Turbojet Compressor Stage Thermal Protection Sheet Immobilization
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Solution Overview
Problem
Current turbine or compressor stages in turbojet engines face issues with radial vibration and reduced service life due to incorrectly immobilized thermal protection sheets and radial temperature gradients, leading to increased stresses in locking members.
Innovation Solution
Incorporating a radially thicker thermal protection sheet with extra thickness and radial support features, such as annular bosses, to immobilize the sheet and reduce radial prestress, thereby preventing vibration and enhancing the locking member's resistance to operational stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a thin thermal protection sheet is used, then the device complexity is reduced, but the sheet cannot be correctly immobilized and vibrates in operation
Solution Approach 1:
The patent applies local quality by adding extra thickness only at specific locations (annular boss or circumferential bosses) rather than throughout the entire sheet. This localized reinforcement provides immobilization where needed while keeping the overall structure simple and minimizing material usage.
Solution Approach 2:
The patent transitions from a two-dimensional thin sheet to a three-dimensional structure by adding radial thickness in the form of bosses. This dimensional change enables the sheet to be radially immobilized against the locking member while maintaining simplicity elsewhere.
2Strength
If the locking member is engaged with high radial prestress, then the ring sector is securely clamped, but temperature gradients cause straightening and increased stresses reducing service life
Solution Approach 1:
The patent applies local quality by positioning extra thickness (bosses) at specific locations on the locking member or sheet to provide targeted radial support. This localized reinforcement reduces stresses in critical areas without requiring high prestress throughout the entire locking member, thereby extending service life while maintaining secure clamping.
3Device complexity
If the thermal protection sheet is not radially immobilized, then the device complexity is reduced, but the sheet vibrates and deteriorates in operation
Solution Approach 1:
The patent merges the thermal protection sheet with the locking member by creating radial abutment between them through the extra thickness (bosses). This integration provides immobilization without requiring separate mechanisms, reducing overall device complexity while improving reliability.
Solution Approach 2:
The patent incorporates the extra thickness (bosses) into the design of the locking member or sheet before assembly. This preliminary structural feature ensures radial immobilization is built-in from the start, preventing vibration and deterioration during operation without requiring additional components or complex assembly steps.
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 immobilizes the thermal protection sheet and reduces stresses in the locking member, improving the performance and service life of the turbojet engine by maintaining consistent radial clearances and reducing the risk of vibration and thermal protection sheet deterioration.
Implementation Method 1
a substantially cylindrical thermal protection sheet being interposed between the ring and the wall of internal revolution of the locking member
Implementation Method 2
the sheet, or the wall of internal revolution of the member, comprises at least one extra thickness which extends radially towards the member, or the sheet, respectively, and comprises means for radial support on the member, or the sheet
Implementation Method 3
This radial support provides a slight radial prestressing of the sheet which is then immobilized radially and is prevented from vibrating in operation of the turbojet engine
Implementation Method 4
In operation, there appears a relatively large radial temperature gradient in each ring sector, which leads to a 'straightening' of this ring sector
Data Source
Figure 1~2
Figure 3~4
AI summary
Turbine or turbojet compressor stage, comprising at least one rotor wheel mounted inside a sectored ring (120) carried by a housing (116) and comprising a circumferential rim (132) radially clamped on an annular rail (136) of the housing by a locking member (138) with a C-section which is axially engaged on the housing rail and on the rim of the ring, a cylindrical thermal protection plate (146) being interposed between the ring and the member, the plate or the member comprising at least an overthickness (150) which is bearing on the member, or the plate respectively, to radially immobilize this plate.