Simulation Analysis Of Coolant Flow And Heat Transfer On Hydraulicfree Piston Diesel Engine

In China, Its late to start research the hydraulic free piston engine, until now, there haveonly a few universities studied it. As hope for the future of the internal combustion engineindustry, it is a collection of modern hydraulic technology, internal combustion engines,control technology in one of a new specialty engines. Although starting, frequency controland hydraulic are central to the preliminary design of HFPE, the engine’s cooling systemshould not be neglected.Cooling system is one of the important parts of the engine. To ensure that the engineoperates at a normal temperature range, we need rational design of the cooling system. Inaddition to the necessary accessories, the high-quality structure of the water jacket is themost important factor to affect the cooling effect. On the one hand, the good structure ofwater jacket allows the coolant flow more uniformity, then reducing the thermal load,improving the reliability and durability of the engine; the other hand, good structure of waterjacket may reduce the coolant flow resistance, and thus reduce engine power consumptionand increase the engine’s economy indirectly. Currently, computer simulation is the mostimportant means to study the flow and heat transfer of the cooling water jacket.For the above, attached to the project of research group, this paper carried out thesimulation and calculation of water jacket’s flow and heat tranfer for the hydraulic freepiston engine with the three-dimensional CFD software. Through the analysis of thecalculation results, we optimized design to structure of the water jacket. This provides areference for the design of key parts of the engine.This thesis has six chapters, the first and second chapters are about the background andtheory; the third, fourth and fifth chapters is the main content of the full paper; the chaptersixth is about the summary the outlook. The first chapter has a brief description with thestatus of the development and structure principle of hydraulic free piston engine，and there isa brief description about research methods、feasibility analysis、research background and significance in domestic and foreign; the second chapter is about the basic theory of thenumerical simulation of flow and heat transfer, including the introduction of CFD software,the equations of numerical simulation, solving of equations, boundary conditions, turbulencetheory and thermal elasticity theory; the next three chapters is the main content about flowfield: firstly, we have a simulation for the flow of the cooling water jacket: The use ofPRO/E software to establish a three-dimensional model of the engine, and then import it intoICEM to mesh, finally, calculating in FLUENT. The analysis concluded: there is some lowvelocity regions in cylinder head; the inlet side if the flow is too large, the upper area of theair intake exist insufficient cooling, the total pressure is distributed uniform; the loss of totalpressure from import to export is11kpa; then propose optimization scheme based on flowfield analysis results. Increasing the size of the four outlet in different levels, adding a newwater jacket structure in the nose area, modify the upward angle of the water jacket inletfrom30°to25°; finally, import the modified model into ANSYS, knowing from thecontours of stress and strain that the maximum strain is0.2441mm, the maximum stress is210Mpa, they are all within the scope of the material can withstand. The results prove thatthe optimization of the engine water jacket structure is right, the effect is obvious.