A Proposed Relation for Knock Auto-Ignition Induction Period Evaluation in a LPG Fueled SI Engine

In the present study, a relation for the evaluation of knock auto-ignition induction period was studied in the case of a spark ignition engine for heavy-duty transportation fueled with commercial LPG.

Because the existing formulas for knock auto-ignition induction time were determined for quasi-steady mixture conditions and in general for pure hydrocarbons, it was considered interesting the establishing of a such a relation using pressure data recorded from a internal combustion engine; in this case being took in account the influence of combustion cyclic variability and also of using a mixture of hydrocarbons.

The results obtained after knock was characterized in terms of intensity and onset crank angle and a two zone combustion model was developed and applied for obtaining the unburned zone temperature, were conducted in the way of determining and verifying possible relations for knock auto-ignition induction time.