Turbofan Intermediate Casing Bypass Channel for Oil Flow
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Solution Overview
Problem
The existing intermediate casings for turbofan engines have a large main cross section in structural arms, which limits the flow of hydraulic fluids, such as oil, from an upstream region to a downstream outlet, necessitating a reduction in the cross section to facilitate oil circulation while maintaining structural support and service passage.
Innovation Solution
Incorporating a bypass channel in the hollow arm that extends from upstream to downstream of the transmission shaft, allowing hydraulic fluids to bypass the shaft and reach an outlet downstream, thereby increasing the cross-sectional passage for oil flow without interfering with the primary and secondary flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the main cross section of the hollow arm is reduced to decrease the influence on primary and secondary flows, then the flow restriction is improved, but the cross section of flow for oil passage is limited
Solution Approach 1:
The hollow arm is segmented into multiple functional zones: an upstream region, a downstream region, and an intermediate bypass channel region. This segmentation allows the arm to have different cross-sectional characteristics in different zones, enabling optimized oil flow while minimizing interference with primary and secondary flows.
Solution Approach 2:
A bypass channel is introduced as an intermediary passage within the hollow arm. This bypass channel serves as a dedicated mediator for oil flow from the upstream region to the downstream outlet, allowing sufficient oil circulation without requiring the main cross section of the arm to be large.
2Ease of operation
If the main cross section of the hollow arm is reduced to facilitate oil circulation, then the structural influence on flows is minimized, but the structural integrity may be compromised
Solution Approach 1:
The hollow arm exhibits local quality variations along its length. The bypass channel region has different structural characteristics compared to the upstream and downstream regions. This allows the arm to maintain sufficient structural integrity where needed while providing optimized oil flow passages in other regions.
Data Source
AI summary
An intermediate casing comprising an inner annular hub, an outer annular barrel and an annular part for separating flows situated between the hub and the outer barrel. A primary stream is delimited between the hub and the separation part. A secondary stream is delimited between the separation part and the outer barrel. At least one hollow arm extends radially from the hub to the outer barrel, passing through the primary and secondary streams. A transmission shaft extends radially in the hollow arm. The hollow arm comprises a hydraulic-fluid outlet situated downstream of the transmission shaft. The arm further comprises a bypass channel or pocket able to bypass the transmission shaft.