| In order to adapt to the changing trends of the shipping market and meet emission requirements,large-scale propellers have begun to be used on a large scale in ship design and construction.The longer-stroke,lower-speed G-type diesel engine is welcomed by the market,but its ultra-long stroke brings a great challenge to the cooling and lubrication of the cylinder liner.The cylinder liner is an important part of the combustion chamber.The cooling effect of the cooling water directly affects the stability of the thermal load of the combustion chamber.Therefore,the cooling water needs to have good cooling performance,so as to ensure that the cylinder liner has sufficient strength and good performance.Lubrication to ensure the stable operation of the diesel engine.The research on the cooling water flow and heat transfer of the G-type low-speed diesel engine cylinder liner cooling water cavity has important practical significance,and can provide references for the improvement of the cooling performance,reliability performance and structural optimization of diesel engines and their parts.The main content of this paper includes:(1)According to the original data of the 7G80ME-C diesel engine,the geometric model of the cylinder liner assembly is established,and the three-dimensional model of the cooling water cavity in the cylinder liner is extracted to establish a simulation calculation model.(2)Simulate the cooling water in the cooling water cavity,and comprehensively evaluate its cooling performance based on the parameters such as flow rate,pressure,and convection heat transfer coefficient.(3)Use GT-power to establish a model of the 7G80ME-C diesel engine and simulate the convective heat transfer coefficient of the gas in the cylinder and the near-wall temperature.Based on the fluid-solid coupling analysis method,the near-wall temperature and heat transfer coefficient of the cooling water obtained by the simulation are loaded on the cylinder liner through the mapping of the coupling surface,and the steady-state heat transfer analysis of the cylinder liner is combined with other boundary conditions to obtain the rated operating conditions The steady state temperature field and heat flux density of the lower cylinder liner.(4)According to the simulation results,the structure of the cooling water cavity is optimized and improved,and the simulation results of different schemes are analyzed and compared with the original model simulation results,revealing the influence of the structural changes of the cooling water cavity on the fluid flow and heat transfer characteristics in the cooling water cavity law.According to the analysis results,the overall cooling water flow of the G-type low-speed diesel engine liner is good,there is no flow dead zone;the pressure distribution in the water cavity is uniform,and the inlet and outlet pressure loss is 36 kPa,which mainly occurs in the area of the cooling hole;The maximum temperature of the inner wall of the cylinder liner is 356.8?,which is located in the clean ring area.The temperature in most areas is lower than 300?.In addition,the temperature of the inner wall is higher than the dew point temperature of SO2 and SO3,which can effectively prevent low-temperature corrosion;The circumferential temperature distribution of the cylinder liner is uniform,and the cooling is good,which can ensure the stable operation of the diesel engine.The increase of the radius of the cylinder liner cooling water hole plays a certain role in the cooling of the diesel engine cylinder liner.As the diameter of the cylinder liner cooling water hole increases,the pressure loss of the cooling water decreases,and the maximum temperature of the inner wall of the cylinder liner drops significantly.Through the analysis of the cooling water flow and heat transfer of the cylinder liner,it provides a certain theoretical basis for the optimization of the structure and the improvement of the reliability of the cylinder liner of the G-type two-stroke diesel engine. |
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