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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.

位于einer zyklonk<e:1> hlkammer的研究项目Wärmeübertragung已经设计了4年。目前的建议是该项目的第二阶段（第三和第四年）。前2年，利用粒子图像测速仪（PIV）对旋流器轴向和周向速度场进行了实验研究，并利用热致变色液晶（TLCs）瞬态技术对旋流器冷却室的传热进行了测量。利用开源程序OpenFOAM对流动和传热进行了额外的模拟。重点是对不同出口几何形状的研究。因此，对180°弯管和切向出口进行了详细的研究。结果表明，这种出口几何形状的改变对旋流管内的流场没有显著影响。这对旋涡管在燃气轮机叶片冷却通道中的应用具有重要意义。有偏转的出口几何形状的流动无关性表明，旋流冷却在未来的技术应用中有很好的应用前景。旋流器冷却室内复杂的流场和换热受到稳定效应的强烈影响。在这种情况下，旋流数对流场的稳定性和管中心回流区的发生起着重要的作用。以往的研究只涉及高旋流数，因此在所有情况下都会出现回流区。因此，缺乏对低旋流数回流区产生的详细研究。因此，该项目第二阶段的目标是了解和描述管芯回流的基本原理及其对传热的影响。特别是对涡旋击穿及其过渡区域的影响进行了详细的研究。在这里，非常有趣的是，在堆芯回流区形成的旋流数以及它如何影响旋风冷却室的冷却能力。此外，先前的研究表明形成了一个稳定的螺旋涡结构。这些二次涡对旋流管内的换热有很大的影响。因此，该项目的进一步目标是扩大对主涡旋和次涡旋之间能量传递的了解。因此，对旋流管注水进行了详细的研究。由于注水，额外的能量将被添加到系统中。其原理是利用蒸发热来控制管芯内固体涡旋的角速度。因此，需要详细研究对固体涡和传热的影响。