Turbulence Driven Convective Heat Transfer in a Direct Injection Diesel Engine
There is a history of over 70 years in the study of heat transfer in internal combustion engines. Formerly, interest is concentrated on the global heat transfer for cooling load predicting and engine cycle simulation. More recently, there is growing interest in the study of spatial heat transfer in order to be able to predict better the combustion and the pollutant formation processes which are progressing from the single zone models to the multi-zone or multidimensional models. In a diesel engine, there are two forms of heat transfer, namely, convection and radiation. Convection is the major form of heat transfer but radiation generated at the diffusion combustion stage can account for 10% to 50% of the total heat flux. Convective heat transfer has been considered to be highly dependent on the in-cylinder flow which includes the turbulence level set up by the engine motion and by the combustion process. In most previous studies, the major driving force for convection is the tangential velocity component. However recent experiments performed by the authors indicate that at a point quite near to the cylinder axis, where the flow is supposed to be very low, the magnitude of heat flux is comparable with locations where the tangential flow is very high. In this paper, a new approach is proposed to model the convective heat flux.
KeywordsCombustion Convection Total Heat Diesel
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- V.D. Overbye, J.E. Bennethum, O.A. Uyehara and P.S. Myers, Unsteady heat transfer in engines, SAE Vol.69 461–493 (1961)Google Scholar
- J.Y. Yang, Convective heat transfer predictions and experiments in an IC engine, PhD thesis, The University of Wisconsin-Madison (1988)Google Scholar
- K.Y.Huh, I.P.Chang and J.K.Martin, A comparison of boundary layer treatment for heat transfer in IC engine, SAE 900252Google Scholar
- R.Diwakar, Assessment of the ability of a multidimensional computer code to model combustion in a homogeneous-charge engine, SAE 840230Google Scholar
- C.Borgnakke, G.C.Davis and R.T.Tabaczynski, Predictions of in-cylinder swirl velocity and turbulence intensity for an open chamber cup in piston engine, SAE 810224Google Scholar
- S.Kono, A.Nagao and H.Motooka, Prediction of in-cylinder flow and spray formation effects on combustion in direct injection diesel engines, SAE 850108Google Scholar
- G.C.Davis and C.Borgnakke, The effect of In-cylinder flow processes (swirl, squish and turbulence intensity) on engine efficiency — model predictions, SAE 820045Google Scholar
- R.J. Pu, The study of direct injection diesel engine’s in-cylinder heat transfer, MSc Thesis, Division of Internal Combustion Engine, Xian Jiaotong University (1992)Google Scholar