Unsteady Interaction Between a Transonic Turbine Stage and Downstream Components

Abstract

Results from a numerical simulation of the unsteady flow through one quarter of the circumference of a transonic high-pressure turbine stage, transition duct, and low-pressure turbine first vane are presented and compared with experimental data. Analysis of the unsteady pressure field resulting from the simulation shows the effects of not only the rotor/stator interaction of the high-pressure turbine stage but also new details of the interaction between the blade and the downstream transition duct and low-pressure turbine vane. Blade trailing edge shocks propagate downstream, strike, and reflect off of the transition duct hub and/or downstream vane leading to high unsteady pressure on these downstream components. The reflection of these shocks from the downstream components back into the blade itself has also been found to increase the level of unsteady pressure fluctuations on the uncovered portion of the blade suction surface. In addition, the blade tip vortex has been found to have a moderately strong interaction with the downstream vane even with the considerable axial spacing between the two blade-rows. Fourier decomposition of the unsteady surface pressure of the blade and downstream low-pressure turbine vane shows the magnitude of the various frequencies contributing to the unsteady loads. Detailed comparisons between the computed unsteady surface pressure spectrum and the experimental data are shown along with a discussion of the various interaction mechanisms between the blade, transition duct, and downstream vane. These comparisons show overall good agreement between the simulation and experimental data and identify areas where further improvements in modeling are needed.

Unconventional centrifugal bladeless turbine for low power range turboexpander applications

“…Total-to-static efficiency curves depicted in figure 5 show that 1D model has acceptable accuracy till u/C0=0.4 and then the discrepancy sees a constant increase. This is likely to be due to additional losses from interaction of transonic discharge flow with a downstream hood which are only captured via transient simulations as described by Davis (2004).…”

Impact of Turbine-Strut Clocking on the Performance of a Turbine Center Frame

“…In addition to efficiency improvement, clocking can also influence the time-resolved characteristics of a turbomachinery system, resulting in a reduction of noise and vibrations. Davis et al [9] investigated a transonic HPT with a downstream transition duct and LPT vanes and addressed the interaction among the rotor blade, the intermediate turbine duct, and the second vane. Gadea et al [10] studied the influence of clocking on the time-resolved pressure field of a second vane tested in a 1.5-stage HP turbine without a transition duct.…”

Experimental Heat Transfer Investigation in a Multisplitter LP Vane Architecture

“…Numerical calculations provided velocity distributions and profile losses for three vane configurations with one, two and three smaller aero-vanes. Davis et al [24] reported an experimental and numerical research for a LP vane in a s-shaped duct preceded by a transonic HP stage. The author concludes that interactions between the rotor and second vane increase the unsteadiness in both rows but this slightly affects the overall aerodynamic losses.…”