Experimental and numerical investigation of the flow and heat transfer in conical Swirl Cooling Chambers

锥形涡流冷却室中流动和传热的实验和数值研究

• 批准号: 363548659
• 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
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/363548659?language=en
• 关键词: Experimental; numerical; investigation; flow; heat

The main goals in the development of industrial gas turbines and aero-gas turbines are the reduction of fuel consumption as well as the drastic reduction of pollutant emissions. This can be achieved, for example, by increasing the thermal efficiency of the gas turbine with the help of an increase in the process temperature. However, the increased combustion chamber temperature and the increased turbine inlet temperature are today already well above the melting temperature of the blade material, which makes it necessary to develop efficient turbine blade internal cooling strategies. Currently, various internal cooling concepts are being investigated in detail, such as ribbed channels, pin fins, impingement jets, dimples and cyclone cooling chambers. Cyclone cooling (swirl cooling or vortex tubes) are characterized by very high heat transfer rates. In the first funding period (FP1) of this project, vortex tubes with convergent tube cross-sections in the flow direction were investigated both experimentally and numerically. Here, a very good agreement between measurement results, such as the heat transfer measured with the transient liquid crystal technique and Detached Delayed Eddy Simulations (DDES) could be achieved. In addition, stability effects play an important role in heat and mass transfer processes. Therefore, the stability of the flow in the vortex tube was investigated using various stability criteria, with a focus on the stability criterion by Marsik, which is based on the second law of thermodynamics. In the current proposal for the second funding period (FP2), the investigations are now to be extended to cyclone cooling chambers with diverging cross-sections in the main flow direction. Due to the widening cross-sectional area in the direction of the flow, the swirl and the resulting detachment areas are significantly influenced. The flow is, thus, destabilized in a targeted manner. It is expected that the shaping will lead to higher heat transfer rates. Analogous to FP1, the flow and the heat transfer in the divergent cyclone cooling chambers will be investigated numerically by means of DDES and experimentally by means of PIV and the transient liquid crystal method. Furthermore, stability investigations for this geometry will again be carried out based on the second law of thermodynamics. At the end of the project, after six years, there will be detailed knowledge about the influence of convergent and divergent cross-sectional flows in swirl cooling chambers. This understanding of the very complex flow and heat transfer in convergent and divergent vortex tubes should help to successfully use such cooling systems for blade cooling in the future, for example in new types of gas turbine blades.

工业燃气轮机和航空燃气轮机发展的主要目标是减少燃料消耗以及大幅度减少污染物排放。这可以实现，例如，通过在过程温度的增加的帮助下增加燃气轮机的热效率。然而，随着燃烧室温度的升高和涡轮入口温度的升高，目前已经远远超过了叶片材料的熔化温度，因此有必要开发高效的涡轮叶片内部冷却策略。目前，各种内部冷却概念正在被详细研究，如肋形通道、钉鳍、撞击射流、凹窝和旋风冷却室。旋风冷却（漩涡冷却或漩涡管）的特点是非常高的传热率。在本项目第一资助期（FP1），对管截面在流动方向上收敛的涡管进行了实验和数值研究。在此，瞬态液晶技术测量的传热结果与分离延迟涡模拟（DDES）的测量结果非常吻合。此外，稳定性效应在传热传质过程中也起着重要作用。因此，本文采用各种稳定性判据对涡流管内流动的稳定性进行了研究，重点研究了基于热力学第二定律的Marsik稳定性判据。在第二个筹资期（FP2）的目前提案中，调查现在将扩展到在主要流动方向上具有不同截面的旋风冷却室。由于在流动方向上横截面积变宽，旋流和由此产生的分离面积受到显著影响。因此，以一种有针对性的方式破坏了流的稳定性。预计成形将导致更高的传热率。与FP1类似，本文将采用DDES对发散式旋风冷却室内的流动和传热进行数值研究，并采用PIV和瞬态液晶法进行实验研究。此外，这种几何结构的稳定性研究将再次基于热力学第二定律进行。在项目结束时，也就是6年之后，将会对旋流冷却室中汇聚和发散截面流的影响有详细的了解。这种对汇聚和发散涡旋管内非常复杂的流动和传热的理解，应该有助于在未来成功地将这种冷却系统用于叶片冷却，例如在新型燃气轮机叶片中。