A fundamental investigation into brush seal fluid dynamics

刷式密封是燃气轮机发动机中使用的一种轴封。它们保持了压力降，因为由密集排列的细丝刷毛(通常是金属)组成的静态环提供了高阻力，使其与部件的旋转方向成角度。这种类型的密封具有极低的泄漏率，使其成为燃气轮机设计者非常有吸引力的选择。尽管在燃气轮机中使用刷式密封的好处早已确定，但由于在使用中性能的迅速恶化，它们在航空航天应用中的使用受到了限制。已经确定了这种快速磨损的流体动力机制，如刷毛脱落和压力硬化。为了更容易地在整个燃气轮机中实施刷式密封，并使潜在的好处得以发挥，需要对这些影响有更多的了解。刷式密封通常采用多孔介质方法在理论上模拟，其中密封对流动的影响由一组阻力系数来定义。这些系数必须使用实验数据进行校准，以便能够对发动机状况进行正确的外推。目前文献中明显缺乏已发表的实验值，这项建议旨在通过大规模简化实验的测量来提高对刷状密封的基本理解，并为多孔介质模型提供验证数据。该计划将与世界领先的燃气轮机电刷密封件供应商Cross制造有限公司密切合作。所获得的洞察力将提供一个数据库，该数据库将用于不仅是克罗斯，而且是更广泛的燃气轮机行业，为未来刷式密封配置的设计提供信息。

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.