共查询到20条相似文献,搜索用时 250 毫秒
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针对后视镜引起的前侧窗与车内气动噪声问题,采用计算流体力学(CFD)方法对某商用车进行车外后视镜区域数值模拟和车内噪声预测的研究。稳态分析采用RANS模型中SST(Menter)k-ω模型,瞬态分析采用基于SST(Menter)k-ω的分离涡模拟(DES);通过分析后视镜侧窗区域的稳态静压力与瞬态动压力、速度和涡量云图,揭示了因A柱后视镜而产生车窗表面的湍流压力脉动的机理;同时求解瞬态流场获得两侧车窗表面湍流压力脉动载荷。采用声学FEM方法将车窗表面湍流压力脉动作为边界条件来计算气动噪声的传播,基于车内声学空间不同频率的声压级云图分布规律,说明了车内气动噪声主要集中在中低频段和声压级最大的分布区域;驾驶员左耳旁声压级曲线展示了20-2500 Hz频段内声压级变化规律。最后进行实车道路滑行测试,证实了气动噪声在车速80-110 km/h时较为明显的结论;采用CFD结合声学有限元的方法可较为准确地预测车内100-2500 Hz气动噪声的声压级,为优化后视镜、降低驾驶室内气动噪声提供仿真和试验的技术方案。 相似文献
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《汽车工程学报》2015,(6)
采用计算流体力学(Computational Fluid Dynamics,CFD)和计算气动声学(Computational Aeroacoustics,CAA)分步耦合方法对汽车前端冷却模块气动噪声进行数值分析。将换热器部件等效为多孔介质,利用大涡模拟(Large Eddy Simulation,LES)捕捉冷却模块声源信息。利用声学边界元法(Acoustic Boundary Element Method,BEM)计算气动噪声,并将计算结果和噪声试验结果进行对比。结果表明,冷却模块空间声场低频段轴向偶极特征明显;离散噪声突出而宽频噪声相对较小;场点总声压级随转速的增大而增加;出风口场点总声压级较进风口大;增加等效声源数量可提高气动噪声的数值预测精度。计算结果与试验结果吻合较好,说明CFD和CAA分步耦合方法可为冷却模块低噪声设计提供理论指导。 相似文献
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进排气系统噪声由尾管噪声及壳体噪声共同构成。双层壳体及内层降噪材料可有效地降低壳本噪声;尾管噪声采用线性频率范畴模型法及非线性时间范畴法进行预测并综合处理系统所产生的实际噪声。进排气系统的设计兼顾发动机性能和声学效果,其关键是正确预测压力损失参数。 相似文献
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采用具有线性和非线性连接子结构的自由界面模态综合法,建立整车系统声固耦合非线性动力学模型。用该模型对发动机激励产生的车内噪声进行数值仿真,并通过试验对仿真结果进行验证。 相似文献
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Air flow inside an automotive HVAC module was visualized using a high-resolution PIV technique with varying temperature control
modes. The PIV (particle image velocimetry) system used for the experiment consisted of a 2-head Nd:YAG laser (125 mJ), a
high-resolution CCD camera (2 K × 2 K), optics and a synchronizer. A real automotive HVAC module was used as a test model,
and some of its casing parts were replaced with transparent windows to capture the flow images of the laser-light-sheet illumination.
In addition, instant velocity fields were measured for three different temperature control modes by adjusting the temperature
baffle. Characteristics of the air flow inside the automotive HVAC were then evaluated based on the time-averaged PIV data.
Results from the experiment showed that flow for the warm mode loses more momentum due to its complicated flow path. Thus,
the present PIV data can be used to validate numerical prediction and to improve the performance of HVAC modules. 相似文献
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支持向量机在交通流量实时预测中的应用 总被引:5,自引:3,他引:5
实时、准确的交通流量预测是正在发展的智能交通系统的关键问题之一,对于交通控制和交通流诱导都有着直接的影响。提出一种基于支持向量机的交通流量实时预测模型,通过采用序贯最小优化算法,能够实现对交通流量的有效预测。应用实例表明,支持向量机具有良好的泛化性能,在输入信号混有10%噪声的情况下,支持向量机的鲁棒性更好,预测的平均误差为4.25%,预测结果优于BP神经网络和动态递归神经网络。 相似文献
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M. S. Xie G. R. Zhang J. H. Li R. Fritsch 《International Journal of Automotive Technology》2014,15(4):565-571
Automotive brake systems today have many factors that can contribute to brake noise. Modern approaches to reduce the propensity of brake noise mostly target high frequency brake squeal. A more difficult constituent of brake noise to address is low frequency moan, which is typically caused when the brake system excites a suspension member with a constrained natural frequency in the range of excitation. Although most modern CAE techniques utilized to diagnose and solve brake noise issues focus on new brake pad condition, this paper will show the benefit of understanding a common wear mechanism “Taper Wear,?and attempt to correlate its effects on brake moan. In order to study this phenomenon, a finite element model of a disc brake is established, and a complex eigenvalue analysis (CEA) of the brake system is performed. The propensity of brake moan noise is evaluated on basis of damping ratio of a dynamic brake system model. By using the finite element model, effects of the brake pad taper wear on brake moan noise is studied. The results show that the brake pad taper wear is a significant factor for generating the instability causing the brake moan noise. The study is performed at various levels of brake pad taper wear. When the brake pad taper wear is more than 0.5 mm, the value of negative damping ratio rapidly increases, and the propensity of brake moan noise is greatly magnified. In this study, the simulation result correlated well with the test result, which provides the theory and guidance for brake moan noise control. 相似文献
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对某种轿车空调HVAC内部结构以及蒸发器、加热器等关键部件设计进行改进。改进后的HVAC空调系统在满足整车装配的前提下,通过台架性能试验和环境模拟试验,表明其制冷性能和整车降温性能得到明显改善,并且HVAC的噪声和功耗也明显降低。 相似文献