Swirling flows in an annular-to-rectangular transition section

Mechanisms for generation of axial vorticity by swirling flows in rectangular nozzles have been investigated experimentally and computationally. A detailed experimental investigation is described that demonstrates the formation of axial vortices in the nozzle is dependant on the vorticity distribution at the turbine exhaust. Further, mechanisms providing for the formation of axial vortices are identified. A parallel computational investigation was carried out that not only confirmed the relationship between the turbine exhaust vorticity and the vortex patterns formed in the nozzle, but also provided details of the flowfield between the turbine discharge and the nozzle exit. On the basis of this more detailed understanding, it is now possible to "tailor" the vortex distribution at the nozzle exit by design of the turbine discharge and the intervening passage.