Experimental visualization of two-phase flow inside a real-size piston of a crosshead-type marine engine

Abstract

ABSTRACT The oscillating cooling method is one of the most effective cooling solutions to improve the piston cooling ability for diesel engines. Most of the experimental studies were focused on the simplified model, and few were based on the actual complex piston cooling cavities. To give a better insight into the flow mechanism inside the actual cavities, a flow visualization test rig was built based on a real-size piston model with a stroke of 1550 mm and a cylinder diameter of 350 mm. The model replicates the piston and cooling cavities of a typical low-speed two-stroke crosshead marine engine MAN B&W 6S35ME. The test rig ensures that the coolant supply mode, the coolant flow path, and the kinematic curve of the piston head are consistent with the real machine. The piston model is an exact replica of the original scale made of PC material. A high-speed camera was used to capture the transient flow patterns of the gas-liquid two-phase flow inside the cooling cavities during the reciprocating motion of the whole stroke. More accurate boundary conditions are thus provided for the numerical simulation method, which significantly improves the accuracy of previous simulations under the same research topic. Analysis of the piston’s oscillatory cooling method is beneficial to optimizing the thermal management of engines in the future.