Dual Wall Liner Plenum for Obstructed Exhaust Cooling
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Solution Overview
Problem
In gas turbine engines, certain regions such as the end portions of exhaust liners are obstructed, preventing direct impingement cooling due to support structures, which reduces cooling efficiency.
Innovation Solution
A dual wall exhaust nozzle liner assembly with a plenum chamber that communicates impingement cooling air outboard of obstructions, using a plenum to direct cooling air flow through impingement openings to directly strike the inner liner, enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If support structures are installed in the end portion of the exhaust liner, then structural strength is improved, but cooling efficiency deteriorates due to blocked cooling air flow
Solution Approach 1:
The exhaust liner is divided into multiple sections with different cooling approaches: the main body uses direct impingement cooling through cooling holes, while the end portion uses a plenum chamber with distributed impingement openings to deliver cooling air around the support structure, and the transition zone uses diffusion openings for film cooling. This segmentation allows each region to be optimized for its specific functional requirements.
Solution Approach 2:
A plenum chamber is introduced as an intermediary structure in the end portion to redirect and distribute cooling air flow. The plenum receives cooling air from the cooling air source and channels it through multiple impingement openings that are positioned to strike the inner liner surface around the support structure, thereby delivering cooling effect without requiring direct cooling hole communication with the cooling air source.
2Stability of the object's composition
If cooling holes are blocked by support structures, then structural integrity is improved, but cooling performance deteriorates
Solution Approach 1:
Different cooling mechanisms are applied to different regions of the inner liner: the main body receives direct impingement cooling where cooling holes are unobstructed, the end portion receives cooling through the plenum chamber system that works around support structures, and the transition zone receives film cooling through diffusion openings. This local differentiation allows the structure to maintain integrity where needed while achieving adequate cooling where possible.
Solution Approach 2:
The cooling approach transitions from a two-dimensional planar cooling pattern (cooling holes in the cold side liner) to a three-dimensional cooling system in the end portion. The plenum chamber creates a volumetric cooling zone with multiple impingement openings distributed in space, allowing cooling air to approach the inner liner from multiple directions and angles, thereby overcoming the blocking effect of support structures.
3Loss of energy
If direct impingement cooling is used, then cooling efficiency is improved, but structural complexity increases due to obstruction handling
Solution Approach 1:
The plenum chamber serves multiple functions simultaneously: it acts as a cooling air distribution system, a flow redirection mechanism, and a structural support element. By integrating these functions into a single component, the design avoids the need for separate complex systems to handle each function, thereby limiting the increase in overall structural complexity while maintaining high cooling efficiency.
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 plenum chamber ensures effective impingement cooling at obstructed regions, maintaining desired temperature and protecting the inner liner from extreme temperatures by providing direct impingement of cooling air, thereby improving cooling efficiency.
Implementation Method 1
The impingement flow provides the desired cooling effects by directly striking the hot side liner
Implementation Method 2
Cooling is provided by cooling air flowing through the cold side liner and impinging on the hot side liner
Implementation Method 3
Air flowing from the diffusion openings generates a insulating film of cooling air along the hot side of the inner liner
Implementation Method 4
Air flowing from the diffusion openings generates a insulating film of cooling air along the hot side of the inner liner
Data Source
AI summary
An exhaust nozzle assembly includes an inner liner exposed to hot combustion gases and an outer liner spaced a radial distance from the inner liner to form an annular chamber. The inner liner includes a hot side that is directly exposed to the hot combustion gas flow and a cold side is exposed to cooling air within the chamber. The outer liner includes an outer surface exposed to cooling air flow up to a restriction preventing communication of cooling air flow. A plenum is attached to the outer liner to define a plenum chamber that extends into an end portion. The plenum chamber receives cooling air flow from a supply opening and communicates that air to an end portion through a plurality of impingement openings that provide impingement flow of cooling air outboard of the restriction.