## 3 Presentation of the Modifications Made to the Fuel Injector Sprays  
The purpose of spray modification is to improve the fuel injection process in a modern diesel engine with a Common Rail system powered by vegetable fuel. The fuel injection process can be considered in terms of quantity and quality. The quantity, describing the quantitative aspect, is the injection dose, while the qualitative aspect includes the shape, range, width, opening angle, speed, and atomization of the stream of fuel flowing from the atomizer. Figure 1 shows a modified fuel atomizer with spiral-elliptical ducts Osipowicz [22].  
The element of the fuel injector responsible for the correct process of fuel injection into the combustion chamber is the atomizer (Figure 1). It consists of a body and a needle. The fuel flows into the needle chamber through channel 2, then flows around the non-working part of needle 1. Annular channels made on the non-working part of the needle, as a result of the reciprocating movement of the needle, cause additional fuel turbulence. When the cone valve 4 opens the holes in the fuel atomizer, injection into the combustion chamber takes place. The purpose of the atomizer modification is to improve the atomization process of vegetable fuels in the combustion chamber of the engine, due to the turbulence caused by the atomizer and the accompanying phenomena. The parameters affecting the quality of the injected fuel stream are viscosity and density. Table 1 presents selected physical parameters of conventional and vegetable fuels. As can be seen, the viscosity and density of vegetable fuels have higher values than conventional fuel, therefore, according to the authors, the use of spiral-elliptical ducts on the non-working part of the needle will affect the physical parameters of the fuel and improve the atomization process in the combustion chamber of the compression ignition engine.  
One of the features of turbulent flows is the fluctuation of momentum and kinetic energy of turbulence [PERSON] [23], and the phenomenon of heat exchange during flow [PERSON] [24], [PERSON] [25]. The viscosity and density of liquids depending on the temperature. If the temperature increases locally under the influence of additional vortices, then the physical parameters of the fuel will also change, which will affect the spraying process [PERSON] et al. [26]. Previous work related to the analysis of fuel flows in atomizers, and its atomization have not taken into account the induction of additional turbulence in the area of injectors. The concept of creating additional turbulence is innovative, and has not been used anywhere until now.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Diesel Fuel** & **Rapeseed Oil Methyl** & **Rapeseed Oil** \\  & & **Ester** & **Rapeseed Oil** \\ \hline Density [kg/dm\({}^{3}\)] 20 \({}^{\circ}\)C & 0.817–0.856 & 0.86–0.9 & 0.91–0.92 \\ Kinetic viscosity [mm\({}^{2}\)/s] 15 \({}^{\circ}\)C & 2.90–5.50 & 6–9 & 68–97.7 \\ Ignition temperature [\({}^{\circ}\)C] & 20–84 & 111–175 & 317–324 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Physical parameters of diesel fuel B100 and raps oil  
Figure 1: The modified fuel atomizer. (**1**) Channels in the non-working part of the needle, (**2**) the fuel supply channel, (**3**) the precision atomizer pair, (**4**) the injection holes [22].