Turbine Shroud Sealing via Vane Compression
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Solution Overview
Problem
Existing gas turbine engine designs fail to completely prevent leakage between turbine rotor shrouds and adjacent nozzles due to high temperature environments, leading to undesirable gas flowpath leakage.
Innovation Solution
A turbine shroud configuration incorporating compressed honeycomb seals and spline seals, where the shroud segments have arcuate bodies with seal slots and arcuate stationary seal members, and the turbine vanes are mounted to compress the seals, forcing the shroud radially outward against the casing to prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compressed honeycomb seals are used to minimize leakage gap, then leakage is reduced, but leakage is not completely prevented
Solution Approach 1:
The shroud is divided into multiple shroud segments with gap seal slots between them. Spline seals are installed in these slots to seal the gaps between adjacent shroud segments, preventing gas leakage through the segmented structure while maintaining the benefits of modular design.
Solution Approach 2:
Arcuate stationary seal members made of abradable material are positioned between the turbine rotor blades and the shroud segments. These intermediary seal members prevent direct contact between metal parts, reduce leakage, and can be replaced without replacing the entire shroud assembly.
2Reliability
If turbine vanes are mounted to compress seals, then sealing is improved, but mounting complexity increases
Solution Approach 1:
The turbine vane mounting structure is combined with the seal compression function. The turbine vanes are directly mounted to compress the arcuate stationary seal members against the shroud segments, integrating the sealing mechanism into the existing mounting structure and eliminating the need for separate sealing assemblies.
Solution Approach 2:
The seal compression force is controlled by the mounting parameters of the turbine vanes. By adjusting the mounting position and force of the turbine vanes, the compression of the abradable seal members is optimized to achieve effective sealing while maintaining simple mounting procedures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The configuration significantly reduces leakage and air temperature in the cavity, enhancing engine performance and protecting casing components from high temperatures, thereby extending service life.
Implementation Method 1
the turbine vane is mounted to the case so as to bear against the stationary seal member, compressing it and forcing the shroud segment radially outward against the casing
Implementation Method 2
Prior art designs have attempted to minimize the leakage gap through the compression of the honeycomb on the shroud
Implementation Method 3
at least one spline seal is received in the seal slots so as to span the gap between adjacent shroud segments
Implementation Method 4
the stationary seal member is formed of an abradable material and the tip shroud bears radially outward against the stationary seal member
Data Source
AI summary
A turbine shroud apparatus for a gas turbine engine having a centerline axis includes: a shroud segment having: an arcuate body extending axially between forward and aft ends and laterally between opposed end faces, wherein each of the end faces includes seal slots formed therein; and an arcuate stationary seal member mounted to the body; a turbine vane disposed axially aft of the shroud segment; and a casing surrounding the shroud segment and the turbine vane; wherein the turbine vane is mounted to the case so as to bear against the stationary seal member, compressing it and forcing the shroud segment radially outward against the casing.