Developing Heat Transfer Coefficients Using Inverse Optimization
Abstract: When utilizing casting process simulation for the modeling of the permanent mold process, one variable that is often difficult to determine is appropriate heat transfer coefficients between material groups that are in contact with each other. In casting process simulation the heat transfer coefficients (HTC) between materials describes how and to what extent heat transfers across the boundaries between the two materials, for example, the casting surface that is in contact with the surface of the mold. Many variables can affect the heat transfer between two materials that are in contact. In the permanent mold process, the application of mold coating plays a large role in how heat moves between the casting and mold surface, and the mold coating can be influenced by factors such as application method, coating thickness and coating type. The process of obtaining appropriate heat transfer coefficient values has been extremely challenging in the past due to the uncertainty of heat transfer between materials. This paper details what is commonly referred to as the “inverse method” for determining appropriate heat transfer coefficients that can be used in casting process simulation. By utilizing the inverse methodology, foundries can match thermocouple curves taken during actual testing with virtual thermocouples placed in the virtual model, thus determining precisely the heat transfer coefficient of different types of coatings and their influence on the casting process. This paper will focus on the steps involved in the inverse method, and it will detail the outcome of an inverse optimization study that was performed for the gravity permanent mold process.