Changing regularity of diesel cylinder heads thermal state under variable altitude condition
ZHANG Bowen, LIU Zhentao, ZHANG Yu, CHEN Sinan, YU Xiaoli
(Power Machinery and Vehicular Engineering Institute, Zhejiang University, Hangzhou 310027, China)
 

Abstract: Aiming at some diesel engine cylinder head partial ablation in plateau, the heat transfer process in cylinder of diesel engine and cylinder head thermal state under variable altitude condition was investigated, and temperature fields of the cylinder head under different altitudes were gotten by simulation. Boundary conditions of the bottom side of cylinder head were gotten by numerical calculation in condition of only considered the effect of convection and considered the effect of both convection and radiation according to real machine experiment. The regularity of cylinder head temperature field changing with altitude under two kinds of boundary conditions was compared. The results indicate that the convective heat transfer would reduce when altitude increases. If only considers the effect of convection, the highest temperature in cylinder head at an altitude of 4 500 meters would fall by 6.2% when comparing with the plain. The amount of heat transfer would go up when altitude increases and the highest temperature in cylinder head at an altitude of 4 500 meters would rise by 15.6% when comparing with the plain.And it also show the effects of radiation on the heat generates in the cylinder.
Key words: variable altitude; cylinder head; simulation; radiation; thermal state