A rapid compression/expansion machine (RCEM) based on a single-cylinder engine was developed to understand the fundamental phenomenon of knock during spark-ignition (SI) combustion. In order to cause auto-ignition in the end-gas mixture during the flame-propagation process, and also to visualize the processes, the original head of the engine was replaced with a specially designed combustion chamber. The effects of spark timing, compression ratio and equivalence ratio on knock intensity were systematically investigated using the RCEM with n-butane fuel. In addition, the possibility of knock control by the injection of hydrogen into the end-gas region is also discussed. The experimental results indicate that a higher compression ratio, spark-ignition timing at -10 °ATDC and a stoichiometric equivalence ratio cause heavy knock. However, the knock intensity is drastically decreased with hydrogen injection. It was found that the direct injection of hydrogen into the end-gas region enables the reduction of knock intensity more effectively than the premixing of hydrogen with the hydrocarbon fuel. A higher degree of knock intensity reduction is achieved when the hydrogen injection timing is adjusted close to the spark timing. Also, the knock intensity may be reduced to a degree related to the amount of hydrogen quantity injected when the spark timing is near top dead center (TDC). However, the knock intensity may be increased with earlier spark-timing, in which case an excessive flame-propagation speed is observed in the unburned mixture including hydrogen.
Knock Characteristics and Their Control with Hydrogen Injection Using a Rapid Compression/Expansion Machine
Sae Technical Papers
JSAE/SAE International Fuels & Lubricants Meeting ; 2007
2007-07-23
Aufsatz (Konferenz)
Englisch
Photographic Observation of Knock with a Rapid Compression and Expansion Machine
SAE Technical Papers | 1984
|Photographic observation of knock with a rapid compression and expansion machine
Kraftfahrwesen | 1984
|Modeling end-gas knock in a rapid-compression machine
AIAA | 1985
|Modeling end-gas knock in a rapid-compression machine
AIAA | 1984
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