| Since the “Eleventh Five-Year Plan”, China’s shipping industry has developedrapidly, being one of the important shipbuilding countries in the world. As the powerprovider of shipping industry, diesel engine is in favor with its high efficiency, lowenergy consumption and high power. As one of the key parts of diesel engine, intakeport has a great effect on the amount of air entering the cylinder and the ability toform vortex, which affect the formation of the mixture gas in the cylinder and thecombustion process, thereby affect the power performance, economy and emissionsperformance of the diesel indirectly. In this paper, A ship diesel engine intake port istaken for the study, with the aid of computer aided design technology CAD, the authorbuilds the parametric model of intake port, analysis the velocity field, turbulentkinetic energy field and trace line graph of the intake system made up of intakeport-valve-cylinder by means of three-dimensional numerical simulation technologyCFD. At last, the optimization of the intake port is studied by using multidisciplinarydesign software Isight. The specific contents is as follows:(1) This paper expounds the design ways of intake port and the related theory ofnumerical simulation, analysis the energy loss inside the intake port, researches theway to calculate the flow property evaluation parameters of intake port.(2) On the basis of the further reading literature at home and abroad, the authoranalysis three parametric modeling methods of the helical intake port. The modelestablished by every method is used for the numerical simulation of steady flow basedon the CFD numerical simulation technology, finally putting forwards a way based onthe involute equation, which can generate new intake port models of different sizesconveniently, improving the design efficiency greatly.(3) Through the three-dimensional numerical simulation, we can get not only themacroscopic flow characteristics such as flow coefficient and swirl rate but also themicro-information of internal flow, which provide an important basis for the designand optimization of the intake port. In this paper, on the platform of CFX software, k-ε turbulence model and SIMPLE algorithm are used for the simulation of the intakeport, the author analysis the flow field information in different value lift, includingvelocity field, turbulent kinetic energy field and trace line graph, calculates the flowcoefficient and swirl rate which are used to evaluate the flow property of intake port as well. Furthermore, the author discusses the effect on the intake port flow propertiesof different key structural parameters, which provide a theoretical basis for theoptimization of the intake port.(4) As the flow performance of helical intake port depends on several structuralparameters, the way to optimize the single parameter cannot meet the needs of intakeport improvement. So in this paper, the systematic experiment design way is carriedout on the intake port and realized based on the optimal Latin hypercube algorithm,obtaining the factors responding to the flow coefficient and swirl rate greatly throughthe experiment design, these factors are regarded as the design parameter ofoptimization(5) In order to get an intake port which owns better flow performance, the authorjoint the multidisciplinary integration platform Isight to research the optimization ofthe intake port on the basis of numerical simulation and experiment design. Theauthor drives the optimization of the intake port automatically by formulating a seriesof command stream files and the batch files, including modeling, meshing, simulatingand calculating flow coefficient and swirl rate. With the Pointer hybrid optimizationstrategy, this paper reaches the target of maximizing the flow coefficient under thedimension constraints and performance constraints. The result indicates that the flowcoefficient is increased by5.83percent, thereby improve the flow performance of theintake port. |
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