Study of three-dimensional boundary layer flow over transonic slotted wind tunnel wall with mass transfer

An experimental study of boundary layer characteristics in a test section of the transonic wind tunnel with slotted lower wall, porous top wall, and solid side walls has been conducted. The results presented are for several mass transfer rates through the lower wall. The experimental data are pressure measurements which were made near the slotted wall and across the viscous layer by a five-hole cone probe mechanism. The slotted wall flow characteristics which relate to the three-dimensional velocity components, boundary layer thickness, and dis placement thickness, are determined from the cone probe pressure measurement. From the mapping of flow field velocity vectors, it was realized that for a single slot over the plenum chamber setup, significant secondary flows exist with the mass transfer from the test section to the wall plenum chamber. These secondary flows were reduced as the number of slots were increased to three. The measured flow velocities across the slotted wall near the wall and at the edge of the boundary layer have demonstrated the effectiveness of mass transfer through the wall. The mass transfer was found to be inhomogeneous along the slots and strongly influenced by the plenum arrangement and the manner of external mass transfer.