The combustion of fuels is and will be in the nearest future a basic way of acquiring the energy, among others, for transport purposes. Transport causes many threats for natural environment. It produces powders and particulates, together with many gaseous noxious substances and is also the source of noise and vibrations. Sources of propulsion, applied in transport, are almost exclusively piston-combustion engines, among which the dominant role play self-ignition engines. In the light of well-known advantages of these engines, they were accepted as most beneficial sources of car vehicles' propulsion in nearest decades, provided they meet the requirements of the future legal regulations regarding the environmental protection. The emission of nitrogen oxides (NOx) and particulate matters (PM) is a problem to be solved in modern engines. This constitutes so called targets conflict, consisting in excluding the alternative of both coefficients' decrease, in the way of regulation the set of an engine and the limiting emissions, permitted by the EURO regulations. From among many different methods of limiting both the formation and emission of NOx, the method of the selective catalytic reduction (SCR) is universally applied. This method requires special installation with the catalyst and the reservoir intended for the "clinically" clean reductive measure. In the aspect of constituting opinions regarding the need of reducing additional installations and media on board the vehicle, it seems that to supply the engine with fuel-water emulsion and especially fuel-water microemulsion becomes an interesting solution.

The paper presents diagnoses of example start-up processes of drive units built in military aircraft operated in the Dęblin's “School of Eaglets” during the flight. The significance of this process is very important, especially from the point of view of flight safety, especially as it concerns the training aircraft, on which officer cadets-candidates for pilots are trained. The diagnosis of the start-up process was conducted using data from on-board flight recorders recorded during a flight training, whose aim was an emergency launch of particular drive units, and with the help of the so-called phase mapping of the selected operating parameters of the particular flight drive systems. The standard diagram of typical start-up systems was shown, while presenting their base subassemblies. At the end, the obtained results and the main problems that need intervention were commented, as well as further preventive activities were proposed.

The modelling of combustion processes of liquid fuels assumes that combustion processes of fuels always occur in gas-phase, gas-phase may be homogeneous or heterogeneous mixture. For homogeneous mixture, course of combustion processes is controlled by kinetics of chemical reactions. For heterogeneous mixture, course of combustion processes is controlled by initial processes, with reference to liquid fuels, vaporization processes of fuel occur. Flow of combustion gases (velocity and kind) intensifies combustion processes, influence of pressure on combustion processes of liquid fuels differs from the influence on combustion processes of gas fuels. The subject of the paper is the modelling of the combustion process of heterogeneous fuels, researches processes of spraying and combustion. The researches of atomization and combustion processes were performed in combustion chamber of the constant volume. To carry out the research, the test equipment was used, which allowed the visualization of atomization and combustion processes by means of the camera to high-speed photographing, measurements of distribution velocity stream atomised fuel with the laser-equipment PIV, LDV and PDPA, and measurement of the pressure in combustion chamber. The model of the combustion process of heterogeneous fuels based on properties of the boundary layer with addition of the mass was worked out.

Detailed knowledge about static friction materials is required for the accurate calculation of the braking torque needed to hold a load at rest. This is particularly important for brakes in cranes, elevators, hoists and mining winding machines, which must meet specifications such as the definite value of the static safe braking factor. The study of static friction is also a useful supplement to the dynamic testing of brake friction materials. In such a study, precise control of the temperature on the surfaces is possible, as well as surface roughness, and existence of the third‐body can be accurately identified. It is an important fact that the coefficient of static friction, μs, is not an invariant, and it cannot be adequately represented in many engineering applications as a single number. The study of static friction dependence upon factors such as stationary contact time, rate of tangential loading, and surface temperature, contributes to a better understanding of friction phenomena. In this paper, a test apparatus is presented, and a series of experiments is described. The experiments reveal the static friction characteristics of some brake friction materials.

The paper contains analysis of the impact on the quality of the fuel spray of droplets on the number and the value of the surface area of the droplets that have a direct impact on the efficiency of the combustion process. It presents a change in the level of toxic exhaust emissions with an increase in the so-called. Sauter Mean Diameter (SMD) of fuel droplets. The presented figures show that the increase in the average droplet diameter SMD in particular causes an increase of toxic exhaust gases emissions, i.e. mainly nitrogen oxides NO, carbon monoxide CO, hydrocarbons HC and Particulate Matter (PM). This tendency is not constant, because it is changing according to changes of the coefficient of equivalence Φ. For example, emissions of nitrogen oxides for the lean mixtures (Φ <1), with an increase in average droplet diameter increases, while now for the rich mixtures (Φ> 1), this trend is significantly changed, i.e. the level of this emission decreases.

Boundary layer is a reflection of the phenomena occurring in the combustion of liquid fuels with perpendicular to the surface of adding mass. For study the influence the thermal boundary layer on the process of combustion a special test stand has been developed, in which the flow of the medium with the addition of mass can be realized. Quartz windows and magnesium oxide powder, which is added for allow visualization of the airflow stream. Quartz windows are placed in the sidewalls of the chamber. The paper presents the test stand. The test stand consists of the following main components: test chamber, the main air preparation module, auxiliary air preparation module, module of particulate cartridge, air compressor, compensation tank, control unit and accessories in the form of filters, valves, pressure gauges and automatic control. Velocity of flow through the test chamber is controlled with air pressure from air preparation units and with the location of the regulatory fin at the end of the measuring chamber. The cartridge unit produces a homogeneous mixture of MgO particulates in air. Test results of the axial velocity profile at a distance of L=0.35 m obtained with LDA and PDPA laser equipment and ANSYS FLUENT numerical computations. Important for the combustion process is laminar boundary layer in laminar flow and laminar sublayer in turbulent flow.

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