四气门直喷式柴油机进气过程缸内流场的模拟研究

Simulation Study of In-Cylinder Flow Field of Intake Period in a Four-Valve Direct Injection Diesel Engine

利用缸内三维流场测量装置 ,运用热线风速仪在稳流模拟试验台上研究了四气门直喷式柴油机进气过程的缸内流场特性 ,并与两气门直喷式柴油机进行了比较 ,揭示了四气门直喷式柴油机进气涡流的形成过程及气门开度对其影响的变化规律 .两气门直喷式柴油机进气涡流主要由进气门轴线至气缸轴线附近的强气流产生 ,缸内主涡流出现在进气门下方 ,副涡流较弱 ;四气门直喷式柴油机的进气涡流主要由气缸周边处的强气流产生 ,缸内主涡流出现在两进气道气门的下方 ,随气门开度的增大而增强 ,副涡流出现在远离进气门的一边 。

With a flow velocity measuring device in cylinder flow fields, an experimental study on the steady flow test bench was carried out by using hot wire anemometer (HWA). Through analysis of in cylinder flow field of intake period in a four valve directed injection diesel engine and two valve directed injection diesel engine, the law of in cylinder swirl formation process and its results under the effects of the changes of valve lift was obtained. Intake swirl of two valve directed injection diesel engine is formed by a strong airflow near intake valve axis to cylinder axis. Main swirl appears below the intake valve, and subsidiary swirl is very weak. Intake swirl of four valve directed injection diesel engine is mainly formed by the strong airflow near the cylinder wall. In cylinder main swirl appears below the two intake port valves, it is stronger along with the larger of the valve lift. The subsidiary swirl is formed far from the valve. When the valve lift is lower, the swirl is stronger.