The Influence of Simulated Residual and NO Concentrations on Knock Onset for PRFs and Gasolines

Influence of autoignition delay time characteristics of different fuels on pressure waves and knock in reciprocating engines

“…This implies the observed marginal knocking combustion was only spasmodic, a result of occasional excursions into a knocking cycle. This phenomenon also was observed in the trace knock experiments of Burluka et al [42], in which only faster burning cycles experienced significant knocking, while the mean cycle might not knock at all.…”

Multi-zone thermodynamic modelling of spark-ignition engine combustion – An overview

“…Such models have therefore been adapted for prediction of autoignition (and so knock) onset by using computed end gas pressure/temperature history to drive autoignition models ranging from simple empirical single step chemistry routines [43] through the well known "Shell" scheme [44] to quite complex chemical reaction schemes [45]; sometimes incorporating feedback of heat release associated with the early stages of autoignition development back into calculation of the in-cylinder pressure and unburned gas temperature. It has been suggested that correct prediction of the normal flame propagation is, via its control of the thermodynamic state of the end gas, the determinant of the accuracy of autoignition onset assessment -such that perhaps only use of the simplest autoignition schemes is currently justified [46], particularly given uncertainties in the detailed chemical mechanisms and associated reaction rate constants for real hydrocarbon fuel mixtures. However, detailed consideration of autoignition modelling is again outside the remit of the current work.…”

Engine autoignition: The relationship between octane numbers and autoignition delay times

“…Different burning velocities create different temporal profiles of pressure and temperature and this affects autoignition. For the same engine operating conditions, it is possible for a fuel to burn faster than a PRF that has an ON equal to the RON of the fuel, reach a higher maximum pressure, and still not autoignite, even when the PRF does [7]. The operational regimes for controlled autoignition engines depart from those in the RON and MON tests even more than do the regimes for spark ignition engines.…”