•Visual experiments are performed on nine-turn acetone charged CLPHP.•Multiple steady states and recovery zone are observed and analyzed.•A flow pattern transition criterion based on velocity is proposed.•Channel wise displacement-velocity-frequency analysis is performed.•Thermo-hydrodynamic characteristics of a CLPHP are synchronized and quantified. Pulsating Heat Pipe (PHP) remains a contemporary research interest due to its promising merits in the field of thermal management of various engineering applications. Thermal performance of a PHP is greatly influenced by various operating parameters. Heat input is one of the significant parameters that alter the intricate two-phase flow physics in a PHP. The present research is aimed to explore channel wise intricate thermo-hydrodynamic characteristics as a function of heat input (10 W–200 W) and its influence on the thermal performance of nine-turn acetone charged Closed Loop PHP (CLPHP). Filling Ratio (FR) is kept as 50% and vertical bottom heating position is considered. Flow visualization is carried out using a high-speed camera (Photron FASTCAM Mini UX100) and images are processed on Photron FASTCAM Analysis (PFA ver. 1.2.0.0) software. Flow patterns, shape of meniscus, liquid-vapor volume fraction, circulating/oscillating characteristic based on channel wise bubble displacement and velocity-frequency distribution are investigated. Synchronization of hydrodynamic characteristics with thermal performance parameters is performed. Multiple steady-states and recovery zone are identified and analyzed. A flow pattern transition criterion based on velocity is proposed. The trend of displacement-velocity-frequency with heat input is developed. The present quantified analysis will be helpful to design and develop CLPHP based engineering applications.