Gas Turbine Flow and Heat Transfer

Pressure Side Results
This figure shows a typical pressure surface result. In this case, the leading edge is at the left of the figure and the base of the blade near the endwall is at the bottom.

Like the suction surface, the mass transfer coefficient is high at the leading edge of the blade and drops as the boundary layer develops on the surface. In this case, however, we reach a minimum that is due to a small flow separation, followed by a flow reattachment. This is a weak separation. At higher velocities, it becomes more distinct.

After the reattachment, the boundary layer reamins laminar due to the high accelaration in the freestream flow. You may notice that there is some waviness in the data over much of the downstream parts of the surface. This waviness is due to a boundary layer instability that causes Taylor-Goertler vortices to develop. We find mass transfer peaks at the downwash position of these TG Vortices and valleys at the upwash positions.

Unlike the suction surface, the mass transfer coefficient is not significantly higher near the endwall region. As described in the flow visualization results, the pressure side leges of the horseshoe vortex system move across the blade passage to the suction surface of the neighboring blade and do not significantly affect the mass transfer on the pressure surface.