Fundamental Investigations on Sability and Structure of Flow and Heat Transfer in Cyclone Cooling Chambers

旋风冷却室流动与传热的稳定性和结构的基础研究

基本信息

批准号：
193145365
负责人：
Professor Dr.-Ing. Bernhard Weigand
金额：
--
依托单位：
Institut für Thermodynamik der Luft- und Raumfahrt (ITLR)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2014-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/193145365?language=en
关键词：
Fundamental Investigations Sability Structure Flow

项目摘要

The research project Wärmeübertragung in einer Zyklonkühlkammer has been designed for 4 years. The present proposal is now for the second phase (3rd and 4th year) of the project. In the first 2 years, the axial- and circumferential velocity field was experimentally studied via Particle Image Velocimetry (PIV) and the heat transfer in the cyclone cooling chamber was measured by a transient technique using thermochromic liquid crystals (TLCs). The flow and the heat transfer were additional simulated with the open source program OpenFOAM. The attention was on the investigation of different outlet geometries. Therefore, a 180° tube bend and a tangential outlet were investigated in detail. It turned out that a change of this sort of outlet geometry has no significant influence on the flow field in the swirl tube. This is a very important result concerning a future application of the swirl tube into a cooling channel in a gas turbine blade. The flow independence for outlet geometries with deflection shows, that swirl cooling can be well applied in technical applications in the future.The complex flow field and the heat transfer in cyclone cooling chambers are strongly affected by stability effects. Here the swirl number plays an important role for the flow field stability and the occurrence of a backflow region in the tube center. The previous investigations dealt only with high swirl numbers, so a backflow region occurred in all cases. Thus, detailed investigation on the generation of a backflow region with low swirl numbers is missing.Because of this the objective of the second phase of the project is to understand and describe the fundamentals of the backflow in the tube core and the influence on the heat transfer. Especially the effect of the vortex breakdown and its transition region shall be investigated in detail. Here, it is very interesting for which swirl number a backflow region in the core develops and how it influences the cooling capability of the cyclone cooling chamber.Furthermore the previous investigations show the formation of a stable helical vortex structure. These secondary vortices have a big influence on the heat transfer in the swirl tube. So a further objective of the project is to extent the knowledge of the energy transfer between the main and the secondary vortices. Therefore a water injection into the swirl tube shall be investigated in detail. Due to the water injection additional energy will be added to the system. The idea is to manipulate the angular velocity of the solid body vortex in the tube core with the evaporation heat. Thus, the influence on the solid body vortex and on the heat transfer shall be studied in detail.

EinerZyklonkühlkammer的研究项目Wärmeübertragung已设计了4年。目前的提案现在是该项目的第二阶段（第三年和第四年）。在最初的两年中，轴向和周向速度场是通过粒子图像速度计（PIV）实验研究的，并且使用热颜色液晶（TLC）通过瞬态技术测量了气旋冷却室中的热传递。使用开源程序OpenFOAM额外模拟流量和传热。注意力集中在不同的出口几何形状的投资上。因此，详细研究了180°的管弯曲和切向出口。事实证明，这种出口几何形状的变化对漩涡管中的流场没有显着影响。这是一个非常重要的结果，即将漩涡管将来应用于燃气轮机刀片中的冷却通道中。出口几何形状的流动独立性显示，将来可以在技术应用中很好地应用漩涡冷却。复杂的流场和旋风冷却室中的热传递受到稳定效应的强烈影响。在这里，漩涡数对于流场稳定性和试管中心中的回流区域的出现起着重要作用。先前的调查仅处理高漩涡数，因此在所有情况下都发生了回流区域。这是关于缺少漩涡数低的回流区域的生成的详细研究。因此，该项目的第二阶段的目的是理解和描述管芯中回流的基本原理以及对传热的影响。尤其是涡流分解及其过渡区域的影响，应详细研究。在这里，非常有趣的是，在核心开发中，旋转数量A的回流区域以及它如何影响旋风冷却室的冷却能力。Furthermore先前的投资显示了稳定的螺旋涡流结构的形成。这些次级涡旋对旋流管中的传热影响很大。因此，该项目的进一步目标是了解主要涡流和次要涡流之间能源转移的知识。因此，应详细研究注入漩涡管中的水。由于注水，将添加额外的能量。这个想法是通过蒸发热来操纵管芯中固体涡流的角速度。这是对固体涡流和热传递的影响，应详细研究。