Compressibility effects on the flow past a T106A low-pressure turbine cascade

The present numerical investigation delves into the intricate interplay between Mach number (M-s), flow characteristics, and vorticity dynamics within a T106A low-pressure turbine (LPT) blade passage. The two-dimensional (2D) compressible Navier-Stokes equations are solved using a high-accuracy, dispersion relation preserving methodology, which is validated against benchmark direct numerical simulations. Four M-s ranging from 0.15 to 0.30 are computed in order to display the intricate response of compressibility on the separation-induced transition process. The emergence and evolution of unsteady separation bubbles along the suction surface of the T106A blade are explored, revealing a growing trend with M-s. The time-averaged boundary layer parameters evaluated along the suction surface display a delayed separation with a smaller streamwise extent with increasing M-s. However, an overall increase in the blade profile loss and a decrease in turbulent mixing are observed with increasing M-s, suggesting a detrimental effect on LPT performance. Applying the compressible enstrophy transport equation (CETE) to the flow in a T106A blade passage reveals that while a linear relationship exists between M-s and certain CETE budget terms, other terms have a nuanced dependency, which paves the way for future investigations into the role of compressibility on enstrophy dynamics.

Automated summary

The present numerical investigation explores the relationship between Mach number, flow characteristics, and vorticity dynamics in a T106A low-pressure turbine blade passage. The results show that as the Mach number increases, the separation phenomenon is delayed, but there is an overall increase in blade profile loss and a decrease in turbulent mixing, which negatively affects LPT performance.