## 5 Conclusions  
Analyzing the results of simulation tests, it can be seen that modification of the non-working part of the atomizer needle changes the characteristics of the fuel flow. Spiral-elliptical ducts created additional turbulence around the spire (Figure 4). The qualitative parameters of the fuel stream depend on the velocity of the liquid at the outlet and the degree of its turbulence. The flow velocity depends on the pressure, while the degree of stream penetration is influenced by the physical parameters of the fuel, such as density and viscosity. The purpose of the modification is to intensify turbulence during fuel flow through the atomizer. The most important property of turbulent motion is the presence of many vortices of varying sizes that transfer momentum, mass and heat from one flow point to another. Vorticity \(\Omega\) is the rotation of the velocity vector V. It is possible to use the kinetic energy of the rotational motion (imparted by modification of the non-working part of the needle) in order to increase the kinetic energy of the translational motion of the stream of injected fuel into the working space of the cylinder. Additionally, rotating flow around the needle has an influence on the temperature, leading to a higher Reynolds number. This phenomenon causes local changes in the physical fuel parameters, like viscosity and density. Viscosity is a parameter that affects the characteristics of the stream of fuel injected into the combustion chamber. By reducing its value as a result of the temperature rising, it is possible to improve the qualitative characteristics of the fuel injection. This process is of particular importance for a plant fueled engine, whose physical parameters are different from those of standard diesel fuel. Qualitative parameters of the injected fuel stream play an important role during the combustion process of fuel in compression ignition engines. The results of laboratory tests have shown that the changes made to the non-working part of the fuel atomizer needle do not affect the amount of injection and overflow doses. Based on the results of the measurements, the fuel flow parameters (Reynolds number and flow speed) in the atomizer and stream were calculated. The nature of the liquid flow is determined by the Reynolds number, which depends on the speed. According to the Bernoulli equation, the results of calculations showed that in the fuel atomizer, due to high pressures, laminar fuel flow prevails (Figure 3), while in the stream the flow is hyper turbulent. The modification of the inoperative part of the needle caused additional fuel turbulence in the atomizer (Figure 4). Increased turbulence causes the temperature of the entire system to rise (Figure 8). As a result of this temperature increase, the viscosity of the fuel decreases, which affects the qualitative course of the fuel injection process. In addition, additional vortices affect the kinetic energy of the forward movement of the stream. The results of research using an infrared camera show that the temperature of the modified fuel injector is  
Figure 11: Initial fuel spray research, pressure 30 MPa, injection time 300 μs. (**A**) Fuel injector with a standard nozzle; (**B**) fuel injector with spiral-elliptical ducts. higher than that in a standard fuel injector during tests (Figure 10). Initial fuel stream visualization (Figure 11) indicates the changes in the injected fuel quality. The fuel stream was dispersed during the injection process. The analytical simulation shows that fuel in spiral-elliptical ducts has an increased temperature, due to additional turbulence. This causes a lowering of the fuel density and dynamic viscosity. These parameters have an influence on the fuel stream shape. Based on the theoretical analysis, it can be concluded that it is possible to change the quality parameters of the stream of injected fuel into the cylinder working space. The spiral-elliptical ducts created caused additional turbulence in the fuel flow.