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ProQuest Number: 27591477
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fos^ iaillatiag «©â $h# Wt wir#
#$ ## F©X|r|«<^[d© #$* i© &. P, Nwrl©#$©»#
fh# gather 1# âae^ly app%#*&*tlve «et mXf tm hi# may iamlaahi#
#a###%lea# #M wltl#!##, Wt #1## far $h# wn^ a###lfi#h hoar#
#p#m% %y Mm Im th# Imhermtoyy.
fh# gather Ms# *!#&## to ##moal#6# with #la##r# ##pr##i-
atloa th# «oatrihatloa# of tfe# follealmg:
Mr. Malm P. MlII#r$ #o*vor%#r, for M# lm#tra®tlom Im th#
faaetloa# of th# oom##a#mt ipmrt# of th# #l*#trl@oI olromlt mmi Mo
iaflait# pmtiomo# la tk# ooaotraotloa of th# hot air##*
]^r. #. B, ioadloy» for M# #a##e#tlom# Im tho rokall&lm# of
•om of tho olooirlml @o#omomt# of th# olroMt#
Mr. ftotm femlm, for M# &#el»tamo« la th# moklao #b#p*
Mr. Pmml Mhhy, for m^ortWElm# tk# major portlom of t&#
ooaotraotioa aotfe oa tk# hot wlro proho.
SSB E Æ JE ÎS S
£süJo.
îwmmefvm............................................................ i
?h# Import »f Tartol#»*#................. S
ef i^aratM ...................... k
tm Hs» wiæi 7
HISS3SI0AÏ, Mcmmam m ms jm wïks mmmtm............... lo
fh* Olsmlesl Verfc «f t. ?. Klmg.................... 10
Th# %e*k «t OqpA#* «mI K#*th#...................... 15
iw m w s................................................................................... 20
@#m#r*l ef Prétest Appsrsts..................... 90
%# mnage ............................................ a
&« Amplifier#..................................... H
Sh# Mime# Isverter............. 22
$h# M ultiplier........................ 23
«et *ir* Obit................. 23
rot SIS* OA&iBR&tio* wmmm ................. 25
the Titrmter ................................ 27
the Diffuser..................................................... 2f
srotœss» OAî,»uflos gmomome. ..................................... 31
corotimiro mwacs. .................... 32
Himsirass............... 33
nsmts ........................ 3*1
Im the #Wly of for### pp@#8#»& mpm# oOJ«et«
ljHi«r##d im a #$r#*# of Mr, them# or# two fmimmulml typ#« of flow
vhloh mr« of th# ^romtoet importmm##, mmmely Imimr or #tr##mlim#
flow mmd tmrWlmt flow, hmimt flow 1# @har&ot*ri##& hy otrommlimo#
which <Milaeld# with th# path of th# fluid partiel##, th$r* I# mo vmri-
mtiom im rolocity at may oho##m poeitim la th# field of flow with
time, mt 1# thor# may wafiatiom im woloeity ## th# fluid #l#m#mt pro-
cood# Mom# it# path. Tarhalomt flow, om th# o##r hmmd# i# m mmotoMy
tfpê of motiom. ft##### of Mr, hmwim# ill-d#fim#d hoamd#ri##, po###«#
# flmctmmtia# motiom which are #m#*ri##o##d mpea th# sMm flow. %#
velocity at my choeern polmt im the field of flow therefore varie# with
time a# well a# with poeitiom#
All flmetuatiom# of epeed with time, however, are m t termed
tarhaleace. Im wimd tammel# there are very «low fliictmtiom# im epeed
dm# to email #am#e Im the horeepower omtpmt of the drivim# mmit. %e#e
mey have a period of ? to 10 eecomd#. There are alee flmctmatiom# due
to the vlhratioa of the hody who## aeredyaamle characterietic# are
hein$ ascertMmed. Thee# are ale# m t cmeidered a# tmrhmlemce. Im
gemeral all flaetmatiom# of fregmemoy greater them 10 to 20 cyele# per
eecomd are comaidered a# tmrhmlmce. lowever, there i# me eharp lime
of demareatiem. It I# epparemt therefore that the deflmitiom of tmrhm-
lemoe ie purely arhitrary# At the iatiomal Bureau of Standard#, the
egmipmemt ie deeigmed to reepoad to flmctmatiom# of 1 to 2 cycle# per
e e c o m d / t h e w # r limit of frecmemelee whi# comld he imveetlgated
2*
|« fixed the liarltetiexe ef exletiag imetnwmmte.
Whee the flmetaetiea# ef the eir m&eeee ere reMem la mature,
the reet mm e#are vaWee ef the eeapememts are e#ai. fhle ie
defimed ae "ieetrepie* tmrhulemee amd ie the type ef ttirhuXeaee ea-
eemmtered Im wind tmmmele. Im the wake ef ehjeete amd im the flew
aear a eurfaee, however, tMre ie a defimite eerrelatiem hetweem the
eeapemeat veXeeitiee parallel amd perpendieMar to the direotiem of
flow, reeaXtiag im a tramefer ef mmmtm aeroee the direotiem of mem
flow, Ihydem^ prefer# to call the latter type of ^ow ae *eddyimg
flow" amd the limitim# eaee, im which there l« eero eorrelatiom or
leotrepie tmrhmlemoe ae "turhmlemoe". to «hall adept a metatiom, how
ever, im which turhttlemoe will refer to mem-ieotrepie tmrhmlemoe# m-
lee# otherwiee epeoified.
!%# Import of fmrhalgaoe
AlthomM^ Oehorme Eeyaolde wa« the firet to dieeover W&e
effect# of turWLemee, it warn mot until oomflie ting valmee of drag
eoeffiaient# for a «phare were pmhliehed that farther reeearoh mpoa
the effect# of tmrhalemoe to explain the dieerepaney wae under taken.
It wa« finally eetahllehed that the value of the drag ooeffioient im
a eritioal rmg* of teymold# Bhaher# wae affected %y the initial ieo-
tropic turWleme# of the wimd tunnel, funnel# wiWi a relatively h i#
peromtage turhulemoe had the effect of ohamging the houmdary layer
over the eurfeee of the «phere fro# laaimar to turhulemt at a lower
fteymolde ftmmher, oaueimg a MMward mvewmt of the eeparatiom point
* #&a«#gu#mt reduction im »i#e of the wake and drag. Im tumeie
ef ee#ermtlv#iy lew tmrWLemee, hewever# thie phemeaemem eeeurred amah
later, expXaimimg whf two different tmmmeie exhibited m&rked differemeee
im drag eeeffieiemt# at idemtiml leyaelde ftmebere.
Imitial ieetrepie turbmleme# wat alee femd te affect meaemre-
m«mt# made upem mirehip emdele, and Mee te a eaaller emtmt ©pern air
foil ebareeterietie#. While thee# dieerepameiee did met meeeeearily
meem that the wimd tmmmel wm meeleee to the de#i##r, it did eerre to
imdieate that the tmrWleme# eharaoterietiee of a tmmel meeded to he
aeoertaimed amd iaielligeatly applied to meaeurememt# if a eorreot im-
terpretatiea of the reemlte wae lo he ohtmimed.
A relatiomehip wae flmally eetahliehed hetweem the pereemtage
tmrhmlemee ef the tammel amd value of the fteymelde Bamher at which the
drag eoeffieieml of a «phare wae O.J, a vMa# al%my# located am the
eteep part of the ^ ve. ft.B. earve. % a plot of pereemtage tmrWlmoe
agaimet the 1*1. for which the ooeffielemt of drag of a ephere wae O.J,
it heoame peeeihle to determime the tmrbalemee of aay wimd etrea* hy
the eiepl# erpediemt of mmim a ephere drag teet.^^^^ Baheegmemt
imveetigatiom# V the earn# mthere ehewad that the eritieal leymelde
tueher of a #here wae alee affected by the eoale of tarhmlemee, ee
that the eunree deeerihed above were at beet a fair eppremiaatioa. It
mi#t he well at # ie point to defime turhmlemo# a# the ##&r# root of
the aeam value of #e «tmre of the velooity Umotuatiome divided %r
the meam velooity. Am air#tr«#m turhulemoe of 1$ oorreepmde, there
fore, to a aim# wave fluotuatiom of velocity of maxim» amplitude Ofual
I© l.hl# »f jBtan velocity.
feature# ef
#ne dietimgaiehimg feature ©f the epperetm# mt #e Imetitmt#
which Juetifie* thle reeeareh ie mm electric multiplier, Becmuee the
multiplier ie cepmhle cf multiplyim# fluctumtimg velceity ccepcmemte
of eimiler frequm#^ whi# ere reepectlvely pmrmllel mà perpeadiculmr
te the âireetiem of flew, m mmmrê cf the ehemrimg etree*
ie directly mtteimmhle, % mi table ewitchimg arrengememte, the eguare
root# ef the aeea of the e#mr#e of the## velocity fluctuatiome are
eaeily attained, redueim# the determiaatiom ef the eorrelatiom coefficient.
// * ir^ -
B « to three readiage, namely «/ - - ■
amd a eimpl# operatic* om th# elide rule*
where u* «* coapommt of velocity flmctuatiom parallel to the airetrwm.
V» « co##omemt of velcci% fluetuatiem perpendicular to the
airetream.
Another feature ie the two-wire imetrumemt. two platinum wire#
(.006" dim.) are placed parallel to one another one dimmeter apart.
Velocity fluctuation# normal to the plane of the wire# are the u* com-
penemte, thoee in the plane, v* ecepenente.
the object of thie reeearch warn to aid in making refimememte cm
the hot wire epparatue at thie Inetitute, and to evolve and ecnetruet
the hot wire calibrating cgMpment. It time permitted, the procedure
of hot wire calibration wae to have been etandardiced, and correlation
mwmarememt# mad# Im Ik# komWy layef ©f a flat plat# mtlmg tk#
multiplier.
To tk# mtWr*# W#wl#d#, exiatls^ method# of determlmlmg th#
#err#lmti@m oeefflelemt Imirolve at lemet fear etepei %m t# meaear#
the Imetamtawea# predmet ef a* amd v* and two to meaeare the valmee
amd • The preeedmre prevlemely deeorlhed ie evidently
am laprevem#mt, elm## ^ # eelealatlem ie redmoed to three etepe.
One of th# *##ode meed Im mmmximg oorrelatiom la other
lahoratoriee ha# keen th# me# of two wire# eo plam#d that both are
Idemtleally ©rleatated im a vertical plaae parallel to the airflow
hmt wl# a defimite dowmetreaa #aolmg* % taklmg th# reepemee of
both wire# and epplyimf the oerreotlom for the time lag# eorrelatiom
I# deteralmed. At the iatiomal Bmrem of Btamdarde, one wire hae Wm
meed plaoed Im a vertical plaae parallel to th# airflow %mt Imcllaed U5®
to the emrfamt. Is this potitles, the wire reepomde to both the m» amd
V* eomposemte of the flow amd it# reepemee mey be expreeeed ae#
1| » am* e bv*
##»rimg* « a4t*^ * 2 aba*v* # b^v*^
the hot wire ie them revereed ISO", makCsg the reepemee
%g * am* - bv*
b | • a^m’^ - i abm*v* v b^v*^
Bow the difference betweem the two readiagei
» k abm*v* ^ ehearimg etree ».
the major dieadvmtag# with thie hot wire ie th# fact that
6.
it# $xtr#w Imgik to Ik# «urfact under lmv##t&g*tl@m ###
set MIew ese te sake a eMfleiest mmber ef rWUlsg# is # bwsdery
layer Irsveree ssd avemgee ©vwp » eespsrmtiveiy great lemg#. Tk#
methed seed is tki* laberateiy will k# deeeriked is ## eeeties dee-
erikisg ## eyparatsft*
fkle mpm% ks# diemeeed tk# varies# lypee ef flew lepertnat
is aeredysasle» end tk# tvmMmdes# isfisesee ef turksiese#. tk# fell#*-
isg eeeties# deeevik# tk# ket Mr# #s#sea#t#r$ give a «kert ki#teri##&
kiuskgroesd ef %tm isstrssast» and fisaUy eemelude# with a d###ripti#m
#f tk# «udikratisg #cMp»#mt wkiek kae keen ees# true ted.
