Heat Transfer Enhancement due to Coolant Extraction on the Cold Side of Effusion Cooling Plates

Effusion cooling represents one the most innovative technique to limit and control the metal temperature of aero-engine combustors liner and, recently, attention has been paid by the scientific community on the characterization and the definition of design practices of such devices. Most of these studies were focused on the heat transfer on the hot side of effusion cooling plates while just few contributions deal with the effusion plates cold side convective cooling. This paper reports a numerical survey aimed at the characterization of the convective cooling at the effusion plates cold side. Several effusion holes spacing are accounted for in conjunction with representative operating conditions. The study led to the development of an empirical correlation for the prediction of the cold side heat transfer coefficient enhancement factor EF: it expresses the EF related to each extraction hole as a function of the pressure ratio β and the effusion plate porosity factor.