A fundamental investigation into brush seal fluid dynamics

刷式密封件是在燃气涡轮机发动机内使用的一种类型的轴密封件的一个示例。它们通过一个由密集排列的细钢丝刷毛（通常是金属的）构成的静态环提供的高流动阻力来保持压降，这些钢丝刷毛与部件的旋转方向成一定角度。这种类型的密封可以实现极低的泄漏，使其成为燃气涡轮机设计人员极具吸引力的选择。尽管在燃气涡轮机中使用刷式密封的好处早已确立，但由于使用性能的迅速恶化，它们在航空航天应用中的应用尤其受到限制。已经确定了这种快速磨损的流体动力学机制，如刷毛吹落和压力硬化。为了更容易地在整个燃气轮机中实施刷式密封，并允许利用潜在的好处，需要更好地了解这些影响。刷式密封通常使用多孔介质方法进行理论建模，其中密封对流量的影响由一组阻力系数定义。这些系数必须使用实验数据进行校准，以便能够正确地外推到发动机条件。目前文献中明显缺乏已发表的实验值，本提案旨在通过大规模简化实验测量，提高对刷式密封的基本理解，并为多孔介质模型提供验证数据。该计划将与Cross Manufacturing Ltd.密切合作，世界领先的燃气涡轮机行业刷式密封供应商。所获得的见解将提供一个数据库，该数据库将用于通知未来刷式密封配置的设计，不仅是Cross，而且是更广泛的燃气涡轮机行业。

Brush seals are one example of a type of shaft-seal used within gas turbine engines. They maintain a pressure drop by virtue of the high resistance to flow provided by a static ring of densely packed, fine wire bristles (usually metallic) that are angled in the direction of rotation of the component. Very low leakage is possible with this type of seal making it a highly attractive option for gas turbine designers.Although the benefits of using brush seals in gas turbines have long been established, their utilisation in aerospace applications especially has been limited due to the rapid deterioration of in-service performance. Fluid-dynamic mechanisms for this rapid wear have been identified such as bristle blow-down and pressure stiffening. For brush seals to be implemented more readily throughout gas turbines and to allow the potential benefits to be exploited, a greater understanding of these effects is required. Brush seals are typically modelled theoretically using a porous medium approach where the influence of the seal on the flow is defined by a set of resistance coefficients. These coefficients have to be calibrated using experimental data to enable correct extrapolation to engine conditions. There is currently a distinct lack of published experimental values available in the literature.This proposal aims to improve the fundamental understanding of brush seals and provide validation data for porous media models by making measurements in large-scale, simplified experiments. The programme will be conducted in close collaboration with Cross Manufacturing Ltd., a world-leading supplier of brush seals to the gas turbine industry. The insight obtained will provide a database which will be used to inform the design of future brush seal configurations, not only by Cross but also the wider gas turbine industry.