Mathematical Model of Piston Ring Sealing in Combustion Engine

This paper presents a mathematical model of piston-rings-cylinder sealing (TPC) of a combustion engine. The developed model is an itegrated model of gas flow through gaps in TPC unit , displacements and twisting motions of piston rings in ring grooves as well as generation of oil film between ring face surfaces and cylinder liner. Thermal deformations and wear of TPC unit elements as well as heat exchange between flowing gas and surrounding walls , were taken into account in the model. The paper contains descriptions of: assumptions used for developing the model , the model itself, its numerical solution as well as its computer application for carrying out simulation tests

Przyrodnicza historia Gniezna - plemiennego ośrodka kultu i centrum wczesnopiastowskiego państwa polskiego Civitas Schinesghe

The stronghold complex in Gniezno located on the Lech's Hill belonged to the main centers of the early Polish State described for the first time in historical documents as Civitas Schinesghe - the Gniezno State. Recent archaeological studies indicate that the site on Lech's Hill was originally a tribal cult center. Palaeoecological studies provided records of environmental changes and cultural landscape development in the prehistoric periods and early historical times. Reconstructed changes of floristic diversity correlate well with the cultural processes

Symulacyjne badania wpływu szczelności komory spalania na sprawność silnika o zapłonie samoczynnym

Combustion chamber leakage, caused mainly by blowby, results in a reduced engine performance and higher fuel consumption. The blowby rate is, to some extent, determined by the design of the piston-ring-cylinder assembly (PRC) and the blowby rate varies throughout the life of an engine due to wear of the said assembly. The paper presents a quantitative evaluation of the influence of the combustion chamber blowby on the engine performance and fuel consumption on the example of two diesel engines: older generation naturally aspirated indirect injection diesel engine and a modern turbocharged direct injection engine. The assessment was made based on a simulation research using the AVL Boost software and the input data for the calculations were ascertained based on measurements performed on actual objects. The results have shown that a reduction of the blowby by half compared to the values occurring in engines of good technical condition would increase the maximum torque and power by approx. 0.5% for both investigated engines. The results of the simulation have also shown that increases in the blowby occurring in engines after long service lead to increased fuel consumption from 1% to 7% and the lower the engine speed and load the greater theses values.Nieszczelności komory spalania silnika spalinowego, spowodowane głównie przedmuchami spalin do skrzyni korbowej, są przyczyną mniejszych osiągów silnika oraz większego zużycia paliwa. Wartości natężenia przedmuchów spalin mogą być, w pewnym zakresie, kształtowane przez konstrukcję układu tłok–pierścienie–cylinder (TPC), ponadto zmieniają się one w czasie eksploatacji silnika na skutek zużycia układu TPC. W artykule dokonano ilościowej oceny wpływu nieszczelności komory spalania na osiągi i zużycie paliwa na przykładzie dwóch silników o zapłonie samoczynnym: starszej generacji niedoładowanego silnika z wtryskiem pośrednim oraz nowoczesnego, turbodoładowanego silnika z wtryskiem bezpośrednim. Oceny dokonano na podstawie badań symulacyjnych prowadzonych z wykorzystaniem programu AVL Boost, przy czym dane wejściowe do obliczeń ustalono na podstawie pomiarów przeprowadzonych na obiektach rzeczywistych. Wyniki badań wykazały, że zmniejszenie o połowę przedmuchów spalin, w stosunku do wartości spotykanych w silnikach będących w bardzo dobrym stanie technicznym, pozwoliłoby na zwiększenie maksymalnego momentu obrotowego i mocy maksymalnej o około 0,5% dla obu badanych silników. Wyniki symulacji wykazały również, że spotykane w eksploatacji wzrosty natężenia przedmuchów spalin powodują wzrost zużycia paliwa od 1% do 7%, przy czym wartości te są tym większe, im mniejsze są obciążenie silnika i jego prędkość obrotowa

A numerical model for calculation of piston rings wetted area in a combustion engine

Assumptions made while modelling the oil film between the ring and the cylinder liner in IC engines, especially concerning the boundaries of the wetted area of the ring face surface, were discussed and the assumptions adopted for the developed model were presented in this study. It was assumed that the model should take into account partially flooded lubrication, which meant that the boundaries of the ring wetted area had to be determined. Based on the adopted assumptions, a model for calculation of the oil film thickness between the cylinder and moving rings, and thickness of the oil film left on the cylinder by the ring pack was developed. A computer application operating in the Windows operation system was developed to carry out numerical calculations. The results of initial numerical calculations were also presented. The proposed model can be utilized to determine the effects of the ring pack geometry, especially the geometry of the ring surface, on parameters of lubrication. These parameters, including the oil film thickness, distribution of pressure in oil film or tangential force, are crucial for friction and wear of cooperating surfaces, oil consumption, and flow of gas from the combustion chamber to the crankcase, thus playing a role in the durability, fuel consumption and emission of an engine

Effect of friction force determination method on results obtained from model of gas flow from combustion chamber to the crankcase

The paper presents investigation of the influence of the friction force calculation method on the results of simulations run with the use of the model ofgas flow from the combustion chamber to the crankcase and piston rings motion in the grooves. The first series of simulations was run using the gas flow and ring motion model in which the friction force was calculated from the empirical equation. The second series was run with the use of the gas flow and ring motion model fully integrated with the ring lubrication model. In that case the friction force was derived from the hydrodynamic model of ring lubrication. Comparison of the results obtained in the first and second series of simulations indicated that despite the fact that the friction forces calculated with these two methods differed considerably, the method of friction force calculation had insignificant effect. This refers to the ąuantities determined in the simulations which are most important from practical point of view - i.e. displacements of the rings in the grooves, pressure courses in inter-ring regions and blowby rate. It is not necessary to integrate the gas flow and ring motion model with the model of ring lubrication, and doing so to complicate it very much, if the aim of the calculations is simulation of blowby and rings behaviour in the grooves

Application of fem in the analysis of the structure of a trailer supporting frame with variable operation parameters

W pracy zaprezentowano numeryczną analizę konstrukcji ramy naczepy o zmiennej długości i podwyższonej nośności przeznaczonej do transportu ładunków ponadnormatywnych. Prowadzone badania miały na celu opracowanie adekwatnych modeli numerycznych MES umożliwiających identyfikację wytężenia konstrukcji oraz stanu odkształcenia w warunkach obciążeń eksploatacyjnych. Zastosowanym do analizy narzędziem numerycznym był program Abaqus/Standard, umożliwiający prowadzenie obliczeń w zakresie geometrycznie nieliniowym z wykorzystaniem przyrostowo-iteracyjnej metody Newtona-Raphsona. W wyniku przeprowadzonych prac ustalono newralgiczne obszary ramy w których występowały niebezpieczne naprężenia. Umożliwiło to modyfikację konstrukcji pozwalającą na zmniejszenie naprężeń do bezpiecznego poziomu.This work presents a numerical analysis of the structure of a trailer frame of adjustable length and an increased load capacity designed for the transportation of oversize loads. The study was aimed at developing adequate numerical FEM models which would allow identification of the effort of the structure and the state of strain under operating loads. The analysis was carried out using ABAQUS/Standard, a numerical tool which enables calculations in the geometrically nonlinear range with the use of the incremental-iterative Newton-Raphson method. As a result of the analysis, trouble areas in the frame were found in which dangerous stresses occurred. This enabled modification of the structure, leading to a reduction of the stresses to a safe level

Design of a frame to a semi low-loader

The paper presents the process of design of a frame for a semi low loader for the transportation of oversize loads, especially wheeled and tracked machines. After considering different solutions of a frame, a central beam was chosen and an initial design was developed. The initial model of the frame was analyzed with the use of FEM and was then modified. Two final versions of the frame were prepared. One of them was used in a 4 axle trailer with a load deck that can be extended in length and width to carry oversize and heavy loads. An important advantage of the trailer is its versatility and the fact that in a non-extended state it meets the regulations for standard trailers and can carry loads without a special permission. The paper focuses on the application of FEM analysis in the design of the part of the beam where highest stresses were located. A design solution for a ladder frame, a schematic image of a box-type central beam, a design solution for rear ramps, geometrical models of semitrailer frame with boundary conditions, stress distributions in a non-extended and extended frame model, a section of the rear part of the frame with sliding plates visible and a pin guide bar for blocking frame extension, stress distribution in the front part of the frame, single and double supporting rib, side wall supporting plate and stress distribution after the use of plates and one supporting rib, stress distribution after the employment of plates and two supporting ribs, stress distribution in the alternative gooseneck design, main dimensions of the semitrailer, extended semitrailer are presented in the paper

Overlay Multicast Optimization : IBM ILOG CPLEX

IBM ILOG CPLEX Optimization Studio delivers advanced and complex optimization libraries that solve linear programming (LP) and related problems, e.g., mixed integer. Moreover, the optimization tool provides users with its Academic Research Edition, which is available for teaching and noncommercial research at no-charge. This paper describes the usage of CPLEX C++ API for solving linear problems and, as an exhaustive example, optimization of network flows in overlay multicast is taken into account. Applying continuous and integral variables and implementing various constraints, including equations and inequalities, as well as setting some global parameters of the solver are presented and widely explained

Ekologia historyczna miasta : uwarunkowania środowiskowe i podstawy gospodarcze wczesnomiejskiego zespołu osadniczego na Ostrowie Tumskim w Poznaniu

Environmental conditions, animal and plant economy of the Early Medieval stronghold complex at Ostrów Tumski - and island on Warta river - have been discussed. The stronghold complex with the nearby open settlements, its role as a center of administration, church, and trade center have been considered as the early urban type of settlement. It finally developed into main economic and cultural center of western Poland - Poznań city