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 />
Figure<br />
2.3:<br />
Tang gential Velocity<br />
Pr<strong>of</strong>i ile for a<br />
Conc centrated<br />
(Stee enbergen et al.,<br />
1998) ).<br />
Fig gure 2.4:<br />
Sche ematic <strong>of</strong> Different<br />
Regi ions in Tangentia ial<br />
Velo ocity Pr<strong>of</strong>ile for a<br />
Con ncentrated Vortex x.<br />
Mod dification <strong>of</strong><br />
illus stration by (Islek<br />
A.A A., 2004).<br />
Chapter 2<br />
Figure 2.4 gives a de escription <strong>of</strong> ddifferent<br />
regioons<br />
in the tanngential<br />
velociity<br />
pr<strong>of</strong>ile <strong>of</strong> a concent trated vortex. As discussedd<br />
earlier in caase<br />
<strong>of</strong> Rankinne<br />
vortex, the vortex cor re has a forcedd<br />
vortex pr<strong>of</strong>ile<br />
until a radiial<br />
distance ‘ r a ’<br />
where the t maximum m tangential veelocity<br />
is obseerved.<br />
In real swirling flowws,<br />
the radial<br />
position ‘ r a ’ in figure 22.4<br />
is determiined<br />
by tangeential<br />
velocitiees,<br />
viscosity y, turbulence,<br />
<strong>and</strong>/or the introduction <strong>of</strong> non-rotating<br />
fluid at thhe<br />
vortex center c (Vanyo o, 1993). The ‘wall layer’ hhas<br />
very largee<br />
gradients annd<br />
flow in n this region, , in cylindriccal<br />
enclosures,<br />
is probably y influenced bby<br />
Görtler vortices (Escu udier et al., 22006).<br />
Görtler vortices are ssecondary<br />
flowws<br />
that app pear in a boun ndary layer floow<br />
along a conncave<br />
wall see Saric (1994) fo for<br />
details. Further, in the t near wall region, vorticcity<br />
is generatted<br />
due to skkin<br />
friction n factor acting as an externall<br />
force to a verry<br />
thin fluid laayer<br />
attached to<br />
the wall<br />
(Ebrahimi et t al., 2007). Thhe<br />
region in bbetween<br />
the foorced<br />
vortex annd<br />
wall lay yer is ‘Annular<br />
region’. Thhe<br />
flow in thhis<br />
region shoould<br />
ideally bbe<br />
irrotatio onal (based on n description o<strong>of</strong><br />
Rankine voortex).<br />
However,<br />
in real flowws<br />
this reg gion has a very y low vorticity. . The visualizaation<br />
results byy<br />
Escudier et aal.<br />
(1982) show s ring-like e large vorticees<br />
in the outer<br />
region <strong>and</strong> appear to be <strong>of</strong><br />
Taylor-G Görtler type; distorted by the axial floow<br />
<strong>and</strong> also responsible ffor<br />
uniform mly distributin ng the small amount <strong>of</strong> voorticity<br />
from highly vorticcal<br />
vortex core. c Alekseen nko et al. (19999)<br />
also founnd<br />
out that thhe<br />
experimenttal<br />
15<br />
<strong>Swirling</strong> Flows