Riassunto analitico
Internal combustion engines are machines that convert the thermal energy produced during the oxidation of fuel into mechanical energy. However, this process is inherently inefficient, with a significant portion of energy being lost as heat, necessitating an effective cooling system to dissipate it. In high-performance engines, the thermal and mechanical loads are compounded, leading to thermo-mechanical fatigue phenomena, making thermal management a critical consideration.
Designing cooling systems for these engines is a complex task, as the fluid temperature often approaches saturation, creating conditions conducive to the formation of vapor films that impede heat transfer. Currently, the most advanced method for designing water jackets in ICEs is Computational Fluid Dynamics (CFD), which can simulate both fluid dynamics and the potential formation of vapor bubbles or films. While CFD offers high accuracy, it comes with the significant drawback of requiring substantial computational resources and extended simulation times.
This thesis presents a methodology that uses empirical correlations to account for the variation in the fluid-wall heat transfer coefficient due to nucleate boiling phenomena, within thermomechanical Finite Element Analysis (FEA). This approach enables early detection of boiling phenomena in engine head design, where complex biphase CFD simulations are too computationally expensive and time-consuming, offering improved thermal predictions during initial structural simulations. A review of relevant literature identifies the most suitable empirical boiling correlations, balancing accuracy and simplicity. These correlations are then implemented within FEA software through the use of user subroutines, specifically utilizing Dassault Systems Abaqus and MSC Marc. This approach provides a valuable tool for solving non-standard problems in engine thermal management.
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