The results of comparative diesel and biodiesel (Rapeseed oil Methyl Ester (RME) and Rapeseed Oil (RO)) fuel jet structure studies by optical scanning method are presented. There is an interrelation between the dynamics of fuel jet development by the Common Rail (CR) with single-phase injection and Conventional Design System (CDS) and the parameters of mixture formation, which are typical for transferring the operation of the Diesel Engine (DE) from mineral diesel to RME and RO. The structure of the Diesel Fuel (DF) jet is significantly more heterogeneous by the size and number of droplets in CDS in comparison with CR. From the moment of the injection the presence of zones less saturated with fuel contributes to a relatively short induction period – 5° ca. compared to 11…12° ca. in the CR system. Using RME in the CR system in comparison with DF, increases the heterogeneity of the fuel jet, thereby causing a shorter (by 1…2° ca.) induction period in the whole investigated range of injection pressures of 60…160 MPa. The injection of a non-heated RO is accompanied by the shape and structure fluctuations of the fuel jet. RO heating to 65 °C stabilizes the structure of the jet and increases the share of less saturated zones. Promising way of use for the optical scanning method in the mathematical modelling of the DE working process is proposed.

Applying of pixels separation brightness threshold is usually used to find the object boundaries. It is proposed to use a method for dividing the brightness of pixels to assign them to one of the zones of the fuel jet. A low brightness area with higher concentration of fuel, and vice versa, a zone with sufficient brightness (except the background luminance) has a lower concentration. Studying the dynamics of the change in brightness in the zones of a jet, we can talk about the quality of fuel atomization nozzles that can be different under different conditions.

BACKGROUND: At the present time all worldwide diesel engine manufacturers have directed their development strategies on the way of reduction of harmful emissions, fuel efficiency improving and increasing of the power per liter. Using only accumulator type system is not sufficient for the goals achievement. It is necessary to use new auxiliary units, such as an exhaust catalyst, an exhaust recirculation system, injection of additional liquids together with diesel fuel, as well as to improve the existing units. Increasing the accuracy of injection rate of a nozzle will make it possible to adjust the engine fuel system more precisely, that will have a positive effect on all development directions of diesel engine engineering. Injection rate of a nozzle is dependent on fuel pressure in the nozzle inlet and on control signal timing. Pressure pulsation with stable timing cause irregularity of injection rate of a nozzle. Possibility of decreasing of nozzle inlet pressure pulsation is mainly defined by design of a high-pressure fuel pump, as it supplies fuel partially. The design optimization will make it possible to increase the accuracy of injection rate, that will make a positive effect on development of the diesel engines promising areas. AIMS: Study of irregularity of fuel supply by fuel pumps of various diesel engines designs with the Common Rail fuel accumulation system, aimed to decrease fuel oscillations and to improve stability of injection rate of a nozzle. METHODS: In order to assess the efficiency of high-pressure fuel pump designs, these designs were simulated in the specialised software. Theoretical studies of fuel supply irregularity for various designs of the pumps were carried out. RESULTS: Graphs of non-uniformity of fuel supply of high-pressure pumps depending on their design are obtained. CONCLUSIONS: Based on simulations, the conclusions about design influence on fuel supply irregularity of various designs of pump are made, recommendations for use are given.

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