Estimation of heat transfer coefficient using CFD techniques on a solid cylinder

Heat transfer coefficient (HTC) is one of the essential parameters to evaluate the thermal stresses in the steam turbine components like rotor, casing, etc, using finite element methods. HTC is used to predict the local temperature distributions and the induced stresses in the component with finite element methods. HTC depends on number of variables like thermal properties of fluid, hydrodynamic characteristics of the flow regime and boundary conditions. There are numerous empirical equations available in literature to calculate HTC in different fluids, flow regimes, geometries and under different thermodynamic conditions. However, it is necessary to use these equations carefully, as they are defined for a specific range of parameters and their applicability to complicated geometries of steam turbine components needs to be verified. The inaccuracy in HTC values leads to incorrect estimation of the local temperature distributions and the induced stresses. To overcome this uncertainty, an empirical correlation is formulated to estimate HTC based on Conjugate Heat Transfer Study on a solid cylinder which is close representation of typical steam turbine casing. The results of the proposed study are within acceptable limit of ±25% compared with available correlations for the range of Reynolds Number 1.5x10⁵ to 7.55x10⁵.