【作者】 王东屏；

【导师】 兆文忠；

【作者基本信息】 大连交通大学 ， 机械制造及其自动化， 2006， 博士

【摘要】 计算流体动力学(CFD)技术是20世纪90年代以来工程应用基础研究的一大突破，也是本世纪的重要发展方向之一。论文首先给出了CFD的定义和内涵，并对国内外CFD技术的研究现状及发展趋势进行了综述。高速动车组(HST)是铁路机车行业中的复杂产品之一，论文讨论了在空气动力领域降低HST物理样机投资风险的可行性及紧迫性。在HST设计中，有一系列空气动力内流场及外流场问题需要解决，一个典型的例子是随着列车速度提高，气动阻力剧烈增加，以至于气动性能起更重要的影响。所以，本文主要致力于研究如何建立一些有价值的CFD模型，并且将这些模型应用到HST设计中。本文的研究内容包括：考虑到模型质量的重要性，论文首先对二维马赫数4和1.83(M4和M1.83)拟似冲击波流动进行数值仿真及试验验证。由于激波是一个非常薄的间断面，如何能准确捕捉到激波是计算流体动力学的难题之一。同时，采用纹影实验和液晶实验对拟似冲击波的结构和边界层流动进行分析。计算结果与试验结果对比的良好一致性说明了论文采用的CFD模型具有很高的精度。对M1.83拟似冲击波也进行了数值仿真及验证。仿真获得的实验难以得到的拟似冲击波内部参数变化对认识拟似冲击波内部流动结构和流动机理有很大的帮助。此项研究为后续的动车组内外流场数值仿真建模的感悟极有帮助。其次，针对高速动车组内外流场的实际工程问题创建了一系列仿真模型，其仿真结果获得了工程验证。1．关于内流场(1)基于液固耦合，对水箱晃动的多相流问题进行CFD数值模拟，提取了水对水箱各个部位中最具破坏的压力波产生的作用力，并以此提供给有限元模型计算它的最大响应。屈曲分析结果与水箱实际破坏情况基本吻合，说明流固耦合计算模型可靠。(2)针对离心风机一类问题，对机车离心通风机进行了CFD数值模拟与流场优化，获得增加风压的方案，为高效率离心通风机的设计提供了一个有用的范例。(3)针对空调通风均匀性问题，对列车的风道和车内气流组织进行建模与仿真计算，数值仿真结果与实验结果基本符合，证明所创建的CFD仿真模型可靠。(4)针对涡轮增压器压气机叶轮三维流动问题，对转速21720r/min、压比3.1的机车涡轮增压器压气机叶轮内的三维流场进行CFD建模与数值仿真，捕捉到了叶轮中长短叶片的吸力面上存在超声速流动现象。2．关于外流场(1)针对高速列车气动外流场进行了CFD建模与数值仿真，获得了列车阻力随速度的变化规律、列车表面压力系数分布和高速列车尾流场的变化规律，加深了对外流场流动规律的认识。(2)针对气动噪声问题，采用大涡模拟算法，获得高速列车周围观察点上的声压、声压级的变化规律，并对同一时间下功率谱密度随频率的变化规律进行了研究，提供了利用CFD进行空气动力噪声分析的技术路线。论文创新点：(1)首次针对M4拟似冲击波的非对称现象进行了数值仿真。计算结果与试验结果的一致性证明了CFD模型的可靠性，仿真计算揭示的拟似冲击波内部流动参数变化规律对深刻认识其复杂的流动机理具有重要意义。(2)首次对M4的拟似冲击波流动现象进行了液晶显示实验。试验获得了边界层分离、再附着等重要流动特征。基于试验结果分析，首次提出了应使液晶在受测表面上轻微流动的新观点，填补了国内采用液晶显示技术研究拟似冲击波边界层流动的空白。(3)首次对我国高速动车组CFD内外空气动力流场进行了一系列建模研究。其中包括：列车空调通风系统，机车离心通风机，列车水箱晃动、高速列车远场空气动力噪声等，仿真结果的工程验证表明了模型的可靠性。更多还原

【Abstract】 Computational Fluid Dynamics (CFD) technology was one of the most important developments in the engineering application in 1990s. Now, it still is one of important subjects applied in engineering. In this paper, the definition of CFD is firstly described briefly including its current achievements and future trend at home and abroad.High Speed Train (HST) is one of most complex products in railway industry. The urgency and feasible decreasing the investment risk in the HST physical prototype are discussed as well. In the HST design, there are many fluid dynamic issues that should be solved urgently not only related with the inner fluid fields but also with exterior fluid fields. A typical example is when HST speed increases, its aerodynamic force increases so much that its aerodynamic performance will definitely play an more important role then before. So, in this paper, the main research works are how to create some useful CFD models and how to apply these models into HST.Due to the important of creating models, this paper first created two models related with Mach 4 and 1.83 Pseudo Shock Wave (PSW) in a two-dimensional square duct respectively. Since shock wave is a very thin discontinuous surface, capturing this kind of shock waves had been one difficult issue in CFD field. At the same time, in a pressure-vacuum supersonic wind tunnel, a high-speed color schlieren photography visualization technique is used to show the inner structure of M4 PSW, and the shear-sensitive liquid crystal technique is applied in the investigating its boundary layer. Fortunately, the results from CFD numerical simulation are very close to the experimental results. Further, the flow quantities, which are very difficult to be obtained experimentally, could be analyzed by numerical simulation. The better consistency between those results shows that the numerical simulation definitely is useful as well if we are able to put these experiments of creating models above into creating CFD models of HST.Secondly, in order to solve some engineering issues including the inner and outer fluid fields related with HST, some kinds of models have been created and proved.1. About Inner flow field(1) With regard to the fluid-solid coupling issue happened in the water tank of HST, a CFD model related with the water sway has been created, which has successfully provided maximum force into a FEA model to calculate its maximum response. The result from buckling analysis is close to the practical failure manner which indicated the CFD model is reliable.(2) With regard to the centrifugal ventilator issue, based on the CFD numerical analysis in 3D and corresponding optimum design, based multi-domain optimum software, a better design has been obtained. This is a useful demo for high-efficiency centrifugal ventilator design.(3) With regard to the air-condition vent issue, the air duct and inner air flow of HST is simulated numerically, and the numerical results close to the real one indicated this kind of CFD model is reliable.(4) With regard to the turbine supercharge compressor impeller issue, a CFD model, with 21721 r/min and pressure ratio 3.1, has been created, the shock wave phenomena are captured happen on the suction face of the long and short blades.2. About exterior flow field(1) With regard to the 3d exterior flow issue, a CFD simulation model has been created. Based on this model, the resistance influential laws, the surface pressure coefficient and the trail flow field are investigated.(2) With regard to the fast running noise issue, the LES (Large Eddy Simulation) is applied to analyze its aero-noise. The aero-noise information around the HST has been obtained including acoustic pressure, acoustic pressure level varied in time, and the power spectrum.In summarization, in this paper the innovations are as follows:(1) M4 pseudo shock wave is first numerically modeled, and its asymmetric structure is numerically obtained. The simulation result is very close with its experimental result. That means while the created CFD model is creditable, then the CFD simulation could obtain more information than test in the research field of pseudo shock wave.(2) The shear-sensitive liquid crystal technique is first applied in investigating the boundary layer fluid properties of M 4 pseudo shock wave. According to the experiment results, it is clear if liquid crystal should slowly flow during the experiment so that more information related with the stress magnitude and direction can be obtained.(3) One set of HST CFD models is created including inner and exterior flow, which include the air-condition vent system, the multi-domain optimum, water sway in coupling, aero-noise etc. The numerical results have been proved that the CFD models are reliable in engineering application.更多还原