INFLUENCE OF GEOMETRIC AND HYDRO-DYNAMIC PARAMETERS OF INJECTOR ON CALCULATION OF SPRAY CHARACTERISTICS OF DIESEL ENGINES
Abstract
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.
Dates
- Submission Date2010-09-03
- Revision Date2011-02-27
- Acceptance Date2011-03-01
References
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Volume
15,
Issue
4,
Pages1095 -1109