Experimental and Numerical Study of Swirling ... - Solid Mechanics
Experimental and Numerical Study of Swirling ... - Solid Mechanics
Experimental and Numerical Study of Swirling ... - Solid Mechanics
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Experi imental <strong>and</strong> <strong>Numerical</strong> N Stud dy <strong>of</strong> <strong>Swirling</strong> g Flow in Scaveenging<br />
Processs<br />
for 2-Stroke<br />
Marin ne Diesel Engin nes<br />
Fig gure 4.9:<br />
Tan ngential Velocity for f<br />
L3=4 4D.<br />
<strong>and</strong> sca ans for the local l minimuum<br />
<strong>of</strong> the inn-plane<br />
veloccity<br />
magnitudde<br />
2 2<br />
u v (Cartesian coordinates) iin<br />
the region cclose<br />
to the cyylinder<br />
axis.<br />
The pro <strong>of</strong>ile shape re esembles closeely<br />
to the moodel<br />
<strong>of</strong> Burgeer<br />
vortex i.e. a<br />
rotation nal flow core region r with riggid<br />
body rotattion<br />
(forced vvortex)<br />
followeed<br />
by an ir rrotational/ po otential flow region also rreferred<br />
to as ‘free vortex’ oor<br />
‘annular r’ region. Sinc ce, in this expeeriment,<br />
no mmeasurements<br />
wwere<br />
conducteed<br />
close to cylinder wall l, the velocity pr<strong>of</strong>ile in thee<br />
high velocityy<br />
gradient ‘waall<br />
layer’ re egion cannot be b seen.<br />
At posit tions very close<br />
to the cylindder<br />
inlet, the ssize<br />
<strong>of</strong> the vorttex<br />
core is smaall<br />
compare ed to outer potential<br />
flow/ / free vortex rregion<br />
<strong>and</strong> thee<br />
peak value o<strong>of</strong><br />
non-dim mensional tang gential velocitty<br />
in the rotattional<br />
region iis<br />
higher at loow<br />
Reynold ds number Re eB compared too<br />
ReA. This diifference<br />
dimiinishes<br />
with thhe<br />
swirl de ecay <strong>and</strong> grow wth in the foorced<br />
vortex rregion<br />
downsttream<br />
the floow<br />
direction<br />
at z5. At z6 a small peak in the magnittude<br />
<strong>of</strong> tangential<br />
velocity is<br />
observed d as a result <strong>of</strong> f the flow beinng<br />
acceleratedd<br />
due to small diameter outlet<br />
pipe (z6 6 at L3 is comp paratively closser<br />
to cylinderr<br />
outlet than z9 <strong>and</strong> z13 at LL2<br />
<strong>and</strong> L1 respectively). r<br />
In I general, thee<br />
effect <strong>of</strong> variiation<br />
in Reynnolds<br />
number is<br />
only ob bserved in the vortex core reegion<br />
<strong>and</strong> thee<br />
potential floww<br />
region seemms<br />
to be insensitive<br />
to su uch variation aat<br />
all the measuuring<br />
positionns.<br />
4.2.3<br />
Axial Vel locity Pr<strong>of</strong>i file<br />
Chapter 4<br />
The axial<br />
velocity V exhibits a ‘wake-like’<br />
pr<strong>of</strong>iile<br />
(Figure 4.100).<br />
The effect <strong>of</strong><br />
z<br />
Reynold ds number see ems to be moore<br />
pronounceed<br />
compared to V not onnly<br />
<br />
in term ms <strong>of</strong> size <strong>of</strong> inn ner forced vorrtex<br />
but also inn<br />
the magnituude<br />
<strong>of</strong> Vz at thhe<br />
58<br />
<strong>Swirling</strong> Flow in a Pipe
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