单气道柴油机气缸内近壁面流场与不同截面涡流比分析

构建单螺旋气道柴油机的气道-气门-气缸的计算机辅助设计(CAD)模型,开展油流法稳流试验及不同截面涡流比测量,并进行计算流体力学(CFD)模拟,利用试验结果验证CFD计算,分析缸内近壁面的流场及气缸不同截面涡流比的变化。结果显示:采用质量比为8∶8∶3的甲基硅油、油酸、铝粉的油剂配方所显示的缸内近壁面流场信息最为清晰完整;距进气口最近的气缸内近壁面形成气流高流速区,高流速区面积会随着气门开度的增大而增加,在高流速区域气缸壁面润滑油膜厚度减小,存在磨损加剧的风险。在进气过程中,随着气门开度逐渐增大,缸内的涡流比会逐级提升;随着涡流比测量面逐渐远离缸盖,各测量面的涡流比逐渐降低。

Visual Measurement of Near Wall Flow Field and Swirl Ratio of Different Cross Sections in the Cylinder of Single Port Diesel Engine

Construct a CAD model of the air-valve-cylinder of a single-spiral diesel engine, conduct oil flow method steady flow test and vortex ratio measurement of different sections, and perform CFD simulation. Use the test results to verify the CFD calculation and analyze the near-wall surface of the cylinder. Changes in the flow field and the vortex ratio in different sections of the cylinder. The results show that the information about the near-wall flow field in the cylinder using the formula of methyl silicone oil, oleic acid and aluminum powder with a mass ratio of 8: 8: 3 is the most clear and complete; the position of the air inlet in the cylinder head will be in the The near-wall surface of the cylinder nearest to it forms a high-flow velocity region. The area of the high-speed region increases with the increase of the valve opening. In the high-flow region, the thickness of the lubricant film on the cylinder wall decreases, and there is a risk of increased wear. During the intake process, as the valve opening gradually increases, the vortex ratio in the cylinder will gradually increase; as the vortex ratio measurement surface gradually moves away from the cylinder head, the vortex ratio of each measurement surface gradually decreases.