Stator-Rotor Interaction in Axial Turbine: Flow Physics and Design Perspective

Abstract

The stator-rotor interaction is an important issue in turbomachinery design when the highest performances are targeted. Different characters mark the interaction process in high-pressure or low-pressure turbines depending both on the blade height and on the Reynolds number. For small blade heights, being the stator secondary flows more important, a more complex interaction is found with respect to the high blades, where the stator blade wake dominates. In low-pressure turbines, the stator wake promotes the transition to turbulent boundary layer, allowing for an efficient application of ultra-high lift blades. First, a detailed discussion of the flow physics is proposed for high-and low-pressure turbines. Some off-design conditions are also commented. Then, a design perspective is given by discussing the effect of the axial gap between the stator and the rotor and by commenting the effects of three-dimensional design on the interaction.

Clocking effects on aerodynamics of a gas turbine low pressure axial turbine, part 2: Unsteady simulation

“…For instance, LI value of R2-1 at a specific time and desired CLP, such as CLP4, represents the R2-1 loading in comparison to an averaged-LI of the all blades of the second rotor computational domain in CLP4 and CLP1. For example, the loading index for R2-1 blade at t/T = 0 is mathematically shown by equation (17). Figure 22 shows time-dependent LI variations for the second rotor blades at their mid-span in CLP4 and CLP1 cases.…”

“…Through researches on rotor-stator blades rows interactions in a twin-shaft turbine, Gaetani concluded that the maximum efficiency can be achieved when the upstream wake impinges on the next stator blade leading edge. 17 He also concluded that at low Reynolds numbers, upstream wakes causes transition to occur while they interact with the blade suction side boundary layer. Although, this transitional flow causes the losses to increase, it makes the boundary layer to encounter with streamwise adverse pressure gradient, and as a result, prompts the flow separation point to move downstream.…”

Topology optimization of compressible subsonic flow considering turbulence and real gases.

“…tends to create a narrow blade at the suction side of the blade domain. This is expected as vortex generation from the pressure side is different from the suction side (Gaetani, (Gaetani 2018)). According to the fluid nature of entering through the cavity, e.g.…”