Departmental Bulletin Paper 火花点火機関燃焼室における熱伝達率算出式の検討(燃焼室内主流が無視できる場合)

中川 皓貴  ,  長瀬, 慶紀  ,  友松, 重樹  ,  木村, 正寿

46pp.47 - 52 , 2017-07-31 , 宮崎大学工学部
In order to solve an environmental problem, it is necessary to improve the thermal efficiency of an internal combustion engine. There is a heat loss, which amounts to about 30% of thermal energy occurred in a combustion chamber of an engine. To reduce the heat loss, it is required to understand the heat transfer on a combustion chamber wall surface from combustion gas. Therefore, it is necessary to calculate the heat transfer coefficient between combustion gas and combustion chamber wall surface. In past studies, the correlation between the gas flow and the heat transfer coefficient was indicated in the high velocity range, through it is not possible to be applied in the low velocity range. In order to solve this problem, this laboratory developed an empirical formula between the Fourier number which is a dimensionless number of a time and the Nusselt number which is the dimensionless number of heat transfer coefficient. In this study, the heat flux on a combustion chamber wall of an S.I. engine was measured using the heat flux probe in negligible gas flow conditions, and we investigated the validity of the developed formula. As a result, it was found that the developed heat transfer calculation formula is more accurate than Woschni's equation, and even if the turbulence intensity differs, the decline tendency of the heat transfer coefficient in the low flow velocity region is reflected.

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