Turbomachine Exhaust Casing Aerodynamic Pocket Redesign
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Solution Overview
Problem
The existing turbomachine exhaust casing design with radially projecting yokes and pockets impede aerodynamics, leading to performance losses and mechanical strength issues due to pocket contact with the gas stream.
Innovation Solution
A ring portion is introduced under the pockets to reshape the gas flow duct, preventing pocket contact with the gas stream and allowing for reduced pocket thickness and reinforcement without affecting aerodynamics, by attaching it between flanges or to the external ferrule using clamping or riveting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pockets are hollowed into the external ferrule to reinforce the yokes, then mechanical strength is improved, but aerodynamics deteriorates due to pocket projection into the gas flow duct
Solution Approach 1:
The invention relocates the pockets from projecting radially inward into the gas flow duct to being positioned radially outward on the external ferrule. This dimensional repositioning eliminates the aerodynamic interference while preserving the structural reinforcement function for the yokes.
Solution Approach 2:
The invention introduces a reinforcement element that extends between the hub and the external ferrule, positioned to provide mechanical support to the yokes without protruding into the gas flow path. This intermediary structure mediates between the need for strength and aerodynamic efficiency.
2Reliability
If yokes are positioned radially at the level of the external ferrule for mechanical withstand, then structural reliability is improved, but aerodynamic performance deteriorates due to pocket projection
Solution Approach 1:
The pockets are repositioned from the radial interior dimension (projecting into the duct) to the radial exterior dimension (on the outer surface of the ferrule), maintaining yoke support while eliminating aerodynamic disruption.
Solution Approach 2:
The reinforcement features are localized to specific regions on the external ferrule where yoke attachment is required, rather than projecting into the general gas flow path. This localized approach preserves aerodynamic quality in the flow region while providing structural reinforcement where needed.
Data Source
AI summary
A turbomachine exhaust casing extending about an axis including a hub extending about the axis; an external ferrule; arms which extend between the hub and the external ferrule, attachment yokes radially projecting toward the outside of the external ferrule; pockets hollowed into the external ferrule and wherein the yokes are arranged, the pockets extending in a hollow radially projecting toward the inside of the external ferrule; a ring portion which extends radially under the pockets and forms a duct wall by delimiting with the hub a portion of a gas flow duct.