Harmonisation of Coolant Flow Pattern with Wake of Stator Vane to Improve Sealing Effectiveness Using a Wave-Shaped Rim Seal

Seungjin Lee,Joong Park,Daehan Kim

doi:10.3390/en12061060

Abstract

The rim seal of the gas turbine is intended to protect the material of the turbine disk from hot combustion gases. The study of the rim seal structure is important to minimise the coolant flow and maximise the sealing effect. In this paper, a wave-shaped rim seal for stator disks is proposed and its effect is confirmed by numerical analysis. To characterise the flow phenomena near the wave-shaped rim seal, a simplified model of the wave-shaped rim seal (Type 1 model), which excludes the rotor blade and stator vane, is analysed and compared with the conventional rim seal. Then, through analysis of the wave-shaped rim seal geometry (Type 2 model), which includes the rotor blade and stator vane, a reduction in egress and ingress flow was observed owing to the wave-shaped rim seal, and the sealing effectiveness on the stator disk of turbine was increased by up to 3.8%. Implementation of the wave-shape geometry in the radial seal is a novel choice for turbine designers to consider in future for better-performing and more-efficient turbines.

Highlights

To increase the thermal efficiency of the gas turbine, the inlet temperature of the gas needs to be increased [1]
Results and Discussion created by the rotor blade [23], and coolant flow, which were considered and achieved in Type 2 models
It is necessary to observe the sole influence of the wave-shaped rim seal geometry

Summary

Introduction

To increase the thermal efficiency of the gas turbine, the inlet temperature of the gas needs to be increased [1]. Hot gas reduces the turbine’s lifespan, owing to thermal loading and fatigue failure of the turbine material. In preceding gas turbine studies, it was revealed that the cause of the ingress flow (hot mainstream gas) and egress flow through the wheelspace is the pressure difference near the interface between the mainstream gas path and the wheelspace [2] (Figure 1a). When passing through the mainstream gas path, the flow is affected by the wake of the stator vanes and rotor blades (Figure 1b(i)), causing non-axisymmetric variations in velocity and pressure (Figure 1b). The coolant flow is injected into the wheelspace to cool the turbine disk material and block the incoming hot gases (Figure 1a). The egress of the coolant flow through the gap between the stator and rotor disks interferes with the mainstream flow, and this deteriorates the aerodynamic performance. The maximisation of cooling and sealing effects, while minimising coolant flow in gas turbines, has long been an important topic for engineers

Methods

Results

Conclusion