Combustion in High-Speed Direct Injection Diesel Engines—A Comprehensive Study

Abstract

This paper reports the latest results of a comprehensive project investigating the performance of a Ricardo Hydra direct injection diesel engine. Early work covered a number of aspects of research into the gross behaviour of this engine: this paper concentrates on techniques for obtaining quantitative data from photographs of the combustion process. Iligh-speed photographs, at framing rates up to 20000 framesls, were taken using a piston with a quartz bowl, at engine speeds up to 3000 rjmin. The pre-combustion period was illuminated using a synchronized copper vapour laser. After the initiation of combustion, the process is self-illuminating and information on the combustion process was obtained by analysing the radiation emitted by the carbon particles. The two-colour method was used to evaluate the temperature ofthe combustion gases over the full$eld of view. The images have also been analysed by a cross-correlation technique to obtain velocity information. Tests have been performed on the engine over a wide range of operating conditions, but this paper concentrates on the effect of swirl ratio on combustion. It will be shown that too much swirl increases the ignition delay period and results in an increase in the NO, emissions but a decrease in the soot. I t will also be shown that the velocity pattern after combustion is in good agreement with that evaluated by Arcoumanis et al. at the end of compression, which implies that swirl persists through the combustion period despite significant decay. NOTATION

Effects of intake-port throttling on combustion behaviour in diesel low-temperature combustion

“…Although Miles 2 reported a reduction in the premixed burn fraction and peak heat release with increasing swirl – attributed to reduced ignition delay compensating for the supposed swirl-induced increase in initial fuel/air mixing during the ignition delay period – the majority of the literature suggests that increasing swirl leads to increased premixed burn fractions and peak heat release rates as a result of enhanced premixing efficacy. 23 Of particular relevance within the literature is an optical and numerical study on high-dilution LTC diesel combustion, that is, a similar operating strategy to Condition II of the present work, by Kook et al, 5 who report similar combustion trends as observed in the present work. Specifically that for fixed injection timing, increasing swirl levels lead to reduced ignition delay, advanced combustion phasing for the early (premixed) phase of heat release, and an increase in peak heat release values.…”

Experimental and numerical analysis of high pressure diesel spray–wall interaction

“…Consequently, data are very poor, challenging and expensive to obtain and most of the experiments reported in literature are carried out in simplified laboratory configurations (Katsura et al, 1989;Saito et al, 1993;Fujimoto et al, 1990;Arcoumanis and Chang, 1994;De Vita et al, 2002;Di Stasio et al, 2000;Allocca et al, 1993Allocca et al, , 2002Amagai and Arai, 2004;Winterbone, 1994).…”

Application of a high-repetition-rate laser diagnostic system for single-cycle-resolved imaging in internal combustion engines

“…8 To study fuel sprays, researchers used high-speed photography in combination with laser illumination, with high-repetition-rate Cu ϩ lasers. 9,10 Cycle-resolved point and 2-D flow measurements by use of laser Doppler velocimetry 11 and particle image velocimetry 12,13 have been reported. Planar laser-induced fluorescence ͑PLIF͒ imaging has been used to acquire image pairs in engines by use of double-pulsed lasers for fuel tracer PLIF 10 and residual gas PLIF.…”