Leakage flow analysis in the gas turbine shroud gap

Abstract

Purpose The purpose of the study is to measure the mass flow in the flow through the labyrinth seal of the gas turbine and compare it to the results of numerical simulation. Moreover the capability of two turbulence models to reflect the phenomenon will be assessed. The studied case will later be used as a reference case for the new, original design of flow control method to limit the leakage flow through the labyrinth seal. Design/methodology/approach Experimental measurements were conducted, measuring the mass flow and the pressure in the model of the labyrinth seal. It was compared to the results of numerical simulation performed in ANSYS/Fluent commercial code for the same geometry. Findings The precise machining of parts was identified as crucial for obtaining correct results in the experiment. The model characteristics were documented, allowing for its future use as the reference case for testing the new labyrinth seal geometry. Experimentally validated numerical model of the flow in the labyrinth seal was developed. Research limitations/implications The research studies the basic case, future research on the case with a new labyrinth seal geometry is planned. Research is conducted on simplified case without rotation and the impact of the turbine main channel. Practical implications Importance of machining accuracy up to 0.01 mm was found to be important for measuring leakage in small gaps and decision making on the optimal configuration selection. Originality/value The research is an important step in the development of original modification of the labyrinth seal, resulting in leakage reduction, by serving as a reference case.

Feasibility Study of Fluidic Sealing in Turbine Shroud

“…The GEnx low-pressure turbine (LPT) introduces Titanium Aluminide blades to stages 6 and 7, reducing engine weight by approximately 150 kg (400 lbs) and contributing to increased fuel efficiency of the GEnx engine [19,20].…”

“…Several turbulence models were tested, and none of them produced accurate predictions for both C D and pressure distribution. The impact of the turbulence model on C D and flow structure was analyzed in [19].…”

“…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].…”

Numerical investigations on leakage performance and flow mechanism of spiral groove seal for shrouded blade in axial turbine

“…As shown in Figures 5(c) and (d), all walls are equipped with boundary layer grids. The shear-stress transport (SST) model, 28 which gives a good matching with the experimental data in previous investigation about turbine shroud leakage flow, 29 is chosen as the turbulent model, thereby the grid size in boundary layer needs to ensure that the dimensionless wall distance y + is less than 1.…”

Experimental and numerical tip leakage flow visualization in the LP turbine labyrinth seal

“…Despite the fact that state-of-the-art sealing solutions such as brush seals or finger seals reduce leakage much better [2], labyrinth seals are favoured mostly due to resistance to high temperature, highpressure ratios, high speed, rubbing and solid particles contamination [3]. Historically, a significant effort in labyrinth seals evaluation, including experiments [4][5][6], CFD calculations [7][8][9][10] and analytical methods [11][12][13] have been presented in the literature. The research to evaluate and assess labyrinth seals works has been going on since the 1970s when Detroit Diesel Allison performed some of the first experimental campaigns [14].…”