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1

Research of combustion system with semi-open combustion chamber in a commercial spark ignition engine

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2016

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Vol. 23, No. 4

283--290

EN

During the research of a new combustion system with semi-open combustion chamber for SI engines with use of the rapid compression machine (RCM) and visualisation experimental engine (VEE) it was proved that the application of this system results in shortening of the combustion time, increasing of the maximum cycle pressure and, in effect, increase of the combustion efficiency. The aim of the research using a commercial spark ignition engine was to prove that the similar results (as in RCM and VEE) could be obtained in a wide range of automotive engine operating parameters. In this research the two cylinder, four-stroke air-cooled SI engine, with volume displacement 650 cm³ from Fiat 126 motorcar was used. This engine was fitted with a modified cylinder head and ignition distributor. Two types of prechamber with different shape were installed in different locations into the cylinder head but the ignition distributor had fixed, preadjusted, ignition advance angle in the full range of engine speed. The wide-open throttle characteristics including power, specific fuel consumption and exhaust emission versus engine speed and load characteristics including: specific fuel consumption and exhaust emission versus engine torque were determined for different ignition advance angles. In the lower range of the ignition advance angle the engine showed stable operation at lower speed but unstable at high speed and, inversely, if the ignition advance angle was high the engine operation was stable at the higher speed and unstable at the lower. The engine characteristics during unstable operation were deteriorating. The research results show that improvement of the engine characteristics can be obtained in the full range of operating parameters if the ignition advance angle is varied continuously with the variation of engine speed. The ignition advance angle for the engine fitted with the new combustion system, which was subject of this research, was different form the ignition advance angle for standard engine.

2

Influence of compression ratio on combustion, turbulence, swirls into model combustion chamber of SI engines

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2015

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Vol. 22, No. 4

179--186

EN

The results of the visualization researches, with the pressure measurement results are presented in the paper. Researches deal with the combustion system with semi-open combustion chamber for spark ignition engines. This system was elaborated in Aircraft Engine Department of Heat Engineering Institute of Warsaw University of Technology. During researches the influence of CR on a flame front propagation and turbulences into combustion chamber, when CR and ignition advance are varied, was determined. The model combustion chamber was made with the constant volumes ratio (the prechamber volume to the prechamber plus main combustion chamber volumes) of 28%. The CR were varied: 6:1, 8:1, 10:1 and 12:1, by changing of combustion chamber length and establish high. The researches were performed using rapid compression machine (RCM). The combustion sequences were recorded using high-speed digital camera with speed of 5000 frames per second. Simultaneously with combustion sequences recording, the high-speed pressure courses were registered. The research results show that the growth of compression ratio causes an improvement of combustion system performances; an increase of maximum cycle pressure and useful work field. The improvement of the performances is caused mainly by shortening of the combustion time and intensification of the turbulences and approaching of supposed combustion course.

3

Research effects of novel combustion system with semi-open combustion chamber using rapid compression machine

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2014

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Vol. 21, No. 4

297--310

EN

The combustion system with semi open combustion chamber (SOCC) was originally elaborated in Aircraft Engine Department of Warsaw University of Technology. In this system the original combustion chamber of the standard SI engine, was divided by partition in prechamber and main combustion chamber, but yet this division exists only when the piston is close to TDC, on the contrary by the rest of the cycle the chambers are fully open. The system operation mechanism, the visualization research results, the high speed changed of the pressure measurements, was presented in this paper. The influence on the system performances of the different combustion systems parameters: the prechamber volume, the nozzle hole diameter in the partition, the ignition place, the compression ratio, and the ignition advance angle (IAA), on the basis of the research results, using rapid compression machine was presented in this paper. All research results show, that the best results of the system operation can be obtained if the stream outflow from prechamber to main combustion chamber starts when the piston is at TDC, and if the stream energy will be so big to displace all main combustion chamber before the clearance between partition and piston crown was opened. If the system operated correctly, the combustion time shortening, the growth of the maximum cycle pressure, and the combustion efficiency increase were obtained.

4

Flame front propagation in combustion system with semi - open combustion chamber with different compression ratio

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2013

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Vol. 20, No. 4

227--235

EN

Researches of the combustion system with semi-open combustion chamber for spark ignition engines. This system was elaborated in Aircraft Engine Department of Heat Engineering Institute of Warsaw University of Technology. The researches concern the determination of influence CR on a flame front propagation into combustion chamber when CR and ignition advance are varied. The model combustion chamber make up with the constant volumes ratio of the prechamber volume to the prechamber plus main combustion chamber volumes, of 28%, but the CR were varied: 6:1, 8:1, 10:1 and 12:1, by changing of combustion chamber length. The researches were performed using rapid compression machine (RCM). The combustion sequences were recorded using high-speed digital camera with speed of 5000 frames per second. Simultaneously with combustion sequences recording, the high-speed pressure measurements were performed. The results of the visualization researches, with the pressure measurement results are presented in the paper. The research results show that the growth of compression ratio caused an improvement of combustion system performances; an increase of maximum cycle pressure and useful work field. The improvement of the performances is caused mainly by shortening of the combustion chamber length and approaching of supposed combustion course.

5

Combustion process visualisation in rapid compression machine modelling combustion in spark ignition engines

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2013

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Vol. 20, No. 4

219--226

EN

Mixture preparation and combustion processes in internal combustion engines are very complex and very difficult to investigate. These processes run very quickly and their parameters are changed quickly and in wide ranges. Therefore, the interpretation of measurement results is very difficult and uncertain. The visualization methods applied in the combustion researches can help to interpret the results. For many years, the visualization methods have been developed at the Aircraft Engine Department of Heat Engineering Institute of Warsaw University of Technology, in the field of combustion in engines, detonation and gas dynamics research. In these researches, different method of registration of very fast changes of combustion were applied. The combustion experiments have been performed in constant volume bomb, rapid compression machines and experimental visualisation engines. In the last case, the electronic digital camera of Photram SA 1.3 has been used. This paper refers to the experiments, which were conducted using rapid compression machine. Their goal was explanation the combustion mechanism in combustion system with semi-open combustion chamber under different parameters of this system. The obtained results show a strong influence of combustion system parameters on combustion mechanism, especially on a compression ratio and ignition timing. The strong swirls were registered at all sharp edges on combustion chamber during compression stroke. These swirls had a strong influence on the combustion system operation.

6

Combustion process control in system with semi-open combustion chamber for spark ignition engines

Leżański T., Sęczyk J., Wolański P.

Combustion Engines

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2013

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R. 52, nr 3

434--441

EN

A few operation examples of combustion system with semi open combustion chamber for spark ignitron engines has been presented in this paper. This system has been designed in Aircraft Engine Department of Heat Engineering Institute of Warsaw University of Technology. The principal problem of operation this system is to assure that jet-stream commences to outflow from prechamber to main combustion chamber when the piston is at TDC and that it will have a sufficient energy quickly to displace all main chamber. This is a task for combustion control system. This can be obtained by correct selection of the system operating parameters: the volume ratio of prechamber to total combustion chamber, the hole diameter in partition, the igniter locations, the ignition advance angle. If this system has operate correctly it was obtained the shortening of combustion time about 2.2 time, growth of maximum cycle pressure 1.9 time and increase of combustion efficiency 1.4 time, in comparison to standard combustion chamber. This research results concern the test conducted using rapid compression machine.

PL

W artykule przedstawiono kilka przykładów pracy systemu z półotwartą komora spalania przeznaczonego dla silników o zapłonie iskrowym. System ten został opracowany w Zakładzie Silników Lotniczych Instytutu Techniki Cieplnej Politechniki Warszawskiej. Podstawowym problemem pracy tego systemu jest zapewnienie, że początek wypływu strumienia z komory wstępnej do zasadniczej nastąpi wówczas, kiedy tłok znajduje się w GMP i że energia strugi będzie wystarczająca, aby szybko przebyć całą komorę zasadniczą. Takie jest zadanie układu sterowania. Może to być osiągnięte przez właściwy dobór parametrów pracy systemu: proporcji objętości komory wstępnej do całej objętości komory spalania, średnicy otworu w przegrodzie, miejsca zapłonu oraz kąta wyprzedzenia zapłonu. Jeśli ten system działał prawidłowo, to uzyskiwano: skrócenie czasu spalania około 2.2 razy, zwiększenie ciśnienia maksymalnego cyklu 1,9 razy i wzrost sprawności spalania 1,4 razy, w porównaniu ze standardową komorą spalania. Wyniki te dotyczą badań, które były prowadzone z zastosowaniem maszyny pojedynczego sprężu.

7

Design of the rapid compression machines for combustion researches in spark ignition engines

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2012

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Vol. 19, No. 4

379-391

EN

The rapid compression machines (RCM) are extensive applied to combustion process researches and mixture process preparation research in the internal combustion engines (ICE). The principal advantage of these arrangements is easy optical access to the inside space of combustion chamber. This enables to observe the course of ignition process and the flame propagation process. There are some RCM designs, which they differ, first of all, the modelling method of piston movement into cylinder. The most known designs use the pneumatic and hydraulic drives. Their concern is that they enable the modelling compression stroke only but combustion is performed in constant volume combustion chamber. It was not relevant for the research of the new combustion system elaborated at Aircraft Engine Department of Warsaw University of Technology (AED). The RCM elaborated at AED has unique form it includes the crank mechanism, speedy operating electromagnetic clutch and flywheel. The applying of this design enables modelling the compression stroke and working stroke (two-stroke from engine cycle). It enables assessment of the system with semi-open combustion chamber what it will be impossible using other RCM designs. The different designs RCM used for combustion research at the research and development centres, on worldwide will be compared with the design of RCM developed at AED. The most known designs of the different RCM were described and the research result examples were given in this paper. The advantages and disadvantages of the different designs were discussed too in this paper.

8

Control strategy combustion of system with semi – open combustion chamber of spark ignition engines

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2012

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Vol. 19, No. 4

367-377

EN

The attempts to increase the engine combustion efficiency of the spark ignition (SI) engines have led to development of the new combustion system with semi-open combustion chamber. This system is similar to flame jet ignition systems, which were applied in many production internal combustion engines. The similar pulsed jet combustion system was elaborated by Professor A. K. Oppenheim. In the system developed at Aircraft Engine Department of Warsaw University of Technology (AED) the standard combustion chamber of SI engine was divided on prechamber and main combustion chamber using partition. The ignition in prechamber is more reliable and repeatable but total burning time in the prechamber and main combustion chamber is shorter than in standard combustion chamber. The principal problem of efficient operation of this system and obtaining of the required performance is securing the relevant control strategy. The performances of this system are dependent from: the rate of this prechamber volume to total combustion chamber volume, the orifice diameter in a partition, the ignition place and the ignition advance angle (ignition timing). Among these parameters the ignition timing only may be varied in the continuous manner during the engine operations without of the engine disassembling. Therefore constant values separate parameters (prechamber volume, orifice diameter, ignition place) should be selected in comprehensive, time consuming researches for different engine operation conditions (engine speed, load and environment conditions) and subsequently the map of ignition advance angles should be determined at state remaining separate parameters. The values of the ignition advance angle should be selected and programmed in electronic control unit, which will be control the ignition advance angle at different engine operating conditions. The dependences between engine operating parameters and the ignition timing are not linear and therefore mechanical control system is not effective. Some research results concerning the best engine operating parameters has been presented in this paper.

9

Efekty zastosowania nowego systemu spalania w produkcyjnym silniku tłokowym o zapłonie iskrowym

Leżański T., Sęczyk J., Wolański P.

Silniki Spalinowe

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2011

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R. 50, nr 3

PL

Wyniki badań przy zastosowaniu maszyny pojedynczego sprężu oraz badawczego silnika wizualizacyjnego, pokazują, że zastosowanie systemu z półotwartą komorą spalania może spowodować: skrócenie czasu spalania w komorze spalania, zwiększenie ciśnienia maksymalnego cyklu oraz zwiększenie sprawności spalania. Celem badań w silniku produkcyjnym było wykazanie, że takie pozytywne efekty można uzyskać również w szerokim zakresie parametrów pracy trakcyjnego silnika spalinowego. Badania prowadzono przy zastosowaniu zmodyfikowanego silnika samochodu Fiat 126p. Określono charakterystyki zewnętrzne i obciążeniowe przy różnych konfiguracjach komory spalania i różnych wartościach kąta wyprzedzenia zapłonu. Uzyskane wyniki pokazują, że dzięki zastosowaniu systemu z półotwartą komorą spalania, o właściwie dobranych parametrach systemu, można uzyskać poprawę osiągów silnika oraz zmniejszenie toksyczności spalin.

EN

The research results of a new combustion system with semi-open combustion chamber for SI engines with use of the rapid compression machine (RCM) and visualisation experimental engine (VEE) shown up that the application of this system could be resulted in shortening of the combustion time, increasing of the maximum cycle pressure and, in effect, higher combustion efficiency. The aim of the research with using a commercial spark ignition engine was to prove that the similar results (as with RCM and VEE) could be obtained at a wide range of automotive engine operating parameters. In this research modified two cylinder, four stroke air cooled SI engine, with volume displacement 650 cm3, from Fiat 126, motorcar was used. This engine was fitted with a modified cylinder heads and ignition distributor. Two types of prechamber with different shape were installed in different locations in the cylinder head but the ignition distributor enabled to keep fixed level, preadjusted, ignition advance angle at the full range of engine speed. The wide open throttle characteristics including: power, specific fuel consumption and exhaust emission versus engine speed and load characteristics including: specific fuel consumption and exhaust emission versus engine torque were determined for different ignition advance angles. The research results show that improvement of the engine characteristics can be obtained in the full range of operating parameters if the ignition advance angle is varied continuously with the variation of engine speed.

10

Research of flame propagation in combustion system with semi-open combustion chamber for gasoline SI engines

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2011

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Vol. 18, No. 2

251-260

EN

Some results of visualization researches of combustion system with divided, semi - open combustion chamber for SI engines, using rapid compression machine (RPM) and experimental visualization engine (EVE) are presented in his paper. Short description of combustion system operation, description of test stands and research equipment can be found in the paper. The tests were performed at stoichiometric ratio natural gas-air and propane-air mixtures. A few the most characteristic of results are shown; to explain how should be operate the combustion system, to yield the better performance. They are compared the research results (photographs of combustion sequence, diagrams of in-cylinder pressure histories) during visualization testing with using RCM and EVE. During RCM testing we obtained the combustion photographs in the plain pass in cylinder axis but during ECE testing at the plain perpendicular to the cylinder axis. All researches shown that the best performance are yielded when a spark advance angle (ignition timing) is such selected that stream outflow prechamber to main combustion chamber starts when the piston is at TDC and it has adequate energy to travel a main combustion chamber with higher velocity than burning velocity in quiescent chamber. Then the shortest time of combustion, the highest peak pressure in the cycle and bigger useful working are yielded. The impact of spark advance angle on flame propagation process into combustion chamber in extreme cases has been analyzed too.

11

Some problems of combustion system operation with semi-open combustion chamber for spark ignition engine

Leżański T., Sęczyk J., Wolański P.

Journal of KONES

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2010

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Vol. 17, No. 4

287-294

EN

The some problems concern of the new combustion system operation with semi open combustion chamber, which can be used in spark ignitions internal combustion engines are presented in this paper. These considerations are based on the visualization research results, with using rapid compression machine (RCM). In this researched combustion system the original combustion chamber was divided by partition in prechamber and main combustion chamber. This division of the original combustion chamber exists only when the piston is close to TDC, for the rest of the cycle the chambers arefully open. Ignition is initiated in the prechamber using electric spark plug, but the mixture in main combustion chamber is ignited by the stream of the burned gases injected from prechamber through the orifice in partition, if the ignition advance angle is correct. If the ignition advance angle is incorrect the mixture from prechamber will be outflowing through the orifice in partition and through the slot which is created between the partition and piston crowns. This last stream is swirled on the partition edge, what causes decrease of the stream speed outflowed from the orifice in partition to main combustion chamber. If the ignition advance angle is too big, then a peak pressure and compression work is very big because the burned gases are compressed instead of the fresh air/fuel mixture. This causes that the effective work is small and combustion efficiency is small.

12

Influence of ignition advance angle on combustion in internal combustion spark ignition engines with semi open combustion chamber

Leżański T., Sęczyk J., Wolański P.

Silniki Spalinowe

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2009

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R. 48, SC2

365--370

EN

In this paper the research results of combustion system of spark ignition engines with semi open combustion chamber has been presented. The major stress in this research has been put on determining of influence of the ignition advance angle on combustion. The research with using the rapid compression machine, the high speed photography system and the measuring system of high speed varied pressure has been carried out. The results include the images of combustion courses and the curves of high speed varied pressure. An angle of ignition advance influences the most evidently on engine performance in point of view combustion system with semi-open combustion chamber. Moreover it is the only parameter which may be permanently controlled during engine operation. Three cases of the ignition advance angle values has been considered in this research: a well suited angle, too small angle and too big angle advance. The best angle of ignition advance is if the beginning of the outflow of the burned gases and the radicals, from prechamber occurs when the piston reaches TDC. As results it will obtained high velosity of a flame front travelling through the main combustion chamber, a high maximum cycle pressure and a high combustion efficiency.

PL

W publikacji przedstawiono wyniki badań nowego systemu spalania z półotwartą komorą spalania, który może być stosowany w silnikach o zapłonie iskrowym. Największy nacisk w tych badaniach położono na wyjaśnienie wpływu kąta wyprzedzenia zapłonu na spalanie. W badaniach wykorzystano: maszynę pojedynczego sprężu, system szybkiej fotografii cieniowej, system pomiarów szybkozmiennych ciśnień. Wyniki obejmują: przebiegi spalania oraz przebiegi szybkozmiennych ciśnień. Badania wykazały, że kąt wyprzedzenia zapłonu ma najistotniejszy wpływ na przebieg spalania w systemie z półotwartą komorą spalania. Ponadto trzeba stwierdzić, że jest to jedyny parametr, który może być w sposób ciągły zmieniany podczas pracy silnika. Rozpatrzono trzy przypadki wartości kąta wyprzedzenia zapłonu: kiedy kat jest dobrze dobrany, kiedy jest zbyt mały i kiedy jest zbyt duży. Najkorzystniejsza wartość kąta wyprzedzenia zapłonu jest taka przy której początek wypływu strumienia palących się gazów i rodników z komory wstępnej do zasadniczej następuje wówczas kiedy tłok znajduje się w położeniu GMP.

13

Investigation of new combustion system with prechamber for spark ignition engines

Leżański T., Wolański P.

Journal of KONES

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2007

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Vol. 14, No. 3

347-354

EN

In the study the high speed Schlieren photographs of combustion process and suitable pressure traces in cylinder, in experimental four cylinder four stroke internal combustion engine with the new combustion system, are presented. The new combustion system for spark ignition is the original system in which combustion chamber is divided into the prechamber and main chamber. The research engine was modified to operate with one cylinder only, but the other three cylinders operated without combustion. The cylinder head of this engine was equipped with specially designed lateral valve timing system. The research cylinder was equipped with quartz windows, mirrors and lenses system to provide optical access into the combustion chamber, in parallel direction to the cylinder axis. The crankshaft of research engine was driven with electric motor by the belt gear, with constant speed of 750 rpm. Research conditions: volume of prechamber - 27% of total volume combustion chamber and orifice diameter in partition - 3mm were established in research using rapid compression machine. The ignition advance angle in range of 0°CAD (TDC) to 30°CAD BTDC was changed. For these conditions the maximum values of pressure in combustion chamber and the best of combustion efficiency were obtained. The research clearly demonstrates that ignition timing play a main role in combustion intensification, because energy of burning mixture spray, which flows out from orifice in partition, depends on the ignition advance angle. In this research the best ignition timing, for test conditions, was determined.

PL

W artykule zaprezentowano fotografie Schlieren procesu spalania oraz wyniki pomiarów ciśnienia w cylindrze w eksperymentalnym czterocylindrowym czterosuwowym silniku z nowym systemem spalania. Nowy system spalania silnika z zapłonem iskrowym jest oryginalnym systemem, w którym komora spalania jest podzielona na komorę wstępną i główną. Silnik badawczy został zmodyfikowany w taki sposób, żeby pracował na jednym cylindrze, a pozostałe trzy cylindry pracowały bez zapłonu. W cylindrze badawczym umieszczono system wzierników i luster pozwalających na przekazywanie obrazu spalania do szybkiej kamery fotograficznej. Silnik badawczy był napędzany silnikiem elektrycznym z prędkością obrotową 750 obr/min. Warunki badań: objętość komory wstępnej 27%, średnica otworu w przegrodzie - 3mm.W badaniach zmieniano kąt wyprzedzenia zapłonu w granicach 0° OWK - 30° owkprzed GMP. Stwierdzono istnienie optymalnej wartości kąta wyprzedzenia zapłonu dla tych warunków badań. W pracy przedstawiono: stanowisko badawcze oraz wybrane przebiegi procesu spalania. Stwierdzono istotny wpływ wstępnej komory spalania na intensyfikację procesu spalania w silniku.

14

Investigation of combustion process in rapid compression machine using high speed schlieren photography

Glinka W., Leżański T., Wolański P.

Journal of KONES

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2007

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Vol. 14, No. 4

91-100

EN

The paper presents results of experimental investigation of combustion process in rapid compression machine. New combustion system for spark ignition engines, in which combustion chamber was divided into the prechamber and main chamber was applied. It is known as Jet Dispersion Combustion (JDC) because intensification of combustion process is achieved by the injection of the burning mixture jet into the main chamber. Experimental set up and testing procedure is briefly described. Schlieren system was used to visualize combustion process. Development of combustion process was recorded with high speed camera. The research was focused on study of the influence of prechamber volume, spark location, ignition timing and orifice diameter on flame propagation and pressure variation inside the main combustion chamber. To avoid soot deposition on glass windows of combustion chamber all tests were conducted for propane/air mixture of stoichiometric composition. The research results show that the application of new combustion system allows obtaining the increase of maximum rate ofpressure rise and maximum pressure as well as maximum combustion efficiency.

PL

W pracy przedstawiono wyniki badań eksperymentalnych procesu spalania w maszynie pojedynczego sprężu. W badaniach zastosowano oryginalny system spalania, opracowany w Zakładzie Silników Lotniczych Politechniki Warszawskiej, w którym dokonano podziału komory spalania na komorę wstępną i główną. System ten, znany jako JDC (Jet Dispersion Combustion), intensyfikuje proces spalania w wyniku wtrysku palącej się strugi mieszaniny z komory wstępnej do komory głównej. W artykule przedstawiono opis stanowiska badawczego i stosowanych procedur badawczych. Do wizualizacji procesu spalania został wykorzystany smugoskop. Przebieg procesu spalania był rejestrowany szybką kamerą. Badania prowadzono przy zastosowaniu mieszaniny propanu z powietrzem o składzie stechiometrycznym, w celu uniknięcia zaczernienia wzierników w komorze badawczej. Celem pracy było zbadanie wpływu objętości komory wstępnej, miejsca zapłonu, wyprzedzenia zapłonu oraz średnicy otworu w przegrodzie na szybkość rozprzestrzeniania się płomienia oraz na przebieg ciśnienia w komorze głównej. Wyniki badań wskazują, że zastosowanie tego systemu spalania pozwala uzyskać zwiększenie maksymalnych wartości szybkości narastania ciśnienia, ciśnienia oraz sprawności spalania.

15

Prechamber combustion system studies using rapid compression machine

Leżański T., Rychter T., Teodorczyk A.

Journal of KONES

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2000

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Vol. 7, No. 1-2

324-329

EN

The results of the preliminary studies of the new, proposed combustion system are introduced. The system is equipped with the semi-open prechamber which allows for the use of all the known advantages of that type of arrangement with no penalty of the loss of efficiency caused by the difficulty to wash out the prechamber of the combustion gases from the previous engine cycle. The general idea is to separate the prechamber from the main chamber only close to the TDC piston position and to leave it open for the rest of the engine cycle. The results of this study performed with the use of the rapid compression machine clearly show that the practical realization of that type of the combustion system is feasible and it is worthwhile to conrinue investigations.

PL

W artykule przedstawiono wyniki wstępnych badań oryginalnego systemu spalania o półotwartej komorze spalania. System ten umożliwia wykorzystanie znanych zalet komory wstępnej (w silnikach ZI) dla intensyfikacji spalania zwłaszcza ubogich mieszanek przy jednoczesnym uniknięciu wad takiej geometrii komory, a zwłaszcza trudności z usuwaniem z niej spalin z poprzedniego cyklu pracy silnika. Przedstawiono wyniki badań wstępnych przy użyciu maszyny pojedynczego sprężu, które przejrzyściwe wykazały, że mozliwa jest praktycznie realizacja takiej koncepcji.

16

Głowice do silnika badawczego umożliwiające wizualizację procesu spalania

Kośmicki T., Bocian P., Leżański T., Rychter T.

Journal of KONES

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1999

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Vol. 6, No. 3-4

147-155

PL

Powszechnie znaną i bardzo często stosowaną metodą wizualizacji procesów spalania w silniku tłokowym jest tzw. metoda smug [1]. Założenia tej metody wymagają, aby wiązka laserowa pozwalająca utrwalić obraz spalania na taśmie filmowej przechodziła przez komorę spalania na przestrzał. Jeśli intencją badacza jest rejestracja procesu w płaszczyźnie prostopadłej do osi cylindra, to szklane wzierniki umożliwiające wizualizację muszą znajdować się w denku tłoka oraz w górnej części głowicy. Skonstruowanie tłoka ze szklanym wziernikiem w denku praktycznie nie nastręcza trudności. Pewne problemy występują natomiast w odpowiednim zamontowaniu wziernika w głowicy. Przeszkodą są zawory układu rozrządu silnika. Jednym ze sposobów rozwiązania tego problemu jest zastosowanie głowicy o tzw. dolnozaworowym układzie rozrządu [1], Rozwiązanie takie przedstawiono na rys. 1. Uzyskana w ten sposób swoboda jeśli chodzi o zamontowanie szklanego wziernika jest okupiona pewnymi wadami całej konstrukcji. Przede wszystkim rozwiązanie takie uniemożliwia objęcie procesem wizualizacji całej komory spalania (przestrzeń nad zaworami pozostaje niewidoczna), co z punktu widzenia badań może być w pewnych warunkach dość poważną niedogodnością. Ponadto dolnozaworowy układ rozrządu utrudnia uzyskanie większych stopni sprężania i na ogół wymusza stosowanie płaskich komór spalania, co z kolei jest niekorzystne przy badaniu różnych kierunków propagacji płomienia. Opisanych wyżej wad nie posiada badawcza głowica kolejnej generacji, która wykorzystuje tzw. boczny układ zaworów. Głowica taka została niedawno zaprojektowana oraz wykonana w ITC PW i z powodzeniem wykorzystano ją w prowadzonych ostatnio eksperymentach.

EN

Schlieren system is widely known and very often used method for visualisation of combustion process. The principles of this method require laser beam (allowing to register process onto film) to go across combustion chamber. For that reason quartz glasses must be installed in piston crown and in upper part of cylinder head. Glass installation in piston crown seems to be rather easy, while glass installation in cylinder head can cause some problems, especially connected with valves mechanism which was described in the paper. One of the ways of dissolving this problem is to apply side valves cylinder head. Construction of such head is presented in the paper. Examples of numerous combustion process visualisations with usage of this head are presented at the Figures. The head can be successfully used to study different combustion systems.

17

Metoda badania kształtu wtryskiwanej strugi paliwa gazowego

Leżański T., Wojciechowski J., Bocian P., Czub B., Rychter T.

Journal of KONES

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1998

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Vol. 5, No. 1

190-195

PL

Zasilanie tłokowego silnika spalinowego poprzez wtrysk gazu do komory spalania wymaga dobrego mieszania paliwa z powietrzem. Aby zapewnić dobre mieszanie gazów dąży się do uzyskania odpowiedniej geometrii i znacznej turbulencji wtryskiwanej strugi. W publikacji przedstawiono metodę badania kształtu wtryskiwanej strugi paliwa gazowego. Dla celów badawczych zbudowano model wtryskiwacza gazowego w skali 10:1. Konstrukcja wtryskiwacza umożliwia dwojaki sposób doprowadzania gazu do jego wnętrza. Gaz może być wprowadzany stycznie lub prostopadle do wewnętrznej, walcowej komory wtryskiwacza. Zasilanie styczne nadaje wypływającej strudze kret co prowadzi do zwiększenia kąta wypływu strumienia. Badania wykonano dla wielu końcówek wtryskiwacza. Wypływ gazu badany był metodą smugową. W celu umożliwienia wizualizacji wtryskiwacz zasilany był dwutlenkiem węgla. Przebieg procesu rejestrowany był na kamerze video, a następnie przetwarzany w komputerze. W publikacji opisano model wtryskiwacza, stanowisko badawcze oraz przedstawiono przykładowe wyniki badań.

EN

The proper gas fuel with air mixing is a crutial element of the combustion proces in an IC engine with direct injection of the gaseous fuel. The method for the determination of the best shape of the gaś fuel jet which can assure proper mixing with air is presented. The injector tip was modelled in the 10:1 scale. The outflow from the injector can be either axial or tangential or in between. The framed photography was used for flow visualisation and the gas jet velocity profiles were determined by hot-wire measurements. The paper is illustrated with the examples of the results.