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Optimal design of the intake system

100%

Pogorevc P. , Kegl B.

tom Vol. 10, No. 1-2

213-219

The intake system geometry of the internal combustion engine has a major effect on the gas exchange process. Therefore it affects the performance of the engine and its emissions. In order to improve engine performance, it must assure uniform distribution of fresh air among the cylinders and minimal pressure losses along the channels. The optimisation of the intake systems is of an interest to the engine designers sińce the beginning of the 20th century. The paper deals with the optimal design of the intake system for the four-stroke four-valve internal combustion engine with the intention of increasing its power. Special geometry demands and constraints had to be taken into consideration. Optimisation was carried out using the optimisation program iGO based on a gradient-based approximation method. For the response calculation the computational fluid dynamics program BOOST was used. The connection between iGO and BOOST was established by simple wrapper programs that took car e for the correct data exchange. The results comparison confirmed the adequacy of the program BOOST in our example.

Design of intake system with special demands

100%

Pogorevc P. , Kegl B.

Journal of KONES

2002

tom Vol. 9, No. 1-2

217-224

The intake system provides the internal combustion engine with fresh air and it has a major effect on engine performance and emissions. Therefore great attention has to be focused on the design of the intake system. Many investigations are related to the improvement of the breathing capacity of the engine, to the minimization of pressure losses along the pipes and to the distribution uniformity of air among the cylinders of the engine. This paper deals with the design of the intake system of the racing car engine with special demands. The imposed constraint is a single circular restrictor in the intake system, positioned between the throttle and the engine. All engine airflow passes through this restrictor of 20 mm diameter for gasoline-fuelled cars. The only allowed sequence consists of a throttle, restrictor and engine. Keeping these requires in mind, the flow and pressure loss reduction in the engine intake region are investigated with computational fluid dynamics software. On the basis of numerically obtained results, the intake system is designed and practically manufactured in our racing car engine.

Injection characteristics of an in-line fuel injection system using the alternative fuels

80%

Volmajer M. , Kegl B. , Pogorevc P.

Journal of KONES

2002

tom Vol. 9, No. 1-2

259-267

The ever increasing ecological requirements encourage the use of alternative fuels. Some alternative fuels have advantages in production, some in transport and some in excellent injection as well as engine characteristics. Till today several alternative fuels for compression ignition engines have been investigated. This paper deals with the bio-diesel and with the wasted cooking oil. Biodiesel is produced from different plants (rape, Canola, Soya beans, palm tree...), while the wasted cooking oil is received from the catering industry. In this paper attention is focused on the fuel injection as well as fuel spray characteristics using diesel, bio-diesel and wasted cooking oil. The analysis of the fuel injection characteristics is obtained using the one-dimensional mathematical model for numerical simulation of injection process. In this model the influence of the snubber valve, the cavitation phenomena as well as variable fuel properties are taken into account. The influence of alternative fuels on spray characteristics is investigated using some empirical models. Furthermore, a computational fluid dynamics package is used for some analyses of the nozzle flow characteristics. Finally, on the basis of the numerically and experimentally obtained results, the harmful emissions using alternative fuels are predicted to some extent.