Effect of preheated fuel supply by gas reflux on thermodynamic characteristics in a cavity-based integrated combustor

For achieving higher combustion performance under the premise of reliable ignition and flame stability, a novel preheated fuel supply method, which consists of the air-entraining parts and evaporation chamber designs, is proposed for the cavity-based integrated combustor. Herein, comparison experiments are conducted under ambient pressure to investigate the discrepancies in terms of lean ignition, blowout, and combustion characteristics accompanied by numerical flow fields. Furthermore, the time-averaged CH* intensity and local equivalence ratio of flame are acquired using a colorful CCD camera and processed via an image-processing algorithm based on probability density function. The results indicate that the novel preheated fuel supply method can widen the maximum Ma number for successful pilot-ignition, and decrease the lean ignition and blowout fuel/air ratio by 42.2% and 45.4% at low inlet temperature, respectively. The CH* intensity within the cavity in the Novel layout is much higher than that in the Original layout, due to the higher equivalence ratio accumulated by the larger recirculation zone. The flame structure in the mainstream is determined by the contest between jet penetration momentum and entrainment of wake-region. Moreover, the altered temperature distribution in Novel layout is more suitable for engineering combustors with higher requirements on circumferential flame propagation.