Thermal Science 2011 Volume 15, Issue 4, Pages: 1095-1109
https://doi.org/10.2298/TSCI100903046F
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Influence of geometric and hydro-dynamic parameters of injector on calculation of spray characteristics of diesel engines
Filipović Ivan (Faculty of Mechanical Engineering Department for IC Engines and Vehicles, University of Sarajevo, Sarajevo, Bosnia and Herzegovina)
Pikula Boran (Faculty of Mechanical Engineering Department for IC Engines and Vehicles University of Sarajevo, Sarajevo, Bosnia and Herzegovina)
Bibić Dževad (Faculty of Mechanical Engineering Department for IC Engines and Vehicles University of Sarajevo, Sarajevo, Bosnia and Herzegovina)
The main role in air/fuel mixture formation at the IC diesel engines has the
energy introduced by fuel into the IC engine that is the characteristics of
spraying fuel into the combustion chamber. The characteristic can be defined
by the spray length, the spray cone angle, the physical and the chemical
structure of fuel spray by different sections. Having in mind very complex
experimental setups for researching in this field, the mentioned
characteristics are mostly analyzed by calculations. There are two methods
in the literature, the first based on use of the semi-empirical expressions
(correlations) and the second, the calculations of spray characteristics by
use of very complex mathematical methods. The second method is dominant in
the modern literature. The main disadvantage of the calculation methods is a
correct definition of real state at the end of the nozzle orifice (real
boundary conditions). The majority of the researchers in this field use most
frequently the coefficient of total losses inside the injector. This
coefficient depends on injector design, as well as depends on the level of
fuel energy and fuel energy transformation along the injector. Having in
mind the importance of the real boundary conditions, the complex methods for
calculation of the fuel spray characteristics should have the calculation of
fuel flows inside the injector and the calculation of spray characteristics
together. This approach is a very complex numerical problem and there are no
existing computer programs with satisfactory calculation results. Analysis
of spray characteristics by use of the semi-empirical expressions
(correlations) is presented in this paper. The special attention is
dedicated to the analysis of the constant in the semi-empirical expressions
and influence parameters on this constant. Also, the method for definition
of realistic boundary condition at the end of the nozzle orifice is
presented in the paper. By use of this method completely avoid a use of the
coefficient of total losses inside the injector. At the same time,
semi-empirical expressions have the universal constant that does not depend
on the injector design.
Keywords: injector, spray, diesel fuel