FLOW AND HEAT-TRANSFER IN SIMULATED REENTRY VEHICLE TILE GAPS

Experiments were performed to investigate the flow patterns and convec tive heat transfer characteristics in intersecting tile gaps on space vehicles. The flow in a water channel simulates the external flow, and gaps with a depth to width ratio of 20 are mounted as recesses in the bottom wall. A ''parallel'' gap is installed at 18 deg to the flow di rection and ends in a perpendicular gap normal to the flow direction. Gap flow patterns and temperature distributions are obtained as functi ons of the gap-width-based Reynolds number, the relative height betwee n tiles at the T intersection, and the temperature difference between gap and external flows, using dye entrainment, liquid crystals. and a grid of surface thermocouples. External flow penetration into the perp endicular gap was limited to roughly two gap widths while greater entr ainment occurred in the parallel gap. The 18-deg angle of the parallel gap led to asymmetries about the centerline in the perpendicular gap now patterns and convection coefficients. Natural convection was the p redominant mode of heat transfer in the bulk of the perpendicular gap. The Reynolds number and relative tile-height differences had the stro ngest influence on heat transfer and affected both the magnitude and t he asymmetry of the temperature and flowfields.