Turbine Cavity Mainstream Ingestion Assessing Method Based on Penetration Depth Analysis

Abstract

The turbine cavity faces challenges from external mainstream ingestion, mitigated by sealing flow from the compressor side. Despite these efforts, achieving complete sealing remains difficult. This study focuses on introducing the ingress penetration depth δp as a novel perspective for evaluating the consequences of external ingestion in turbine cavities. Penetration depth describes how deeply the mainstream ingestion can affect the turbine cavity. The study commences with an examination of the flow within the turbine cavity, specifically highlighting the radial stratification resulting from external ingestion. The examination is grounded in detached eddy simulation (DES) results, which are subsequently validated through experimental data. The radial stratification characteristics observed lay the foundation for introducing the concept of penetration depth. Subsequently, the study proposes a criterion for assessing penetration depth, utilizing the radial distribution pattern of the swirl ratio. To incorporate the penetration depth into the evaluation of sealing effectiveness, a one-dimensional correlation of sealing effectiveness based on turbulent diffusion assumption is established and validated using experimental data from both the current study and existing literature. Based on the correlation method and the penetration depth, the study proposes a series-connected model. The series-connected model is segmented by the penetration depth δp: in regions where r>δp, the one-dimensional correlation is applicable, while in regions where r<δp, the lumped parameter models from existing literature remain valid. The series-connected model can be applied in future turbine cavity investigations and secondary air system reduced-order modeling.