Wyniki wyszukiwania - BazTech

1

Study of the influences of blending different proportions of propane into methane on combustion characteristics at the knock threshold by using RCM

Shokrollahi F., Wyszynski M., Sundell J.-P.

Journal of KONES

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2018

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Vol. 25, No. 1

339--346

EN

A spark-ignited Rapid Compression Machine (RCM) has been used to investigate the influences of the different proportions of methane-propane mixtures on the combustion characteristics at knock threshold operating condition. First, the threshold operating points of the mixtures have been obtained and the results indicated that the piston driving pressure reduces from 142 bars to 90 bars as the propane content in the mixture increases. As a spark plug was fitted in this RCM, the optimum spark timing was also investigated. It was established that spark timing should be set synchronize with the piston at TDC, due to the free movement of the piston. In most RCMs, piston can move toward TDC following the equilibria of forces due to the absence of con-rod. Finally, knock intensity of the different mixtures has been studied. Pre-heating system in RCM with and without trace heating system; effects of flow-rate and lambda variations on peak pressure, ignition delay time and ARR; threshold operating conditions of pure methane, 90% methane and 10% propane, 80% methane and 20% propane, 70% methane and 30% propane; effect of driving pressure on the knocking intensity for mixture of methane and propane for heavy and light knockings are presented in the article.

2

Description of knock onset in SI turbocharged gas engine

Klir V., Takats M.

Silniki Spalinowe

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2010

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R. 49, nr 2

40-46

EN

Knock is an abnormal combustion process occurring in SI engines. To describe engine knock reliably is still challenge. Based on measured in cylinder pressure, the techniques of knock onset determination are introduced. The findings about knock intensity are discussed. Simulation of knock phenomena is mentioned. The results from model and experiment are compared.

PL

Spalanie stukowe jest anormalnym procesem spalania w silniku o zapłonie iskrowym. Ciągle brakuje wiarygodnego opisu zjawiska stuku. Przedstawiono sposób określania początku stuku na podstawie pomiaru ciśnienia w cylindrze. Omówiono spostrzeżenia dotyczące intensywności stuku. Wspomniano o modelowaniu zjawiska stuku. Porównano wyniki modelowania z wynikami eksperymentalnymi.

3

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.