LOCAL HEAT/MASS TRANSFER MEASUREMENTS IN A SHROUDED ROTOR-STATOR CAVITY

Local heat/mass transfer and flow characteristics data applicable to the cooling design of the wheel space with rim seal in the gas turbine engine are essential. Experimental facility was designed to obtain local heat/mass transfer coefficients on stator and rotor surface in rotor-stator cavity with hub injection flows using the naphthalene sublimation method. This study investigated three configurations of rotor-stator cavity; unshrouded, shroud on rotor, and shroud on stator. The experiments were conducted for various rotational Reynolds numbers (Re-Phi=0, 5.6x10(5),1.12x10(6)), gap ratios (G=0.03, 0.0375, 0.05) and non-dimensional flow rates (C-w=7.0x10(3), 14.0x10(3)). The local Sherwood numbers appeared similar in the circumferential direction, so the radial Sherwood numbers were analyzed. At low radius (r/b<0.4), the heat/mass transfer is dominated by the hub injection flow, and the Sherwood number on rotor and stator surfaces are similar due to small gap ratio (G<0.05). At large radius (r/b>0.5), the Sherwood number on rotor increase as rotational Reynolds number increases, however the Sherwood number on stator is independent. At the low opening ratio (G(o)=0.17), the shroud increases the pressure in the cavity and reduces the Sherwood number regardless of the shroud installation location. Especially, at large radius, the Sherwood number on stator is reduced significantly. At the large opening ratio (G(o)=0.5), there is no effect of the shroud on heat/mass transfer. And the shroud on the rotor enhances the overall Sherwood number on the rotor and stator under high injection flow conditions. Thus, the shroud clearly changes the flow and heat/mass transfer in the rotor-stator cavity at low opening ratio conditions.