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An investigation of rotor tip leakage flows in the rear-block of a multistage compressor.

机译：对多级压缩机后缸体中转子尖端泄漏流的研究。

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摘要

An effective method to improve gas turbine propulsive efficiency is to increase the bypass ratio. With fan diameter reaching a practical limit, increases in bypass ratio can be obtained from reduced core engine size. Decreasing the engine core, results in small, high pressure compressor blading, and large relative tip clearances. At general rule of 1% reduction in compressor efficiency with a 1% increase in tip clearance, a 0.66% change in SFC indicates the entire engine is sensitive to high pressure compressor tip leakage flows. Therefore, further investigations and understanding of the rotor tip leakage flows can help to improve gas turbine engine efficiency.;The objectives of this research were to investigate tip leakage flows through computational modeling, examine the baseline experimental steady-stage performance, and acquire unsteady static pressure, over-the rotor to observe the tip leakage flow structure. While tip leakage flows have been investigated in the past, there have been no facilities capable of matching engine representative Reynolds number and Mach number while maintaining blade row interactions, presenting a unique and original flow field to investigate at the Purdue 3-stage axial compressor facility.;To aid the design of experimental hardware and determine the influence of clearance geometry on compressor performance, a computational model of the Purdue 3-stage compressor was investigated using a steady RANS CFD analysis. A cropped rotor and casing recess design was investigated to increase the rotor tip clearance. While there were small performance differences between the geometries, the tip leakage flow field was found independent of the design therefore designing future experimental hardware around a casing recess is valid. The largest clearance with flow margin past the design point was 4% tip clearance based on the computational model.;The Purdue 3-stage axial compressor facility was rebuilt and setup for high quality, detailed flow measurements during this investigation. A detailed investigation and sensitivity analysis of the inlet flow field found the influence by the inlet total temperature profile was important to performance calculations. This finding was significant and original as previous investigations have been conducted on low-speed machines where there is minimal temperature rise.;The steady state performance of the baseline 1.5% tip clearance case was outlined at design speed and three off-design speeds. The leakage flow from the rear seal, the inlet flow field and a thermal boundary condition over the casing was recorded at each operating point. Stage 1 was found to be the limiting stage independent of speed. Few datasets exist on multistage compressor performance with full boundary condition definitions, especially with off-design operating points presenting this as a unique dataset for CFD comparison.;The detailed unsteady pressure measurements were conducted over Rotor 1 at design and a near-stall operating condition to characterize the leakage trajectory and position. The leakage flow initial point closer to the leading edge and trajectory angle increased at the higher loading condition. The over-the-rotor static pressure field on Rotor 1 indicated similar trends between the computational model and the leakage trajectory.
机译：提高燃气轮机推进效率的有效方法是增加旁通比。当风扇直径达到实际极限时，可以通过减小核心发动机的尺寸来增加旁通率。减小发动机核心，会导致小的高压压缩机叶片和较大的相对叶尖间隙。通常，压缩机效率降低1％，叶尖间隙增加1％，则SFC变化0.66％表示整个发动机对高压压缩机叶尖泄漏流敏感。因此，进一步研究和理解转子叶尖泄漏流可以帮助提高燃气轮机效率。本研究的目的是通过计算模型研究叶尖泄漏流，检查基线实验稳态性能，并获得非稳态静力。压下，在转子上方观察叶尖泄漏的流动结构。尽管过去已经对叶尖泄漏流进行了研究，但是还没有能够在保持叶片行相互作用的同时使发动机代表雷诺数和马赫数相匹配的装置，从而提供了一个独特的原始流场，供普渡3级轴流式压缩机研究为了帮助设计实验硬件并确定间隙几何形状对压缩机性能的影响，使用稳定的RANS CFD分析研究了Purdue 3级压缩机的计算模型。研究了裁剪的转子和外壳凹口设计以增加转子尖端间隙。尽管几何尺寸之间的性能差异很小，但发现尖端泄漏流场与设计无关，因此围绕套管凹口设计未来的实验硬件是有效的。根据计算模型，流量裕度超过设计点的最大间隙为4％的尖端间隙。；在此研究期间，Purdue 3级轴流式压缩机设施进行了重建和设置，以进行高质量，详细的流量测量。对入口流场的详细调查和敏感性分析发现，入口总温度曲线的影响对性能计算很重要。这一发现意义重大且具有独创性，因为先前的研究是在温度升高幅度最小的低速机器上进行的。在设计速度和三种非设计速度下概述了基准1.5％尖端间隙情况的稳态性能。在每个工作点记录来自后密封件的泄漏流，入口流场和壳体上的热边界条件。发现阶段1是与速度无关的极限阶段。在具有完整边界条件定义的多级压缩机性能方面，很少有数据集存在，特别是非设计工况点将其作为CFD比较的唯一数据集呈现出来;在设计和接近失速工况下，对转子1进行了详细的非定常压力测量表征泄漏的轨迹和位置。在较高的载荷条件下，泄漏流的起始点更靠近前缘和轨迹角增加。转子1上的整个转子静压力场表明，计算模型和泄漏轨迹之间的趋势相似。

著录项

  • 作者

    Brossman, John Richard.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Engineering Aerospace.;Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 212 p.
  • 总页数 212
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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