Effects of incorporating baffles into the cooling system of an internal combustion engine. Study through ANSYS® CFD software

Abstract

As of 2021, even with growing concerns about climate change, internal combustion engines still power more than 99% of the vehicles on the planet, from the smallest of motorcycles to the largest container ships. Internal combustion engines are thermal machines subject to great irreversibilities that have peak thermal efficiencies well below 50% and thus reject large amounts of heat. As a consequence of this, they require cooling to keep their temperature below the maximum service temperature of their constitutive materials. In most modern engines, cooling is achieved through the forced circulation of a liquid coolant through the engine. The homogeneity of this refrigeration is critical as uneven cooling creates great thermal stresses that would severely reduce the durability and reliability of the engine. In this work, the cooling jacket of the cylinder on an internal combustion engine was modelized and analyzed through computational fluid dynamics simulations using the academic version of the commercial software ANSYS® Fluent®. First, a simplified model based on the cooling jacket on a single-cylinder liquid-cooled 125 cc spark-ignited engine was elaborated and validated through comparison with data available in the literature. Boundary conditions were obtained from a combination of experimental and literature data and the academic version of ANSYS® Fluent® proved being sufficient to perform a semiquantitative analysis. Once its results were validated, this system was then modified by including different combinations of baffles and additional outlets with the aim of improving its heat transfer characteristics, especially in terms of cooling homogeneity. Results were especially promising for the system containing the combination of additional outlets on the top part of the cooling jacket and a baffle on its outer wall. Uniform and enhanced cooling was achieved in the area of influence of the baffle while a notable pressure drop reduction in the cooling jacket was attributed to the presence of the additional outlets