Study on the Influence Mechanism of Spoiler on Flow and Combustion Process in Rotary Engine Cylinder

Abstract

The spoiler is vital for optimizing rotary engines, yet its impact on the flow and combustion process within the cylinder remains ambiguous, thereby impeding the optimization efforts for rotary engines. This article, by analyzing the motion of the rotary, discovers a form of high-speed local gas flow within the cylinder due to local pressure differences resulting from interactions among the combustion chamber, cylinder body, and spoiler structure. This phenomenon is named “pressure differential flow” to differentiate it from the forced flow induced by the spoiler. Using mathematical models and three-dimensional simulations, we analyze the intensity of pressure differential flow at various spoiler heights and its regulatory effects on the flow and combustion characteristics within the cylinder. The results indicate that the flow caused by the spoiler in the cylinder is primarily divided into forced flow and pressure differential flow, with the intensity of the latter increasing as the spoiler height increases. When the spoiler height is greater than 75% of the maximum height, the pressure difference flow becomes more apparent, with both forced flow and pressure difference flow coexisting in the cylinder; when the spoiler height is less than 75% of the maximum height, the pressure difference flow is less noticeable, and the forced flow caused by the spoiler dominates. Pressure differential flow can reduce ignition delay and increase the maximum cylinder pressure, but it can also delay ignition timing and reduce combustion stability.