Turbine Stator Radial Decoupling for Thermal Expansion Sealing
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Solution Overview
Problem
Conventional turbojet engine turbines face issues with gas leakage and wear due to varying gaps between abradable elements and wipers, caused by thermal expansion differences, leading to unsatisfactory sealing.
Innovation Solution
A turbine stator assembly with a sealing ring and crown sectors that allow radial decoupling, featuring sliding means like pins and oblong openings for assembly, and a brush seal to reduce leaks and maintain alignment, ensuring consistent radial gaps and improved sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the guide vane assembly is secured rigidly to the casing, then the structure is simple and easy to manufacture, but the gap between the abradable element and wipers varies due to thermal expansion differences, causing increased gas leakage and accelerated wear
Solution Approach 1:
The guide vane assembly is made dynamically adjustable relative to the casing through sliding means (pins in oblong openings) that allow radial movement. This enables the assembly to adapt its position based on thermal expansion conditions, maintaining consistent sealing performance between the abradable element and wipers while accommodating temperature variations during operation.
Solution Approach 2:
The guide vane assembly is divided into separable components (crown sectors) that can move independently relative to the casing. This segmentation allows each sector to adjust radially through the sliding mechanism, enabling precise control over the gap between sealing surfaces while maintaining overall structural integrity.
2Reliability
If the gap between the abradable element and wipers increases, then wear is reduced, but gas leakage increases and sealing performance deteriorates
Solution Approach 1:
The sliding mechanism provides automatic feedback adjustment: as thermal expansion changes the relative position between the guide vane assembly and casing, the pins move within the oblong openings to maintain the optimal gap. This self-adjusting mechanism ensures consistent sealing performance without requiring external control systems.
3Ease of manufacture
If the crown sectors are rigidly connected to the sealing ring, then the assembly is simpler to manufacture, but thermal expansion causes misalignment and compromises sealing effectiveness
Solution Approach 1:
The connection between crown sectors and sealing ring transitions from rigid to dynamic through the sliding means. The pins moving in oblong openings allow radial adjustment while maintaining circumferential alignment, enabling the assembly to accommodate thermal expansion without compromising precision or requiring complex manufacturing 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 solution effectively reduces gas leaks and maintains consistent sealing performance across operating phases, enhancing the accuracy of leakage flow rates and simplifying assembly while preventing pin loss.
Implementation Method 1
During the operation of the turbojet engine, the guide vane assembly is exposed to higher temperatures than the disc of the movable wheel and the thermal inertia of the guide vane assembly is generally lower than that of the disc, which results in a variation of the gap between the abradable element and wipers.
Implementation Method 2
the sealing means comprising a brush seal bearing axially on the one hand on the crown sectors and on the other hand on the sealing ring or on a part secured to the sealing ring
Data Source
AI summary
A turbine stator assembly including a guide vane assembly and a sealing ring bearing an abradable element of a dynamic sealing ring. The assembly includes pins secured to the sealing ring and cooperating with respective oblong openings formed in the guide vane assembly so as to allow a radial movement of the ring with respect to the guide vane assembly in order to compensate for differential thermal expansions. A seal is arranged so as to compensate for circumferential spaces between ring sectors forming the guide vane assembly.