Heat Transfer Enhancement through Advanced Casting Technologies

There is growing interest in additive manufacturing technologies for prototype if not serial production of complex internal combustion engine components such as cylinder heads and pistons. In support of this general interest the authors undertook an experimental bench test to evaluate opportunities for cooling jacket improvement through geometries made achievable with additive manufacturing. A bench test rig was constructed using electrical heating elements and careful measurement to quantify the impact of various designs in terms of heat flux rate and convective heat transfer coefficients. Five designs were compared to a baseline - a castable rectangular passage. With each design the heat transfer coefficients and heat flux rates were measured at varying heat inputs, flow rates and pressure drops. Four of the five alternative geometries outperformed the baseline case by significant margins. The numerical margins were dependent on design constraints; for example, the heat transfer coefficient at a given flow rate, or heat transfer coefficient versus required pumping power.

The authors also recognize the practical limitations of additive manufacturing technologies for serial production. A second important aspect of this work was to address practical methods for incorporating the findings in volume engine production. Several approaches are discussed, and initial assessments of practicality are presented.