Study On Design Of Flow Channel Structure In Bridge Zone Of Cylinder Head Considering Enhanced Heat Transfer

Due to the poor working environment,the cylinder head often fails due to heat load,and its cooling ability becomes a key factor restricting the development of the diesel engine toward high power density.At present,the means to improve the cooling capacity of the cylinder head mainly focus on the optimization of flow parameters and the layout of the incylinder flow channel.However,few studies have been conducted on the heat transfer enhancement of the surface structure of the water channel.To this end,this paper aimed at the heat load of the nasal bridge channel,through the design of different surface structure,so as to enhance the heat transfer capacity of the bridge area.Under high heat load,convection and boiling both forms of heat transfer in the nasal passages.Therefore,the energy equations of boiling heat transfer and convection heat transfer are respectively analyzed,and the field synergy principle of velocity field and temperature field is obtained for the theoretical guidance of enhanced heat transfer.And by increasing the core of vaporization and the bubble detachment,Strengthen the direction of boiling heat transfer.Finally,the flow channel surface structure is designed to enhance the flow disturbance and expand the heat transfer surface area.In order to improve the heat transfer in the nasal bridge,the simulation of the performance of a high-strength diesel engine is carried out by using the performance simulation software.The thermal boundary conditions for the fluid-solid coupling simulation of the cylinder head are obtained.Coupled heat transfer simulation analysis.The simulation results were post-processed,and the data of flow conditions in the nasal bridge were extracted as the boundary conditions for subsequent experimental study.In the experiment,the section of the exhaust bridge nasal bridge along the runner section was simplified and a simplified flow boiling heat transfer experimental platform was set up,and the working condition data extracted from the above simulation was used as the experimental boundary condition.The design of the structure of the surface flow heat transfer experiments to study the heat transfer characteristics of various structures.The heat flow distribution model of boiling wall is selected to simulate the fluid-solid coupling heat transfer of simplified flow paths of various structures.Based on the condition of the cylinder head water chamber,the bubble diameter and bubble average diameter in the boiling model were checked to improve the simulation accuracy.Through the simulation and experiment,the simulation of heat transfer on the structure surface is carried out,and the structural optimization design is carried out according to the related results.Finally,the surface structure of the nasal flow channel with high heat transfer capability is obtained.