Gas Turbine Nozzle Flaps with Variable Thickness
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Solution Overview
Problem
Convergent-divergent nozzles in gas turbine engines face challenges in managing thermal gradients, which lead to thermal stresses due to the use of composite materials that are more vulnerable to these gradients compared to metallic alloys.
Innovation Solution
The design incorporates a liner assembly with flaps made of ceramic or organic matrix composites, featuring varying thickness and inclined surfaces, along with troughs that create thin and thick sections to mitigate thermal stresses, and are spaced apart to allow cooling air for temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used for nozzle flaps, then weight is reduced and thermal resistance is improved, but thermal stress resistance deteriorates
Solution Approach 1:
The nozzle flap employs varying thickness distribution along its length, with the root section having greater thickness than the tip section. This local quality variation provides enhanced thermal stress resistance at the root where thermal gradients are most severe, while maintaining lighter weight at the tip where thermal exposure is reduced.
Solution Approach 2:
The invention utilizes composite material construction for the nozzle flaps, combining lightweight properties with tailored thermal and mechanical characteristics. The composite structure allows optimization of material distribution to balance weight reduction with thermal stress resistance.
2Ease of manufacture
If uniform thickness is used for nozzle flaps, then manufacturing is simplified, but thermal stress distribution deteriorates
Solution Approach 1:
Rather than uniform thickness, the design implements local quality variation with different thickness zones along the flap length. The root section uses greater thickness to handle high thermal stresses, while the tip section uses reduced thickness to minimize weight and accommodate lower thermal exposure.
3Strength
If thicker sections are used for thermal protection, then thermal stress resistance is improved, but heat dissipation deteriorates
Solution Approach 1:
The varying thickness design places thicker sections strategically at the root where thermal stress resistance is critical, while maintaining thinner sections toward the tip where heat dissipation is less critical due to lower thermal exposure. This local differentiation optimizes both thermal protection and heat management.
Solution Approach 2:
The invention addresses the thickness-dissipation trade-off by introducing dimensional variation along the longitudinal axis of the flap. Instead of uniform thickness in one dimension, the design varies thickness along the length, creating a gradient that optimizes both structural strength and thermal management across different locations.
Data Source
AI summary
A liner assembly includes a plurality of flaps arranged about a central axis and operable to move relative to the central axis. Each of the plurality of flaps defines a forward end and an aft end, lateral sides, and an inner surface and an outer surface relative to the central axis. Each of the plurality of flaps has a thickness between the inner surface and the outer surface, and thickness varies in a lateral direction between the lateral sides.