Knock in a Spark Ignition Engine Fuelled with Gasoline-Kerosene Blends

Gasoline blended with kerosene, which is considered to be ‘adulterated’ fuel in South Asian countries, has been shown to increase knocking tendency in spark-ignition engines. The current study involves the use of known gasoline-kerosene blends to fuel a single cylinder Ricardo E6 engine and characterize the knocking of such blends. This paper presents results and discusses the variation of knock limited spark timing with change in kerosene proportion in the blend and with air-fuel ratio. Knock characterization is quantitatively evaluated by applying Fast Fourier Transform (FFT) and bandpass filtering techniques to the cylinder pressure data. Knock intensity of the gasoline-kerosene blends with varying proportion of kerosene is compared. An increasing amount of kerosene in the blends has been shown to increase both the knocking tendency as well as the intensity of knock.

Comparison is also made between the data processing techniques based on data recorded at approximately 10 samples per crank angle and data recorded at 1 sample per crank angle. Results indicate that the lower sampling rate is also satisfactory for identifying knock. It has also been shown that the cylinder pressure traces have similar characteristic frequencies irrespective of knock intensity.