Research on multi-disciplinary coupling mechanism between internal flow heat transfer and solid deformation in turbine

Abstract

The turbine of an aircraft engine involves a multi-disciplinary coupling problem that interacts among the flow field, temperature field and solid structure. This study focuses on conducting numerical simulations of a second-stage low-pressure turbine incorporating a disc cavity. Two different multi-disciplinary coupling approaches, namely Conjugate Heat Transfer and Thermal-Fluid-Structure Interaction, are employed to compare the disparities in aerodynamic performance and flow field characteristics. This study aims to illuminate the characteristics of solid deformation and the underlying mechanisms influencing the flow field. The results indicate that the radial deformation of the rotor blade is predominantly governed by thermal load, while the axial and twist deformations are driven by the aerodynamic load. Additionally, circumferential deformation is influenced by both aerodynamic and centrifugal loads. As a result of these deformations, the reduction in the high-loss region at the tip of the rotor blade leads to a localized enhancement in efficiency, while the intensification of secondary flow at other positions along the blade height leads to a reduction in local efficiency. In general, although the deformation at the tip of the rotor blade is the largest, approximately 4.1 mm, the mass flow rate at this location accounts for a small percentage, approximately 3% of the overall flow. Therefore, the increase in local efficiency at the blade tip is insufficient to compensate for the decrease in efficiency at other positions. As a result, the turbine's efficiency exhibits a decreasing trend after deformation, with an average reduction of 0.53% compared to before deformation. Moreover, the radial and axial clearances at the rim are influenced by the centrifugal and aerodynamic loads respectively. Under hot-state, changes in the clearance at rim can reduce gas ingestion, thereby enhancing the cooling effect on solid components inside the disc cavity. The radial clearance at the sealing teeth is primarily influenced by centrifugal load. During hot-state, a reduction in the radial clearance at the sealing teeth leads to an increased accumulation of coolant air at the bottom of the disc cavity, thereby enhancing both cooling and sealing capabilities. Ultimately, the conclusions about the multi-disciplinary coupling mechanisms between internal flow heat transfer and solid deformation provide theoretical insights for designing high-performance turbines.