e#"le$ n 'eneral@ For e=ample a lot of
a&tomot4e )n!2t&nnel$ #a4e
been &p!ate! )t# !fferent ?n!$ of 'ro&n! $m&laton
te"#nP&e$ n or!er to properly
repre$ent real roa! "on!ton$ 3( 6 an! 'ro)n' "omp&ter po)er
#a$ allo)e!
"omp&tatonal fl&! !ynam"$ 8CFD9 en'neer$ to "reate
m&"# more "ompl"ate! an!
!etale! mo!el$ to te$t n a $m&late! en4ronment@
T#e n"rea$n' "omple=ty of mo!el$ allo)$ en'neer$ to more
t#oro&'#ly n4e$t'ate
!fferent a$pe"t$ a$$o"ate! )t# arflo) aro&n! t#e 4e#"le( for
e=ample( en'ne2bay arflo) an! t$ ntera"ton )t# &n!erbo!y flo)
or flo) "ontrol by 4orte= 'enerator$@
1.2. Project goals
T#e man 'oal of t#e proe"t $ to fn! a )ay to re!&"e f&el
"on$&mpton of pa$$en'er
4e#"le$ by re!&"n' t#e aero!ynam" "ontrb&ton to
re$$tan"e for"e$@ T#e man area of
ntere$t $ )#eel an! )#eel2#o&$e aero!ynam"$ an! t$ ntera"ton
)t# &n!erbo!y an!
"ooln' flo)@
Tra!tonally t#e re$$tan"e effe"t$( "o&ntera"tn' 4e#"le
prop&l$on for"e( !&e to ar
en4ronment are only 4e)e! from t#e per$pe"t4e of aero!ynam" !ra'
for"e@ For a
typ"al me!&m2$e! E&ropean pa$$en'er 4e#"le( )t# #'#)ay
$pee!$ abo4e 0+2:+
?m#o&r( an! a$$&mn' le4el roa!$( t#$ for"e !omnate$ all
ot#er for"e$ 1( $ee F'&re 5@
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Figure %. Aerodynamic drag force and rolling resistance force
versus vehicle velocity for a typical
passenger vehicle
A$ )ll be $#o)n later( t#ere are al$o ot#er effe"t$( or'natn'
from t#e ntera"ton of
4e#"le part$ )t# t#e ar( )#"# $#o&l! be ta?en nto
a""o&nt f one )ant$ to a"#e4e a
!eeper &n!er$tan!n' of pa$$en'er24e#"le aero!ynam"$ an!
mpro4e $m&laton mo!el$
t#at are "&rrently ben' &$e!@ One of t#e effe"t$(
n4e$t'ate! n t#$ proe"t( $ t#e
4entlaton re$$tan"e moment a"tn' on rotatn' )#eel$@
To be'n )t#( 4entlaton re$$tan"e $ !efne! an! !$"&$$e!@ Sn"e
t $ not ea$y to
mea$&re t#$ re$$tan"e( !fferent problem$ a$$o"ate! )t# t#$
pro"e$$ are #'#l'#te!@
Later( a $t&!y at Vol4o Car Corporaton )n!2t&nnel $
pre$ente! an! t#e re$<$ are
analy$e! an! !$"&$$e!@
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2. Passenger vehicle aerodynamics
A$ alrea!y !$"&$$e!( aero!ynam" for"e$ #a4e an mportant role
for pa$$en'er "ar$( an!
e4en t#o&'# t#er effe"t$ on 4e#"le performan"e 8ma=m&m
$pee! an! a""eleraton9 an!
em$$on$ are probably mo$t 4tal( t $ mportant to remember ot#er
a$pe"t$ relate! to ar
flo) aro&n! t#e 4e#"le@
Fr$tly( menton $#o&l! be ma!e of "ooln' an! t#ermal
mana'ement $n"e t#ere are
n&mero&$ "omponent$ t#at reP&re temperat&re
mana'ement )t#n $tr"t "rtera( for
e=ample en'ne( tran$m$$on( bra?e$( "on!en$er an!( n t#e "a$e of
#ybr! an! ele"tr"al
4e#"le$( battery pa"?$@ T#$ $ &$&ally a"#e4e! by !re"tn'
$ome of t#e ar t#ro&'# t#e
area$ $pe"fe!( )#ere t#e e="e$$4e #eat $ remo4e! by t#ermal
"on!&"ton an!
"on4e"ton@
Anot#er mportant area to "on$!er $ "abno""&pant "omfort@ T#$
n"l&!e$/ 4entlaton
of t#e pa$$en'er "ompartment( )#"# may al$o reP&re ar
"on!tonn' an! )n! no$e(
e$pe"ally from rear 4e) mrror$( t#at may be P&te
!$t&rbn' for t#e !r4er an!
pa$$en'er$@
Aero!ynam"$ #a$ a $'nf"ant effe"t on t#e 4e#"le $tablty on t#e
roa!/ lft2 or
!o)nfor"e "an "on$!erably "#an'e t#e a4alable tra"ton or 'rp
for"e$( t#ereby affe"tn'
#an!ln' of t#e "ar@ Moreo4er $!e2)n!$ an! e$pe"ally $&!!en
'&$t$ may ntro!&"e
a!!tonal for"e$ t#at t#e !r4er $#o&l! "ompen$ate for@
Menton $#o&l! al$o be ma!e re'ar!n' 4$blty an! "ontamnaton
a$pe"t$@ On roa!$ t#e
ar $ ne4er "lean t "ontan$ !&$t an! m&! part"le$ t#at
ten! to $t"? to !fferent $&rfa"e$
of t#e 4e#"le@ In )et "on!ton$ t $ al$o mportant to "on$!er
$pla$# an! $pray t#at nee!
be "ontrolle!@
2.1. Driving resistance
Dr4n' re$$tan"e $ t#e total re$$tan"e for"e a"tn' on t#e 4e#"le
)#en t $ mo4n'
&$&ally t#$ for"e $ e=pre$$e! &$n' eP&aton ,
,+/
# $ %$ &$ # !' $ %' *+,- $ ' ,./ - $ 01 231 8,9
T#e fr$t term #ere( !'$ 4e#"le ma$$ m<ple! by 4e#"le
a""eleraton t repre$ent$!r4er be#a4o&r n term$ of a""eleraton
or !e"eleraton@ Coeff"ent !$ &$e! to ta?e ntoa""o&nt t#e
nerta of rotatn' part$( e@'@ fly)#eel( $#aft$( 'ear$ et"@ T#e
$e"on! term $ fort#e rolln' re$$tan"e( a$ "an be $een t $
proportonal to t#e normal for"e bet)een t#e
tyre$ an! t#e roa! 8- $ an n"lnaton an'le of t#e roa!9@ %$ a
"oeff"ent of rolln're$$tan"e )#"# !epen!$ on )#eel an! roa!
properte$( an! $ome ot#er fa"tor$@ Q&te
often t $ a$$&me! to be "on$tant for $mpl"ty rea$on$@ T#e
t#r! term #ere "#ara"tere$
t#e part of 'ra4tatonal for"e t#at a"t$ on a 4e#"le )#en 'on'
&p#ll or !o)n#ll@ T#e
la$t term n t#e eP&aton $ &$&ally !enote! a$
aero!ynam" !ra' for"e or $mply
aero!ynam" !ra'@
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A$ "an be $een from eP&aton ,( aero!ynam" !ra' for"e $
proportonal to ar !en$ty 3an! t#e $P&are of 4elo"ty( t $ a
relat4e 4elo"ty bet)een t#e 4e#"le an! t#e ar@Anot#er "omponent of
t#e eP&aton $ referen"e area2( )#"# $ t#e proe"te! frontal
areaof t#e 4e#"le@ T#e la$t term #ere $ an aero!ynam" !ra'
"oeff"ent of t#e 4e#"le@ It$ a !men$onle$$ fa"tor t#at manly
!epen!$ on t#e 'eneral $#ape of t#e 4e#"le an! "an
4ary from +@1 , for ol!er 4e#"le$ !o)n to 4al&e$ aro&n!
+@,3 +@*5 for mo!ern
"on"ept 4e#"le$ ,,( ,*@ Often )#en "omparn' t)o 4e#"le$ a
pro!&"t of frontal areaan! !ra' "oeff"ent 829 $ &$e!@ It $
$ometme$ referre! to a$ !ra' fa"tor an! t allo)$"ompar$on of
aero!ynam" "#ara"ter$t"$ of 4e#"le$ of !fferent $e$ an! $#ape$@
2.2. Aerodynamic drag of passenger cars
>#en tal?n' abo&t t#e aero!ynam" !ra' of 4e#"le$ t $
mportant to menton t)o
"omponent$ of t#$ for"e/ pre$$&re an! 4$"o&$ !ra'@
;re$$&re !ra' or'nate$ from t#e fa"t t#at t#e $tat"
pre$$&re aro&n! t#e 4e#"le 4are$ to
a "on$!erable e=tent( $ee F'&re 1 for a
pre$$&re2"oeff"ent plot( at t#e $ymmetry plane(
of a $mplfe! pa$$en'er 4e#"le obtane! 4a CFD $m&laton@
Figure '. Pressure coefficient at the symmetry plane of the
vehicle
One "an $ee t#at n front of t#e 4e#"le t#ere $ an area of #'#
pre$$&re( &$&ally referre!to a$ t#e $ta'naton re'on@ On
t#e ot#er #an! at t#e rear t#e pre$$&re $ not a$ #'#@ T#$
!fferen"e '4e$ net for"e a"tn' a'an$t t#e mo4ement of t#e "ar(
t#$ for"e $ "alle!
pre$$&re !ra'@
T#e $e"on! $o&r"e of aero!ynam" !ra' $ 'enerate! by
4$"o&$ $&rfa"e fr"ton bet)een
t#e ar an! t#e 4e#"le@ T#$ fr"ton re$<$ n $#ear for"e$
a"tn' parallel to 4e#"le
$&rfa"e$@ T#e !ra' a$$o"ate! )t# t#e$e for"e$ $
&$&ally "alle! 4$"o&$ or fr"ton !ra'@
For a typ"al pa$$en'er 4e#"le pre$$&re !ra' !omnate$ o4er
4$"o&$ !ra'( b&t a$ 4e#"le$
be"ome more an! more $treamlne! t#e relat4e mportan"e of
4$"o&$ !ra' $ n"rea$n'
1( ,+@
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2.3. Wheel and heelhouse aerodynamics
>#eel$ are e$$ental part$ of any pa$$en'er 4e#"le( b&t
!&e to lmtaton$ n $m&laton
te"#nP&e$ t#e mportan"e of t#e )#eel$ #a$ not been
$t&!e! for P&te a lon' tme@ T#ere
#a4e been a n&mber of early $t&!e$ n4e$t'atn' )#eel )a?e
an! t#e effe"t$ of rotaton
on !ra' an! lft "oeff"ent ,-( ,5@ E4en t#o&'# t#e$e
$t&!e$ )ere 4ery mportant for
&n!er$tan!n' t#e arflo) aro&n! t#e )#eel( t#e
re$<$ )ere #ar! to apply to real lfe"a$e$( $n"e t#e )#eel$
)ere $t&!e! n $olaton an! all t#e te$t$ )ere "on!&"te!
&$n'
$"ale mo!el$@ >t# t#e a!4an"e$ n )n!2t&nnel eP&pment
more t#oro&'# n4e$t'aton$
#a4e be"ome po$$ble 0( ,1( ,0@
T#e real$aton of t#e mportan"e of proper roa! $m&laton an!
rotaton of t#e )#eel$ #a$
le! to 'eneral mpro4ement$ for a&tomot4e )n!2t&nnel$(
an! to t#e fa"t t#at no)a!ay$
more an! more )n! t&nnel$ are eP&ppe! )t# !fferent
mo4n'2'ro&n! $y$tem$ )t#
proper bo&n!ary2layer treatment@ It #a$ been $#o)n t#at
ntro!&"n' of $&"# $y$tem$
n"rea$e! t#e "omple=ty of t#e arflo)( e$pe"ally n t#e area of
)#eel#o&$e$( an! #a$ le!
to t#e re!&"ton of o4erall !ra' for"e "ompare! to a
$tatonary "a$e ,:@ It #a$ al$o lea!
to n"rea$e! "omple=ty of mea$&rement pro"e!&re$ $n"e
t#ere are for"e$ 'enerate!
bet)een t#e tyre an! mo4n' belt )#"# m&$t be $&btra"te!
n or!er to obtan "orre"t
4al&e$ for !ra' an! lft for"e$@
It $#o&l! al$o be mentone! t#at )t# t#e n"rea$e! "omple=ty
of t#e eP&pment an!
better &n!er$tan!n' of t#e flo) fel! aro&n! t#e )#eel(
t#ere #a$ been a $#ft to more
"omple= mo!el$ for e4al&atn' t#e aero!ynam" performan"e of
4e#"le$@ One of t#e
met#o!$ $ to ta?e aero!ynam" re$$tan"e moment nto "on$!eraton@
T#$ p#enomenon
$ $ometme$ referre! to n lterat&re a$ p&mpn' lo$$e$(
aero!ynam" re$$tan"e torP&e or
4entlaton re$$tan"e 0( ,3( ,6@
2.!. Different methods for assessing aerodynamics on
passengercars
In t#$ t#e$$ t#e man fo"&$ $ on t#e e=permental
mea$&rement$ of !fferent for"e$( b&tbefore !$"&$$n' )n!
t&nnel $et2&p$( t $ &$ef&l to brefly !e$"rbe ot#er
met#o!$
a4alable to aero!ynam" en'neer$ )#en n4e$t'atn' aero!ynam"
performan"e of
!fferent part$ an! pa$$en'er 4e#"le$( n 'eneral@
2.4.1 Computational fluid dynamics
T#e fr$t approa"# t#at $ often &$e! $ CFD or
Comp&tatonal Fl&! Dynam"$@ Here t#e
'o4ernn' eP&aton$ for t#e flo) n fl&! !ynam"$/
"ontn&ty( moment&m an! ener'y(
are $ol4e! n&mer"ally &$n' fnte 4ol&me met#o! 8FVM9
an! t#e "omp&tatonal po)er
offere! by "on$tantly e4ol4n' "omp&ter$@ In t#e be'nnn' t#$
met#o! only allo)e! t#e
$ol4n' of 4ery $mple "a$e$ b&t )t# "omp&ter performan"e
!o&bln' e4ery t)o year$(
a""or!n' to Moore$ la) *+( t#e "omple=ty of t#e mo!el$ an! "a$e$
'ro)$ all t#e tme@
No)a!ay$ t $ #ar! to ma'ne fl&! !ynam"$ )t#o&t CFD
tool$@
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2.4.2 Coast down tests
T#e $e"on! approa"# $ probably t#e ol!e$t $n"e t !oe$ not
reP&re b&l!n' any fa"lte$
or #a4n' "omp&ter "l&$ter$@ T#$ met#o! n4ol4e$ !r4n' t#e
4e#"le on a flat roa!(
!$en'a'n' t#e "l&t"# an! $m<aneo&$ly re"or!n'
4elo"ty an! !$tan"e tra4elle!( tllt#e 4e#"le $top$ *,@ It $ often
"alle! t#e "oa$t2!o)n te$t an! #a$ a n&mber of
lmtaton$( e@'@ "ompen$atn' for t#e )n! $pee!( $eparatn' rolln'
re$$tan"e from
aero!ynam" re$$tan"e( et"@
2.". Wind tunnel tests
T#e t#r! an! t#e la$t met#o! !$"&$$e! #ere $ )n!2t&nnel
te$tn'@ >n! t&nnel$ #a4ebeen &$e! by 4e#"le
man&fa"t&re$ for many year$@ In t#e be'nnn' aerona&t"al
)n!2
t&nnel$ )t# a 'ro&n! plane to repre$ent t#e roa! )ere
&$e! **@ Later( t#e fr$t !e!"ate!
a&tomot4e )n!2t&nnel$ )ere b< *-@ T#e$e )n!
t&nnel$ #a! a $tatonary 'ro&n!( b&t
a$ tme pa$$e! t#e re$ear"# rea"#e! t#e pont )#en t )a$ 'enerally
a""epte! t#at rotatn'
)#eel$ an! a!4an"e! mo4n'2'ro&n! $m&laton $y$tem$ )ere
ab$ol&tely ne"e$$ary for
proper $m&laton of t#e on2roa! "on!ton$@
T#e !ea of &$n' a mo4n' belt for $m&latn' real$t"
bo&n!ary2"on!ton$ &n!er t#e
4e#"le $ not ne) *5( b&t t #a$ e4ol4e! $'nf"antly )t# tme@
In t#$ part !fferent
mo4n' 'ro&n! $y$tem$ &$e! n a&tomot4e
)n!2t&nnel$ are !$"&$$e!@
2.5.1 Single belt system
T#e fr$t $y$tem to be !$"&$$e! $ a $n'le belt( often
referre! to a$ a f&ll2)!t# $y$tem(
$ee F'&re 0@ In t#$ "a$e t#ere $ one belt t#at mo4e$
&n!er t#e 4e#"le@ T#$ belt $ )!er
an! lon'er t#an t#e mo!el te$te!@
Figure (. Single belt moving ground system
To'et#er )t# a $&"ton $"oop an! !$trb&te! $&"ton
one$( remo4n' bo&n!ary2layer ar
before t#e belt( t#$ $y$tem pro!&"e$ almo$t !eal
&n!erbo!y flo)@ T#$ $ one of t#e
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6
rea$on$ t#$ $y$tem $ pop&lar for ra"n' "ar !e4elopment@
Anot#er appl"aton of t#$ $et2
&p( !&e to t$ $mpl"ty( $ n $"ale2mo!el )n! t&nnel$
*1@
One of t#e !ra)ba"?$ of t#$ $y$tem $ t#at t#e 4e#"le #a$ to be
$&$pen!e! by an
o4er#ea! or rear $tn'( t#e for"e balan"e $ &$&ally
lo"ate! n$!e t#e mo!el@ T#e $tn' #a$
to $&pport t#e )e'#t of t#e mo!el( t#erefore !epen!n' on t#e
mo!el $e t "an be rat#er
lar'e( "on$eP&ently pro!&"n' $ome nterferen"e effe"t$
an! affe"tn' for"emea$&rement$ *0( *:@ A!!tonally t may be
rat#er !ff"< to $eparate rolln'
re$$tan"e of t#e )#eel$ from aero!ynam" !ra'( $n"e t#e )#eel$
are n "onta"t )t# t#e
r&nnn' belt@ One of t#e )ay$ to $ol4e t#$ problem $ to
&$e $eparate )#eel $tr&t$( one to
$&pport ea"# )#eel( $ee F'&re : for an e=ample from
C#almer$ )n!2t&nnel@
Figure ). Single belt moving ground set*up in Chalmers +ind
tunnel
In t#$ "a$e t#e )#eel$ are "ompletely !eta"#e! from t#e mo!el(
an! aero!ynam" for"e
mea$&rement$ for t#e 4e#"le bo!y are no lon'er a problem@ In
or!er to mea$&re for"e$
a"tn' on t#e rotatn' )#eel$( $eparate )#eel balan"e$ may be
&$e! *3@ Interferen"e
effe"t$ of )#eel $tr&t$ m&$t al$o be ta?en nto
a""o&nt@
2.5.2 Five-belt system
Anot#er pop&lar mo4n'2'ro&n! $y$tem $ a f4e2belt one(
$ee F'&re 3 for a $mplfe!
4e)@
Figure ,. Five*belt moving ground set*up
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,+
T#$ $y$tem an! t$ 4araton$( !$"&$$e! later( are P&te
pop&lar for f&ll2$e te$tn'@ Here
t#e 4e#"le $ $&pporte! by fo&r $tr&t$ lo"ate!
&n!erneat#( t#&$ t#ere $ no nee! for an
o4er#ea! $tn'@ In or!er to enable )#eel rotaton( t#e )#eel$ are
po$tone! on $mall belt$
or roller$( &$&ally referre! to a$ )#eel !r4e &nt$
or $mply >D%$( an e=ample from t#e
Vol4o )n!2t&nnel $ $#o)n n F'&re 6@ T#e >D%$ an!
4e#"le $tr&t$ are all "onne"te!
to t#e 4e#"le balan"e( lo"ate! &n!er t#e te$t $e"ton
permttn' !re"t mea$&rement of
aero!ynam"2!ra' for"e )t#o&t nterferen"e of rolln'
re$$tan"e@
Figure -. Five*belt moving ground system used in olvo
aerodynamic +ind tunnel /courtesy of olvo
Car Corporation0
In or!er to $m&late t#e mo4n' 'ro&n! t#ere $ a lon'
"entre2belt r&nnn' &n!er t#e
4e#"le@ T#e !ra)ba"? of t#$ $y$tem $ t#at !&e to t#e
po$tonn' of t#e 4e#"le $tr&t$ t#e
"entre belt $ lmte! n )!t# an! t !oe$ not "o4er t#e entre
&n!erbo!y t#erefore
altern' t#e arflo) n t#e re'on@ In or!er to "ompen$ate for t#$(
tan'ental blo)n' an!
!$trb&te! bo&n!ary2layer $&"ton may be &$e! 3@
It m&$t al$o be remembere! t#at t#e
$tr&t$ t#em$el4e$ "an pro!&"e $ome nterferen"e effe"t$
on t#e for"e mea$&rement$@
2.5.3 Ote! moving g!ound systems
It $ lo'"al t#at "o4ern' a lar'er area )t# mo4n' belt$ )ll
n"rea$e t#e a""&ra"y of t#e
arflo) repre$entaton &n!er t#e 4e#"le t#erefore a n&mber
of mo!f"aton$ to f4e2belt
$y$tem$ #a4e been ntro!&"e! !&rn' re"ent year$@ T)o of
t#em are pre$ente! #ere(
F'&re ,+@
Figure 1. 2*belt and three*belt moving ground systems
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,,
T#e left2#an! e=ample $ "alle! t#e T2belt $y$tem( #a4n' t)o
a!!tonal belt$ n front of
t#e 4e#"le *6@ T#ere are al$o "on"ept$ &$n' nne or e4en
ele4en belt$ -+@
T#e r'#t2#an! e=ample n F'&re ,+ #a$ a re!&"e!
n&mber of belt$ n "ompar$on )t#
t#e f4e2belt $y$tem b&t #a$ an n"rea$e! area "o4ere! by t#e
belt$@ In t#$ "a$e t#e 4e#"le
$ $tll $&pporte! by $tr&t$ an! >D%$ are repla"e! by
t#e a!!tonal lon' belt$@
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. !orces acting on rotating wheels and ventilationresistance
A rotatn' )#eel $ a "omple= $y$tem an! t#ere are many for"e$ an!
moment$ a"tn' ont@ In or!er to $mplfy matter$( a *2!men$onal
p"t&re )ll be "on$!ere! moreo4er
$n"e for"e$ #a4e !fferent appl"aton pont$ an! !fferent !re"ton$
mo$t of t#e for"e$)ll be repla"e! by eP&4alent for"e an!
moment$ a"tn' at t#e "entre of 'ra4ty 8CoG9 of
t#e )#eel@
3.1. #orces classification
In !ynam" $t&aton$ )#en t#e )#eel rotate$( t#e for"e$ "an be
!4!e! nto e=ternal an!
nertal "omponent$ a$ $#o)n n F'&re ,,@
Figure 11. Forces acting on a rotating +heel
Inertal for"e$ n"l&!e/ moment of nerta of t#e rotatn' )#eel
t#at only o""&r$ )#en t#e
rotatonal 4elo"ty $ "#an'n' an! !$trb&te! nertal for"e$ or
"entrf&'al for"e$@ T#e
la$t ten! to "#an'e t#e 'eometry of t#e tyre( a$ #a$
pre4o&$ly been n4e$t'ate! -,@ In
F'&re ,* a $mplfe! f'&re $#o)n' a=al "ompre$$on an!
ra!al e=pan$on of t#e tyre
$ repre$ente!@
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,5
Figure 1". 3eformations due to inertial forces
Depen!n' on t#e loa! on t#e tyre( an! tyre "#ara"ter$t"$( a=al
"ompre$$on may be a$
#'# a$ 023 mm from ea"# $!e -*( lea!n' to a $'nf"ant "#an'e of
t#e tyre 'eometry@
Ra!al e=pan$on "an al$o be rat#er $'nf"ant( &p to $ame 023mm
n"rea$e o4er t#e
ntally loa!e! )#eel@ T#$ e=pan$on )ll re$< n t#e a=le of
rotaton of t#e )#eelmo4n' &p n$!e t#e )#eel#o&$e@
E=ternal for"e$ "an be !4!e! nto me"#an"al an! aero!ynam"
"omponent$@ Here(
aero!ynam" lft( !ra' an! aero!ynam" re$$tan"e moment$ or'nate
from t#e fa"t t#at
t#e )#eel $ rotatn' n mo4n' ar@ T#e me"#an"al part n"l&!e$
all ot#er element$@
One 4ery mportant moment from t#e me"#an"al part( t#at m&$t
be mentone! $eparately(
$ rolln'2re$$tan"e moment@ It o""&r$ !&e to an
&ne4en pre$$&re !$trb&ton n t#e
"onta"t pat"# )#en t#e )#eel $ rolln'( $ee F'&re ,-@ So( t#e
eP&4alent normal for"e $ $#fte! $l'#tly for)ar! of t#e )#eel
"entre t#e moment # 4 5 $ "alle! rolln'2re$$tan"e moment@
Figure 1&. 2he origin of rolling resistance moment
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,1
3.2. $entilation resistance
T#e aero!ynam" "omponent of a re$$tan"e moment ( a$ alrea!y
mentone! n"#apter *@-( $ $ometme$ referre! to a$ p&mpn' lo$$e$(
4entlaton torP&e or 4entlaton
re$$tan"e@ In t#$ t#e$$ t#e la$t notaton )ll be &$e!( or
$ometme$ t )ll be referre! to
a$ 4entlaton momentJ to a4o! "onf&$on )t# aero!ynam" !ra'J
or aero!ynam"
re$$tan"eJ( )#"# $ &$&ally "on$!ere! to be a for"e n t#e
lon't&!nal !re"ton@
3.2.1 "entilation !esistance o!igins
Ventlaton re$$tan"e moment( $mlarly to aero!ynam" !ra' for"e(
$ee "#apter *@*( #a$
t)o or'n$/
" ;re$$&re "omponent( pro!&"e! by t#e non2&nform
normal pre$$&re !$trb&tonaro&n! t#e )#eel
" V$"o&$ "omponent( or'natn' from t#e $&rfa"e fr"ton
a"tn' on !fferentrotatn' part$@
In t#e "a$e of t#e )#eel( t#e rotatn' part$ are/ t#e tyre( t#e
rm( an! t#e bra?e !$" an!
t#erefore t#e 4entlaton moment a"tn' on )#eel $ !epen!ent on t#e
$#ape an! $e oft#e$e "omponent$@
3.2.2 "entilation !esistance measu!ements
Mea$&rn' 4entlaton re$$tan"e n CFD $ relat4ely ea$y@ It "an
be !one by $mply
$ele"tn' !fferent part$ of t#e )#eel an! nte'ratn' normal an!
tan'ental $tre$$e$ o4er
t#e $&rfa"e$( to "al"&late t#e 4entlaton moment
aro&n! t#e a=le of rotaton@
In t#e "a$e of )n!2t&nnel te$tn' t $ not t#at ea$y(
be"a&$e t#e me"#an"al "omponent$
of for"e$ an! moment$ #a4e to be $eparate! from aero!ynam"@
Moreo4er( nertal(
t#ermal an! ot#er "#an'e$ m&$t be ta?en nto a""o&nt@
C&rrently t#ere are t)o !o"&mente! met#o!$ !e$"rbn'
4entlaton2moment
mea$&rement$ n )n! t&nnel$( bot# reP&re "#an'e$ to a
$tan!ar! )n!2t&nnel $et2&p@
T#e fr$t one &$e$ a po)er approa"#( an! n4ol4e$ "#an'n' t#e
!r4etran of t#e 4e#"le
to permt mea$&rement of t#e po)er reP&rement to rotate
t#e )#eel ,3@ T#e $e"on!(
t#at $ 'on' to be !$"&$$e! #ere n more !etal( &$e$ t#e
approa"# $t&!yn' for"e$( an!
n4ol4e$ mea$&rement of tra"ton for"e bet)een t#e )#eel an!
t#e )#eel !r4e &nt --@
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,:
#. $%perimental set&up
In t#$ "#apter an e=permental $et2&p &$e! to mea$&re
t#e 4entlaton re$$tan"e moment
of )#eel$ )t# !fferent rm$ $ brefly !$"&$$e!@ For more
!etale! !e$"rpton$ $ee --(
-5@
!.1. %he ind tunnel set&up
T#e Vol4o )n!2t&nnel $ eP&ppe! )t# a f4e2belt mo4n'
'ro&n! $y$tem )t# an
a!4an"e! bo&n!ary layer treatment $y$tem@ A 'eneral
!e$"rpton( a!4anta'e$ an!
!$a!4anta'e$ of $&"# a $et2&p )ere !$"&$$e! n $e"ton
*@1@* a more !etale!
!e$"rpton "an be fo&n! n 3@
A$ t #a$ been !$"&$$e!( )t# $&"# a $et2&p t#e )#eel$
are rotate! by )#eel !r4e &nt$(
$ee F'&re ,5@ In or!er to mea$&re 4entlaton2re$$tan"e
moment t )a$ !e"!e! &$e loa!
"ell$ n$!e >D%$ to mea$&re t#e tra"ton for"e pro!&"e!
n t#e "onta"t pat"# of ea"#)#eel( an! t#en $olate t#e part
re$pon$ble for o4er"omn' 4entlaton re$$tan"e@
no)n' t#e for"e an! t#e len't# of t#e le4er arm( )#"# n t#$ "a$e
$ t#e ra!&$ of
!eforme! )#eel( t#e 4entlaton moment "an be "al"&late!@
Figure 1%. Wheel drive unit /courtesy of olvo Car
Corporation0
In a $tan!ar! $et2&p( )#en only n4e$t'atn' aero!ynam" !ra'
an! lft for"e$( tra"ton
for"e mea$&rement$ are &$&ally 'nore!@ T#$ $ for t)o
rea$on$/ fr$tly( $n"e bot#
4e#"le $tr&t$ an! )#eel !r4e &nt$ are "onne"te! to t#e
$ame balan"e( t#$ for"e $nternal an! t#ereby #a$ no effe"t on !ra'
or lft for"e$ a"tn' on a 4e#"le $e"on!ly(
$n"e t#e >D%$ are rotatn' t#e )#eel$( t#e po)er $&pple!
to t $ &$e! to o4er"ome not
only 4entlaton re$$tan"e( b&t all ot#er re$$tan"e$ an!
lo$$e$ a$$o"ate! )t# )#eel an!
tyre rotaton/
Rolln' re$$tan"e moment
Inertal re$$tan"e moment
Lo$$e$ n bearn'$
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,3
Lo$$e$ n bra?e$
Lo$$e$ a$$o"ate! )t# !r4e2$#aft an! 'earbo=
Lo$$e$ !&e to $lp n a "onta"t pat"# of t#e )#eel
Sn"e t#e obe"t4e of t#$ te$t )a$ to mea$&re 4entlaton
re$$tan"e( all ot#er re$$tan"e
for"e$ mentone! abo4e m&$t be et#er remo4e! or mea$&re!@
For t#$ rea$on a mo!fe!
)n!2t&nnel $et2&p $ reP&re!@
To be'n )t#( t#e !r4e2$#aft$ )ere !$"onne"te! an! t#e bra?e pa!$
remo4e!@ T#e $#o"?
ab$orber$ )ere remo4e! an! repla"e! )t# re$trant po$t$ )t#
t#rea!e! ro!$( #en"e
allo)n' a f=e! )#eel po$ton n$!e t#e )#eel#o&$e( $ee
F'&re ,1@
Figure 1'. 4odified suspension &&!
After f=n' t#e )#eel$ n$!e )#eel#o&$e$ t#e entre 4e#"le )a$
lfte! &p &$n' $tr&t$ to
#a4e almo$t no "onta"t bet)een )#eel$ an! >D%$@ T#$ )a$ !one
to mnm$e rolln'
re$$tan"e moment a$ m&"# a$ po$$ble( an! at t#e $ame tme
mantann' t#e "onta"t
reP&re! to ?eep t#e )#eel$ rotatn'@
!.2. 'inimising losses
T#e ntal rolln' re$$tan"e moment )a$ mnm$e! an! t#e part left
)a$ mea$&re!@ D&e
to !$trb&te! nertal for"e$ !$"&$$e! n "#apter -@,( t#e
tyre ra!&$ )a$ "#an'n' )t#
n"rea$e of rotatonal 4elo"ty( n"rea$n' t#e 4ert"al loa! n t#e
"onta"t pat"#@ In or!er to
"ompen$ate for t#$ "#an'e t#e 4e#"le 'ro&n! "learan"e )a$
altere! to mantan "on$tant
an! relat4ely lo) rolln' re$$tan"e@ Moreo4er( $n"e t#e tyre
!eformaton n t#e "onta"t
pat"# )a$ ne'l'ble t#ere )ere no temperat&re
fl&"t&aton$ for t#e tyre t$elf an! of t#e
ar n$!e( t#erefore t#e tyre nflaton pre$$&re an! rolln'
re$$tan"e "oeff"ent "o&l! be
"on$!ere! "on$tant -1@
T#e nertal re$$tan"e moment )a$ "on$!ere! to be ero( $n"e all
mea$&rement$ )ere
"on!&"te! at "on$tant $pee! $tep$ from 3+ ?m#o&r to *++
?m#o&r )t# a $tep n"rement
of *+ ?m#o&r@
Lo$$e$ a$$o"ate! )t# bra?e$( !r4e2$#aft an! 'earbo= )ere
"on$!ere! to be ero $n"e
t#e bra?e pa!$ )ere remo4e! an! $#aft$ !$"onne"te!@ Lo$$e$
!&e to $lp n t#e "onta"t
pat"# )ere al$o ne'le"te! $n"e t#e "onta"t pat"# area )a$
$mall@
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,6
La$tly( re$$tan"e moment n bearn'$ )a$ e$tmate! )t# a
!ynamometr" $"re)!r4er
an! "on$!ere! to be "on$tant -0@
!.3. %est objects
T#e $et2&p !e$"rbe! )a$ &$e! to mea$&re 4entlaton
re$$tan"e of )#eel$ )t# !fferent
rm !e$'n$@ In or!er to en$&re t#e $ame tyre "#ara"ter$t"$
an! !eformaton$( an! to
mnm$e ot#er po$$ble error$ a$$o"ate! )t# "#an'n' of )#eel$
!&rn' t#e te$t( a
!e"$on )a$ ma!e to &$e a $et of pre4o&$ly !e4elope!
mo!&lar )#eel$ -:@ Ea"# of t#e
)#eel$ )a$ a f4e $po?e( ,: al&mn&m rm( an! a n&mber
of nter2"#an'eable a!!2on
part$ man&fa"t&re! &$n' $ele"t4e la$er $ntern' 8SLS9
rap! prototypn' )a$ &$e!( $ee
F'&re ,0@
Figure 1(. 4odular +heel system
Sn"e "#an'n' t#e rm "onf'&raton )a$ po$$ble )t#o&t
!$mo&ntn' or "#an'n' t#e
)#eel( t#e tme bet)een te$tn' !fferent !e$'n$ )a$ mnmal@
D&e to t#e lmtaton$ of t#e 'eometry of t#e ba$e rm all )#eel
!e$'n$ )ere lmte! to
f4e $po?e$ an! ,: !ameter@ De$'n$ n4e$t'ate! "an be $een n
F'&re ,:@ A$ "an be$een t#e !e$'n$ !ffer n $e an! $#ape of t#e
$po?e$( an! n t#e area "o4era'e from
nner to o&ter ra!@ One !e$'n #a$ no openn'$ at all( $ee
F'&re ,:8b9( an! t)o !e$'n$
#a4e t#ree2!men$onal bla!e $po?e$( F'&re ,:8!( e9( one
!e$'ne! to '&!e t#e ar o&t
from t#e )#eel#o&$e an! t#e $e"on! one to p&mp ar n@
One !e$'n t#at !e$er4e$ $pe"al attenton( t#e #'# !ra' profle(
$ee F'&re ,:8?9( )a$
ntro!&"e! to #a4e a referen"e pont an! enable "ompar$on
bet)een !fferent
"onf'&raton$@
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*+
8a9 Ra) rm 8b9 F&lly "o4ere!
rm
8"9 Slm o&ter
ra!&$ "o4er8!9 Fan bla!e
IN
8e9 Fan bla!e
O%T
8f9 T#"? o&ter
ra!&$ "o4er
8'9 T#"? $&n
bla!e$
8#9 Slm $&n
bla!e$
89 Ka$e $po?e$ 89 T#"? $po?e$
8o&ter ra!&$
"o4er9
8?9 H'# !ra'
profle8ref9
8l9 Star "o4er
8m9 T#"? ba$e
$po?e$9
8n9 Flo)er "o4er
Figure 1). Rim designs investigated in Paper II
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*,
'. (esults and discussions
".1. (ntroduction of ventilation drag coefficient
Sn"e t#e for"e mea$&re! !&rn' t#e e=perment )a$ part of
t#e tra"ton for"e re$pon$ble
for o4er"omn' 4entlaton re$$tan"e ( t $ po$$ble to repla"e
4entlaton re$$tan"emoment )t# eP&4alent re$$tan"e for"e
"o&ntera"tn' 4e#"le mo4ement@ T#$for"e "an be a!!e! to !r4n'
re$$tan"e for"e( $ee eP&aton ,( n or!er to n"l&!e effe"t
of
4entlaton re$$tan"e/
# $ %$ &$ $ 8*9
T#e 4entlaton re$$tan"e moment "an be "al"&late! &$n'
eP&aton -/
()# ()46() 8-9
6()$ t#e !ynam" tyre ra!&$( t#at "#an'e$ )t# $pee!( $ee
F'&re ,3@
Figure 1,. entilation resistance measurement
T#e po)er reP&re! to o4er"ome 4entlaton re$$tan"e moment "an
be )rtten n t)oform$/
()# () 4"() 859
an!
()# () 4 819
EP&aton$ - an! 5 allo) repre$entn' t#e eP&4alent
4entlaton re$$tan"e for"e n term$
of tra"ton for"e mea$&re! !&rn' t#e e=perment789:; ( $ee
eP&aton$ 026@
() 4 # ()# () 4 "() 809
() 4 # ( ) 4 6 ( ) 4 "() 8:9
() 4 # () 4 839
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**
# 869
A$ "an be $een t#e eP&4alent 4entlaton re$$tan"e for"e $
eP&al to part of t#e tra"ton
for"e re$pon$ble for 4entlaton re$$tan"e moment@ Smlarly to t#e
aero!ynam" !ra'
for"e( "an be )rtten n t#e form of/
# 01 ()231 8,+9
)#ere()"an be "alle! 4entlaton !ra' "oeff"ent( analo'o&$ to
aero!ynam" !ra'"oeff"ent(
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*-
Figure 1-. entilation resistance comparison for different rim
configurations
It )ll be $een t#at t#e be$t !e$'n n term$ of 4entlaton
re$$tan"e moment )a$ t#e
T#"? o&ter ra!&$ "o4er( $n"e t #a! t#e lo)e$t ()
t#ro&'#o&t almo$t t#e entre4elo"ty ran'e@ A po$$ble rea$on
for t#$ may be t#at t#e e=po$e! part$ of $po?e$ n
t#$"onf'&raton #a4e lo)er relat4e $pee!( $n"e t#e $po?e len't#
)a$ $#orter an! t#ey are
po$tone! "lo$er to t#e "entre of rotaton of t#e )#eel@ T#$ meant
t#at t#e lea!n' e!'e
of t#e $po?e )a$ $&be"te! to a lo)er pre$$&re( "ompare!
)t# t#e Star "o4er
"onf'&raton( for e=ample@
T#e $e"on! be$t "onf'&raton( Fan bla!e o&t( #a!
aero!ynam"ally $#ape! )#eel $po?e$
!e$'ne! to p&mp t#e ar o&t from t#e )#eel#o&$e(
t#ereby re!&"n' pre$$&re n$!e@ T#e
$moot# "orner$ on t#e lea!n' e!'e of t#e $po?e$ may #a4e al$o
"ontrb&te! to lo)er
4entlaton re$$tan"e moment@
>t# re'ar! to t#e ot#er !e$'n$( a$ e=pe"te! t#e H'# !ra'
profle )a$ pro4e! to be t#e)or$t !e$'n( an! t#e Star "o4er #a! t#e
$e"on! )or$t performan"e o&t of all t#e ,0
!e$'n$@
One "onf'&raton t#at !e$er4e$ $pe"al attenton $ t#e
F&lly "o4ere! rm $n"e t )a$
alrea!y ?no)n for pro!&"n' really 'oo! re$<$ for
aero!ynam" !ra' for"e -:@ It$
performan"e n term$ of 4entlaton re$$tan"e )a$ $l'#tly belo)
a4era'e@ T#$ may #a4e
$e4eral e=planaton$@ Fr$tly( #a4n' no openn'$ n t#e rm permt$ an
atta"#e! flo) on
t#e o&ter $!e of t#e rm t#$ "an re$< n n"rea$e!
$&rfa"e fr"ton@ Se"on!ly( )t# $&"#
a "onf'&raton t#e ar "annot pa$$ t#ro&'# t#e rm an! t#e
pre$$&re n$!e t#e )#eel#o&$e
may be affe"te!@
5.2.2#e!odynamic d!ag fo!ce
F'&re *+ $#o)$ t#e per"enta'e !fferen"e bet)een !fferent
)#eel rm !e$'n$ n term$
of aero!ynam" !ra' of t#e 4e#"le n relaton to 4elo"ty@
)* 1** 12* 1#* 1+* 1)* 2**&*
&2'
&2*
&1'
&1*
&'
*
velocity ,km-h.
/f
orc0
1vent2
,&.
!an blade 345
5hick outer radius cover
!ully covered rim
6ase spokes
7igh drag profile
8tar cover
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*5
Figure ". Aerodynamic resistance comparison for different rim
configurations
A$ e=pe"te!( "#an'n' t#e )#eel rm$ !! not #a4e a$ $'nf"ant
effe"t on t#e
aero!ynam" !ra' of t#e 4e#"le a$ t #a! on 4entlaton re$$tan"e of
t#e )#eel$t#em$el4e$@ Al$o( a$ pre!"te!( t#e F&lly "o4ere! rm
!e$'n pro!&"e! t#e lo)e$t
aero!ynam" re$$tan"e( "lo$ely follo)e! by t#e T#"? o&ter
ra!&$ "o4er@ T#e mportan"e
of "o4ern' t#e o&ter ra!&$ of t#e )#eel rm( n or!er to
a"#e4e lo)er aero!ynam" !ra'
for"e( #a$ alrea!y been n4e$t'ate! -3( -6@
It $#o&l! al$o be $tate! t#at t#ere )a$ no ob4o&$
"orrelaton ob$er4e! bet)een
aero!ynam" !ra' for"e an! 4entlaton re$$tan"e moment@
5.2.3 $otal ae!odynamic !esistance
A$ !e$"rbe! n $e"ton 1@,( $n"e aero!ynam" !ra' "oeff"ent (
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*1
Figure "1. 2otal aerodynamic resistance comparison for different
rim configurations
T#$ 'rap#( to'et#er )t# F'&re ,6 an! F'&re *+( $#o)$ t#e
mportan"e of 4entlaton
re$$tan"e@ One "an $ee t#at t#e F&lly "o4ere! rm #a$ rat#er
'oo! o4erall re$<$( b&te4en t#o&'# t #a$ $#o)n t#e
be$t performan"e n term$ of aero!ynam" !ra' for"e( t )a$
not t#e be$t !e$'n )#en t "ame to total aero!ynam" re$$tan"e@
T#$ )a$ !&e to t#e
relat4ely #'# 4entlaton re$$tan"e moment 'enerate! by t#$
"onf'&raton@
T#e be$t re$< )a$ $#o)n by t#e T#"? o&ter ra!&$
"o4er( $n"e t pro!&"e! t#e lo)e$t
4entlaton moment an! performe! rat#er )ell n term$ of aero!ynam"
!ra'@ T#$
"onf'&raton )a$ al$o better t#an t#e F&lly "o4ere! rm
from a bra?e "ooln' pont of
4e)( $n"e t allo)e! ar e="#an'e t#ro&'# t#e rm@
T#e Fan bla!e o&t !e$'n t#at #a! relat4ely lo) 4entlaton
!ra' "oeff"ent( $#o)e! only
nterme!ate re$<$ n term$ of total aero!ynam" re$$tan"e@
De$pte t#$ fa"t( a better
!e$'ne! 4er$on of t#$ "onf'&raton may #a4e a lot of potental
,6@
".3. Alternative ay to introduce ventilation resistance into
drivingresistance e)uation
Sn"e t#e 4entlaton !ra' "oeff"ent()$ #'#ly !epen!ent on 4e#"le
4elo"ty t $!ff"< to &$e eP&4alent 4entlaton re$$tan"e
for"e n t#e form of eP&aton ,+ for!r4n' re$$tan"e for"e
8eP&aton ,*9 "al"&laton$@ In or!er to o4er"ome t#$ lmtaton
an
alternat4e form of eP&aton ,+ $ $&''e$te!@
In F'&re ** one "an $ee t#e "al"&late! eP&4alent
4entlaton re$$tan"e !epen!en"y on
t#e 4e#"le 4elo"ty for fo&r )#eel$ )t# !fferent rm$@ >t#
t#e e="epton of t#e H'#
!ra' profle( F'&re ,:8?9( )#"# )a$ a rat#er e=treme an!
&nreal$t" !e$'n for a rm( all
!e$'n$ $#o) lnear !epen!en"y of t#e for"e $t&!e! to t#e
4e#"le $pee!@ T#at allo)$ t#e
eP&aton for to be )rtten n t#e follo)n' form/
# 01 3 8,-9
)* 1** 12* 1#* 1+* 1)* 2**&)
&9
&+
&'
&
&2
&1
*
velocity ,km-h.
/f
orc0
,&.1ventialtion:aerodynamic2
!an blade 345
5hick outer radius cover
!ully covered rim
6ase spokes
7igh drag profile
8tar cover
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*0
or
# 01 LMNGO>F?GH
P 31 8,59
Figure "". 56uivalent ventilation resistance force vs vehicle
velocity
"an be "alle! 4entlaton re$$tan"e "oeff"ent an!( ba$e! on t#e
mea$&rement$"on!&"te! !&rn' t#e e=perment( t#$
"oeff"ent may be "on$!ere! to be "on$tant for
ea"# $pe"f" )#eel !e$'n@ Ka$e! on t#e 4al&e$ for one of t#e
)or$t !e$'n$ n term$ of
4entlaton re$$tan"e moment 8Ka$e $po?e$9 an! t#e be$t one 8T#"?
o&ter ra!&$ "o4er9(
t "an be "on"l&!e! t#at t#$ "oeff"ent 4are$ bet)een *@* an!
*@0QR
S T@
%$n' t#e form of repre$entaton $#o)n n eP&aton ,5 one "an
re2)rte t#eeP&aton for !r4n' re$$tan"e n t#e follo)n' form/
# !' $ %' *+, - $ ' ,./- $ 01 L2 $MNGO>F?GH
P 31 8,19
)#ere$ "on$tant for a "#o$en )#eel "onf'&raton@ A$ one "an
$ee( by t#e a!!tonof one $mall term t $ po$$ble to n"l&!e
4entlaton re$$tan"e nto t#e eP&aton for
!r4n' re$$tan"e@
".!. *+ample of poer comparison
M<plyn' bot# $!e$ of eP&aton ,1 by 4e#"le 4elo"ty( one
"an 'et total po)erreP&rement to o4er"ome t#e !fferent
re$$tan"e$@ In F'&re *- an e=ample of t#e$e
po)er reP&rement$ "an be $een for a typ"al mo!ern
4e#"le@
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*:
Figure "&. Po+er re6uirement to overcome different
resistances
Ob4o&$ly t#e "ontrb&ton of 4entlaton re$$tan"e to t#e
o4erall po)er reP&rement $
not a$ $'nf"ant a$( for e=ample t#at "omn' from rolln' re$$tan"e
b&t a$ "an be $een
for #'#)ay 4elo"te$( 4entlaton re$$tan"e play$ an mportant role
an! $#o&l! not be
ne'le"te!@
".". ,imitations
In t#e e=perment t#e fo"&$ )a$ $olely on mea$&rn' t#e
effe"t$ of !fferent rm !e$'n$on t#e 4entlaton re$$tan"e moment of
t#e )#eel$@ A$ !e$"rbe! n $e"ton -@*@,( t#$
moment !epen!e! on !e$'n of t#e entre )#eel( n"l&!n' bra?e
!$" an! tyre( t#erefore
t $ re"ommen!e! for f&t&re n4e$t'aton$ to te$t rm an!
tyre "ombnaton$( $n"e
!fferent tyre !e$'n "an lea! to $'nf"ant !fferen"e$ n
re$<$@
%nfort&nately( !&e to lmtaton$ of t#e mo!&lar )#eel
$y$tem a4alable( t )a$ only
po$$ble to te$t ,: )#eel rm$@ In4e$t'atn' 4entlaton re$$tan"e
!epen!en"y on )#eel
rm $e $#o&l! al$o be n4e$t'ate!@
It $#o&l! al$o be note! t#at n $ome "a$e$ 4entlaton
re$$tan"e may be partally mea$&re!
!&rn' rolln' re$$tan"e te$t$( an! later be n"l&!e! n
rolln' re$$tan"e "oeff"ent@
T#erefore before applyn' eP&aton ,1 one $#o&l! "#e"? #o)
t#e rolln' re$$tan"e )a$!efne!@ Ne4ert#ele$$( $n"e t#ere $ no
on"omn' arflo) !&rn' t#e rolln' re$$tan"e
te$t( t#e 4entlaton re$$tan"e ma'nt&!e n real lfe may be
$'nf"antly !fferent an!
$#o&l! not be ne'le"te!@
Anot#er t#n' to "on$!er t#at t#e 4entlaton re$$tan"e a!!re$$e! n
t#$ t#e$$ may only
be a part of t#e total aero!ynam" re$$tan"e moment/ t#e part
t#at or'nate$ from t#e
rotatn' )#eel$@ Sn"e t#ere are more rotatn' part$ $&be"te!
to t#e arflo)( for e=ample
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*3
$#aft$ or fan$( t#e total aero!ynam" re$$tan"e moment may be
$'nf"antly #'#er(
e$pe"ally f ta?n' nto "on$!eraton "ooln' fan$ of t#e
4e#"le$@
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*6
+. ;onclusions
T#e n4e$t'aton #a$ $#o)n t#at t#ere are !fferent met#o!$
a4alable to mea$&re
4entlaton re$$tan"e moment n t#e )n! t&nnel@ All met#o!$
reP&re mea$&rn' or
elmnatn' n&mero&$ re$$tan"e moment$ an! po)er lo$$e$
a$$o"ate! )t# t#em@ Mo$t
mportantly( rolln' re$$tan"e moment $#o&l! be ta?en "are of@
In or!er to !o t#at( t $
ne"e$$ary to ma?e "ertan mo!f"aton$ to a $tan!ar! )n!2t&nnel
te$t pro"e!&re@ >t# amo!fe! $et2&p t $ entrely po$$ble
to mea$&re t#e 4entlaton re$$tan"e moment@ One
of t#e met#o!$ )a$ !e$"rbe! n t#e ;aper II an! $ome of t#e
re$<$ )ere pre$ente!@
T#e ma'nt&!e of t#e 4entlaton re$$tan"e( an! more mportantly
t#e po)er reP&re! to
o4er"ome t( $#o)$ t#at t#$ p#enomenon #a$ a $'nf"ant
nfl&en"e on t#e total
aero!ynam" re$$tan"e of t#e 4e#"le an! $#o&l! not be
ne'le"te!@
It #a$ been "onfrme! t#at 4entlaton re$$tan"e !epen!$ on t#e
!e$'n of t#e )#eel$@ T#e
rm$ )t# a t#"? o&ter ra!&$( t#at )ere ?no)n to #a4e a
relat4ely 'oo! performan"e n
term$ of aero!ynam" !ra' for"e( #a4e $#o)n t#e be$t re$<$
n term$ of 4entlaton
re$$tan"e@ Moreo4er t )a$ fo&n! t#at t#$ "onf'&raton )a$
$l'#tly more eff"ent t#an
a f&lly "o4ere! rm( )#en "omparn' total aero!ynam"
re$$tan"e$@ Anot#er )#eel rm
"onf'&raton t#at $#o&l! be mentone!( an! t#at may #a4e
"ertan potental( $ t#e one
)t# aero!ynam"ally !e$'ne! -2!men$onal $po?e$@
In $e"ton$ 1@, an! 1@- t)o !fferent met#o!$ of n"l&!n'
4entlaton re$$tan"e effe"t$ n
t#e eP&aton for !r4n' re$$tan"e for"e )ere pre$ente!@
EP&aton ,1 $#o&l! be preferre!(
$n"e t#e 4entlaton re$$tan"e "oeff"ent( )#"# $ &$e! n t#$
eP&aton( !epen!$only on t#e tyre an! rm "onf'&raton
&$e!( an! $ n!epen!ent of 4e#"le 4elo"ty@
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-,
9. !uture work
To "ontn&e t#e n4e$t'aton of 4entlaton re$$tan"e moment t $
$&''e$te! "on!&"tn'
a $ere$ of n&mer"al $t&!e$( &$n' CFD "o!e$ t#at are
a4alable@ T#$ )ll allo) not only
t#e "orrelaton of n&mer"al re$<$ to e=permental !ata
from t#e )n! t&nnel( b&t al$o
n4e$t'aton of t#e n!4!&al "ontrb&ton$ of tyre$( rm$ an!
bra?e !$"$ to t#e4entlaton re$$tan"e of )#eel$@
A$ !$"&$$e! n $e"ton 1@1( t $ po$$ble to e=ten! 4entlaton
re$$tan"e n4e$t'aton$
from )#eel$ to all ot#er part$ of t#e 4e#"le rotatn' n t#e ar@
For e=ample( rotatn'
"ooln' fan$ "on$&me a lot of po)er to !r4e t#e ar
t#ro&'# t#e "ooln' pa"?a'e( an! t#e
maorty of t#$ po)er $ ben' "on$&me! o4er"omn' 4entlaton
re$$tan"e@
Anot#er $&''e$ton for t#e "ontn&aton of t#$ proe"t
)o&l! be to te$t ot#er rm $e$
an! more $op#$t"ate! -D "onf'&raton$ of t#e )#eel rm$@
F&rt#ermore( t#e
!epen!en"y of 4entlaton re$$tan"e ma'nt&!e to tyrerm
"ombnaton$ "o&l! be
n4e$t'ate!@
La$tly a more !etale! n4e$t'aton of t#e arflo) n$!e t#e
)#eel#o&$e an! aro&n! t
"an be "on!&"te! n or!er to e4al&ate ntera"ton bet)een
4entlaton re$$tan"e an!
&n!erbo!y flo)@
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--
). (eferences
, ;ro!&"ton $tat$t"$( OICA( T#e Internatonal Or'anaton of
Motor Ve#"le
Man&fa"t&rer$( Onlne@ A4alable/
#ttp/o"a@net"ate'orypro!&"ton2$tat$t"$@
A""e$$e! +* +5 *+,-@
* Clmate "#an'e an! CO*( OICA( Internatonal Or'anaton of Motor
Ve#"le
Man&fa"t&rer$ ( Onlne@ A4alable/
#ttp/o"a@net"ate'ory"lmate2"#an'e2an!2
"o*@ A""e$$e! +* +5 *+,-@
- Re!&"n' CO* em$$on$ from pa$$en'er "ar$( E&ropean
Comm$$on( Onlne@
A4alable/
#ttp/e"@e&ropa@e&"lmapol"e$tran$port4e#"le$"ar$n!e=en@#tm@
A""e$$e! +* +5 *+,-@
5 Spot ;r"e$( %@S@ Ener'y Informaton A!mn$traton( Onlne@
A4alable/
#ttp/)))@ea@'o4!na4petpetpr$pt$,m@#tm@ A""e$$e! +* +5 *+,-@
1 >@ H@ H&"#o( Aero!ynam"$ of Roa! Ve#"le$( %SA( So"ety
of A&tomot4e
En'neer$( In"( ,663@
0 M@ ;fa!en#a&er( G@ >"?ern an! @ )"?er( On t#e
nfl&en"e of )#eel$ an! tyre$on t#e aero!ynam" !ra' of t#e
4e#"le$( n IRA International Conference on
Vehicle Aerodynamics( ,660@
: G@ >"?ern( @ )"?er an! M@ ;fa!en#a&er( Rotatn'
>#eel$ 2 T#er Impa"t on
>n! T&nnel Te$t Te"#nP&e$ an! on Ve#"le Dra'
Re$<$@( n SAE International
!a"er #o$ %&'())*( >arren!ale( ;A( ,66: @
3 @ SternU&$( T@ >al?er an! T@ Ken!er( %p'ra!e of t#e
Vol4o Car$ Aero!ynam"
>n! T&nnel( n SAE +echnical !a"er ,''&-'(-('.)(
*++:@
6 E@ D&ell( A@ #ara( S@ M&ller( >@ Ebeln' an! E@
Mer"?er( T#e KM> AV >n!
T&nnel Center( n SAE International conference/ !a"er #o0
,'('-'(-'((1( *+,+@
,+ R@ Karnar!( Roa! Ve#"le Aero!ynam" De$'n( Corn)all( Great
Krtan/ Me"#aero
;&bl$#n'( *++,@,, Vol?$)a'en Me!a Ser4"e$( Vol?$)a'en to
pro!&"e XL, !e$el pl&'2n #ybr! at
O$nabr"?( *+,-@ Onlne@ A4alable/
#ttp/)))@'reen"ar"on're$$@"om*+,-+*=l,2*+,-+**,@#tml@ A""e$$e!
*6 +5
*+,-@
,* S@ K"?er$taffe( Mer"e!e$2Ken K2Cla$$(A2tomoti3e Engineer/
4ol@ O"tober *+,,(
pp@ ,*2,-@
,- >@ R@ Staplefor! an! G@ >@ Carr( Aero!ynam"
"#ara"ter$t"$ of e=po$e! rotatn'
)#eel$( nMIRA Re"0 #o0 (%&'4,( MIRA( ,606@
,5 A@ S"bor2Ry$l?( Roa! 4e#"le aero!ynam"$( Lon!on/ ;ente"#
;re$$( ,635@
,1 E@ Mer"?er( N@ Kre&er( H@ Kerneb&r' an! H@ @
Emmelmann( On t#e Aero!ynam"
Infl&en"e D&e to Rotatn' >#eel$ of ;a$$en'er Car$( n
SAE "a"er #o0%(')(((,66,@
,0 @ >e!ermann( T#e Infl&en"e of Gro&n! Sm&laton
an! >#eel Rotaton on
Aero!ynam" Dra' Optmaton 2 ;otental for Re!&"n' F&el
Con$&mpton( n
SAE "a"er #o0%5'5&,( ,660@
,: ;@ Elof$$on an! M@ Kann$ter( Dra' Re!&"ton Me"#an$m$
D&e to Mo4n' Gro&n!
an! >#eel Rotaton n ;a$$en'er Car$( n SAE !a"er #o0
,'',-'(-'6)(( SAE
>orl! Con're$$( *++*@
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-5
,3 >@ Mayer an! @ >e!emann( T#e Infl&en"e of Rotatn'
>#eel$ on Total Roa!
Loa!( n SAE !a"er #o0 ,''&-'(-('.&( SAE >orl!
Con're$$( *++:@
,6 F@ Mo!ln'er( R@ Dem&t# an! N@ A!am$( Ne) Dre"ton$ n t#e
Optmaton of t#e
Flo) aro&n! >#eel$ an! >#eel Ar"#e$( n MIRA
International Conference on
Vehicle Aerodynamics( Co4entry( En'lan!( *++3@
*+ G@ E@ Moore( Crammn' more "omponent$(Electronics/ 4ol@ -3(
no@ 3( ,601@
*, I@ ;re!a( D@ Co4a"& an! G@ Colan( Coa$t Do)n Te$t
T#eoret"al An!
E=permental Approa"#( n C7#A+,'('.')'( *+,+@
** R@ IESELKACH( Stromlnena&to$ n De&t$"#lan!2Aero!ynam?
m ;?)2Ka&
,6++ b$ ,651( St&tt'art/ o#l#ammer( ,63*@
*- MIRA( T#e MIRA Story( Onlne@ A4alable/
#ttp/)))@mrate"#nolo'ypar?@"omte"#nolo'y2par?t#e2mra2$tory@a$p=@
A""e$$e! *1 +5 *+,-@
*5 A@ lemn( A Kelt Met#o! of Repre$entn' t#e Gro&n!( 8o2rnal
of Aerona2tical
Science/ 4ol@ ,( pp@ ,632,66( ,6-5@
*1 T@ Ken!er( T#e Ne) Lola Car$ 1+B S"ale Aero!ynam" >n!
T&nnel(( n SAE
+echnical !a"er ,'''-'(-)6.&( *+++@*0 K@ Het#ern'ton an! D@
Sm$2>llam$( >n! T&nnel Mo!el S&pport Str&t
Interferen"e( n SAE +echnical !a"er ,''.-'(-'1'5( *++5@
*: K@ Het#ern'ton an! D@ Sm$2>llam$( S&pport Str&t
Interferen"e Effe"t$ on
;a$$en'er an! Ra"n' Car >n! T&nnel Mo!el$( n SAE
+echnical !a"er ,''5-'(-
'656( *++0@
*3 C@ mmermann( T% Mn"#en / >aa'e *:+,AA albrerber"#t &r
Ver$on
A+*( Te"#n"al Report( *+,,@
*6 A@ Co'ott( T#e Ne) Mo4n' Gro&n! Sy$tem of ;nnfarna >n!
T&nnel( n SAE
!a"er #o0 ,''&-'(-('..( *++:@
-+ A@ Henn'( N@ >!!e"?e( T@ &t#a!a an! @ >e!emann(
N&mer"al Compar$on of
Rolln' Roa! Sy$tem$( SAE Int0 80 Engines/ 4ol@ 5( no@ *( pp@
*0162*0:+( *+,,@-, C@ Lan!$trom( L@ o$ef$$on( T@ >al?er an! L@
Lof!a#l( Aero!ynam" Effe"t$ of
Dfferent Tre Mo!el$ on a Se!an Type ;a$$en'er Car( SAE Int0 80
!asseng0 Cars -
Mech0 Syst0/ 4ol@ 1( no@ ,( pp@ ,-02,1,( *+,*@
-* ;@ Mlnar" an! S@ Sebben( In4e$t'aton of t#e Infl&en"e of
Tyre Defle"ton an!
Tyre Conta"t ;at"# on CFD ;re!"ton$ of Aero!ynam" For"e$ on a
;a$$en'er Car(
n MIRA International Conference on Vehicle Aerodynamics(
Co4entry( En'lan!(
*++3@
-- A@ V!o4n( S@ Kont( C@ Lan!$trom an! L@ Lof!a#l( In4e$t'aton
of >#eel
Ventlaton2Dra' &$n' a Mo!&lar >#eel De$'n Con"ept(
SAE Int0 80 !asseng0
Cars - Mech0 Syst0/ 4ol@ 0( no@ ,( *+,-@
-5 S@ Kont( An n4e$t'aton nto t#e aero!ynam" 4entlaton !ra'
n"&rre! by )#eelrotaton on a pa$$en'er "ar( an! t$ nfl&en"e
on t#e total roa! loa! of t#e "ar(
Ma$ter T#e$$( T% Kerln( Kerln( Germany( *+,*@
-1 S@ Clar? an! R@ Do!'e( A Han!boo? for t#e Rolln' Re$$tan"e of
;ne&mat" Tre$(
Ann Arbor/ T#e %n4er$ty of M"#'an( ,6:6@
-0 SF( E$tmaton of t#e fr"tonal moment( Onlne@ A4alable/
SF@"om
;ro!&"t$ Intera"t4e En'neern' Catalo'&e Rolln' bearn'$
;rn"ple$ of
bearn' $ele"ton an! appl"aton Fr"ton @ A""e$$e! ,1 ,+ *+,*@
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-1
-: @ Q&( C@ Lan!$tr#eel De$'n$ on Aero!ynam" Dra' of a Se!an
Type ;a$$en'er
Car( n SAE International( >arren!ale( ;A( *+,,@
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