Fig. 6 shows the effect of various injection frequencies
on Mhf throughout the case studies at different engine speeds
and throttle openings. The injection frequencies studied were 1
(1if), 2 (2if) and 4 (4if) injections per engine cycle. On the
whole, the Mhf at 4if showed the lowest value compared to the
other two smaller injection frequencies. The lower the Mhf, the
closer it was to the Mch4.s, and thus the better the mixing quality.
Hence, injection frequency at 4if exhibited the best mixing
quality in TBIM.