Gas Turbine Flow and Heat Transfer

Suction Side Results
This figure shows the mass transfer coefficient distribution on the blade suction (convex) side. The mass transfer coefficient is presented in dimensionless forma as a Sherwood number. This figure is presented at an odd viewing angle, so that it is possible to see more of the 3-D distribution. The leading edge of the blade is to the right, while the bottom of the blade is at the top edge.

The mass transfer coefficient is high at the leading edge, where the flow stagnates. It drops quickly as a laminar boundary layer develops along the surface. You will notice a large increase near the top of the figure (actually, at the bottom of the blade near the endwall). This is the region that is affected by the vortices that develop in the passage. As you can see, they cause a drastic increase in the local mass transfer coefficient.

If you look closesly, you'll notice that there are actually two peaks in the region affected by the secondary flow. One is due to the "downwash" flow from the main part of the passage vortex. The other is due to the downwash flow from the wall vortex. The small valley between the peaks occurs at the "upwash" region between these counter-rotating vortices.