Transient Thermal Response of Pin-Fin Sandwich Panels to Hot Jet Impingement

The transient thermal response of a sandwich panel with pin-fin core subjected to nonuniform impinging jet heating was investigated theoretically and experimentally. Forced convection flow passing through the sandwich channel was employed to remove heat imposed nonuniformly on the pin-fin sandwich. A semi-empirical model was developed to predict the transient thermal fields in the front and back facesheets of the sandwich, in the pin-fins, and in the forced convective flow. Transient heat transfer measurements were conducted to validate the model with hot air impinging jet heating. The temperature history of the sandwich was predicted under two different boundary conditions: (1) continuous and (2) cyclic heating from a flame impinging jet. Heating by the flame impinging jet was modeled by prescribing heat flux distribution expressed with an exponential function. For continuous heating, systematic parametrical studies were carried out to examine the effects of convection Reynolds number, fin pitch, fin thickness, and facesheet thickness on the maximum facesheet temperature. For cyclic heating, the thermal performance of the sandwich as a function of heat flux intensity was quantified. It was demonstrated that pin-fin sandwiches are capable of thermally managing nonuniformly distributed heat fluxes having high intensities, either continuously or cyclically imposed.