Optimum Cylinder Cooling for Advanced Diesel Engines

Abstract

Continuous demand for higher specific engine output simultaneously introduces problems of higher mechanical and thermal stresses of the engine components. Uneven temperature distribution in the cylinder wall of a diesel engine, especially when air-cooled, is well known. Peak local temperatures, large circumferential and longitudinal temperature gradients provoke deformations that, in turn, affect the reliability of the engine. As the result of intensive numerical and experimental investigations, a horizontal, curved channel fed with engine lubrication oil was introduced in the upper part of the air-cooled cylinder. Optimization of the channel design, its position, and determination of suitable asymmetrical split oil flow have led to more favorable cylinder temperature distribution, similar to that obtained by advanced water-cooled engines. Analyses of the local laminar oil-flow phenomena and local heat transfer distribution in curved channels are discussed in the paper and can be successfully applied to advanced liquid-cooled engines.