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Designing and analysing the cooling of a medium speed engine piston using MPS method

Designing and analysing the cooling of a medium speed engine piston using MPS method

Sami Ojala, Wärtsilä Finland Oy

Abstract

Important constraint in designing a piston for a medium speed engine is maximum temperature of the piston.
Too high piston temperature causes for example hot corrosion and decrease in material properties.
When piston is developed for a new engine it is usually required that several piston geometries are tested. In early stage of the development one must be convicted that piston temperatures do not exceed general design limits. To calculate the piston temperatures thermal boundary conditions must be known.
Thermal load can be determined by approximate methods or more precise combustion simulation. Determining the cooling effect of oil inside piston cooling gallery is rather difficult. Oil splashing inside piston is free surface flow which is difficult flow scenario to be simulated. Particleworks which utilizes MPS method offers an effective way to simulate oil flow and also to calculate the heat transfer coefficient.
As a mesh-free method it enables quick evaluation of different designs without using long time to pre-processing. Also the actual simulation time is short compared to traditional methods. The use of MPS method and validation results are shown in the paper.

Speech presented at the International CAE Conference and Exhibition 2018 - Automotive Session

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