Turbine Support Case Ribs for Rotor Tip Clearance Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft engine components, particularly the scroll case, experience thermal growth leading to increased tip clearance in turbine rotors due to non-uniform thermal distortions, which impairs performance.
Innovation Solution
A turbine support case with spokes and stopping ribs is used to secure the turbine exhaust case independently of the scroll case, featuring an anti-rotation mechanism to prevent rotation and shear stress on fasteners, ensuring structural integrity and reducing thermal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the turbine support case is secured to the scroll case, then the structure is simplified, but thermal growth of the scroll case causes non-uniform thermal distortions leading to increased rotor tip clearance
Solution Approach 1:
The support structure is divided into two independent parts: the scroll case and the turbine support case. The turbine support case is secured to the bearing housing via spokes rather than to the scroll case, creating thermal isolation between the two components. This segmentation prevents thermal distortions from the scroll case from affecting the turbine support case and rotor tip clearance.
Solution Approach 2:
The bearing housing acts as an intermediary structure between the scroll case and the turbine support case. The turbine support case is secured to the bearing housing through spokes, creating an independent thermal path that isolates the turbine support case from thermal growth of the scroll case, thereby maintaining rotor tip clearance precision.
2Manufacturing precision
If the turbine support case is independently secured to the bearing housing, then rotor tip clearance is maintained, but the device complexity increases due to additional spokes and stopping ribs
Solution Approach 1:
The turbine support case is segmented into a modular structure with discrete spokes radiating from the bearing housing. This segmentation allows the support case to be independently positioned and thermally isolated from the scroll case, maintaining rotor tip clearance while using a relatively simple spoke-based construction rather than a complex continuous structure.
3Reliability
If stopping ribs are added to prevent rotation, then structural integrity is improved, but the device complexity increases due to additional anti-rotation features
Solution Approach 1:
Stopping ribs are strategically positioned on the turbine support case to create asymmetric features that prevent rotation relative to the bearing housing. These ribs engage with corresponding features on the bearing housing, providing rotational constraint with minimal additional structure. The asymmetric placement of stopping ribs provides effective anti-rotation functionality without requiring complex mechanisms.
Data Source
AI summary
An aircraft engine, has: a turbine; a scroll case connected to a source of combustion gases and to the turbine, and a conduit extending around a central axis; a bearing housing including a support flange; a turbine support case secured to the bearing housing, the turbine support case having spokes extending through the scroll case and radially supported by the bearing housing, a spoke of the spokes having a distal end secured to the support flange via one or more fasteners; and ribs secured to the support flange and distributed around the central axis, a rib of the ribs circumferentially and axially overlapping the distal end of the spoke, the rib having a rib face in radially opposed facing relationship to a spoke face of the spoke, a projection of the rib face in a circumferential direction relative to the central axis intersecting the spoke face.