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1

Study of Atkinson cycle in two-stroke diesel engine with opposed pistons

Mitianiec Władysław

Combustion Engines

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2019

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R. 58, nr 3

121--128

EN

The paper presents possibilities of change working parameters of two-stroke diesel engine with opposed pistons. Obtaining of higher engine efficiency is realized by applying of Atkinson cycle. Modification of scavenging process by changing pistons' position connecting with two crankshafts enables asymmetrical scavenge timing. Decreasing of shorter time of closing exhaust ports before compression process and longer expansion process give higher engine work and with high charging ratio increases engine power. These types of engines are recently recommended for power plant stations. The paper includes full analysis of engine work with scavenge and combustion processes for different timing phases based on geometry of the CI Leyland L60 engine by using of CFD modelling and own 0D model. Simulation tests indicate a high scavenge efficiency, good penetration of injected fuel and fast combustion process. The work contains figures of pressure, temperature traces and emission of main chemical species in exhaust gases with comparison of engine works for different timing phases. Atkinson cycle in two-cycle work of engine and full combustion process enables to achieve high total efficiency. The study is an input for realization of such processes in a future of power plant engines with different fuelling systems.

2

Rozwinięcie metody analizy numerycznej wymiany ładunku w silnikach o tłokach przeciwbieżnych

Kalke J., Mazuro P., Sulikowski P.

Combustion Engines

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2015

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R. 54, nr 3

511--519

PL

Moc i sprawność całkowita silników dwusuwowych jest silnie zależna od sprawności wymiany ładunku, dlatego też optymalizacja tego procesu jest krytyczna z punktu widzenia wydajności. Głównym celem tego artykułu jest pokazanie potencjału łączenia ze sobą różnych narzędzi inżynierskich w celu znacznego przyspieszenia fazy koncepcyjnej weryfikacji różnych systemów wymiany ładunku. Proponowany algorytm postępowania używa różnorakich języków programowania do łączenia komercyjnych (w tym przypadku Ansys Workbench, Siemens NX, MathWorks Matlab, Microsoft Excel) i niekomercyjnych pakietów (Cantera) by uzyskać najważniejsze informacje tak wcześnie jak jest to możliwe. Proponowane narzędzie obsługuje model 0-wymiarowy procesu spalania (z zadanym stężeniem gazów wylotowych), podziału geometrii i dyskretyzacji przestrzennej, zautomatyzowanego ustawiania programu obliczeniowego i postprocesora do danych numerycznych, przygotowanych specjalnie dla rozrządu sterowanego tłokami. Przeprowadzono prostą ocenę zaoszczędzonego czasu dzięki zaproponowanej metodzie postępowania. Ostania część jest krytycznym podsumowaniem zaproponowanej metody i wskazuje pewne ciekawe kierunki rozwoju takie jak kosymulacja z programami 1D oraz bardziej zaawansowane modelowanie spalania.

EN

The power and overall efficiency of two-stroke engines are strongly dependent by scavenging efficiency, thus optimization of this process is vital to performance. Main aim of this article is to show the potential of combining different engineering tools to substantially speed-up the conception verification phase of various scavenging systems. The suggested algorithm uses a variety of programming languages to interconnect commercial (in this case Ansys Workbench, Siemens NX, MathWorks Matlab, Microsoft Excel) and non-commercial packages (Cantera) to get the most important information as soon as possible. Presented tools cover 0-D combustion process model (with desired exhaust gases concentration), geometry division and meshing, automated solver-setting and numerical-data postprocessor, prepared especially for piston ported valves. A simple evaluation of time savings by using proposed method was conducted. Last part is a critical sum-up of presented method and pointing out some interesting directions of development, concerning co-simulation with 1D software and more sophisticated combustion modeling.

3

Analysis Of Possibilities In Using Crankshaft Casing Pressure Measurements For Diagnosing Technical Condition Of The Prc System

Abramek K.

Journal of Polish CIMAC

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2009

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Vol. 4, no 2

7-13

EN

In the paper is presented statistical analysis of the effect of compression-ignition engine working time on the phenomenon of exhaust gas pressure increase in crankcase and cylinder liner, pistons and rings wear. Characteristics of the crankcase pressure variations were made for the start-up speed and for selected rotational speeds of the 359 compression-ignition engine crankshaft as well as micrometric measurements of the cylinder liner and pistons and rings wear. The engine was operated under normal traction conditions while pressure analyses and cylinder liner micrometric measurements were made, respectively, after an operational run of: 5378 km, 100128 km, and 204864 km. Crankcase exhaust gas pressure measurements were made both with air vent open and closed for a cold (lubricating oil temperature of 285 K) and a warm engine (333 K). Basing on the analysis of obtained examination results, it was showed that crankcase exhaust gas pressure measurement (also during the start-up) may be used for determination of engine run and life.

4

Around-nest 'cemeteries' of Myrmica schencki Em. (Hymenoptera: Formicidae) : their origin and a possible significance

Czechowski W.

Polish Journal of Ecology

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2008

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Vol. 56, nr 2

359-363

EN

Unusual rubbish piles of Myrmica schencki Em. colonies nesting within territories of Formica polyctena Forst. are described. The piles tightly surrounded M. schencki nest entrances and consisted mainly of remains of F. polyctena corpses (with a small addition of corpses of other local ant species) previously collected as food by M. schencki foragers in F. polyctena waste disposal zones. This observation shows that, under certain conditions, M. schencki can actually be a specialised myrmecophagous scavenger. The peculiar finding of M. schencki rubbish piles, in connection with other observations of using dead bodies and other remains by ants, suggests that such piles can play some role in interspecific relations in ants. This possibility is considered in the context of the competitive hierarchy of ant species.