【作者】 闫朝；

【导师】 徐建中；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 工程热物理， 2004， 博士

【摘要】 非定常流和非定常设计是当前叶轮机械气动热力学领域研究的焦点之一。因此，本文尝试性地论述了非定常设计的两个重要组成：非定常流型和缘线匹配，并对它们进行了初步研究。由于叶轮机非定常实验的困难，CFD方法成为研究非定常流动的主要手段。本文以编制叶轮机流动时间精确模拟程序为开端，进行了以下研究工作： 一、作为实现非定常设计的软件基础，开发了能够对叶轮机内部流动进行多排、多通道时间精确模拟的二维和三维计算程序。鉴于缺乏相关的非定常实验数据，采用商业CFD软件FLUENT和NUMECA分别与二维和三维程序进行了互校。在应用于流动研究前，对所开发程序进行了网格无依赖和物理时间步长无依赖两个方面的研究，确定出适当的网格和物理时间步长配置。结果表明，所开发程序应用于叶轮机非定常流求解具有令人满意的精度。 二、非定常流型是叶轮机非定常气动设计中二维层面的重要技术，论文采用二维数值方法初步研究了这一问题。研究以一涡轮叶栅基元为对象，通过在入口边界施加非定常条件来模拟叶轮机内的非定常环境，结果显示了流动的非定常性对叶栅性能的影响，并与定常、准定常环境下的叶栅性能进行了对比，得出了尾迹亏损程度、进气角度和尾迹移动速度等因素影响叶栅性能的规律。此外，还对叶栅的升力滞回现象做出初步研究。以上工作初步展示了未来关于叶轮机非定常流型研究方面的部分内容。 三、二维时序效应属于非定常流型研究中的一个重要部分，论文通过对1.5级静／动／静布局的涡轮叶栅进行数值模拟，首先对时序效应进行了现象及机理研究；其后探索了叶排间轴向间距和动叶转速对时序效应的影响，发现两种因素均会给时序效应带来一些新的现象，比如时序效应提升效率潜力的变化，尾迹输运时间的变化等等。这一研究在促进对时序效应流动机理的认识继续深入的同时，进一步细化了时序效应的研究，为三维时序研究和应用提供有益的指导。 四、缘线匹配是叶轮机非定常气动设计三维层面上用于多排排间匹配的重要技术，也是本文的主要内容。因此，论文首先全面介绍了缘线匹配的理论基础、两种应用方式摘要及其初步验证。然后，作为对该理论继续验证和应用的实例，首次将时序效应纳入缘线匹配框架之下，利用缘线匹配思路进一步拓展了时序效应潜力。通过修改二级静叶的根、尖相位组合和修改一、二级静叶叶尖相位组合两种方式，使研究对象的气动效率在从时序效应受益的基础上进一步获得提升。研究以三维CFD程序为工具，采用缘线匹配应用中最为耗时的全优化方式，综合预估了包括效率在内的代表叶轮机性能的多种参数的时均量和脉动量，显示出缘线匹配这一设计自由度在非定常设计体系中所起到的重要作用。更多还原

【Abstract】 Nowadays, unsteady flow and unsteady design are parts of the main focuses of turbomachinery aerodynamics research. Hence, the present dissertation attempts to discuss two important parts of unsteady design: Unsteady Flow Pattern and Edge Matching, on which preliminary investigations are performed. Because of the difficulty rising from experiment of unsteady turbomachinery flow, the author has to select CFD as a main method to conduct unsteady researches. Consequently, this dissertation begins with programming the time-accurate flow solvers and the main efforts are listed as follows:1. To be the basis of fulfilling unsteady turbomachinery design, 2D and 3D Reynolds-Averaged N-S solvers are developed with the capabilities of simulating unsteady flow of turbomachine with multiple blade rows and passages. Due to lack of data from unsteady experiment, the 2D and 3D CFD codes are validated by comparing with FLUENT and NUMECA respectively. Before putting the codes into the following researches, studies about grid and time step dependence have been conducted. Reasonable grid and time step are determined so that the numerical results can be convinced. All these indicate that the codes are reliable for unsteady flow simulation.2. Unsteady Flow Pattern is an important technique in 2D unsteady turbomachinery design.A turbine cascade is adopted as an example in unsteady flow pattern study, in which time-accurate inlet profiles are imposed to produce the cascade unsteady flowfield. The effects of unsteady flow onto cascade performance are studied and compared with those of the equivalent steady and quasi-steady cases. The main concerns focus on how the wake defect, flow angle and wake moving speed in pitchwise influence the cascade performance. Also, ’time-lag’ phenomenon of cascade lift is investigated preliminarily. All these researches display some aspects of unsteady flow pattern study introductorily in future.3. As an important part of unsteady flow pattern study, 2D clocking effect is investigated ona 1.5 stage turbine cascades with stator/rotor/stator configuration. Not only the knowledge about the mechanism of clocking effect is obtained, but also the influences ofaxial gap and rotor rotating speed onto clocking effects are further demonstrated by 2D CFD simulations. Results show that the two kinds of influence both can bring some new phenomena onto clocking effect, such as the changing of potential in improving the efficiency of turbomachinery, changing of wake-transport time and so on. This study can not only advance the understanding of the mechanism of clocking effect, but also make the investigation on clocking effect more detailed, from which 3D clocking effect study and application will be benefited subsequently.4. Edge Matching is an important technique in 3D unsteady turbomachinery design which mainly aimed at the ’matching’ between multiple blade rows. To be an important part of this dissertation, it is introduced comprehensively about the theory of Edge Matching, two methods of manipulating and its preliminary validation firstly. Then, as an example to testify and apply the theory, a new idea is suggested that the clocking effects can be more perfect when they are taken into account in the frame of Edge Matching theory. In order to exemplify this potential, two ways of applying edge matching are selected: one is from combinations of hub and tip section of the second stator; the other is from combinations of the two tip sections of both two stators, the intention of which is to see if the turbine aerodynamic efficiency can be further promoted over the original well clocked one. 3D numerical optimizations are conducted based on the full-optimizing method, which is the most time-consuming one in the two manipulating ways of Edge-Matching theory. Results show the importance of Edge Matching for further promoting the benefit of clocking effects. This indicates edge matching provided a new degree of design freedom for turbomachinery unsteady design.更多还原