In-Cylinder Flow Oriented Intake Port Development of Diesel Engine

摘要

With the increasingly stringent emission standards and economical efficiency, it is an inevasible challenge to improve higher efficiency combustion of the diesel engine. Due to the development of engine design and accessorial technology, the research direction of the modern diesel engine turns to accurate control and optimization of the engine system. The design of the intake ports has direct and significant impact on in-cylinder air motion intensity and distribution. The diesel engine's combustion is relative to the conditions of the fuel spray, the shapes of the combustion chamber and the air flow intensity in cylinder. The traditional development of the intake ports of the diesel engine was just focused on the steady-state characteristics of the intake ports, the main parameters to evaluate the intake ports were flow coefficient, swirl ratio and tumble ratio etc. But those macroscopic parameters could not truly estimate the influence of the intake ports performance during the diesel engine dynamic process. Especially, we can not get the accurate information about the movement and distribution state of the engine dynamic process from the stationary flow test bench, and so it is not effective to accurately control the combustion and emission. During the development of intake ports of the diesel engine, we found that the influence on the dynamic intensity of the swirl motion in cylinder was obvious when the same intake port matching with different combustion chambers. Hence, it is not imagine the reality mixture flow conditions in cylinder if we just insist on the intensity of the swirl motion measured from the stationary flow test bench. Based on those reasons, we bring for- ward the conception of in-cylinder flow oriented intake port development. With the help of the stationary flow test, steady and dynamic CFD, the method of accurately controlling the air flowing in-cylinder can instruct the intake port design and development.