Internal flow characteristics of radial rotating oscillating heat pipe filled with acetone or water

Abstract

The study investigates the internal flow dynamics of radial rotating oscillating heat pipes (RaRo-OHPs) to assess their potential applications in rotations. It examines influences of heat flux and centrifugal acceleration on thermal conditions and internal flow in RaRo-OHPs. Results show that both Bo and Fr rise significantly with increased centrifugal acceleration and heat flux, emphasizing radial rotation's impact on internal flow. With increment of heat flux and centrifugal acceleration, flow pattern analysis reveals shifts from slug/annular flow to churn flow/separation of vapor-liquid phases; motion modes progress from pendulum oscillation to circulation, then oscillation or single/double-side boiling. Visualizations underscore the importance of maintaining vapor slugs and liquid plugs for effective circulation flow and heat transfer. It is noted that under radial rotation, slug flow and the circulation of chains of vapor slugs and liquid plugs were still observed, achieving Bo of 8.26 for acetone and 5.10 for water as the working fluid. Compared with the static state, radial rotation can promote the internal flow, the velocity increases by 228% and 185% for RaRo-OHPs filled with acetone and water, respectively. The study emphasizes the capillary effect's role in enhancing internal flow under radial rotations, crucial for improving thermal performance.