基于CFD和试验的商用车高位引气管预滤性能的 分析与优化

为延长恶劣工况下某商用车进气系统空气滤清器滤芯的使用寿命，避免频繁更换滤芯，提出了增加旋流扇的高位引气管方案，并通过优化旋流扇夹角来提高进气系统预滤灰尘和液雾的效率，达到降低成本的目的。首先，采用计算流体力学（computational fluid dynamics，CFD）方法，对进气过程中高位引气管的内部流场进行数值模拟，分析了3款高位引气管的速度流线图和速度梯度云图，得到了高位引气管预滤灰尘和液雾的机理，并基于高位引气管速度流场的变化规律，提出了旋流扇夹角优化方向；其次，利用台架试验对优化后的高位引气管进行灰尘和液雾的预滤试验，并计算出灰尘和液雾的预滤效率；最后，对比不同高位引气管预滤灰尘和液雾的效率，根据两预滤效率的变化趋势，选择旋流扇最优夹角为75°。仿真和试验结果表明：旋流扇夹角对进气系统工作过程中高位引气管的流场及预滤效率有重要影响，优化旋流扇夹角有助于提高进气系统的预滤性能，从而减少进入空气滤清器的灰尘和液雾，达到延长空气滤清器滤芯寿命的目的。

Analysis and optimization for pre-filteration performance of high inlet pipe of commercial vehicle based on CFD and test

In order to improve the life of air filter element which mounts the air intake system of the commercial vehicle and avoid frequent replacement of filter element in the harsh working condition, a high inlet pipe scheme designed for increasing the swirling fan is proposed, and the efficiency of pre-filtering dust and liquid mist of the air intake system is improved through the optimizing the swirling fan angle to achieve the goal of reducing costs. Firstly, the computational fluid dynamics (CFD) method was used to simulate the internal flow field of the high inlet pipe during the air intake process. The velocity streamline diagram and the velocity gradient cloud chart of three types of high inlet pipes were analyzed，and the mechanism of dust and liquid mist pre-filtered by high inlet pipe was obtained. Based on the variation law of velocity flow field of high inlet pipe, the optimum direction of vortex fan angle was proposed. Secondly, by using the rack test, the test of dust and liquid mist pre-filtered by optimized high inlet pipe was carried out, and the pre-filtration efficiency of dust and liquid mist was calculated. Finally, comparing the different dust and liquid mist pre-filtration efficiencies of high inlet pipes, the optimal angle of swirling fan was set as 75° according to the intersection of the two pre-filtration efficiency trends. The simulation and experimental results showed that the angle of the swirling fan had an important influence on the flow field and pre-filtration efficiency of the high inlet pipe during the working process of the intake system. The optimal angle of the swirling fan can help to improve the filtration performance of intake system, which reduces the dust and liquid mist entering the air filter and extends the life of the air filter element.