Pressure oscillation and vortex in an asymmetric T-junction

The T-junction structure with one inlet and two outlets is ubiquitous in natural and aerospace systems. However, previous research has mainly focused on vortex breakdown under steady-state flow in symmetrical structures. Limited research has been conducted on vortex breakdown in asymmetric structures, where the radii of the two channels differ. This creates a flow rate difference between the outlets, and the ratio of mass flow rate in the small channel to the large channel is defined as the splitting ratio. To study the appearance of vortex structures in the outlet channel under different flow rates and splitting ratios, a split-type asymmetrical circular cross-section pipeline experimental system that can be flexibly disassembled was designed and built. Pressure signals of each channel using pressure sensors were measured and analyzed. It is worth noting that a string tracing technology combined with particle image velocimetry (PIV) technology to monitor the outlet channel was adapted to visualize the flow. Results show that the pressure oscillations in the channels of the T-junction are related to the splitting ratio. Besides, asymmetric T-junction structure exhibits different large vortex structure formation and breakup processes in the two outlet channels, and these processes are influenced by the splitting ratio.