Wyniki wyszukiwania - BazTech

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Example of flow modelling characteristics in diesel engine nozzle

Kolaric D., Kolaric M.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2016

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z. 90

123--135

EN

Modern transport is still based on vehicles powered by internal combustion engines. Due to stricter ecological requirements, the designers of engines are continually challenged to develop more environmentally friendly engines with the same power and performance. Unfortunately, there are not any significant novelties and innovations available at present which could significantly change the current direction of the development of this type of propulsion machines. That is why the existing ones should be continually developed and improved or optimized their performance. By optimizing, we tend to minimize fuel consumption and lower exhaust emissions in order to meet the norms defined by standards (i.e. Euro standards). Those propulsion engines are actually developed to such extent that our current thinking will not be able to change their basic functionality, but possible opportunities for improvement, especially the improvement of individual components, could be introduced. The latter is possible by computational fluid dynamics (CFD) which can relatively quickly and inexpensively produce calculations prior to prototyping and implementation of accurate measurements on the prototype. This is especially useful in early stages of development or at optimization of dimensional small parts of the object where the physical execution of measurements is impossible or very difficult. With advances of computational fluid dynamics, the studies on the nozzles and outlet channel injectors have been relieved. Recently, the observation and better understanding of the flow in nozzles at large pressure and high velocity is recently being possible. This is very important because the injection process, especially the dispersion of jet fuel, is crucial for the combustion process in the cylinder and consequently for the composition of exhaust gases. And finally, the chemical composition of the fuel has a strong impact on the formation of dangerous emissions, too. The research presents the influence of various volume mesh types on flow characteristics inside a fuel injector nozzle. Our work is based upon the creating of two meshes in the CFD software package. Each of them was used two times. First, a time-dependent mass flow rate was defined at the inlet region and pressure was defined at the outlet. The same mesh was later used to perform a simulation with a defined needle lift curve (and hereby the mesh movement) and inlet and outlet pressure. In next few steps we investigated which approach offered better results and would thus be most suitable for engineering usage.

2

The viewpoints of chemical air pollution caused by traffic subsystems and presented by the example of emission measurements of trucks' exhaust gases

Kolaric D.

Transport Problems

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2011

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T. 6, z. 1

49-62

EN

For a long time, experts have been emphasizing that we are in an era, in which dangerous climatic changes are getting more and more notable. We have been witnessing large climatic changes, caused by greenhouse gases, for several years. The question is no more “Are there climatic changes or are there not?”, nor “Are they being accelerated by human actions or are they not?” The fact is, the climate is changing more and more rapidly and that extreme weather conditions are becoming a daily matter. Furthermore, even if we stopped polluting the atmosphere immediately, the processes triggered by human-caused pollution would be going on for several decades. Modern logistic systems cannot operate without means of transport which enable the realization of transport. They form a transport system that makes the function of other economic systems possible. The use of different ways of transport has a bad influence on the environment in which we daily live and work. The damage of transportation has a bad influence on human health and nature, too. For that reason, we cannot treat the safety of the transportation means only through the technical impeccability of the devices which make possible direct execution of particular technological phases in different traffic subsystems. Ecological impacts of particular traffic subsystems are very complex, they have a long-term impact on our everyday existence and despite that we still do not devote enough attention to this. We have been aware that traffic, especially road and air traffic, is one of the largest sources of emissions of harmful exhaust gases of combustion engines and particles into the environment. The environmental impact of traffic is especially large due to greenhouse gases, which are part of exhaust gases being produced by internal combustion engines. In addition to that, there are many more toxic components in exhausted gases.

3

Operating the railway traffic control system

Pepevnik A., Kolaric D.

Transport Problems

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2011

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T. 6, z. 2

71-78

PL

Ze względu na wagę polityki transportowej i strategii rozwoju Republiki Słowenii koleje słoweńskie muszą brać pod uwagę rozwojowe i strategiczne cele kolei europejskich. Perspektywa postępu jest zdeterminowana przejęciem europejskiego systemu zarządzania ruchem kolejowym. Technologia i organizacja systemu ruchu kolejowego przedstawiają sumę wszystkich elementów oraz procesów technologicznych i organizacyjnych. Pojęcie systemu jest definiowane z matematycznego punktu widzenia jako całość, która jest zwykle skomplikowana, dlatego też system kolejowy jest również złożony i z tego powodu musi być precyzyjnie zarządzany. W węższym sensie zarówno technologia, jak i organizacja pracy obejmują różne środki i procedury w celu realizacji podstawowej działalności, którą może być proces przewozu pasażerów i towarów w systemie transportowym.

EN

Due to the valid traffic policy and development strategy of the Republic of Slovenia, the Slovenian Railways have to consider the developmental and strategic aims of European railways. The perspective of progress is basically determined by skimming the European system development, by taking over the European system and managing the railway traffic in the connection with the European railway system. Technology and organization of the railway traffic system present the sum of all technological and organizational elements and processes that takes part in providing aims of the system. The aims are defined as solving transport problems in railway system. The term system is defined, from the formal mathematical viewpoint, as a whole that is usually complicated or even very much complicated. Therefore, the railway system is complex as well, and that is why it has to be managed precisely. In the narrow sense of meaning, technology and work organization both comprises a variety of means and procedures to realize basic activity that can be seen as a perfect unit, and that can be the process of passengers and freight transport in a transport system. Because of the prompt development of microelectronics and computer engineering, a new generation of electronic signal-safety devices appeared. Because of the prompt development of microelectronics and computer engineering, a new generation of electronic signal-safety devices appeared. All these changes from the past few years that have been introduced into railway technology, enable railway to become attractive and competitive to other means of traffic. Therefore, the Slovenian Railways have to follow novelties in traffic technology development and gradually modernize its railway network.