Dimensionless Numbers Relationships for Outer Air Seal of Low Pressure Turbine

Abstract

The dimensional analysis and the numerical parametric study of the typical outer air seal from a low-pressure turbine were performed in the framework of the presented paper. The most crucial variables for the flow through the outer air seal were identified and further dimensionless numbers were derived. The dependent quantities resulting from the analysis were: the axial Reynolds number (formulated with the bulk velocity, corresponding to the mass flow through the seal), the outlet swirl ratio (incorporating the exit flow angle, important for mixing) and the windage heating (related to the internal losses). Additionally, the discharge coefficient was cross-checked enabling further comparison with the available literature. The comprehensive numerical parametric study included all important contributors for the flow through the seal with a parameter operating range appropriate for engine outer air seals.