Experimental and Numerical Study of Swirling ... - Solid Mechanics
Experimental and Numerical Study of Swirling ... - Solid Mechanics Experimental and Numerical Study of Swirling ... - Solid Mechanics
Experi imental and Numerical N Stud dy of Swirling g Flow in Scaveenging Processs for 2-Stroke Marin ne Diesel Engin nes Figu ure 2.12: Sketch h of mirror vortex x effect of wall. The wal ll is illustr rated by a thick line l at y/h h=0 (Velte et al., 2009) ). Chapter 2 Figure (2.13) shows the t sketches oof different moodels of axisymmmetric heliccal vortex filaments f where l is pitch oof the helix, V Vz axial velocity and z annd are e the axial and d tangential vvorticity compponents respectively. For thhe same Reynolds R and swirl numbeers different aaxial velocity profiles can bbe observe ed i.e. uniform m axial velocitty with rectilinnear vortex linnes and infiniite helix pi itch (Figure 2.13a), 2 jet-likee axial velocityy profile geneerated by righht handed d helical vortex x (Figure 2.13bb) and wake-liike profile gennerated by a left handed d helical vortex x (Figure 2.133c). In some ccases, the left handed heliccal vortex can result in n generating a counter fl flow regime. Practically thhe existenc ce of different vortex symmeetries indicatees that the Reyynolds and swiirl number rs are not suff ficient to charracterize the ddifferent aspeccts e.g. heat annd mass transfers for the e swirling flowws (Martemiaanov et al., 20004). In real, thhe vortices s have finite size s cores andd even in somme cases the hhelix is not axxis symmet trical. The rad dius of helix annd the pitch caan also vary att different crosss sectiona al positions along the flow and one of thhe many possibble reasons may be the geometrical g sh hape of the inllet and outlet of the vortex chamber whicch affects the t flow prope erties (a contraaction sectionn at the outlet iintroduces axiial strain etc.). e Alekseen nko et al. (20007) have alsoo discussed thhe experimenttal where double d helical l vortex filameents are observved. In non-sttationary heliccal vortices s the helix also o is a function of time in a pperiodic mannner. 26 Swirling Flows
Experi imental and Numerical N Stud dy of Swirling g Flow in Scaveenging Processs for 2-Stroke Marin ne Diesel Engin nes Figu ure 2.13: Schem mes of axisym mmetrical helical vortex. . Modification of f origina al figure from (Aleks seenko et al., 1999 9). Chapter 2 Okulov v et al., (2002) have describeed the vortex breakdown ass a spontaneouus transitio on from right t to left handeed helical vorttices and vice versa under thhe same in ntegral flow parameters. p Thhis continuouss transition beetween the twwo helical vortex v types happens in twoo different wayys as shown inn figure 2.13: (1) The e pitch is posi itive for the riight handed hhelical vortex and during thhe tra ansition the pi itch becomes infinite and tthen attains a negative valuue for r left handed helical h vortex. This type of ttransition is names L (linearr) tra ansition (Figur re 2.14a). (2) In the other case e the positive ppitch for rightt handed vorteex becomes zerro du uring the trans sition before cchanging to nnegative value for left handeed vor rtex. This type e is called R (riing)-transitionn (Figure 2.14aa). 27 Swirling Flows
- Page 1: Experimental and Numerical Study of
- Page 5 and 6: Experimental and Numerical Study of
- Page 7 and 8: Experimental and Numerical Study of
- Page 9 and 10: Experimental and Numerical Study of
- Page 11 and 12: Experimental and Numerical Study of
- Page 13 and 14: Experimental and Numerical Study of
- Page 15 and 16: Experimental and Numerical Study of
- Page 17 and 18: Experimental and Numerical Study of
- Page 19 and 20: Experimental and Numerical Study of
- Page 21 and 22: Experimental and Numerical Study of
- Page 23 and 24: Experi imental and Numerical N Stud
- Page 25 and 26: Experi imental and Numerical N Stud
- Page 27 and 28: Experimental and Numerical Study of
- Page 29 and 30: Experimental and Numerical Study of
- Page 31 and 32: Experimental and Numerical Study of
- Page 33 and 34: Experimental and Numerical Study of
- Page 35 and 36: Experi imental and Numerical N Stud
- Page 37 and 38: Experi imental and Numerical N Stud
- Page 39 and 40: Experi imental and Numerical N Stud
- Page 41 and 42: Experi imental and Numerical N Stud
- Page 43 and 44: Experimental and Numerical Study of
- Page 45: Experi imental and Numerical N Stud
- Page 49 and 50: Experimental and Numerical Study of
- Page 51 and 52: Experi imental and Numerical N Stud
- Page 53 and 54: Experi imental and Numerical N Stud
- Page 55 and 56: Experimental and Numerical Study of
- Page 57 and 58: Experimental and Numerical Study of
- Page 59 and 60: Experi imental and Numerical N Stud
- Page 61 and 62: Experi imental and Numerical N Stud
- Page 63 and 64: Experi imental and Numerical N Stud
- Page 65 and 66: Experi imental and Numerical N Stud
- Page 67 and 68: Experi imental and Numerical N Stud
- Page 69 and 70: Experimental and Numerical Study of
- Page 71 and 72: Experimental and Numerical Study of
- Page 73 and 74: Experi imental and Numerical N Stud
- Page 75 and 76: Experi imental and Numerical N Stud
- Page 77 and 78: Experi imental and Numerical N Stud
- Page 79 and 80: Experi imental and Numerical N Stud
- Page 81 and 82: Experi imental and Numerical N Stud
- Page 83 and 84: Experimental and Numerical Study of
- Page 85 and 86: Experimental and Numerical Study of
- Page 87 and 88: Experi imental and Numerical N Stud
- Page 89 and 90: Experi imental and Numerical N Stud
- Page 91 and 92: Experi imental and Numerical N Stud
- Page 93 and 94: Experi imental and Numerical N Stud
- Page 95 and 96: Experi imental and Numerical N Stud
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 />
Figu ure 2.12:<br />
Sketch h <strong>of</strong> mirror vortex x<br />
effect <strong>of</strong> wall. The wal ll is<br />
illustr rated by a thick line l<br />
at y/h h=0 (Velte et al.,<br />
2009) ).<br />
Chapter 2<br />
Figure (2.13) shows the t sketches o<strong>of</strong><br />
different moodels<br />
<strong>of</strong> axisymmmetric<br />
heliccal<br />
vortex filaments f where<br />
l is pitch o<strong>of</strong><br />
the helix, V Vz axial velocity<br />
<strong>and</strong> z annd<br />
are e the axial <strong>and</strong> d tangential vvorticity<br />
compponents<br />
respectively.<br />
For thhe<br />
same Reynolds R <strong>and</strong> swirl numbeers<br />
different aaxial<br />
velocity pr<strong>of</strong>iles can bbe<br />
observe ed i.e. uniform m axial velocitty<br />
with rectilinnear<br />
vortex linnes<br />
<strong>and</strong> infiniite<br />
helix pi itch (Figure 2.13a), 2 jet-likee<br />
axial velocityy<br />
pr<strong>of</strong>ile geneerated<br />
by righht<br />
h<strong>and</strong>ed d helical vortex x (Figure 2.13bb)<br />
<strong>and</strong> wake-liike<br />
pr<strong>of</strong>ile gennerated<br />
by a left<br />
h<strong>and</strong>ed d helical vortex x (Figure 2.133c).<br />
In some ccases,<br />
the left h<strong>and</strong>ed heliccal<br />
vortex can result in n generating a counter fl flow regime. Practically thhe<br />
existenc ce <strong>of</strong> different vortex symmeetries<br />
indicatees<br />
that the Reyynolds<br />
<strong>and</strong> swiirl<br />
number rs are not suff ficient to charracterize<br />
the ddifferent<br />
aspeccts<br />
e.g. heat annd<br />
mass transfers<br />
for the e swirling flowws<br />
(Martemiaanov<br />
et al., 20004).<br />
In real, thhe<br />
vortices s have finite size s cores <strong>and</strong>d<br />
even in somme<br />
cases the hhelix<br />
is not axxis<br />
symmet trical. The rad dius <strong>of</strong> helix annd<br />
the pitch caan<br />
also vary att<br />
different crosss<br />
sectiona al positions along<br />
the flow <strong>and</strong> one <strong>of</strong> thhe<br />
many possibble<br />
reasons may<br />
be the geometrical g sh hape <strong>of</strong> the inllet<br />
<strong>and</strong> outlet <strong>of</strong> the vortex chamber whicch<br />
affects the t flow prope erties (a contraaction<br />
sectionn<br />
at the outlet iintroduces<br />
axiial<br />
strain etc.). e Alekseen nko et al. (20007)<br />
have alsoo<br />
discussed thhe<br />
experimenttal<br />
where double d helical l vortex filameents<br />
are observved.<br />
In non-sttationary<br />
heliccal<br />
vortices s the helix also o is a function <strong>of</strong> time in a pperiodic<br />
mannner.<br />
26<br />
<strong>Swirling</strong> Flows
Change language