Variable Thickness Aeroengine Mixer Design
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Solution Overview
Problem
Turbine exhaust case mixers in gas turbine aeroengines face durability issues due to vibratory responses, requiring stiffener rings for structural integrity, which increases weight and complexity.
Innovation Solution
A mixer design with circumferential inner and outer flow surfaces featuring a wavy configuration, formed from sheet metal blanks of varying thicknesses, welded together to create a nozzle configuration, allowing for enhanced rigidity and reduced weight without additional support, using a single weld joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the mixer is formed from a single sheet of structural material to minimize weight, then weight is reduced, but structural strength and rigidity deteriorate requiring additional stiffener rings
Solution Approach 1:
The mixer employs variable thickness sheet metal construction where the sheet metal is thicker at the upstream end and thinner at the downstream end. This local variation in material quantity provides enhanced structural strength and rigidity at the upstream end (where it connects to the turbine exhaust case) while minimizing overall weight, eliminating the need for additional stiffener rings.
2Reliability
If stiffener rings are added to restrain end motion and avoid vibratory responses, then reliability improves, but device complexity and weight increase
Solution Approach 1:
The variable thickness design concentrates material where it is most needed for structural integrity and vibration resistance - at the upstream end with thicker sheet metal. This eliminates the need for additional stiffener rings and other complexity-reducing components while maintaining reliability.
3Weight of moving object
If the sheet metal thickness is reduced to minimize weight, then weight is reduced, but manufacturing precision and structural integrity worsen
Solution Approach 1:
The mixer uses variable thickness sheet metal construction with a gradual transition from thicker upstream end to thinner downstream end. This approach optimizes the balance between weight reduction and structural integrity, providing adequate material thickness throughout while minimizing overall weight.
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 design provides improved structural integrity and reduced weight, eliminating the need for stiffener rings, while maintaining the mixer's strength and efficiency in mixing exhaust gases with bypass air streams.
Implementation Method 1
a weld joint extending circumferentially between and joining the circumferentially-endless upstream and downstream portions together
Data Source
AI summary
A mixer of a bypass turbine aeroengine according to one embodiment, includes circumferential inner and outer flow surfaces in a wavy configuration to form a plurality of lobes of the mixer. The mixer has an upstream end portion of sheet metal with a first thickness and a downstream end portion of sheet metal with a second thickness less than the first thickness.