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毕业论文 燃气轮机高温叶片内部冷却系统DES数值分析和实验研究

  • 简介:毕业论文-燃气轮机高温叶片内部冷却系统DES数值分析和实验研究,共95页,32705字,中文摘要,内部冷却是现代燃气轮机透平叶片设计中不可或缺的冷却方式,冷却流量不,足会减小叶片寿命,过多则会降低燃机性能。内部冷却通道中复杂的三
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文件大小:26.51MB
适用专业:能源动力系统及自动化
适用年级:大学
论文编号:209525

论文简介:

毕业论文-燃气轮机高温叶片内部冷却系统DES数值分析和实验研究,共95页,32705字
中文摘要
内部冷却是现代燃气轮机透平叶片设计中不可或缺的冷却方式,冷却流量不
足会减小叶片寿命,过多则会降低燃机性能。内部冷却通道中复杂的三维流动导
致了复杂的传热系数分布,准确预测通道内的阻力系数和传热分布对于提高内部
冷却系统的性能具有重要意义。
作者改造并调试了内部冷却实验台,对不同进出口情况下 37000 到 70000 雷
诺数范围内共计 12 个工况进行实验,采用瞬态液晶技术获得了梯形带肋内部冷
却通道的详细传热分布。针对实验工况,分别采用 DES 和 RANS 数值计算模型
研究其流动和传热机理。结果表明,梯形通道带肋壁面的传热分布具有非对称的
特点,努塞尔数与雷诺数正相关,不同雷诺数下努塞尔数分布相似,其传热特征
由流动特征决定。斜置肋片会引起二次流,二次流的发展导致进出口段传热的沿
程发展;弯头外侧的低速区和弯头下游的回流区造成相应的低传热区域,进而导
致弯头区传热较差;肋片后存在沿肋高长度不等的分离区,流动再附点周围传热
系数最高。相对而言,DES 对于传热分布规律的预测比 RANS 准确,但两种数值
方法均未准确预测弯头处大分离的影响和通道的非对称性特征。
此外实验和数值结果的对比显示,二次流的影响使中心线温度不能代表截面
平均温度,因此实验数据处理不能采用中心线温度沿程插值。数值模拟还表明评
价带肋壁面传热效果不能仅关注肋间传热,还需将肋片的传热量考虑在内。
关键词:燃气轮机,内部冷却,梯形带肋 U 型通道,热色液晶,DES


ABSTRACT
Internal cooling is widely used in modern gas turbines. Insufficient cooling air
will shorten the blade life while too much cooling air will reduce turbine efficiency.
Complex three-dimensional flow inside the internal cooling duct results in complex
heat transfer distribution. Accurately predicting local heat transfer coefficient and
friction loss is important to improve internal cooling system performance.
The present study focuses on detailed heat transfer coefficient measurements of a
two-pass ribbed trapezoidal channel, using the transient thermochromic liquid
crystal(TLC) technique. Results are presented with both bigger and smaller inlet
sections over a range of Reynolds numbers between 37000 and 70000. Heat transfer
and flow features are also studied using RANS model and detached eddy simulation
(DES).Results show that heat transfer on two ribbed walls is non-symmetric, Nusselt
number increases when Reynolds number increases, however follows a similar
distribution pattern. Heat transfer distribution is determined by the flow field. Skewed
ribs induce secondary flow, heat transfer coefficient increases with the development of
secondary flow in both inlet and outlet sections. Heat transfer is low in the turn region
because of low-velocity regions in the outside turn and flow separation region after the
turn. Behind the rib there are flow separation regions of different sizes, Nusselt number
is high where flow reattaches. Flow development and heat transfer distribution
predicted by DES are more accurate than that predicted by RANS, but both numerical
methods fail to capture the non-symmetry features and the bend effect.
Comparing experimental and numerical results, it’s found that the mainstream
temperature along the centerline can not represent surface-averaged temperature,
indicating that it’s inappropriate to use centerline temperature for streamwise
interpolation during data processing. The numerical results also suggest that heat
transfer rate on the ribs should be taken into consideration together with heat transfer
rate between the ribs.
Keywords: gas turbine, internal cooling, two-pass trapezoidal ribbed duct,
thermochromic liquid crystal,DES


目录
第 1 章 引 言 ............................................................................................1
1.1 研究背景 ...........................................................................................1
1.2 研究现状 ...........................................................................................1
1.2.1 实验研究 .......................................................................................1
1.2.2 数值模拟 .......................................................................................2
1.3 本文研究主要内容 ............................................................................3
第 2 章 瞬态液晶实验介绍 .......................................................................4
2.1 研究对象的定义 ................................................................................4
2.2 内部冷却实验台 ................................................................................6
2.2.1 实验台改造 ...................................................................................6
2.2.2 实验台结构 ...................................................................................7
2.3 瞬态液晶测温原理 ............................................................................9
2.4 实验工况 .........................................................................................12
2.5 本章小结 .........................................................................................12
第 3 章 内部冷却通道实验结果 ..............................................................13
3.1 传热分布 .........................................................................................13
3.1.1 不同雷诺数对传热的影响 ...........................................................13
3.1.2 不同进出口条件下的传热分布 ...................................................17
3.2 无量纲压力分布 ..............................................................................23
3.3 几何结构与非对称性分析 ...............................................................25
3.4 本章小结 .........................................................................................27
第 4 章 脱落涡 (DES)及雷诺平均 (RANS)模拟 ........................................28
4.1 数值模拟方法介绍 ..........................................................................28
4.2 计算模型及计算方法 .......................................................................29
4.2.1 网格分布 .....................................................................................29
4.2.2 边界条件 .....................................................................................31
4.2.3 数值算法 .....................................................................................31
4.2.4 DES 方法中 LES 及 RANS 使用区域 ...........................................31
4.3 大进口工况传热及压损分析 ...........................................................32
4.3.1 内部冷却通道传热分布比较 .......................................................32
4.3.2 内部冷却通道无量纲压力比较 ...................................................37
4.3.3 内部冷却通道流动分析 ..............................................................38
4.4 小进口工况传热及压损分析 ...........................................................43
4.4.1 内部冷却通道传热分布比较 .......................................................43
4.4.2 内部冷却通道无量纲压力比较 ...................................................44
4.5 数值模拟对实验的指导作用 ...........................................................45
4.5.1 中心线温度分布 .........................................................................45
4.5.2 忽略肋片传热带来的影响 ...........................................................47
4.6 本章小结 .........................................................................................47
第 5 章 结论与建议 .................................................................................49
5.1 本文结论 .........................................................................................49
5.2 存在不足与改进建议 .......................................................................50
插图索引 ...................................................................................................51
表格索引 ...................................................................................................53
参考文献 ...................................................................................................54
致 谢 .........................................................................................................56
声 明 .........................................................................................................57
附录 A 外文资料的调研阅读报告(或书面翻译) ..................................58


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  • 毕业论文-燃气轮机高温叶片内部冷却系统DES数值分析和实验研究
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