Visualization of the Effect of Injection Strategy on 2-Methylfuran/Diesel Reactivity-Controlled Compression Ignition Combustion

<div class="section abstract"><div class="htmlview paragraph">Based on a single-cylinder optical engine and a high-speed camera combustion analysis system, experiments were conducted to study the effects of main injection timing and pre-injection equivalence ratio (ratio of MF fuel to total fuel mass in reactivity-controlled compression ignition [RCCI] combustion mode) on the combustion characteristics and combustion process of RCCI, and at the same time compared and analyzed with pure diesel combustion. The results show that with the advance of the main injection timing, the ignition delay appears to be advanced and then delayed, the combustion phase is advanced as a whole, and the combustion duration is prolonged. Compared with the pure diesel combustion mode, a smaller pre-injection equivalence ratio of RCCI combustion mode delays the ignition delay, and a further increase in the pre-injection equivalence ratio advances the ignition delay. Changing the pre-injection equivalence ratio causes less change in the combustion phase, and the combustion duration can be effectively controlled. Under the pure diesel combustion mode, if the main injection timing is too early or too late, it will inhibit the combustion process, which results in the flame developing rapidly in the pre-combustion period, the in-cylinder pressure rising at a faster pace, and the flame brightness reaching the highest value at the late period, and pure diesel combustion pattern shows typical diffusion combustion. The distribution of the ignition point of the RCCI combustion mode changes along with the change of the main injection timing, and the main injection timing has a greater influence on it. The peak of the transient heat release rate of the RCCI combustion mode is higher than the pure diesel, but the location of the peak is a little bit higher. RCCI combustion mode is higher than that of pure diesel, but the peak appeared at a delayed position, and the pre-injection equivalence ratio is too large to effectively increase the peak instantaneous heat release rate.</div></div>