On transonic flow over segmented slotted wind tunnel wall with mass transfer

The flowfield on a single and a segmented multi-slotted wind tunnel wall have been studied at transonic speeds by traversing the wall viscous layer using five port cone probes. As expected, the slotted wall flowfield was observed to be three-dimensional in nature for a significant distance above the slot. The boundary layer characteristics measured on the single slotted wall have been found to be very sensitive to the applied suction through the slot. The velocity component perturbations generated due to the flow through the slot decay rapidly in the transverse direction. A vortex-like flow existed on the single slotted wall for natural ventilation but diminished with increased suction flow rate. For flow on a segmented multi-slotted wall, the normal velocity component changes were found to be maximum for measurement points located between the segmented slots atop the active chamber. The lateral influence due to applied suction and blowing, through a compartment, exceeded only slightly that in the downstream direction. Limited upstream influence was observed. Influence coefficients were determined from the data in the least-square sense for blowing and suction applied through one and two compartments. This was found to be an adequate determination of the influence coefficients for the range of mass flows considered.