Negative Incidence Flow Over a Turbine Rotor Blade

The operation of variable cycle gas turbines at negative incidence can result in highly three dimensional separated flows on the turbine rotor pressure surface. These flows can impact both performance and durability. The present program was conducted to experimentally study the behavior of surface flow on a large scale axial flow turbine rotor with incidence varying up to and including negative incidence separation. Fullspan pressure distributions and surface flow visualization were acquired over a range of incidence. The data indicate that at large negative incidence, pressure surface separation occurred and extended to 60 percent chord at midspan. These separated flows were simulated at midspan by applying potential flow theory to match the measured pressure distributions.