Numerical Simulation On Cooling-Water Around Cylinder For Marine Diesel Engine

The flow and heat transfer of cooling water has directly effect on the cooling efficiencyof diesel engine, the heat load of high temperature parts and the heat distribution and energyuse of whole diesel engine. Although, at the view of energy, the engine cooling is an energyloss process, it is the necessary process during the work of diesel engine. Because it isnecessary to keep the temperature of the high temperature parts within the permissible range,in order to ensure the effective and reliable work of the diesel engine. Generally speaking,the research on cooling performance of diesel engine cylinder has great significance onimproving the diesel engine’s cooling efficiency and the reliability of cylinder liner.The computational fluid dynamics is one of the most important research methods in theresearch on diesel engine cooling problems. During the numerical simulation process ofcooling system, because of the boundary conditions of heat transfer is difficult to determine,most researchers only considered the problem of cooling water flow. In addition, whencalculated the heat transfer, they treated the coolant flow as artificial boundary condition. Inthis paper, the fluid-structure coupling method was used; the three-dimensional couplingmodel of cooling water chamber and cylinder was established. In the model, the coolingwater flow field and cylinder temperature field was coupled, in which way the set of fixedwall temperature and coolant flow boundary condition were avoided. Using the UDFmodule of FLUENT to program the transfer coefficient and temperature at the gas side, andthen the third type boundary condition exerted on the gas side was realized. It made theexertion of the boundary conditions more accurate, by coupling between fluids and solid.The coupling method was used to analyze the cooling water flow field, temperaturedistribution, pressure distribution and the cylinder liner temperature distribution, andcompare the calculation results and the traditional fixed boundary condition calculationresults. The more accurate flow condition of cooling water, pressure distribution, the coolingwater temperature at outlet, and the cylinder liner temperature distribution were obtained,through calculating of flow field and temperature field. The calculation results show that thecoupling numerical simulation method could describe the flow and heat transfer problem ofdiesel engine more objectively. And the calculation results could provide importantreference for the optimized design of cooling system.