Passive Reduction of Leakage by Transverse Jet

Abstract

The paper presents investigations of mass flow reduction in a gap above a fin by the air curtain technique. The proposed method uses slots in the fin to generate a bypass flow and to create a fluidic barrier in the gap above the fin. Both numerical and experimental research was conducted and the air curtain proved to be effective, showing the mass flow reduction up to about 20%. The comparison of numerical simulations and experimental data showed good agreement, and the flow structure details were analyzed based on the numerical results. The analysis shows that the blown air in the gap leads to creation of streamwise vortices. They enforce crosswise non-uniformity of the flow velocity in the gap and downstream, what finally influences on higher dissipation effects and mass flow reduction in the gap.

Feasibility Study of Fluidic Sealing in Turbine Shroud

“…This promotes kinetic energy dissipation, increasing the flow resistance and decreasing the flow. The issue was studied in more depth in [18].…”

“…The effectiveness of the air curtain was on the basis of an experiment and numerical simulations. In the studied cases, the modification resulted in a 4-22% reduction in leakage, depending on the gap height and the pressure ratio [18,19].…”

“…Thus, compressing the additional air used in the seal does not have to be taken into account in the effectiveness calculations. A more extensive literature survey of the fluidic seals used in turbine shrouds can be found in [18].…”