Adjustable Turbomachine Blade Cascade for Resonance Reduction
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Solution Overview
Problem
Existing turbomachines, particularly gas turbines, face challenges in optimizing blade cascade arrangements to minimize undesired resonances and improve flow conditions, leading to inefficiencies in performance and suction limits.
Innovation Solution
An adjustable blade cascade system where blades can be adjusted in terms of stagger angles and spacing, allowing for reversible and simultaneous adjustment of adjacent blades to optimize their positions and reduce resonances, utilizing an adjusting device with levers and joints for rotational and translational movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blades are arranged with equal circumferential distances in a cascade, then the structure is simple and uniform, but undesired resonances occur between adjacent blades
Solution Approach 1:
The patent applies asymmetry by varying the circumferential distances between adjacent blades in the cascade. Specifically, at least one blade has a first circumferential distance from one adjacent blade and a second circumferential distance from the other adjacent blade, where the first and second distances differ. This asymmetric spacing breaks the uniformity that causes resonances while maintaining structural feasibility, thereby reducing unwanted vibrational interactions between blades.
2Adaptability or versatility
If blades are fixed in position, then the structure is simple, but flow conditions and performance cannot be optimized for different operating conditions
Solution Approach 1:
The patent implements dynamics by making the blade cascade adjustable rather than fixed. The cascade allows blades to be repositioned in the circumferential direction, enabling changes in stagger angles and blade spacing. This dynamic capability permits optimization of flow conditions and performance for different operating scenarios, while the adjustment mechanism is designed to be integrated into the existing cascade structure.
3Reliability
If all blades are adjusted uniformly, then the adjustment mechanism is simple, but individual blade optimization for resonance reduction is not achieved
Solution Approach 1:
The patent applies local quality by enabling independent or differential adjustment of individual blades within the cascade. While the adjustment device may have a unified structure, it allows for selective repositioning of specific blades to achieve optimal spacing arrangements. This localized adjustment capability permits targeted resonance reduction by modifying circumferential distances between specific adjacent blades without requiring uniform adjustment of all blades.
Data Source
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AI summary
The present invention relates to an adjustable blade grid for a turbomachine, in particular a compressor or turbine stage of a gas turbine, comprising at least one first blade, in particular a guide blade (10), which has a first distance (B) in the circumferential direction from a circumferentially adjacent blade (30), at least one second blade, in particular a guide blade (20), which has a second distance (A) in the circumferential direction from a circumferentially adjacent blade (40), which is smaller than the first distance (B), and an adjustment device (50 - 54) for adjusting, in particular jointly and/or reversibly, the first and second blades from a first position in which at least one blade profile section (11) of the first blade (10) and one blade profile section (21) of the second blade (20) each have a first offset angle (β1B;β1A) has a second position in which these blade profile sections (11, 21) have second step angles (β2B; β2A), wherein the second step angle (β2B) of the first blade (10) is different from the second step angle (β2A) of the second blade (20), in particular larger than the second step angle (β2A) of the second blade (20).;