VISUALIZATION INVESTIGATION ON OSCILLATORY FLOW PATTERN OF TWO-PHASE FLOW IN THE OPEN OIL COOLING GALLERY OF PISTON

In order to investigate the oscillatory flow and heat transfer process of gas-liquid two-phase flow in an open oil cooling gallery, a reciprocating oscillation experimental apparatus modified from a diesel engine was designed and constructed. High-speed photography was used to observe the oscillatory flow patterns of gas-liquid two-phase flow in the experimental open oil cooling gallery. The flow pattern transitions and characteristics of the gas-liquid two-phase flow under varying rotational speeds and nozzle flow rates were obtained. The results show that during the fully oscillating stage, the dominant flow patterns of the gas-liquid two-phase flow are wavy flow and slug flow, with periodic changes in the flow pattern under identical operating conditions, and the heat transfer temperature measurement experiment was carried out to verify the characteristics of the oscillating flow pattern of two-phase flow. The heat transfer performance is primarily determined by the average filling ratio of the oil gallery under different nozzle flow rates. Engine speed influences the flow pattern, flow field stability, and turbulence characteristics under varying nozzle flow rates, thereby affecting heat transfer efficiency. The study reveals the oscillatory flow behavior of gas-liquid two-phase flow in the open oil cooling gallery, providing valuable reference and basis for the analysis of flow and heat transfer in such systems.