Gas Turbine Blade Casing Grooved Abradable Segment
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Solution Overview
Problem
In gas turbine engines, rotor blades experience stress and reduced lifespan due to rubbing loads from abradable materials in the compressor or turbine section, which can lead to deflection and contact with the casing, causing aerodynamic performance issues and potential cracking.
Innovation Solution
A rotor blade casing with an annular abradable segment featuring radially extending grooves that align with the leading and trailing edges of the blades, reducing contact area and rubbing loads by allowing the blades to engage only the non-grooved portions of the abradable segment, thereby minimizing stress and aerodynamic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If abradable material is provided on the inner surface of the casing to maintain acceptable tip clearance, then aerodynamic performance is improved, but rubbing loads are imposed on the rotor blades reducing their lifespan
Solution Approach 1:
The abradable material is segmented into discrete blocks positioned only in specific regions where tip clearance control is needed, rather than providing a continuous coating. This segmentation allows the rotor blades to rotate without continuous rubbing contact, reducing cumulative rubbing loads while maintaining clearance control where blocks are present.
Solution Approach 2:
The abradable blocks are strategically positioned only in regions requiring tip clearance control, creating localized abradable zones rather than a uniform coating. This local quality approach allows clearance maintenance in critical areas while leaving other areas free of abradable material to minimize rubbing loads on the rotor blades.
2Adaptability or versatility
If the rotor blades are allowed to deflect radially during operation, then operational flexibility is improved, but contact with the casing occurs causing stress and potential cracking
Solution Approach 1:
Abradable blocks are pre-positioned in the casing to serve as a cushioning layer before any potential blade-casing contact. These blocks are softer than the blade material, so if blades deflect radially during operation, they contact the abradable blocks first which deform to absorb the impact, preventing direct hard contact between blades and casing that would cause stress concentrations and cracking.
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 grooved abradable segment reduces rubbing loads on the rotor blades, decreases the likelihood of cracking, and minimizes tip clearance and aerodynamic losses, enhancing the operational lifespan and performance of the gas turbine engine.
Implementation Method 1
an abradable member adapted to be rubbed against by the blade tips when the rotor blades expand or deflect radially away from the longitudinal center axis during operation of the gas turbine engine
Data Source
AI summary
A gas turbine engine is described having a rotor with a plurality of rotor blades each extending radially between a blade root to a blade tip and axially between a leading edge and a trailing edge. An annular casing body housing the rotor blades includes an abradable segment of the inner surface facing the blade tips and having an abradable member. The abradable segment having one or more annular grooves, extending into the casing body from an inner surface thereof, and including an edge groove axially aligned with and facing the leading edge or the trailing edge of the rotor blades. The edge groove extends axially between a first position on the inner surface upstream of the leading edge or the trailing edge, and a second position on the inner surface downstream of the leading edge or the trailing edge.