IMECE2002-32095 CFD ANALYSIS OF LIQUID-COOLED EXHAUST MANIFOLDS IN A REAL ENGINE CYCLE

ABSTRACT Liquid-cooled exhaust manifolds are used in turbocharged diesel and gas engines in the marine and various industrial applications in order to minimize heat rejection to surrounding areas, maximize energy to the turbocharger, and maintain a maximum allowable skin temperature. A commercial CFD software FLUENT ® was used to analyze liquid-cooled exhaust manifolds in a real time engine cycle. Detailed information of flow property distributions and heat transfer were obtained in order to provide a fundamental understanding of the manifold operation. Experimental data was compared with the CFD results to validate the numerical simulation. Computations were performed to investigate the parametric effects of operating conditions on the performance of the manifold. Two different geometries were compared. One of them was found to have better performance, resulting in an approximately 2 to 3% fuel consumption improvement. INTRODUCTION Liquid-cooled exhaust manifolds are used on turbocharged diesel engines for marine, oilrig, and other industrial applications. The purpose of cooling the manifold is to prevent possible fire hazards by maintaining a maximum safe temperature on the exposed surfaces or "skin" of the manifold. The adverse effec