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Aerodynamic Design and Characterization of Novel Wound Composite Multistage Counter-rotating Axial Compressors

机译：新型绕线复合多级对转轴流压气机的空气动力学设计与表征

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摘要

This thesis examines two different generations of axial compressor developed within the framework of the patented wound composite impeller technology created at Michigan State University. The technology itself allows for a departure from both the construction and operation of traditional single and multistage axial machines. Rather than using casting and machining methods to produce the impellers, they are wound from carbon fiber or other fiber/matrix material on a mandrel with curved slots. Winding layer-by-layer in the axial direction builds the blades while simultaneously creating the outer (and inner) shroud(s). The winding technique ensures that the fibers are closely aligned with the forces associated with high speed rotation, thereby yielding a high strength, light weight composite rotor capable of operating in chemically aggressive environments once cured. Traditional multistage axial compressors typically have a single drive shaft and hence require unidirectional rotation at a single operating speed. Non-rotating stators are utilized between rotors to impose the appropriate velocity distribution at the subsequent rotor inlet. The stators however do not perform useful work in terms of boosting the total pressure, and they contribute substantially to the overall footprint of a multistage machine. The employment of counter-rotating stages serves to eliminate the need for all intermediate stators as they themselves impose the necessary velocity distribution for the subsequent rotor while simultaneously performing useful work. Counter-rotation can be achieved by integrating a permanent magnet motor with each rotor. Rotors can be mounted on a non-rotating shaft and can therefore be driven in opposite directions through the use of variable frequency drives.;Initially developed for strength and ease of construction, a full geometric characterization of the first-generation "star pattern" impeller is performed and it is found that it operates under the forced-vortex flow regime. Reductions in terms of polytropic efficiency, mass flow rate, and total pressure ratio are seen from analytical prediction to numerical simulation, and again from simulation to experimental measurement. These reductions have led to the development of the second-generation impeller, which operates under the free-vortex flow regime.;Enhanced performance of single stage second-generation impellers in numerical simulation has lead to a vast investigation matching geometrical parameters, rotational speeds, and flow velocities to best-point operating conditions for up to seven counter-rotating stages compressing initially saturated water vapor under vacuum pressure for 22 different inlet temperatures. Numerical simulations of select cases agree well with analytical predictions.;For achieving maximum specific work transfer from the rotors to the working fluid, it is determined that the critical relative Mach number at each rotor tip should always be maximized. Hub/tip ratio at the first rotor inlet, aspect ratio, critical absolute Mach number, and turning angle are all temperature-dependent. The number of stages employed also has a large effect on how each rotor behaves (e.g. the second stage of a three stage machine looks and behaves differently from the second stage in a six stage machine), however utilizing an odd vs. an even number of total stages will have a much larger effect on inlet flow angle and the dimensionless flow coefficient, blade loading coefficient, and specific speed of each rotor.;Seven other gas mixtures have been investigated in similar fashion and exhibit similar behavior. Overall, billions of designs have been evaluated and the best operating conditions are determined for each individual set of inlet conditions and number of stages used. This research lays the necessary ground work for multistage counter-rotating axial compressor construction.
机译：本文研究了在密歇根州立大学创建的获得专利的缠绕复合叶轮技术的框架内开发的两种不同型号的轴流压缩机。该技术本身允许偏离传统的单级和多级轴向机床的构造和操作。而不是使用铸造和机械加工方法来生产叶轮，而是将它们由碳纤维或其他纤维/基体材料缠绕在带有弯曲槽口的心轴上。沿轴向逐层缠绕可构建叶片，同时形成外部（和内部）护罩。缠绕技术确保纤维与高速旋转的力紧密对齐，从而产生高强度，重量轻的复合材料转子，一旦固化，该转子就可以在化学侵蚀性环境中运行。传统的多级轴向压缩机通常具有单个驱动轴，因此需要以单个操作速度进行单向旋转。在转子之间利用非旋转定子，以在随后的转子入口处施加适当的速度分布。但是，定子在提高总压力方面没有做有用的工作，它们对多级电机的总体占地面积有很大的贡献。反向旋转级的使用消除了对所有中间定子的需要，因为它们本身为后续的转子施加了必要的速度分布，同时又进行了有用的工作。通过将永磁电动机与每个转子集成在一起，可以实现反向旋转。转子可以安装在不旋转的轴上，因此可以通过使用变频驱动器以相反的方向进行驱动。；最初是为提高强度和构造的简易性而开发的，是第一代“星形”叶轮的完整几何特征进行了实验，发现它在强制涡流状态下工作。从分析预测到数值模拟，再到从模拟到实验测量，都可以看到多方效率，质量流量和总压比方面的降低。这些减少导致了第二代叶轮的发展，该第二代叶轮在自由涡流状态下运行。改进的单级第二代叶轮在数值模拟中的性能导致了对几何参数，转速，最高速度可达7个反向旋转阶段，并在22个不同的入口温度下，在真空压力下压缩最初饱和的水蒸气。选定情况的数值模拟与分析预测非常吻合。为了实现从转子到工作流体的最大比功转移，应确定每个转子尖端的临界相对马赫数应始终最大化。第一转子入口处的轮毂/叶尖比，纵横比，临界绝对马赫数和转弯角均与温度有关。所采用的级数对每个转子的行为也有很大影响（例如，三级电机的第二级的外观和行为与六级电机中的第二级不同），但是使用奇数和偶数的总级数将对进口流角，无因次流系数，叶片负载系数和每个转子的比速产生更大的影响。七种其他气体混合物已经以相似的方式研究并表现出相似的行为。总体而言，已经评估了数十亿种设计，并针对每组单独的入口条件和所用级数确定了最佳运行条件。这项研究为多级反向旋转轴向压缩机的构造奠定了必要的基础。

著录项

  • 作者

    Gower, Blake Ernest.;

  • 作者单位

    Michigan State University.;

  • 授予单位 Michigan State University.;
  • 学科 Mechanical engineering.
  • 学位 Ph.D.
  • 年度 2018
  • 页码 430 p.
  • 总页数 430
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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