Bladed Rotor Sector Distribution for Turbomachine Mass Balance
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Solution Overview
Problem
Conventional gas turbine rotors with blades distributed equidistantly over the circumference face issues with trailing and back-pressure distributions, and existing designs with non-uniform blade distributions lead to mass imbalances and complexities in storage and assembly.
Innovation Solution
A bladed rotor design with a sector-based blade distribution, featuring odd and greater than two angular sectors, where blades in each sector are arranged with specific angular spacings and mass ratios, allowing for better mass distribution and reduced need for mass balancing, with blades in adjacent sectors having either equal or varying masses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If blades are distributed equidistantly over the entire circumference, then the rotor structure is simple and easy to manufacture, but the trailing and back-pressure distributions are disadvantageous
Solution Approach 1:
The rotor circumference is divided into multiple angular sectors (at least three), with each sector containing a specific number of blades. This segmentation allows different blade distributions in different sectors, optimizing pressure distributions while maintaining manufacturing feasibility through standardized blade designs within each sector.
Solution Approach 2:
Different angular sectors have different numbers of blades (first number NA in first sectors, second number NB in second sectors), creating local variations in blade density. This local quality approach optimizes trailing and back-pressure distributions in specific regions of the rotor without requiring complete non-uniformity across the entire circumference.
2Reliability
If non-uniform blade distribution is implemented to improve pressure distributions, then trailing and back-pressure distributions are improved, but mass imbalances occur requiring additional mass balancing
Solution Approach 1:
The rotor employs an asymmetric blade distribution pattern with at least three angular sectors where the number of blades varies by sector. This asymmetric arrangement improves pressure distributions while the specific design choices (odd number of sectors, controlled blade number variations) help manage mass balance requirements.
Solution Approach 2:
The invention varies blade distribution parameters (number of blades per sector, angular sector count, angular spacing) to optimize both pressure distributions and mass balance. By carefully selecting these parameters - such as using an odd number of sectors and controlling the difference between NA and NB - the design achieves improved performance while reducing mass balancing complexity.
3Reliability
If different numbers of blades are used in different sectors to optimize distribution, then pressure distributions are improved, but storage and assembly become more complex
Solution Approach 1:
The invention employs a first blade design that can be used in multiple first angular sectors and a second blade design for second angular sectors. By standardizing blade types within each sector category and using consistent attachment mechanisms, the design achieves operational flexibility while maintaining ease of storage and assembly through part standardization.
Solution Approach 2:
The rotor is segmented into distinct angular sectors with standardized blade configurations within each sector type. This segmentation allows for modular assembly where identical or similar blades can be pre-grouped and installed together, simplifying storage and assembly operations while still achieving the desired non-uniform distribution across the entire rotor.
Data Source
Figure 1~2D
AI summary
The rotor has multiple blades (2A, 2B) distributed around a circumference of a bladed rotor. A blade distribution of the blades is a natural-number sector count (Z) of angular sectors (A, B). The blades are arranged in the angular sectors. Two blade counts (Na, Nb) of the blades are arranged in the angular sectors, where one of the blade counts is different from other blade count. The blades in the angular sectors are identical and distributed equidistantly from each other and have same mass. The blades are formed integrally with a hub (1). An independent claim is also included for a method for blading a rotor.