Bleed Flow Outlet Panel Mixing Gas Turbine Engine
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Solution Overview
Problem
Conventional bleed flow outlets in gas turbine engines fail to effectively mix hot bleed air with cool bypass air, leading to thermal damage and reduced fan performance due to plume blockage, which increases the likelihood of engine stall and requires larger, heavier bleed assemblies.
Innovation Solution
A bleed flow outlet panel with distinct regions of exit passages, where the first region directs flow substantially aligned with the major axis and the second region directs flow towards the perimeter edge, reducing blockage and enhancing mixing by distributing the bleed flow more effectively into the bypass duct.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional open exit or pepper pot exit is used for bleed flow discharge, then the bleed flow can be discharged into the bypass flow, but the hot bleed flow does not mix effectively with the cool bypass flow, causing thermal damage to the engine casing
Solution Approach 1:
The outlet panel is segmented into multiple distinct regions (first region with exit passages aligned with major axis, second region with exit passages directing flow toward perimeter edge) to create distributed discharge points that enhance mixing of hot bleed flow with cool bypass flow, preventing thermal damage to the engine casing
Solution Approach 2:
Different regions of the outlet panel provide different flow directions: the first region directs flow substantially aligned with the major axis while the second region directs flow toward the perimeter edge, creating locally optimized flow patterns that improve overall mixing effectiveness and reduce thermal damage
2Productivity
If a conventional bleed flow outlet is used, then the bleed flow can be discharged, but the flow creates a plume that blocks the main air flow, increasing the likelihood of engine stall and reducing fan performance
Solution Approach 1:
The outlet panel is divided into multiple regions with exit passages distributed across the panel, breaking up the concentrated plume into distributed flow streams that reduce blockage of the main air flow and minimize the risk of engine stall while maintaining productivity
Solution Approach 2:
The second region of exit passages directs flow toward the perimeter edge, utilizing the radial dimension of the outlet panel to distribute bleed flow laterally into the bypass flow, reducing axial plume blockage and improving fan performance and reliability
3Quantity of substance
If a larger bleed assembly is used to discharge bleed flow, then the discharge capacity is increased, but the size and weight of the bleed assembly increase
Solution Approach 1:
The outlet panel is segmented into multiple regions with numerous exit passages distributed across the panel, providing large discharge capacity through distributed flow paths rather than requiring a single large opening, thereby maintaining lightweight construction while achieving high bleed flow discharge capacity
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 solution improves the mixing of bleed flow with bypass flow, reducing thermal damage and the risk of engine stall while minimizing the size and weight of the bleed assembly, thereby enhancing engine performance and reliability.
Implementation Method 1
the bleed flow does not mix effectively with the cool bypass flow
Implementation Method 2
exit passages being arranged to direct the bleed flow, in use, in different directions
Data Source
AI summary
A bleed flow discharge device for discharging bleed flow into a main fluid flow. The bleed flow discharge device has an outlet panel that comprises distinct first and second regions, both of which have bleed flow exit passages. The first region is at the downstream end of the bleed flow outlet panel relative to the main flow. The exit passages in the first region are closely aligned to a major axis of the outlet panel, whereas the exit passages in the second region have a component that points towards a perimeter edge of the exit panel. This arrangement results in good mixing of the bleed flow with the bypass flow, delayed attachment of the bleed flow onto the bypass duct surfaces, and low noise.