分会场

控制与测试

摘要

Abstract Purpose —With the continued increase of IC engine power density, enhancement of piston cooling capacity is more and more urgent for modern diesel engine. Because of considerable problems for large bore and high speed engines, an actual full-size piston oscillating cooling test bench was rarely carried out, and real flow pattern have not been obtained. The purpose of this paper is to study the real flow pattern of main propulsion marine diesel engine piston cooling cavity and validate CFD simulation model by experimental method. To analyze the heat transfer distribution of different district of cooling cavity and study how the cooling cavity structure affect heat transfer coefficient by simulation method. Design/methodology/approach — An actual full-size piston oscillating cooling of a main propulsion marine diesel engine test bench had been built to study the flow pattern and measure oil throughput. Substitute with the same viscous of actual working oil was used in test. Oscillating cooling of piston was simulated by 2-phase flow method by using Fluent software. The turbulence model SST k-ω is used. Simulation model was validated by flow pattern and oil throughput. The trend of different cooling cavity structure of HTC and filling ratio was analyzed. Findings — The simulation results are in good agreement with the experimental results in terms of the throughput data and the observable flow pattern in a strong turbulent state. By analyzing HTC in different area of simulation results, it is found that the peak value of heat transfer intensity on the surface is just behind the top dead point for the period time. Heat transfer coefficient of different district distribution had been obtained. As for cooling cavity structure, the results show that increasing the sectional area of outer cavity do help with the heat transfer of cooling effect. Increasing the connecting duct can increase the filling ratio, but little effect for inner cavity heat transfer. Originality/value — The 2-phase flow simulation model of piston cooling had been validated by test data on a full-size test bench. The HTC distribution simulation results of cooling cavity are valuable for thermal field prediction rapidly of similar piston structure. The HTC and filling ratio changing trend of different structural cooling cavity are valuable for cooling cavity optimization.

关键词

振荡冷却，活塞冷却腔，流形，换热系数

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