Cycle-to-cycle combustion variability modelling in spark ignited engines for control purposes

Abstract

A control-oriented model of spark ignition combustion is presented. The model makes use of avaliable signals, such as spark advance, air mass, intake pressure, and lambda, to characterize not only the average combustion evolution but also the cycle-to-cycle variability. The conventional turbulent flame propagation model with two states, namely entrained mass and burnt mass, is improved by look-up tables at some parameters, and the cycle-to-cycle variability is estimated by propagation of an exogenous noise with a normal probabilistic distribution at the turbulent and laminar flame speed, which intends to simulate the unknowns at turbulent flow, temperature distribution, or initial kernel distribution. The model is able to estimate which is the expected variability during the combustion evolution and might be used online for characterizing the time response of closed-loop control actions or it can be used offline to improve the control strategies without large experimental test campaigns. Experimental data from a four-stroke commercial engine was used for calibration and validation purposes, demonstrating the capabilities of the model in steady and transient conditions.

Experimental and modeling analysis on the optimization of combined VVT and EGR strategies in turbocharged direct-injection gasoline engines with VNT

“…These six instantaneous pressure signals were registered with a sampling of 0.2 crank-angle degrees, through the PXI 6123 and PXI 6251 acquisition modules programmed with Labview by National Instruments TM. 21,22 The original engine control unit (ECU), designed for the base engine without EGR, was partially bypassed with an ETAS ES910 system to enable any variations on the VVT system, main throttle position, spark timing, and injected fuel. Finally, the VNT position, EGR valve, and intake throttle (Figure 1) were directly managed in open-loop configuration independently from the ECU, by means of the NI 9759 and PXI 7813R control modules.…”

“…Finally, the VNT position, EGR valve, and intake throttle (Figure 1) were directly managed in open-loop configuration independently from the ECU, by means of the NI 9759 and PXI 7813R control modules. 21,22…”

Comparison of dual and single spark ignition in operation of a large piston aircraft engine

“…The non-repeatability analysis is performed as a statistical analysis that does not take into account the order of the examined processes, as it is done in the case of cycle to cycle variation. The method of computational prediction of cycle-to-cycle variations in sparkignition engines is shown by Netzer et al 21 Similar research related to cycle-to-cycle combustion variability modelling in spark-ignited engines for control purposes was presented by Pla et al 22 The use of two spark plugs in the cylinder can affect not only the presence of knocking but also the nature of the combustion process. Research on this subject was presented by Forte et al 23,24 where the Computation Fluid Dynamics (CFD) method supported by experimental in-cylinder pressure data is applied.…”

Reactive computational fluid dynamics modelling methane–hydrogen admixtures in internal combustion engines part II: Large eddy simulation

“…These cycle-to-cycle variations (CCVs) affect the optimal engine tuning, as the fast burning cycles are more prone to knocking and hence limit the overall compression ratio and spark advance, whereas the slow burning cycles lead to increased emissions of unburned hydrocarbons, as discussed in Heywood. 1 Pushed by the demand for ever more efficient propulsion systems, control-oriented models try to take CCV into considerations for an optimal control of the spark advance, such as presented in Pla et al 3 Extensive research has been devoted to study CCV in the past decades. 4 Sources for the observed CCV have been identified such as local variations in equivalence ratio, dilution.…”