Fractal-generated turbulence and mixing: flow physics and some industrial implications

迫切需要基于新的流动概念的新的工业流动解决方案，以满足急剧变化的能源、环境和气候约束所提出的前所未有的要求。我们需要的不仅是对现有解决方案的改进，而且是能够显著提高能源节约和减少对环境的不利影响的激进的新发展。由于现有的湍流模型不能不加区别地应用于全新的流动概念，因此发展新的流动概念最终需要前所未有的数值模拟和实验室实验。一个最新的例子是源于英国的新流动概念是由分形网格产生的湍流。Imperial Innovation最近的专利申请、Imperial的概念验证研究和各种流行的科学和工程期刊(食品制造，2008年6月；《化学工程师》，2008年7月；过程工程，2008年7月；特种化学品，2008年9月；科学计算世界，2008年8月；见http://www3.imperial.ac.uk/tmfc/popular))证明了这一类新的流动概念为工业混合器、静音式空气制动器和扰流板、自然通风、遮阳顶和燃烧提供了替代解决方案。在这项建议中，我们将重点放在新的工业静态在线混合器上。这些新的流动概念也给湍流研究和建模带来了意想不到的挑战。在过去的60年里，湍流方面的工作主要是对特定的湍流进行特别的模拟，进展有限。如果我们想要一系列新的流动概念的发展成为现实的可能性，就需要对湍流动力学有一个基本的了解。为此，需要一个设计良好、针对性强的实验，其中可以脱离关节来设置激流动力学，以便给我们提供如何理解它们的线索，如果可能的话，还可以控制它们。这是本研究方案的另一个重点，它与第一个直接相关，因为两者都与同一个新的流动概念有关：由分形网格产生的湍流。

New industrial flow solutions based on new flow concepts are urgentlyneeded to meet the unprecedented requirements set by the dramaticallyevolving energy, environmental and climatic constraints. What isneeded is not just improvements to existing solutions, but radical newdevelopments that can dramatically increase energy savings and reduceadverse environmental impacts. The development of new flow concepts onwhich such solutions will eventually be based requires unprecedentedfully resolved simulations and laboratory experiments because existingturbulence models cannot be applied indiscriminately on radically newflow concepts.One very recent example of a new flow concept originating from the UKis turbulent flows generated by fractal grids (figure 1). As attestedby recent patent applications by Imperial Innovations,proof-of-concept studies at Imperial and reports in various popularscience and engineering periodicals (Food Manufacture, June 2008; TheChemical Engineer, July 2008; Process Engineering, 18 July 2008;Speciality Chemicals, September 2008; Scientific Computing World,August 2008; see http://www3.imperial.ac.uk/tmfc/popular) this classof new flow concepts offers alternative solutions for industrialmixers, silent airbrakes and spoilers, natural ventilation, sun-roofsand combustion. In this proposal, we focus on new industrial staticinline mixers.These new flow concepts also pose unexpected challenges to turbulenceresearch and modelling. Over the past 60 years, efforts in turbulencehave been mostly in ad-hoc modelling of specific turbulent flows andthe progress has been limited. A fundamental understanding ofturbulence dynamics is needed if we want the development of an entireraft of new flow concepts to become a realistic possibility. For this,a well-designed and well-targeted experiment is required where theseturbulence dynamics can be set out of joint so as to give us clues forhow to understand and, if possible, control them. This is the otherfocus of this research proposal and it directly relates to the firstbecause both relate to the same new flow concept: turbulence generatedby fractal grids.