Antoni Jankowski

Modelling of combustion processes of liquid fuels

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.

ENVIRONMENTAL POLLUTION CAUSED BY A DIRECT INJECTION ENGINE

In the paper, the authors made an analysis of mechanisms of the toxic components formation of exhaust gases in the direct injection engines. The genesis as well as the typical engine construction solution with the use of direct injection in diesel engines and these with positive ignition was developed. The typical construction solution of the Common Rail (CR) system, which is one of many elements increasing the purity of exhaust gases, was also presented. The basic advantages of direct injection, especially in case of the positive ignition engine, were also briefly described. Then, the mechanism for the formation of toxic components of exhaust gases in the direct injection diesel engines was presented. Moreover, the definition and dependency on the indicated mean effective pressure were shown, and the closed indicator graph, which is indispensable to calculate values of this pressure, was also (graphically) presented. In this paper, the mechanisms and processes, with the use of which it is possible to reduce the emission of toxic components of exhaust gases, were quoted. The exhaust gas recirculation with the EGR valve, which allows supplying the exact amount of gases to the engine inlet system, is such an example. The advantages of using this type of solutions were described, and a typical construction solution was presented in the diagram. The paper was completed with a conclusion, which emphasised the importance of direct injection on reducing the emission of toxic components of exhaust gases.

Start-up processes’ efficiency of turbine jet engines

Abstract The paper presents diagnoses of example start-up processes of drive units built in military aircraft operated in the Dęblins “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.

ADVANTAGES CONFERRED BY SHOCK ABSORBERS WITH CYLINDRICAL ACTUATOR APPLICATION TO LANDING GEAR

Shock absorber with cylindrical actuator is a new concept of integrated damper with floating device, in international patent application PCT/EP2016/061515, with wide application in road, rail and aerial vehicles. Comparative to the known solution with rubber sleeves or bellows, the new one is capable to work at more increased pressure being more compact and due to metallic cylinder is more reliable. The other important advantage consists of it applicability at any kind of shock absorber without any special preparation, the solution consisting of replacing the dust shield with a pneumatic cylinder sealed against rod with a gasket and sliding closed in the lower part by sealing element/s fitted in trough/troughs practiced in an annular body fastened against the outer cylinder. For a better behaviour the patent application contains and solutions with double sliding sealing working at high pressure and thus assuring enough floating forces to sustain the vehicle without standard metallic spring so it can be utilized successfully in aerial vehicles landing gear. By using displacement and pressure transducers and equipment of control and command, it becomes an active suspension. The paper presents the double sliding sealing solution and demonstrates, by simulation the advantages confer by this new solution of shock absorber with cylindrical actuator in landing gear. This purpose was realized a virtual suspension model on which simulated hard landing for vehicle load and unload states, for different pneumatic spring preloaded forces.

Influence of the quality of fuel atomization on the emission of exhaust gases toxic components of combustion engines

Abstract 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.

Mechanizmy tworzenia toksycznych składników spalin silników spalinowych

Abstract The paper analyses the mechanisms of creation of toxic exhaust gases, which mainly derived from inexact fuel metering and improper air-fuel mixture preparation. The paper describes the process of creating toxic components in the exhaust gases of piston engines during engine operation, and impact on the emission of these components determining the composition of the fuel mixture determined equivalence factor Φ. The principal mechanisms of formation of toxic exhaust gases, in particular nitrogen oxides, carbon monoxide and hydrocarbons, and also essential according to create each of toxic exhaust gases are the subject of the paper. Moreover, empirical relationships, by means of which it is possible to determine the time of creation of the individual components of toxic exhaust gases, are presented. For example, one of the mechanisms for prompt formation of nitrogen oxides and hydrocarbons graphic illustration of formation as a function of crank angle is described. At the conclusion, the summary and significance of information on creation mechanisms of toxic components in the exhaust gases of piston engines are presented.

Research of water - fuel microemulsions as fuel for diesel engine

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.

Potential non-toxic aqueous emulsion as a diesel fuel

Natural processes occurring on Earth (fires, volcanic eruptions) and human activity in the area of acquisition and processing of energy, is the cause of the continuous contaminating the atmosphere of combustion products. The combustion of fuels is and will be in the near future primary means of generating energy, including for transportation purposes. Transport is the cause of many environmental threats emits dust and particles along with many of gaseous harmful substances and also noise and vibration. Power sources used for transport are almost exclusively equipped with internal combustion engines, among which is dominated by a diesel engines. In view of the known advantages of these motors such as high efficiency and relatively low emissions of toxic compounds in the exhaust gas, they have been accepted as the most preferred source of power motor vehicles in the coming decades, assuming that meet the requirements of future regulations regarding environmental protection. The problem to be solved in internal combustion engines is the emission of nitrogen oxides. In this paper are contained an overview of proven methods and results in the reduction of nitrogen oxides in exhaust gases by means of emulsion fuels, and forming an opinion concerning of the usefulness of such solutions in the future

Impact analysis of air humidity on operating parameters of diesel engine

A major problem in the combustion diesel engines is the different distribution of the mixture of air and fuel and also temperatures inside the combustion chamber. It helps the formation of points of the high and low oxygen concentration in the combustion chamber of the engine. In areas with a high concentration of oxygen, the combustion process produces very harmful NOx, and in places with low oxygen concentration, as a result of incomplete fuel combustion particles are created in the form of soot. This not regular distribution of the mixture of air and fuel and temperatures in the combustion chamber affect the limited maximum engine power and efficiency at his every operating cycle. One method for improving the combustion process is feeding into the engine air with high relative humidity. The study was conducted on a chassis dynamometer at the Department of Vehicles Engineering Wroclaw University of Technology. For the purposes of the study determined the external characteristics, including maximum engine power and maximum engine torque at different air relative humidity and quite similar air temperature. Analysis of the results of research shows that high air relative humidity has a positive effect on the work parameters of the diesel engine.

Impact analysis of internal catalyst converter on operating parameters of VW 1.9 TDI engine

The largest amount of air pollutants is produced by the combustion of fossil fuels (coal, lignite, petroleum, natural gas, etc.). Such combustion releases huge amounts of greenhouse gases into the atmosphere (including carbon oxides (CO, CO2), sulphur oxides (SO2, SO3), nitrogen oxides (NO, NOx)) and dust, ashes and soot. Transportation is a significant share of the air pollution, mainly wheel-based transportation. The combustion process in diesel engine is very complex physico-chemically and varies in time. The process is accompanied by simultaneous exchange of heat and mass and chemical reactions. The development of internal combustion engines is made towards meeting of the increasingly stringent requirements for toxic exhaust emissions, reduction of fuel consumption, and preservation of Earths natural resources. The problem to solve in modern diesel engines is the emission of toxic compounds. One way to reduce emissions is to use a catalytic converter positioned directly in the combustion chamber of an internal combustion engine. The aim of this analysis is assessment of toxic emissions of a diesel engine with an internal catalyst. Qualitative assessment of engine emissions was determined by comparing test results of an engine with ceramic-ally coated valves against one with just conventional valves (commercial valves without a ceramic coating). The study utilized a fourcylinder 1.9 TDI VW engine. It was expected that the use of glow plugs with an active coating would reduce the release of toxic compounds.