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A combined flow-field/temperature field study of the impact of blade tip clearance on turbomachinery-type blading.

机译：叶片尖端间隙对涡轮机械叶片的影响的流场/温度场组合研究。

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摘要

Modifications to both laminar and turbulent approach juncture flows due to the presence of a clearance gap were examined in a low-speed water channel using particle imaging velocimetry and a thermochromic liquid crystal heat transfer measurement technique. When a clearance gap is present, a layer of outer region fluid diverts downward along the juncture body, creating a saddle point on the endwall. From the saddle point, a portion of the impinging flow moves upstream, and the remaining portion flows directly into the clearance gap. Necklace (laminar) and horseshoe (turbulent)juncture vortices, typical of juncture flows without gaps, continue to form upstream of this endwall saddle point, until the gap clearance exceeds h/D ≈20% for a laminar flow or ≈10% for a turbulent flow. The location of the endwall saddle point moves upstream with increasing gap thickness. When a significant gap clearance is present, the primary vortex for both the laminar and turbulent approach juncture flows is cyclically swept (ingested) into the clearance gap.; For a turbulent approach juncture flow, a four-stage cycle was identified, consisting of: (1) vorticity organization; (2) development of a quasi-steady horseshoe vortex; (3) vortex weakening; (4) vortex ingestion. Coherent regions of negative vorticity, advected within the boundary layer, amalgamate with, and maintain the strength of, the horseshoe vortex. As the clearance gap increases, fewer negative vorticity regions amalgamate with the horseshoe vortex, which causes the vortex to weaken, and exhibit longer organization times and less organized behavior.; The presence of a clearance gap in a juncture flow results in several modifications to the endwall surface heat transfer, including: (1) an increase of roughly 25% in the local peak surface heat transfer, (2) a reduction in the extent of the endwall region which experiences elevated surface heat transfer, and (3) a dislocation of the region of highest heat transfer from upstream of the juncture comer to within the leading edge of the clearance gap.
机译：在低速水通道中，使用粒子成像测速仪和热致变色液晶传热测量技术，研究了由于存在间隙而对层流和湍流进场交汇处的修改。当存在间隙时，一层外部区域的流体会沿着接合体向下转移，从而在端壁上形成一个鞍点。从鞍点开始，一部分撞击流向上游移动，其余部分直接流入间隙中。项链（层状）和马蹄形（湍流）接合点涡流（无间隙的典型接合点流）继续在此端壁鞍点上游形成，直到间隙间隙超过h / D≤20％（对于层流）或≤10％为止湍流。端壁鞍点的位置随着间隙厚度的增加而向上游移动。当存在明显的间隙时，层流和湍流进场交汇处的主要涡流都被周期性地扫入（吸入）到间隙中。对于湍流进场交汇处，确定了一个四个阶段的循环，包括：（1）涡度组织； （2）拟准马蹄涡的发展； （3）涡流减弱； （4）涡流摄入。在边界层内平移的负涡旋的相干区域，与马蹄涡旋合并并保持其强度。随着间隙的增加，较少的负涡旋区域与马蹄形涡旋合并，这导致涡旋减弱，并表现出更长的组织时间和更少的组织行为。接合流中存在间隙会导致对端壁表面传热的多种修改，包括：（1）局部峰值表面传热大约增加25％，（2）端壁区域经历了较高的表面传热，并且（3）最高传热区域从接合角上游移到了间隙的前沿。

著录项

  • 作者

    Marini, Bonnie Dawn.;

  • 作者单位

    Lehigh University.;

  • 授予单位 Lehigh University.;
  • 学科 Engineering Packaging.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 192 p.
  • 总页数 192
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 包装工程;
  • 关键词

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