Measurements and Modeling of the Movement Behavior of a Radial Adaptive Seal

The radical change in the energy market with a raising share of renewable energy production leads to new operating cycles in turbo machinery. The machines must be optimized for frequent transient load cycles and part load utilization. New radial adaptive sealing concepts in the secondary air system can help to increase part load efficiency and a long service life. These seals are pressure-activated and change their gap width during operation. The sealing concepts have to be analyzed in more detail to fully understand their operational behavior. In this paper a model to understand and predict the movement of a radial adaptive seal called HALO seal is presented. Experimental results of the gap width, equivalent gap width and pressure distribution are used in combination with computational fluid dynamics (CFD) to gain force distributions across the seal. These data is used to obtain a model to predict the forces acting on the seal as well as the operational gap width.