Simplified Ingestion Model Assessment for 1D Gas Turbine Engine Secondary Flow Network Available to Purchase

Modeling of hot gas ingestion in a gas turbine engine is critical because its accuracy directly affects performance as well as turbine durability. In this paper, ASU ingestion test rig data accompanied by its published ingress/egress discharge coefficients (Cd_i and Cd_e , formulation) are used to propose a simplified 1D ingestion model embedded in the secondary air system software (Network). The proposed externally induced ingress model includes separate boundary nodes with equal static pressure in the annulus hub, and distinct circumferential pressure variation in the form of normalized annulus pressure at the hub (P₁ – P_1avg)/(P_1max – P_1min). The corresponding Cd_i and Cd_e for the engine conditions are scaled based on rig-to-engine non-dimensional minimum purge, Cw_min where engine Cw_min uses the actual (P₁ – P_1avg)/(P_1max – P_1min) derived from previously published CFD data along with the effective rim-seal overlap clearance. The vane pitch integrated driving pressure difference at the hub for the ingestion used in the orifice model comes from an embedded saw-tooth assumption on the circumferential pressure profile. Recirculation of ingested hot gas from the upper rim cavity to the lower wheel space is considered by comparing the supplied purge flow to the rotating disc entrainment requirement. The proposed model is compared with another model based on constant Cd_i / Cd_e ratio of 0.14 published by the University of Bath. Engine test data from a previously published engine configuration is used to assess the appropriate model for engine. The probability of failure in violating the lower rim cavity sealing effectiveness limit based on analysis of variation (AOV) was conducted under both formulations and the results are presented.