Journal of Computational & Applied Research in Mechanical Engineering (JCARME)

Articles in Press

Document Type : Research Paper

Authors

¹ Department of Mechanical Engineering, Iranian Research Organization for Science and Technology, Tehran, 3313193685, Iran

² School of Engineering, Macquarie University, Sydney, 2109, Australia

³ Mechanical Engineering Department, Iran University of Science and Technology, Tehran, 1684613114, Iran

https://doi.org/10.22061/jcarme.2025.11373.2495

Abstract

Hot gas ingestion, due to pressure differences in the turbine’s main flow path, is a challenge for gas turbine designers. It reduces aerodynamic performance, increases temperature gradients and thermal stresses, and decreases disk life. Designers should predict the ingestion and use the precise design of the cooling system, balancing the cooling and sealing flow, to enable the turbine to operate at higher temperatures (TIT) and efficiency to save costs and reduce harmful effects on turbine components. This paper presents a numerical investigation of a 1.5-stage test rig to study the ingestion phenomenon. A numerical tool was developed to enhance the coefficients and constants of a rapid ingestion model in a zero-dimensional secondary air system (SAS) code applicable to power plant turbines, such as Frame 9. Comparisons of CFD and test results demonstrate satisfactory agreement. Combining CFD and experimental validation, a numerical effectiveness map for the selected test rig rim seal is presented. CFD results post-processing reveals that increased cooling flow rate increases the pressure within the wheelspace, reduces swirl in the core region, and improves seal effectiveness. The swirl ratio was highly sensitive to SAS flow, increasing by 90% with a 50% reduction in SAS flow at a dimensionless radius of 0.85. Analysis of flow vectors exiting the axial clearance rim seal indicates that increasing the SAS flow rate enhances the main gas path flow disturbances. Moreover, at a constant flow rate, an increase in the first wheelspace flow rate increases the effectiveness of the second wheelspace by approximately 33%.

Graphical Abstract

Keywords

Main Subjects

Computational Fluid Dynamics (CFD)

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Journal of Computational & Applied Research in Mechanical Engineering (JCARME)

Articles in Press, Accepted Manuscript
Available Online from 18 May 2025

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