| In recent years, the energy conservation and emission reduction aboutautomobiles have been become a hot issue with the rapid development of theautomobile industry, at the same time, it is attracting a great many scholars toinvestigate among domestic and foreign. The structure and shape about the dieselhelical intake port directly affect the flow characteristics. There are swirl ratio andflow coefficient judge the flow characteristics. Therefore, how to effectively improvethe intake port flow characteristics is an effective way to achieve the end of energyconservation and emission reduction. At the end of twentieth century to earlytwenty-first century, with the theoretical and advanced measurement technology, theeffect of bionic non-smooth surface adhesion and resistance reduction has beendeveloped and applied widely in mechanical engineering. From the bionicnon-smooth surface adhesion and resistance reduction theory and the existing researchresults, we can apply it to the inner surface of intake port. Through measuring swirlratio and flow coefficient to verify the bionic non smooth surface positive effect onintake port flow characteristics, and puts forward a new technology to improve dieselengine intake port, making the automobile achieve the end of energy conservation andemission reduction.Based on the model of bionic non-smooth surface intake port numericalsimulation, calculated the swirl ratio and flow coefficient and compared with themfrom the model of smooth surface intake port. Checked the bionic non smooth surfaceon the intake port has promoting effect for the flow characteristics. Firstly, study ofexisting theory and technology, combined with the specific structure and shape ofdiesel engine intake port. Chose four kinds of bionic non-smooth units including pit,convexity, U shape groove and V shape groove, and experimentally selected elementsize. The width of pit and convexity units were chose3mm,4mm and5mm; the widthof U shape groove units were chose4mm,6mm and8mm; the width of V shapegroove units were chose1mm,2mm and3mm. The depth of four kinds of bionicnon-smooth units were chose all of0.5mm,1.0mm and1.5mm. In the process of numerical simulation, software of CAITA is applied to3D modeling; Hypermeshmodel; FLUENT software was used to analyze the flow field.Exported the corresponding data after finishing numerical simulation, computedevery intake port models’ swirl ratio and flow coefficient by Ricardo. Analyzed thedata through listing and drawing the scatterplot and found out the optimal valuesabout every model. At last, found out the optimal level and the primary and secondaryfactors of each kind of bionic non-smooth unit by orthogonal test and extremedifference analysis.Analyzed the swirl ratio and flow coefficient come from the many kinds ofbionic non-smooth surface intake port models and smooth surface intake port model,we can get such results as follows. Small change in the flow coefficient of bionicnon-smooth surface intake port model usually became smaller than the smoothsurface intake port model, but, the data is small. Considering the error caused bynumerical simulation, so it can be regarded as the bionic non-smooth unit does notplay the role of the flow coefficient of intake port. The bionic non-smooth unit has agreat influence on the formation of swirl ratio, can be seen from the data that thebionic non-smooth surface of intake port models swirl ratio generally increased,individual intake port models swirl ratio decreased. Analyzed the reason may bebecause of the bionic cell size difference. From these non-smooth surface intake portmodels, we can result that the pit bionic non-smooth unit affects the swirl better thanother three bionic non-smooth units. The role of4mm-1.0mm in the concave elementon the inlet swirl is the largest, followed by4mm-1.0mm convex shape bionic unit,again is6mm-1.5mmU shaped groove biomimetic units, and finally2mm-0.5mmVshaped groove biomimetic units. |
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