Blade Cascade Sidewall Contouring for Turbine Vibration Detuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing turbomachine blade cascades face challenges in reducing unwanted vibration phenomena and improving efficiency, particularly in gas turbines, where identical blade contours and arrangements can lead to periodic sidewall contouring and radial jumps, affecting performance.
Innovation Solution
A blade cascade design featuring identical blade groups with different individual blades, each having unique airfoil profiles and side wall contours that are aperiodic with the blade pitch but periodic with the blade groups, reducing radial jumps and optimizing efficiency by varying natural frequencies and aerodynamic excitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If identical blade contours are used in the blade cascade, then manufacturing simplicity is maintained, but unwanted vibration phenomena and radial jumps increase
Solution Approach 1:
The patent applies local quality by differentiating the side wall contours of specific blades within the cascade while maintaining identical airfoil profiles. The side walls are contoured differently in the region between the airfoil and hub, creating local variations that detune natural frequencies and reduce vibrations, while the rest of the blade structure remains standardized for ease of manufacturing.
Solution Approach 2:
The patent introduces asymmetry by providing different side wall contours for at least two blades in the cascade. This asymmetric contouring breaks the periodicity of the blade arrangement, preventing synchronized vibrations and reducing harmful vibration phenomena while maintaining overall manufacturing simplicity through the use of identical airfoil profiles.
2Device complexity
If identical blade contours are used, then manufacturing complexity is reduced, but efficiency of the blade cascade deteriorates
Solution Approach 1:
The patent improves blade cascade efficiency by applying local quality variations to the side wall contours while keeping the airfoil profiles identical. This localized differentiation optimizes flow characteristics and reduces losses in specific regions without requiring complete redesign of all blade components, thus improving efficiency with minimal increase in overall complexity.
3Productivity
If side walls are contoured to improve efficiency, then blade cascade efficiency improves, but periodic sidewall contouring with blade pitch creates radial jumps
Solution Approach 1:
The patent eliminates periodic sidewall contouring and associated radial jumps by introducing asymmetric side wall contours. At least two blades have different side wall profiles, which breaks the periodic repetition that causes radial jumps. This asymmetric design maintains efficiency improvements from side wall contouring while avoiding the harmful periodic effects.
Data Source
Figure 1~4
AI summary
The present invention relates to a blade cascade for a turbomachine, in particular a gas turbine, with a plurality of identical blade groups arranged next to one another, each of which has a first individual blade (10) with a blade leaf (12) with a blade profile and a first side wall (11), and one of these have different second individual blades (20) with a blade leaf (22) with a blade profile and a second side wall (21), the first and second side walls (11, 21) having different contours.