高速离心叶轮的气动与结构优化

发布时间：2018-05-04 14:32

本文选题：离心叶轮 + 气动性能　；参考：《天津大学》2012年硕士论文

【摘要】：近年来，离心压缩机不断向高压比、高效率发展。叶轮气动设计的发展直接关系着叶轮机械的发展水平,是叶轮机械气动力学领域研究的重点。半开式离心叶轮因其强度高、极限圆周速度大、单级压比高等优点得到广泛应用。本文采用反命题设计方法，以某离心压缩机级内闭式离心叶轮为研究对象，以提高其效率、压比和扩大稳定工作范围为目标，通过控制叶片载荷分布改变叶片三维结构、改变叶片前缘位置，探讨和研究了离心叶轮优化设计方法；进而对经典叶轮在叶顶处等值切削形成不同间隙值的半开式叶轮进行数值计算，探究叶顶间隙对半开式离心叶轮气动性能和流场的作用机理。在对原始叶轮进行数值模拟、明确内部流动特性和气动性能基础上，采用三种措施进行反命题优化设计：1）以原始叶轮子午型线为基础，通过控制叶片载荷分布改变叶片三维结构，，进而优化叶轮气动性能；2）确定最佳载荷分布形式，改变叶轮出口宽度，以消除出口气流分离为目的优化叶轮气动性能；3）确立适当的叶片前缘位置，改善流动分离现象并扩大叶轮工况范围。通过数值模拟对设计结果进行气动性能分析，确立叶轮叶片的最佳结构设计参数。优化后的叶轮性能明显提高，高效区域范围显著扩大。叶顶间隙值是影响半开式叶轮气动性能的关键因素。研究表明，叶顶间隙导致叶轮顶隙损失增大，性能降低，但间隙值与流动损失的变化成非线性关系；恰当的叶顶载荷分布可有效抑制顶隙内泄漏量；顶隙涡流与主流之间的相互作用主要体现在叶轮的中下游流道，引起当地显著地熵增，不同运行工况形成的叶片前缘间隙泄漏涡旋结构与特征迥异；间隙泄漏流动本身引起的流动损失较小，间隙涡流与主气流相互掺混引起的损失是叶轮效率降低的主要原因。本文研究结果为具有复杂三维结构的离心叶轮的设计提供最优气动与结构匹配参数和优化指导，为高效闭式离心叶轮向大流量半开式应用领域拓展探究流动机理。
[Abstract]:In recent years, centrifugal compressor to high pressure ratio, high efficiency development. The development of impeller aerodynamic design is directly related to the development level of impeller machinery. Semi-open centrifugal impeller is widely used because of its high strength, high limit circumference velocity and high single stage pressure ratio. In this paper, the inverse proposition design method is used to study the inner closed centrifugal impeller of a centrifugal compressor stage. With the aim of improving its efficiency, pressure ratio and expanding the stable working range, the three dimensional structure of the blade is changed by controlling the load distribution of the blade. The optimum design method of centrifugal impeller is discussed and studied by changing the position of blade leading edge, and then the numerical calculation of semi-open impeller with different clearance values formed by equivalent cutting of classical impeller at the top of the blade is carried out. The action mechanism of tip clearance on aerodynamic performance and flow field of semi-open centrifugal impeller was investigated. On the basis of numerical simulation of the original impeller and definite internal flow characteristics and aerodynamic performance, three measures are adopted to optimize the inverse proposition design: 1) based on the original impeller meridian profile. By controlling the blade load distribution to change the three dimensional structure of the blade and then optimize the aerodynamic performance of the impeller, the optimal load distribution form is determined, and the outlet width of the impeller is changed. In order to eliminate the outlet flow separation, the aerodynamic performance of the impeller is optimized. (3) the proper vane leading position is established, the flow separation phenomenon is improved and the working range of the impeller is enlarged. The aerodynamic performance of the impeller blade was analyzed by numerical simulation, and the optimum design parameters of impeller blade were established. After optimization, the performance of impeller is improved obviously, and the area of high efficiency is greatly expanded. The tip clearance is the key factor to affect the aerodynamic performance of semi-open impeller. The results show that the tip clearance increases and the performance decreases, but the change of the gap value is nonlinear to the flow loss, and the proper top load distribution can effectively restrain the leakage in the top gap. The interaction between the top gap vortex and the main stream is mainly reflected in the middle and lower flow channel of the impeller, which results in a significant increase in local entropy, and the leakage vortex structure and characteristics of the leading clearance of the blade formed under different operating conditions are very different. The flow loss caused by interstitial leakage flow itself is relatively small, and the loss caused by the mixing of clearance vortex and main airflow is the main reason for the decrease of impeller efficiency. The results of this paper provide optimal aerodynamic and structural matching parameters and guidance for the design of centrifugal impeller with complex three-dimensional structure, and expand the flow mechanism of high efficiency closed centrifugal impeller to large flow semi-open application field.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH452

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