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decrease, and it remains at a constant value near
Z/dn=150 for the 5-hole nozzle and Z/dn=180
for the single-hole nozzle. It indicates that the
inner region of the 5-hole and the single-hole
spray is dramatically changed within the near
field of the nozzle tip, and the disintegration
processes of those sprays take place actively
within this region. In addition, the disintegration
processes of the 5-hole spray proceed more rap-
idly than that of the single-hole spray.
Figure 9 shows the cross-section mean value of
: Z/dn=31
- L'~--- Z/d.=63
-o- Z/dn=94 do=O.32mm
Pump speed=5OOrpm
Q=7.31mm3/st
~k~ ID=1.1ms
5 10 15 20 25 30
Rid.
(a) 5-hole nozzle
-: Z/dn=31
~'~ -~'- 7-Jd,=63
~, --~- Z/d.=94
d,=O.32mm
q'\ Pump speed=5OOrpm
\ \ Q=T.31mm31st
" ID=0.8ms
~~'~-~....~ - .. ~ ,~
i .... h . . i . . ~ .....
5 10 15 20 25 30
R/d.
(b) Single-hole nozzle
SMD distributions of 5-hole and single-hole
nozzle with radial distance at three axial
positions of Z/d,----31, 63 and 94 (time win-
dows of 20 ms)
• Single-hole nozzle
• --*~--- 5-hole nozzle
dn=O.32m m
Pump speed=5OOrpm
Q=7.31mm~/st
. . . . . , i ........
i i r • , , i ,
100 200 300 400 500 600
Zl d,
SMD distribution along centerline of spray
for 5-hole and single-hole nozzles (time
windows of 20 ms)
• Single-hole nozzle
.... ~-.- 5-hole nozzle
e. dn=O.32mm
~_ Pump speed=500rpm
~.;.,.~.~.,."k~ Q=7.31 mma/st
"%. ....
if, ii , , i', I , , ,1 , , , ; ,
1 O0 200 300 400 500 600
Z/d.
Cross-section mean value of SMD along ax-
ial distance (time windows of 20 ms)多孔和单孔柴油喷嘴的间歇雾化特性
摘要：本实验研究了多孔和单孔柴油喷嘴的间歇喷雾特性。多孔喷嘴的孔数为5， 5孔和单孔喷嘴的孔与固定孔的长径比（ln/dn=2.81）相同。喷雾液滴的直径，包括时间分辨液滴直径，SMD（Sauter平均直径）和AMD（算术平均直径）。当液滴间歇的从两个喷嘴喷到静止的环境中时，用的二文PDPA（相位多普勒粒子分析仪）测定液滴直径。通过对时间分辨液滴直径演变的观察，发现多孔和单孔喷嘴喷雾的结构主要包括三个部分：（a）受周围空气影响并由小水滴组成的前缘；（b）被前缘包围的中心部分和不受空气的阻力影响的混合流动区；（c）中央部分通过所形成的后缘。SMD随着径向距离的增加而逐渐减小，并且5孔和单孔喷嘴在径向距离（标准化孔直径）分别为7-8和6处获得定值。在喷嘴端部附近显示出最大值后，沿喷雾中心线处的SMD随轴向距离的增加而均匀降低。在轴向距离（标准化孔直径）为150和180处，5孔和单孔喷嘴的SMD仍为定值。