AN INVESTIGATION OF THE FLOW CHARACTERISTICS IN THE BLADE ENDWALL CORNER REGION (WING BODY JUNCTION)

An investigation was undertaken to determine the structure of flow in the blade endwall corner region simulated by attaching two uncambered airfoils on either side of a flat plate with semicircular leading edge. The initial portion of the flat plate was artificially roughened and free stream turbulence of the order of 1% was introduced in the flow. The techniques used in the investigation included flow visualization, static and total pressure measurements, determination of mean velocity profiles, Reynolds stress tensor and power spectra. The measurements were carried out at six axial stations along the corner and four stations ahead of the leading edge of the airfoil.;Advection by the horseshoe vortex and the corner vortex was found to create low turbulence intensity regions near the surface of the flat plate in the close vicinity of the corner. A region of negative turbulent shear stress was also observed near this region. The growth of stress induced vortices remove the low turbulence intensity regions from the vicinity of the flat plate surface. The effect of the streamwise vorticity on the turbulence structure was found to be opposite to that of the curvature of the airfoil surface in the present investigation. In the close vicinity of the corner the power spectra in the wave number domain at different axial locations were found to be identical even though the energy associated with different frequencies were not the same.;Three streamwise vortices were identified. A horseshoe vortex forms near the leading edge of the airfoil, within a short distance downstream, a corner vortex was detected between the horseshoe vortex and the surfaces forming the corner. Another vortex forms at the rear portion of the corner between the corner vortex and the surface of the flat plate. The third vortex was established to be the stress induced vortex.