G Index: a novel knock detection method that is simpler and calibration-free
2022-01-0577
03/29/2022
- Event
- Content
- Ever restrictive emissions legislations and fuel efficiency targets have been posing challenges for engine development. Knocking is aloways a limiting factor for spark-ignited engines and has to be tighly controlled during the development phase. There are several methods that address how to detect and measure its occurense. They often require complex calculations with high computational costs that limit them only to laboratorial operation. Moreover, they are often calibrated with subjective factors, for each engine. Thus, this paper offers a novel process that is simpler and does not require previous calibration, called G Index. It is based on the angular position of the peak of maximum pressure rise rate and its relation to the 50% mass fraction burn angular possition. The results showed that there is a locus of knock-free operation with GI between -10 and 0. Higher values lead to a sudden jump towards a locus of knocking operation with GI between 6-10, where the thermodynamic state is prone to autoignition. This method, therefore, an effective knock indicator, regardless of its intensity, that does not need prior calibration and is of simpler usage than current methods.
- Citation
- Martins, M., "G Index: a novel knock detection method that is simpler and calibration-free," SAE Technical Paper 2022-01-0577, 2022, .