Wyniki wyszukiwania - BazTech

1

Investigation of knock suppression characteristics in a boosted methane : gasoline blended fuelled SI engine

Yang Z., Miganakallu N., Rao S., Harsulkar J., Naber J., Lonari Y., Szwaja S.

Journal of KONES

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2018

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Vol. 25, No. 3

517--525

EN

Natural gas has a higher knock suppression effect than gasoline which makes it possible to operate at higher compression ratio and higher loads resulting in increased thermal efficiency in a spark ignition engine However, using port fuel injected natural gas instead of gasoline reduces the volumetric efficiency from the standpoints of the charge displacement of the gaseous fuel and the charge cooling that occurs from liquid fuels. This article investigates the combustion and engine performance characteristics by utilizing experimental and simulation methods varying the natural gas-gasoline blending ratio at constant engine speed, load, and knock level. The experimental tests were conducted on a single cylinder prototype spark ignited engine equipped with two fuel systems: (i) a Direct Injection system for gasoline and (ii) a Port Fuel Injection (PFI) system for compressed natural gas. For the fuels, gasoline with 10% ethanol by volume (commercially known as E10) with a research octane number of 91.7 is used for gasoline via the DI system, while methane is injected through PFI system. The knock suppression tests were conducted at 1500 rpm, 12 bar net indicated mean effective pressure wherein the engine was boosted using compressed air. At 60% of blending methane with E10 gasoline, the results show high knock suppression. The net indicated specific fuel consumption is 7% lower, but the volumetric efficiency is 7% lower compared to E10 gasoline only condition. A knock prediction model was calibrated in the 1-D simulation software GT-Power by Gamma Technologies. The calibration was conducted by correlating the simulated engine knock onset with the experimental results. The simulation results show its capability to predict knock onset at various fuel blending ratios.

2

Combustion characteristics of various fuels during research octane number testing on an instrumented CFR F1/F2 engine

Kolodziej C. P., Wallner T.

Combustion Engines

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2017

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R. 56, nr 4

164--169

EN

The Cooperative Fuels Research (CFR) engine is the long-established standard for characterization of fuel knock resistance in spark-ignition internal combustion engines. Despite its measurements of RON and MON being widely used, there is little understanding of what governs the CFR octane rating for fuels of various chemical compositions compared to primary reference fuels (iso-octane and n-heptane). Detailed combustion characteristics were measured on a highly instrumented CFR F1/F2 engine during RON testing of fuels with significantly different chemical composition. The results revealed differences in the cylinder pressure and temperature conditions, as well as knocking characteristics.

3

Engine knock detection and evaluation: a review

Lasocki J.

Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska

|

2016

|

z. 5/109

41--50

EN

The paper aims at providing a concise revision of current knowledge of engine knock phenomenon based on previously published works. Theories behind the origin of knock are discussed. Differences between knocking combustion in spark-ignition and hard work of compression-ignition engines are explained. An overview of direct and indirect methods of knock occurrence detection is given. The most commonly used indices for the evaluation of knock intensity are presented.

PL

Artykuł ma na celu zwięzłe podsumowanie obecnego stanu wiedzy w zakresie zjawiska spalania stukowego na podstawie dotychczas opublikowanych prac. Omówiono teorie dotyczące powstawania spalania stukowego. Nakreślono różnice między spalaniem stukowym w silnikach o zapłonie iskrowym i twardą pracą silników o zapłonie samoczynnym. Scharakteryzowano bezpośrednie i pośrednie metody wykrywania spalania stukowego, a także przedstawiono najczęściej stosowane wskaźniki do oceny intensywności spalania stukowego.

4

Możliwości wykorzystania zjawiska stuku i zadymienia spalin do regulacji parametrów wtrysku układu common-rail

Różycki A.

Combustion Engines

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2015

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R. 54, nr 3

1046--1052

PL

W artykule opisano zjawiska związane z procesem spalania, które ograniczają osiągi i emisji silnika o ZS. Do głównych zaliczono zjawisko stuku i niecałkowitego spalania. Omówiono sposób optymalizacji parametrów wtrysku, który polegał na doborze kątów początku wtrysku dawki pilotującej i dawki głównej ON Dobór parametrów wtrysku uwzględniał wyżej wymienione zjawiska. Wyniki zostały przedstawione na bazie charakterystyk obciążeniowych jednostkowego zużycia paliwa, stężeń tlenków azotu i zadymienia spalin (współczynnika pochłaniania światła) oraz na charakterystykach prędkościowych momentu obrotowego i kąta wtrysku ON.

EN

The paper describes phenomena related to the combustion process that limit the performances and emission of a diesel engine. Knocking and incomplete combustion were taken into consideration as the most important parameters. The paper describes the way of injection parameters optimization consisting in a proper selection of the injection timing of the pilot and the main diesel oil doses. The results were presented on the basis of load characteristics of specific fuel consumption, nitrogen oxide emissions and smoke level (light absorption coefficient) as well as speed-torque and speed-injection timing curves.

5

Wpływ zasilania dwupaliwowego na wybrane parametry pracy i emisję turbodoładowanego silnika o ZS

Różycki A.

Combustion Engines

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2013

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R. 52, nr 3

1121--1128

PL

W artykule przedstawiono wyniki badań, które miały na celu określenie wpływu maksymalnego udziału paliwa CNG w całkowitym paliwie dostarczanym do cylindra silnika na zjawiska zachodzące w procesie spalania oraz na poziom emitowanych składników szkodliwych spalin. Analizie zostały poddane zarejestrowane przebiegi ciśnień i drgania głowicy. Stwierdzono, że przy nadmiernym wzroście udziału energetycznego CNG w pierwszej kolejności dochodzi do nadmiernego wzrostu ciśnień maksymalnych i szybkości narastania ciśnienia. Dalszy wzrost udziału energetycznego CNG prowadzi do pojawienia się silnych drgań głowicy. Pomiary ciśnienia wykonywane były w pierwszym cylindrze. Analiza drgań głowicy obejmowała wszystkie cylindry silnika. Analiza emisji składników szkodliwych wykazała, że znacznemu zwiększeniu ulega emisja nie-spalonych węglowodorów HC. Stężenia pozostałych głównych składników spalin osiągają wartości na poziomie emitowanym przez silnik zasilany standardowo.

EN

The paper presents results of investigation aimed to determine an effect of the maximum CNG share in the total fuel charge delivered into the cylinder of a turbocharged compression ignition engine operating in a dual fuel mode on phenomena that occur during the combustion process and on the harmful exhaust emission. Pressure courses and engine head vibrations were analysed. It was stated that in the case of an excessive CNG energy share increase, the maximum pressures and the rate of pressure rise increase at first. Further increase of the CNG energy share leads to heavy engine head vibrations. Pressure measurements were done in the first cylinder. The analysis of engine head vibrations comprised all engine cylinders. Analysis of the harmful exhaust emission showed a significant increase of unburnt hydrocarbon emission. Emissions of other principal pollutants reached values comparable with those obtained at standard fuelling.

6

Hydrogen combustion in the supercharged SI engine

Grab-Rogaliński K., Szwaja S.

Journal of KONES

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2012

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Vol. 19, No. 3

149-155

EN

The experimental results of combustion pressure processing from a supercharged spark ignition (SI) engine that was running on hydrogen are exposed in the paper. Hydrogen was delivered in two ways by an injector and mixer installed in an intake port. In-cylinder pressure while combusting hydrogen was analyzed with various coefficient of stechiometry and boost pressure. These parameters were limited by abnormal combustion known as "knock" combustion. Hydrogen fueled engine has tendency to generate "knock", especially this abnormal combustion phenomena increases with increase in boosting pressure. Hence, the thermodynamic parameters such as pressure and temperature of fresh air fuel mixture are elevated. The experimental numeric data analysis permit for compare to naturally aspirated engine such parameters as mean indicated pressure, indicated efficiency. Also for both cases, the coefficient of variation for mean indicated pressure was determined. It was found that combustion duration shortens itself with higher boosting pressure. Thus, optimal spark timing to get the maximum indicated mean effective pressure is shifted closer to the TDC. Another parameter that was expected to be increased was the knock intensity. It was observed, that knock intensity did not increase significantly and was still below the limit for pressure pulsations treated as combustion noise coming from light combustion instabilities.

7

Optymalizacja kąta wtrysku dawki oleju napędowego w dwupaliwowym silniku o zapłonie samoczynnym zasilanym alkoholem etylowym

Różycki A.

Czasopismo Techniczne. Mechanika

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2012

|

R. 109, z. 5-M

267--279

PL

W artykule przedstawiono wyniki badań związanych z optymalizacją kąta wtrysku dawki oleju napędowego inicjującej zapłon w dwupaliwowym silniku o zapłonie samoczynnym zasilanym alkoholem etylowym. Badania przeprowadzono na jednocylindrowym badawczym silniku zapłonie samoczynnym 1HC102 wyposażonym w układ zasilania CR i układ wtrysku alkoholu etylowego. Optymalizację kąta wtrysku oleju napędowego oparto o kryteria: stuku, przedwczesnego zapłonu, wygaszania płomienia i wypadania zapłonów.

EN

The paper presents results of investigation related to the optimization of diesel pilot injection parameters in a dual-fuel compression ignition engine fuelled with ethanol. The test engine was a single-cylinder 1HC102 compression ignition engine equipped with an injection system of the commn-rail type and an injection system for ethanol. Optimization of diesel pilot injection parameters was carried out basing on the following criteria: knock onset, premature combustion, flame extinguishing and engine misfire in successive operation cycles.

8

Identyfikacja spalania stukowego w silniku Wankla zasilanym paliwem wodorowym

Biały M., Wendker M., Gęca M.

Autobusy : technika, eksploatacja, systemy transportowe

|

2012

|

R. 13, nr 4

62-67

PL

W artykule przedstawiono metody wykrywania spalania stukowego w silniku o rotacyjnym ruchu tłoka. Badania przeprowadzono na silniku Wankla Aixro XR 50, który wyposażono w elektroniczny system wtrysku wodoru, benzyny i oleju smarującego. W oparciu o przebieg wartości ciśnienia w przestrzeni roboczej oraz przebieg drań korpusu silnika identyfikowano występowanie niekorzystnego zjawiska, jakim jest spalanie stukowe.

EN

The paper describes the methods to detect a knocking in rotary engine. The study was conducted on the engine, the Wankel Aixro XR 50, which is equipped with an electronic injection system, hydrogen, gasoline and lubricating oil. Based on the course of the indicated pressure in the working space and the course of the vibration motor housing bastard identified the presence of a dangerous phenomenon which is the knock.

9

Twarda praca i stuk w turbodoładowanym dwupaliwowym silniku o zapłonie samoczynnym

Różycki A.

Silniki Spalinowe

|

2011

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R. 50, nr 3

EN

The paper presents the results of the tests aimed at determining the effects of an excessive participation of CNG in the energy charge supplied to the cylinders in the occurrence of combustion noise. Pressure processes and head vibrations were submitted to analysis. It was found that with the excessive growth of the CNG share, an excessive increase in maximum pressure and rate of pressure rising appeared in the first sequence. Further increase in the participation of CNG energy leaded to the appearance of strong head vibration. Pressure measurements were performed in the first cylinder. The analysis of the head vibration embraced/involved all the cylinders of the engine. Significant differences in the level of head vibration deriving from the combustion process in each cylinder were observed. It demonstrates uneven composition of the air-CNG mixture in each cylinder.

PL

W artykule przedstawiono wyniki badań, które miały na celu określenie wpływu udziału energetycznego CNG w ładunku dostarczanym do cylindra na wystąpienie niekorzystnych zjawisk zachodzących w procesie spalania. Analizie zostały poddane zarejestrowane przebiegi ciśnień i drgania głowicy. Stwierdzono, że przy nadmiernym wzroście udziału energetycznego CNG w pierwszej kolejności dochodzi do nadmiernego wzrostu ciśnień maksymalnych i szybkości narastania ciśnienia. Dalszy wzrost udziału energetycznego CNG prowadzi do pojawienia się silnych drgań głowicy. Pomiary ciśnienia wykonywane były w pierwszym cylindrze. Analiza drgań głowicy obejmowała wszystkie cylindry silnika. Zaobserwowano duże różnice w poziomie drgań głowicy pochodzące od procesu spalania w poszczególnych cylindrach. Świadczy to o nierównomiernym składzie mieszaniny powietrze-CNG w poszczególnych cylindrach.

10

Possibility to reduce knock combustion by EGR in the SI test engine

Tutak W.

Journal of KONES

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2011

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Vol. 18, No. 3

485-492

EN

The paper presents the results of modelling thermal cycle of internal combustion engine including exhaust gas recirculation. The test engine can not achieve the optimum parameters of work due to occurrence of the knock combustion. The influence of EGR on the limits of the knock occurrence in the engine was studied. It turned out that few percent of exhaust gases in the fresh charge effectively shifts the knock limit to higher ignition advance angles. The values of the limit ignition timing for the test engine was determined in order to avoid combustion knock. Larger share of EGR caused too much slowing the spread of the flame inside the combustion chamber of the test engine. EGR at constant angle of ignition was very effective in limiting the content of NO in the exhaust, but on the other hand it has an adverse effect on the engine parameters. The engine operate with exhaust gas recirculation in order to obtain the possible best parameters the ignition timing should be optimized. However, that with increasing values of the thermodynamic parameters of thermal cycle of engine increased NO content in the exhaust. The paper presents results of modelling thermal cycle of IC engine, including exhaust gas recirculation and knock combustion. The object of researches was the S320ER spark ignition internal combustion engine supplied with petrol. The engine was operated at a constant speed of1000 rpm. Modelling of the thermal cycle of the test SI engine in the FIRE software was carried out.

11

Producer gas combustion in the internal combustion engine

Cupial K., Szwaja S.

Silniki Spalinowe

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2010

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R. 49, nr 2

27-32

EN

The investigation presented in the paper concerns producer gas combustion in both the spark ignited (SI) and the dual-fuel compression ignition (CI) engine with a diesel pilot of 15% with respect to its nominal dose, at compression ratio (CR) of 8, 12 (for the SI engine) and 17 (for the CI engine). The research tasks were mainly focused on combustion instabilities such as engine work cycles unrepeatability and combustion knock onset. The investigation included also combustion of such gases as methane, biogas and hydrogen, which were taken for making comparison between them and the producer gas. The conducted analysis shows that producer gas is resistant to generate knock even if it contains significant hydrogen content of 16%. However, high work cycles unrepeatability is observed when producer gas is combusted in the SI engine. Obtained results led to conclusion that producer gas can be burnt more efficiently in the dual-fuel CI engine than the SI one. Neither misfiring nor knocking have occurred during its combustion in that engine.

PL

W artykule opisano wyniki badań spalania gazu generatorowego w silniku z zapłonem iskrowym i w silniku dwupaliwowym z pilotową dawką oleju napędowego. Głównie skoncentrowano się na wyznaczeniu stabilności spalania tego gazu za pomocą współczynnika niepowtarzalności kolejnych cykli jego pracy oraz możliwości wystąpienia spalania stukowego. W celu porównania uzyskane wyniki przedstawiono łącznie z odpowiednimi wynikami dla spalania wodoru, metanu i biogazu. Z przeprowadzonej analizy wynika, że gaz generatorowy w porównaniu do pozostałych gazów jest odporny na generowanie spalania stukowego pomimo znaczącej zawartości wodoru (do 16%), jednakże silnik iskrowy zasilany tym gazem wykazuje względnie dużą niestabilność kolejnych cykli spalania. Znacznie lepszą powtarzalność kolejnych cykli spalania zaobserwowano podczas spalania gazu generatorowego w dwupaliwowym silniku wysokoprężnym z zapłonem inicjowanym pilotową dawką oleju napędowego.

12

Irregular ignition events in TC GDI engines: phenomenology, analysis and engine development

Hirsch A., Kapus P., Philipp H., Winklhofer E.

Silniki Spalinowe

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2010

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R. 49, nr 4

23-30

EN

Gasoline engine development has to respond to requirements for fuel efficient and clean combustion. In meeting such targets, the automotive industry has responded with the introduction and continuous improvement of turbocharged gasoline direct injection (TC GDI) combustion systems. Specific challenges to such engines include irregular ignition and combustion events which are rarely met in conventional engines. The paper describes ignition phenomena and mechanisms relevant for the development of such TC GDI engines. Focus then is given to combustion measurement techniques applied for the identification of these spontaneous and riskfull combustion events. As analysis of such ignition events must be done in real, high load multicylinder engine operation, suitable sensors together with measurement and analysis procedures are described. The paper concludes with analysis examples derived from various engine testing situations.

PL

Rozwój silników benzynowych musi podążać za zmieniającymi się wymaganiami dotyczącymi efektywności i czystości spalania. Aby sprostać tym wymaganiom przemysł samochodowy wprowadza ciągłe zmiany i ulepszenia procesów spalania w silnikach benzynowych z wtryskiem bezpośrednim i z turbodoładowaniem. Szczególnym wyzwaniem w konstruowaniu tych silników są zjawiska nieregularnego zapłonu i spalania stukowego rzadko występujące w silnikach konwencjonalnych. Ten artykuł opisuje zjawiska towarzyszące zapłonowi oraz inne mechanizmy istotne z punktu widzenia rozwoju tych silników. Dużo uwagi poświecono technikom pomiaru spalania stosowanym do opisu przypadków niebezpiecznych ze względu na ryzyko niekontrolowanego spalania stukowego. Analiza takich przypadków nieprawidłowego zapłonu musi być dokonana podczas rzeczywistej pracy wielocylindrowego silnika przy dużych obciążeniach. W artykule opisano odpowiednie do tego celu czujniki wraz z metodami pomiaru i analizy danych. W części końcowej artykułu przedstawiono analizę przykładów zaczerpniętych z różnych badań silnikowych.

13

Visualization of auto-ignition of end gas region without knock in a spark-ignition natural gas engine

Tomita E., Kawahara N., Zheng J.

Journal of KONES

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2010

|

Vol. 17, No. 4

521-527

EN

It is important to increase thermal efficiency in a spark-ignition engine for reducing carbon dioxide gas in exhaust emissions. One of the solutions is to increase the compression ratio of the engine. Then, knock is a barrier in increasing in compression ratio because of higher pressure and unburned gas temperature in the end gas region. Therefore, there have been many studies on knock. However, there was an interesting phenomenon under some conditions in a gas engine. There is no pressure oscillation in the end stage of combustion and rate of heat release increased. It is considered that the auto-ignition in the end gas region occurs without knock. In this study, the combustion behavior in the end gas region was visualized with an ultra-high-speed camera. In normal combustion case, the flame propagates in the end gas region. In the knock case, the auto-ignited part burns suddenly and leads pressure oscillation. Under the critical conditions, some shows knock and some shows normal flame propagation. However, in some cases, even if auto-ignition occurs, pressure wave is not produced. Then there is no pressure oscillation, that is, mild auto-ignition without knock can be confirmed. And the rate of heat release shows two peaks. The first peak is due to flame propagation and the second peak is due to auto-ignition in the end gas region. The combustion near the end stage become short and thermal efficiency is expected to be increased because of increase in degree of constant-volume.

14

Analysis of performances of a dual-fuel turbocharged compression ignition engine

Różycki A.

Journal of KONES

|

2010

|

Vol. 17, No. 3

393-399

EN

The paper describes research work on a full-scale dual-fuel 4-cylinder turbocharged compression ignition engine. Compressed natural gas (CNG) was applied as the main fuel. Selfignition of the air-fuel mixture was initiated from a diesel oil dose injected by a common rail system. The research was aimed to establish maximum CNG share in the mixture delivered into the cylinder. An excessive CNG share may result in "hard" engine operation. It may also lead to the occurrence of vibrations of piston-crank construction parts resulting in failure of this mechanism. These vibrations may originate from knocking combustion (selfignition of the air-fuel mixture in the zone of non-combusted mixture) or vibration excitation as a result of rapid pressure rise after selfignition. Boundary values of the CNG energy share were determined by analysing parameters related to the rate of pressure rise and rate of heat release as well as the engine head vibration amplitude represented by the voltage signal generated by the knock sensor. Boundary values of the above mentioned parameters were determined on the basis of measurements done on the engine fuelled in a standard mode. These parameters were registered at operating points corresponding to the maximum power and load. Then, there were done measurements of basic engine operating parameters at dual fuelling in chosen points of the load characteristic for the engine speed at which the engine fuelled in a standard mode had maximum torque. Load characteristics were done for three various diesel oil doses (constant over the whole range of engine load). Load changes were realized by changes ofCNG energy share in the fuel charge. Analysis of combustion process parameters and engine head vibrations showed that CNG energy share may reach 60%. Maximum torque is possible to obtain at 45% CNG energy share. 15% decrease of maximum torque was obtained.

15

Knocking detection using autocorrelation of the wide-band optical radiation intensity

Piernikarski D.

Silniki Spalinowe

|

2009

|

R. 48, nr 1

41-51

EN

The paper presents an evaluation of usability of the autocorrelation function which was calculated from the optical radiation signal and used for the detection of knocking combustion in a spark-ignition engine. The main source of experimental data was the resultant wide-band intensity of optical radiation which was acquired using optical combustion sensor having direct access to the combustion chamber. The gathered light was transmitted by a waveguide bundle to the set of photodetectors and after conversion - recorded using analog-digital card. The scope of the analysis which is described in this paper includes an estimation of the autocorrelation function and its evaluation for the purpose of knockingdetection. Results have shown that occurrence of knocking combustion is accompanied by a high increase of energy transmitted by the optical signal expressed by its root mean square (rms). Moreover, knocking combustion results in a slower drop of autocorrelation function and appearance of some periodic components.

PL

W artykule przedstawiono ocenę możliwości wykorzystania funkcji autokorelacji obliczonej dla sygnału promieniowania optycznego do detekcji spalania stukowego w silnikach o ZI. Głównym źródłem danych eksperymentalnych była wypadkowa, szerokopasmowa emisja optyczna zmierzona za pomocą czujnika z bezpośrednim dostępem optycznym do komory spalania silnika. Sygnał optyczny był transmitowany pękiem światłowodów do zestawu fotodetektorów i rejestrowany po konwersji analogowo-cyfrowej. Analiza opisana w artykule obejmuje estymację funkcji autokorelacji i jej ocenę pod kątem detekcji spalania stukowego. Analiza wyników pozwala na stwierdzenie, że wystąpieniu spalania stukowego towarzyszy znaczący wzrost energii transmitowanej przez sygnał optyczny, wyrażonej przez jej wartość średniokwadratową (rms). Ponadto spalanie stukowe powoduje wolniejszy zanik funkcji autokorelacji i wystąpienie składowych okresowych.

16

Natural gas engines - problems and challenges

Kowalewicz A., Wojtyniak M.

Journal of KONES

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2007

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Vol. 14, No. 2

273-282

EN

At former KONES one of the co-authors presented a paper, is which general information about natural gas properties, reserves, production and distribution were given and application to SI and CI engines was presented, compared and discussed. It was shown, that more promising is dual-fuel CI engine. There is a lot of information on combustion, emissions and performances of dual-fuel natural gas engines, but there are also blank areas and controversial opinions, which were pointed out and discussed in this paper. For example: why combustion processes are delayed in comparison with combustion of diesel fuel only. It is also not clear whether noise of dual-fuel engine is higher than that of diesel engine or lower (there are contradictory data). These problems are shown and discussed in this paper. The proposal of further research is presented. Ignition and combustion in dual-fuel natural gas engines is yet not fully recognized, especially: combustion duration, mechanism at gaseous and condensed phase burning, kinetics and diffusion controlled combustion, noise, knock and cycle-by-cycle variation. Optimization of control parameters on account of efficiency and emissions is still an open problem. Influence of natural gas composition and its changes on engine performance and emissions still demand estimation.

17

Evaluation of knock intensity using wide-band optical signal from the combustion chamber

Piernikarski D.

Journal of KONES

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2006

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Vol. 13, No. 2

371-379

EN

The paper evaluates the possibility of detection and evaluation of knock intensity using wide-band optical signal obtained from the combustion chamber of the gasoline engine. Preliminary data analysis confirmed existence of strong, statistically significant correlations between signals of indicated pressure and intensity of optical emission, and it is expected that optical signal can be successfully used for detection of knocking combustion. As knocking combustion is associated with certain frequencies of successive modes of acoustic vibrations in the combustion chamber, detection of knock and evaluation of its intensity required filtration of optical signal eliminating constant components and high-frequency noise. Knock intensity was characterized by “peak intensity of optical radiation” – defined as positive value of first derivative obtained for the filtered signal. This parameter gives useful quantitative information regarding the intensity of knocking combustion. Data analysis has shown, that occurrence of knock resulted in rapid changes in peak-to-peak amplitudes of the filtered optical signal. Further evaluation of signal properties allows for more precise description of knocking phenomena and of its intensity.