Film cooling performances of short fan-shaped-holes under oscillating freestream

IF 2.8 2区 工程技术 Q2 ENGINEERING, MECHANICAL Experimental Thermal and Fluid Science Pub Date : 2024-06-20 DOI:10.1016/j.expthermflusci.2024.111257
Xin-yu Liu , Jian Pu , Jian-hua Wang , Ran Yao
{"title":"Film cooling performances of short fan-shaped-holes under oscillating freestream","authors":"Xin-yu Liu ,&nbsp;Jian Pu ,&nbsp;Jian-hua Wang ,&nbsp;Ran Yao","doi":"10.1016/j.expthermflusci.2024.111257","DOIUrl":null,"url":null,"abstract":"<div><p>Freestream oscillation presents a significant challenge in optimized design of short fan-shaped-hole, a good choice for more promising double-wall cooled blades. An experimental investigation was conducted to understand detailed effects of key geometrical parameters of the fan-shaped hole, freestream oscillating frequency and cooling air-to-mainstream blowing ratio on the unstable film cooling performances. The selected geometrical parameters included the length-to-diameter ratio, the lateral diffusion angle, and the length ratio of cylindrical section-to-diffusion section. Time-resolved planar quantitative light sheet technique was employed to visualize the temporal variations of jet trajectory and transported scalar concentrations. The experimental results indicated that freestream oscillation causes variations in jet mechanisms, changing the trend in film cooling with blowing ratio and reversing the universally-acknowledged harmful influence of non-fully development of cooling air in short tube. The optimized short-hole can achieve an increment up to 40% in film effectiveness under oscillating freestream, in comparison with the long-hole-jet. The primary principle of the optimized design of short shaped-hole is properly enlarging the lateral expansion angle, aiming at the higher steady film effectiveness while the lower unsteadiness due to the transient fluctuations. Further enlarging the length ratio can improve the stability of film cooling in an oscillating cycle.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"158 ","pages":"Article 111257"},"PeriodicalIF":2.8000,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Experimental Thermal and Fluid Science","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0894177724001262","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
引用次数: 0

Abstract

Freestream oscillation presents a significant challenge in optimized design of short fan-shaped-hole, a good choice for more promising double-wall cooled blades. An experimental investigation was conducted to understand detailed effects of key geometrical parameters of the fan-shaped hole, freestream oscillating frequency and cooling air-to-mainstream blowing ratio on the unstable film cooling performances. The selected geometrical parameters included the length-to-diameter ratio, the lateral diffusion angle, and the length ratio of cylindrical section-to-diffusion section. Time-resolved planar quantitative light sheet technique was employed to visualize the temporal variations of jet trajectory and transported scalar concentrations. The experimental results indicated that freestream oscillation causes variations in jet mechanisms, changing the trend in film cooling with blowing ratio and reversing the universally-acknowledged harmful influence of non-fully development of cooling air in short tube. The optimized short-hole can achieve an increment up to 40% in film effectiveness under oscillating freestream, in comparison with the long-hole-jet. The primary principle of the optimized design of short shaped-hole is properly enlarging the lateral expansion angle, aiming at the higher steady film effectiveness while the lower unsteadiness due to the transient fluctuations. Further enlarging the length ratio can improve the stability of film cooling in an oscillating cycle.

查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
摆动自由流下短扇形孔的薄膜冷却性能
自由流振荡给短扇形孔的优化设计带来了巨大挑战,而短扇形孔是更有前途的双壁冷却叶片的良好选择。为了详细了解扇形孔的关键几何参数、自由流振荡频率和冷却空气与主流吹风比对不稳定薄膜冷却性能的影响,我们进行了一项实验研究。选定的几何参数包括长径比、横向扩散角和圆柱形截面与扩散截面的长度比。采用时间分辨平面定量光片技术来观察射流轨迹和传输标量浓度的时间变化。实验结果表明,自由流振荡导致了射流机制的变化,改变了薄膜冷却随吹气比变化的趋势,扭转了公认的短管内冷却空气未充分发展的有害影响。与长孔喷射器相比,经过优化的短孔喷射器可使自由流振荡下的薄膜冷却效果提高 40%。短形孔优化设计的主要原则是适当增大横向扩张角,以提高稳定的膜效,同时降低瞬态波动引起的不稳定性。进一步增大长度比可以提高薄膜冷却在振荡周期中的稳定性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 去求助
来源期刊
Experimental Thermal and Fluid Science
Experimental Thermal and Fluid Science 工程技术-工程:机械
CiteScore
6.70
自引率
3.10%
发文量
159
审稿时长
34 days
期刊介绍: Experimental Thermal and Fluid Science provides a forum for research emphasizing experimental work that enhances fundamental understanding of heat transfer, thermodynamics, and fluid mechanics. In addition to the principal areas of research, the journal covers research results in related fields, including combined heat and mass transfer, flows with phase transition, micro- and nano-scale systems, multiphase flow, combustion, radiative transfer, porous media, cryogenics, turbulence, and novel experimental techniques.
期刊最新文献
Editorial Board The oscillation of a falling ferrofluid droplet induced by a nonuniform magnetic field Effect of leaflet shape on the left ventricular blood flow pattern in BMHVs Lagrangian analysis of fluid transport in pulsatile post-stenotic flows Implementation of a high-frequency phosphor thermometry technique to study the heat transfer of a single droplet impingement
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1