Gas Turbine Roller Duct Blocker for Thermal Deflection Control
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Solution Overview
Problem
Thermal deflection and hysteresis in the annular plate of traditional rotational duct blockers in gas turbine engines reduce precision control of cooling air flow, affecting engine stability and performance.
Innovation Solution
A rotational duct blocker with a duct blocker rotor and stator featuring roller elements and a vernier pattern, where the rotor includes a plurality of first and second vane segments with curved sidewalls and flow apertures, and a stator with corresponding apertures, allowing precise regulation of cooling air flow through the use of a roller element track and preload to accommodate thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an annular plate is used to regulate cooling air flow, then the duct blocker can control flow quantity, but thermal deflection and hysteresis reduce precision control
Solution Approach 1:
The annular plate is segmented into multiple discrete roller elements (at least three) distributed around the circumference. Each roller element can independently rotate on its axis while the entire assembly rotates around the track. This segmentation allows precise control of cooling air flow by selectively positioning individual rollers to block or permit flow through specific apertures, eliminating thermal deflection issues affecting a solid plate.
Solution Approach 2:
The roller elements are made from a material with a coefficient of thermal expansion matched to the track material. This parameter matching ensures that thermal expansion of the rollers corresponds to thermal expansion of the track, maintaining proper clearance and preventing binding or excessive clearance under thermal conditions, thereby preserving precision control.
2Ease of operation
If the annular plate slideably rotates around a track, then flow regulation is achieved, but thermal expansion causes clearance variations affecting stability
Solution Approach 1:
The roller elements are made from a material with a coefficient of thermal expansion matched to the track material. This parameter matching ensures that thermal expansion of the rollers corresponds to thermal expansion of the track, maintaining proper clearance and preventing binding or excessive clearance under thermal conditions, thereby preserving precision control.
Solution Approach 2:
The roller elements are designed to rotate freely on their own axes as the assembly rotates around the track. This dynamic capability allows the rollers to self-adjust to thermal expansion and contraction, maintaining smooth operation and consistent clearance without binding or excessive play, thereby ensuring stability under thermal conditions.
3Productivity
If the duct blocker rotor includes vane segments with flow apertures, then cooling air flow can be regulated, but wear and hysteresis reduce control precision over time
Solution Approach 1:
The rotor is segmented into discrete roller elements that rotate on fixed axes rather than sliding against the track. This rolling motion significantly reduces wear compared to sliding contact, maintaining control precision over time. The segmented design also eliminates hysteresis associated with flexible annular plates, providing consistent and reliable flow regulation.
Solution Approach 2:
The sliding mechanical contact between the annular plate and track is replaced with a rolling contact system using roller elements. This substitution reduces friction and wear, eliminating the hysteresis and clearance variations that plague sliding systems, thereby maintaining control precision and reliability over extended operation.
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
Enhances precision control and stability of cooling air flow, improving overall engine performance by reducing thermal deflection and wear, and maintaining engine efficiency.
Implementation Method 1
Each of the plurality of roller elements is arranged within a respective one of the roller element wells and is configured to rotate on an axis of the roller element and around the roller element track
Implementation Method 2
The roller elements are made from a material having a coefficient of thermal expansion that corresponds to a coefficient of thermal expansion of the roller element track, which accommodates thermal expansion of the duct blocker rotor and maintains precision control
Implementation Method 3
The roller elements are preloaded against the roller element track, which eliminates clearance between the roller elements and the roller element track, thereby reducing hysteresis in the duct blocker rotor
Data Source
Figure 1~10
Figure 3~4
Figure 5~7
AI summary
A rotational duct blocker for a gas turbine engine includes a duct blocker rotor and a duct blocker stator. The duct blocker rotor includes a plurality of first vane segments that extend radially between an inner rotor platform and an outer rotor platform, and a plurality of first flow apertures that extend axially through the duct blocker rotor. Each first flow aperture also extends circumferentially between respective adjacent first vane segments. The duct blocker stator includes a plurality of second vane segments that extend radially between an inner stator platform and an outer stator platform, and a plurality of second flow apertures that extend axially through the duct blocker stator. Each second flow aperture also extends circumferentially between respective adjacent second vane segments. The first vane segments move circumferentially relative to the second vane segments to regulate fluid flowing between the first flow apertures and the second flow apertures.