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Study on selected parameters of engine with the active combustion chamber

Głogowski Michał, Woźniak Marek, Szydłowski Tomasz, Siczek Krzysztof

Combustion Engines

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2023

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R. 62, nr 3

3--12

EN

The present study was focused on the combustion engine with a variable compression ratio (VCR), namely the four-stroke air-cooled engine with the active combustion chamber (ACC). An indicated pressure, torque, power, and specific fuel consumption of that engine were investigated experimentally as a goal of the present study. Experiments were conducted using two versions of an engine. Two parameters particularly influencing the ACC engine performance including the maximum compression ratio CRmax and the indicator γfm determining the correct operation of the ACC system, were described. It was found that the ACC engine allowed avoiding detonation combustion without changing the amount and composition of the combustible mixture, and even without delaying the ignition advance angle. In addition, the possible range of control of the combustion process allowed the ACC engine to operate with different types of hydrocarbon fuels, for example, in the form of petrol with various alcohol admixtures. The very intense flow of the combustible mixture inside the cylinder of the ACC engine allowed describing the combustion in the ACC engine with zero-dimensional mathematical models with the dual Vibe function providing the proper characterization of the heat release process. The use of very high maximum compression ratios allows the ACC engine to operate to a certain extent as a Homogeneous Charge Compression Ignition (HCCI) engine with high lambda coefficients.

2

New teoretical cycle for active combustion chamber engine

Głogowski Michal Piotr, Kubiak Przemysław, Šarić Željko, Barta Dalibor

Archiwum Motoryzacji

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2019

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Vol. 83, nr 1

23--42

EN

This paper presents calculations of the theoretical cycle of engines with an active combustion chamber depending on energy delivery and dissipation. In the case of ACC engines, a different calculation approach is required to account for the possibility of additional volume change, independent of the piston-crank system. The introduction presents a schematic diagram of volume change, accomplished by two independent piston-crank systems and an active combustion chamber, as proposed by the authors. Moreover, the diagram, which is the basis for analysis in this paper, illustrates characteristic points of the cycle. In existing theoretical cycles of combustion, this issue does not present any difficulties, since the solution is exact and based on known equations. In the case of theoretical ACC engines, however, the situation is different, since this engine can perform not only in typical cycles, but also in new ones. To explain the challenges of these new cycles, authors present a few of the most probable calculation variants, taking into account the new kinematic capabilities of ACC engines. Each comment justifying the choice of a certain calculation variant is illustrated with a theoretical cycle figure and closest approximation of induced pressure course of the ACC engine. At the same time, however, the authors show that this problem can have many interpretations. It has been concluded that the solution depends on the assumptions made about the active combustion chamber, namely its principle of operation.

3

High compression spark ignition engine with variable compression ratio using Active Combustion Chamber

Kubiak Przemysław, Glogowski Michal, Soghabatyan Tigran, Mrowicki Adam, D'Errico Gianluca

Archiwum Motoryzacji

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2019

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Vol. 86, nr 4

5--26

EN

Abstract In this article Authors present the continuation of the calculations for theoretical ACC engine cycle, considering additionally “VCR function” – changeable compression level. For this purpose the self-acting volume change, realized by ACC system, was used. The ACC system was adjusted appropriately to control the compression level. The analysis is based on three cases, representing delayed, premature and optimal reaction of ACC system. Reactions are presented in form of plots with indicated pressure in the combustion chamber. As the result of the conducted analysis and interpretation of obtained graphs, the calculation approach of compression ratio for ACC presented in previous article is being challenged. For the optimal reaction of ACC system, the theoretical operation schematics are devised and presented in the key points of the work. Based on the schematics, the values of theoretical efficiency were calculated for different cycles of theoretical ACC engine, in which regulation of compression ratio takes place. Moreover, the presented analysis includes graphs with optimal courses of indicated pressure for significantly different work parameters of ACC engine, showing its regulation possibilities. Also the time scaled graphs (with millisecond as basic time unit) are presented to show the possibilities of dynamic ACC systems, which are comparable with the combustion time (from 3 to 0,5 ms). In this paper the general discussion is started about the compression ratio in more complex kinematic systems including ACC.