Biradial 터빈의 축방향 높이에 따른 내부 와류 구조와 압력 분포 특성

Abstract

This study investigates the effect of axial blade height (H) on the internal flow and aerodynamic performance of a biradial turbine in oscillating water column (OWC) wave energy converters. The axial-to-radial ratio (H/R) was varied from 0.98 to 1.23, with a focus on analyzing its effects on turbine efficiency (η), pressure fields, and vortex formation within the turbine. The results revealed that H/R = 1.23 delivered the highest efficiency (η ？ 0.72), highlighting the significant impact of axial blade height on the aerodynamic behavior of the turbine. At this ratio, pressure distribution was more uniform, and vortical structures visualized via the λ₂ criterion were coherent and aligned along the axis, indicating improved flow stability. In contrast, the H/R = 0.98 case showed irregular vortices and reduced flow coherence. These results underscore the importance of internal flow behavior and suggest that maintaining H/R between 1.1 and 1.12 offers an optimal balance between efficiency, stability, and pressure recovery for design.