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⋅γⁿ²_a
The exponents n₁ and n₂ do not become constant.
(3) The spray penetration increases as the nozzle diameter increases.
(4) The length of penetration part l_p shows as a similar tendency of the spray penetration l. l_p/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.

View full abstract

This paper presents some results of as experimental investigation on the air movement around the injected diesel fuel spray. The single shot fuel spray was injected into a high pressure chamber charged the high pressure and room temperature air. The volume of the chamber is large enough to avoid the influence of the surrounding walls.
The air movement around the injected fuel spray was measured by the“smoke wire”method using highspeed camera and consequently the air entrainment was achieved quantitatively.
The following conclusions can be drawn in this investigation:
(1) The air entrains almost normally into the penetration part of the spray and the air around dillution part is pushed aside by the spray.
(2) The air velocity around the spray decreases as the ambinet pressure increases.
(3) The air velocity becomes slower as the distance from the nozzle tip longer and at the end of penetration part it becomes nearly equal to zero.
(4) The volume of air entraining into the penetration part of the spray is about a half of the apparent spray volume independent on the ambient pressure and time from injection start.

View full abstract

A rapid compression machine is very useful for the research to analyse fundamentally the spray combustion process of diesel engine. So far as we know about the air motion in the combustion chamber, there exists a considerable literature on the contribution of swirl to the combustion process, but little work has been done in order to estimate that of squish.
This paper presents the effects of the squish on the ignition delay and the heat release rate by means of a rapid compression machine. As a result, the presence of the squish makes the ignition delay shorter, the total heat release increases about 50% by the squish as compared with no squish, and the squish improves the utilization of air not only in the radial direction of cylinder but also in the tangential direction.

View full abstract