Effects of operating conditions on flame evolution and preheating performance of intake manifold burner aided by spray atomization

The intake manifold burner acts as a cold start auxiliary equipment for heavy diesel engines. The typical intake manifold burner, however, has some drawbacks, including unreliable fuel delivery, insufficient combustion, and poor windproof performance. In this study, a novel intake manifold burner with boosted fuel dispersion was designed, and tests were carried out to investigate the effects of injection pressure, injection frequency, injection duration, and airflow velocity on flame behavior. In addition, the fuel–air mixing process was simulated using a three-dimensional CFD (Computational Fluid Dynamics). To explore the impacts of operating conditions on the gas mixture, the variation tendency of gas/liquid fuel mass was analyzed, and the flame area was quantified. According to the findings, optimization of fuel supply parameters and intake parameters is conducive to flame development and intake air heating. Increasing the amount of fuel injection raises the local and global equivalency ratio, expands the fuel vapor distribution region behind the burner, boosting the flame growth. Airflow velocity and combustion heat release both have an impact on flame evolution. The effects of heat release on flame growth are nearly comparable at low airflow velocity (3–5 m/s), however at high airflow velocity, airflow becomes the dominant factor. High-velocity airflow (greater than 9 m/s) increases heat dissipation, limits flame growth, delays ignition and even blow-out phenomenon. When the air velocity is in the range of 6–7 m/s, the preheating effect is the best.