Study On Swirl Characteristics Of Air Cooled Diesel Engine With Swirl Chamber Of Two-pass Channels

In China, small air-cooled diesel engine plays an important role in many fieldssuch as agricultural machinery, small vessels and especially in agricultural economy.However, swirl chamber diesel engine still is of some shortcomings such as highthermal loads, higher fuel consumption and so on. Therefore, further research andimprovement of the performance of swirl chamber air-cooled diesel engine, especiallythe optimization of the combustion system, are of great practical significance inaccordance with the domestic situation. So far, researches on shape, size, location andother factors of connection channel in swirl chamber diesel have always been focused,but study on divergence angle and number of the connecting channel have not beenreported.This paper takes two engineering projects as background, that are DevelopmentBH175F1Dual Vortex Combustion System of the enterprise-entrusted projects andResearch on Small Air-cooled Diesel Engine Combustion System of the researchprojects of Hunan Provincial Department of Education [09K104]. This paper focuseson the influence of the connecting channel divergence angle on the vortex chamberdiesel performance. The nine structure designs of double channel insert block areobtained by first changing the angle of the connecting channel divergence and then byanalyzing the numerical simulation and experimental verification.The main work andinnovations are as follows:Nine kinds of dual-link channel divergence swirl chamber structure with differentangles are rationally devised. The design complies with the swirl chamber dieselengine inserts research foundation and the necking effect to flaring law of fluid motionbased on hydrodynamics theory.Numerical model of gas flow in dual vortex combustion system is establishedbased on fluid dynamics software FLUENT. Three-dimensional unsteady numerical isapplied to three kinds of dual-channel designs. Simulation reflects the impact of thedivergence angle of the connecting channel on the diesel economy, emissions, etc. Itcan be predicted how the different divergence angles of dual swirl chamber influencefuel consumption, smoke number, and other parameters. Simulation and experimentalresults proves the reliability of the proposed simulation model and the effectiveness ofexperimental method. This paper conducts nine programs based on the analysis of numerical simulationand experimental results. From the experimental results, it can be concluded that whenchannel A is fixed and divergence angle of channel B overgrows, performance of dualswirl chamber vortex is deteriorated. Contrarily, the opposite condition is conductiveto its performance. Among the experimental schemes, the best properties of dual swirlchamber vortex are obtained when divergence angle of channel A reaches10°and Breaches5°. This condition is much better in aspects of swirl intensity, channel flowrate and flow resistance, and it provides certain evidence and technical reference forthe improvement of swirl chamber air-cooled diesel engine performance and isbeneficial to both the design and optimization.