COMPUTER SIMULATION OF A DIESEL SPRAY IGNITION AND COMMON RAIL ACCUMULATOR FUEL-INJECTION SYSTEM
Abstract
This paper describes a diesel fuel injection process and a diesel spray formation. A computer simulation of the common rail accumulator fuel-injection system and diesel spray were carried out. The computer simulation enables the observation of the phenomena from rail pressure, which is input data for the calculation of injection parameters, to self-ignition in the diesel combustion chamber. With computer simulation, the pressure values in specific sections of the injection nozzle may be computed, as well as the needle lift, injection rate and total injected fuel. The injection rate is input data for the simulation of the spray. The spray is divided into small elementary volumes in which the amount of fuel and fuel vapour, air, mean, maximum and minimum fuel droplet diameter as well as their number are calculated. In each elementary volume, the total air-fuel ratio and air-fuel vapour ratio are calculated. a new criterion for determining the self-ignition nuclei is described in the paper, based on assumptions that the strongest self-ignition probability lies in those elementary volumes containing the stoichiometric air ratio, where the fuel is evaporated or the fuel droplet diameter is equal to or lower than 0.0065 mm. The most efficient combustion with regard to the consumption and emission will be in that elementary volume containing the stoichiometric air ratio and the fuel droplets with the lowest mean diameters. The injection and combustion parameter
measurements were made in an optically accessible transparent engine. The engine is a single- cylinder transparent engine based on the AUDI V6 engine, equipped with a Bosch Common Rail Injection system. The optical part of the experimental set-up contains two different lasers, while the camera system allows the simultaneous detection of the Mie scattering of the injected fuel, the laser-induced fluorescence of fuel and vapour, the premixed combustion mode and the diffusion mode. A comparison of the computed points with the highest self-ignition probability and the measured points where self-ignition occurred showed good matching.
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References
N. A. Chieger: Energy and Combustion Science, Pergamon Press, U. K., 1979
L. Allevi: Algemeine Theorie über der veränderliche Bewegung das Wasser in Leitungen, Springer Verlag, Berlin, 1909
A. M. Rothrock: Hydraulics of Fuel Injection Pump for Compression-Ignition Engines, NACA Report No. 396
W. Schley: Teoretische und experimentelle Untersuchungen zur analytischen Darstellung der Wellendämpfungen von hydraulischen Einspritzsystemen, Diss. München, 1967
M. Gorokhovski: The Stochastic Lagrangian Model of Drop Breakup in the Computation of Liquid Sprays, Atomization and Sprays, vol. 11, pp.505–519, 2001
N. Levy, S. Amara and J.-C. Champoussin: Simulation of a Diesel Jet Assumed Fully Atomized at the Nozzle Exit, SAE 981067
C. Heimgärtner, A. Leipertz: Investigation of Primary Diesel Spray Break-up Close to Nozzle of a Common-Rail High Pressure Injection System, SAE 2000-01-1799
A. Fath, C. Fettes, A. Leipertz: Investigation of the Diesel Spray Break-up Close to the Nozzle at Different Injection Conditions, Proc. COMODIA 98, Kyoto, Japan, July 1998, pp. 429–434
J. V. Sinnamon, A. Lancaster, I. C. Steiner: An Experimental and Analitical Study of Engine Fuel Spray Trajectories, SAE 800135
G. N. Abramowich: The Theory of Turbulent Jets, MIT Press, Cambridge, Massachusetts
H. Hiroyasu, F. Nishida: Simplified Three-Dimensional Modelling of Mixture Formation and Combustionin in a D. I. Diesel Engine, SAE 890269
K. S. Varde, D. M. Papa: Spray Angle and Atomization in Diesel Sprays, SAE 841055
T. Kamimoto, S. K. Ahn, M. Chan: Measurement of Droplet Diameter and Fuel Concentration in a Non-Evaporating Diesel Spray By Means of an Image Analysis of Shadow Photographs, SAE 840274
M. Arai, M. Tabata, H. Hiroyasu, M. Shimizu: Disintegrating Process and Spray Characterization of Fuel Jet Injected by a Diesel Nozzle, SAE 840275
T. Takeuchi, H. Hiroyasu, J. Senda, K. Yamada: Droplet Size Distribution in Diesel Fuel Spray, JSME 26, No. 215, May 1983
C. Fettes, S. Schraml, C. Heimgärtner, A. Leipertz: Analysis of the Combustion Process in a Transparent Passenger Car DI-Diesel Engine by Means of Multi-Dimensional Optical Measurements Techniques, SAE 2000-01-2860 (2000)
C. Fettes, A. Leipertz: Potentials of a Piezo-Driven Passenger Car Common Rail System to Meet Future Emission Legislations-An Evaluationby Means of In-Cylinder Analysis of Injection and Combustion, SAE 2001-01-3499 (2001)
M. Marcic, Z. Kovacic: Computer Simulation of the Diesel Fuel Injection System, SAE 851583 (1985)
M. Marcic: Calculation of the Diesel Fuel Injection Parameters, SAE 952071 (1995)
