Abstract
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 achieve a long service life. These seals are pressure-activated and adapt 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 hydrostatic advanced low leakage (HALO) seal is presented. Experimental results of the gap width, leakage, and pressure distribution are used in combination with two-dimensional (2D) computational fluid dynamics (CFD) to obtain force distributions across the seal for static operation. These data are used to derive a model to predict the forces acting on the seal as well as the operational gap width, which is necessary for a reliable seal design.
