内燃机换气系统弯曲管道稳态、瞬态流动的研究

Flow in Bent Pipe of Gas-Exchange System in Diesel

为了提高换气系统流动性能 ,采用数值计算方法 ,对内燃机换气系统弯曲管道稳态、瞬态流场进行了研究 .模拟计算采用三维、可压、粘性、湍流模型 .通过研究发现 ,弯曲管道内的流动是典型的三维流动 ,在管道中出现明显的二次流 ,使流体显螺旋式前进 ;管道不稳定流动经一很短时间 ,便可达到稳定 ;管道速度发生变化瞬间 ,入口处产生一高压波 ,该波沿管道长度方向传播 .本文计算结果可作为换气系统管道简化计算和接口边界简化处理的理论依据 .

For improving the flow in diesel pipes, the steady and unsteady flows in bent circular pipe in gas-exchange system were calculated with the three-dimensional compressible viscous turbulent numerical model. Calculations show that the flow in pipelines is typical three-dimension flow;there are secondary flows, the flow in the downstream of pipeline is helical. Little time was used for flow to get steady. There is a high-pressure wave in inlet of pipe when the velocity of pipe change, and it spreads along the length direction of pipe.