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The Study on the Characteristics of Different Intake Port Structures in Scavenging and Combustion Processes on a Two-Stroke Poppet Valve Diesel Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 14, 2020 by SAE International in United States
Two-stroke engines have to face the problems of insufficient charge for short intake time and the loss of intake air caused by long valve overlap. In order to promote the power of a two-stroke poppet valve diesel engine, measures are taken to help optimize intake port structure. In this work, the scavenging and combustion processes of three common types of intake ports including horizontal intake port (HIP), combined swirl intake port (CSIP) and reversed tumble intake port (RTIP) were studied and their characteristics are summarized based on three-dimensional simulation. Results show that the RTIP has better performance in scavenging process for larger intake air trapped in the cylinder. Its scavenging efficiency reaches 84.7%, which is 1.7% higher than the HIP and the trapping ratio of the RTIP reaches 72.3% due to less short-circuiting loss, 11.2% higher than the HIP. The RTIP also behaves better in mixture formation and combustion performance with higher air utilization and superior heat release as well as work capacity. The CSIP has the advantage of higher thermal efficiency but have to face the challenge of high maximum pressure rise rate as the HIP. For the CSIP, the introduction of helical intake manifold makes little difference on this two-stroke poppet valve diesel engine.