The Research On The Flow Charactersin Dieselengine With Bionic Non-smooth Surface On Twin Intake Port By Using CFD Simulations

With the rapid increasing amount of Chinese vehicle in recent years, the pollutionand the consuming of resource has been a public hot topic in China. The way on howto use the energy resourcein efficient and make it more productive have been thefocus in related fields. Regarding the powerful and economic performance of Dieselengine, it had been widely used in many regions, for this reason, optimized importantparts which as the intake port of diesel engine also has been the key factor to improvethe swirl and flow coefficient. Comparing the traditional intake port with the twinintake port, it has optimized the big scale of swirl during high engine speed which willinfluence the followingcombustion process. Also the twin intake port could solve thisissue during low engine speed which lack of intake air flow.The intake air flow playan important role during the intake process, also will affect the engine performance,fuel consumption and the emissions.From the overview of recent years’ research, the main direction of optimization ismainly on the structure and shapes which can improve the flow characteristics ofintake port.With the development of bionic non-smooththeory, which would cooperatewith the reduce resistance theory and attached it onthesurface of helix and tangentialintake port’s internal surface, that can optimized and improved the swirl and flowcoefficient. When designing the elements, we calculated the boundary layer’s scale,based on the results we calculate the depth and scale of the element. By using theuniformity experiment design, which will be more efficiency and precious than theorthogonalexperiment designing.By using the CATIA and Gambit to create the3D model and mesh the model, thencooperate with the Fluent to simulate the steady and transient conditions which willreflect the real working condition, which were set as900rpm,1500rpmand2100rpm.Analyzed the results from Fluent output data, will set the final scales of the intakemodel.From the results of analysis, the bionic non-smooth surface shows a positive effecton improving the swirl. Also the different types’ combination of bionic non-smooth will have differentimprovement level. Through the analysis of transientmovement, the bionic non-smooth surface also optimized the air flow in the cylinderin different engine speed. The final conclusion as followed, at900rpm, the intake portwith pit and convex non-smooth elements with the diameter3mm and depth3mmcould improve the swirl at31.04%. At1500rpm the U groove with the pit non-smooth element will improve the swirl at23.01%, with the diameter2.5mm and depth0.7mm. When engine speed reached2100rpm, the intake port’s surface combinedwith the V shape groove and smooth surface could improve the swirl at27.13%withthe diameter3mm, depth0.7mm.