This paper presents some results of an experimental investigation on the shape and construction of the injected diesel fuel spray. The single shot fuel was injected into a high pressure chamber charged the high pressure and room temperature air. The volume of the chamber is larger enough to avoid the influence of the surrounding walls.
The photographs of the injected fuel spray were taken by the transmitted light using microflash. The shape of the injected fuel spray, i.e., the spray penetration, the spray angle and so on were measured from the photographs.
The following conclusions can be drawn in this investigation:
(1) The fuel spray is constituted of penetration part and dillution part. There are the main jet region in the center of it and around the mixing flow region which consists of initial part and mixing part.
(2) The relation between spray penetration
l and the time from injection start
t and specific weight of charged air γ
a was given by;
l ∝
tn1⋅γ
n2aThe exponents
n1 and
n2 do not become constant.
(3) The spray penetration increases as the nozzle diameter increases.
(4) The length of penetration part
lp shows as a similar tendency of the spray penetration
l.
lp/
l is nearly constant 0.7. The length of the initial part of mixing flow region is nearly constant 10 to 15 mm.
(5) The spray cone angle and apparent spray angle increases as the ambient pressure increases.
(6) The apparent spray volume decreases as the ambient pressure increases.
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