Compact Eductor Oil Cooler Plenum Design for Aircraft Tail Cones
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Solution Overview
Problem
Conventional tandem plenum configurations in aircraft exhaust systems are too long and bulky to fit within converging aircraft tail cones, interfering with the walls and making it difficult to remove line replacement units during repair, and there is a need for a compact and lightweight oil cooler and surge flow plenum system that allows sufficient space between the firewall and APU for maintenance.
Innovation Solution
An eductor assembly with a primary nozzle surrounded by a cooler plenum with decreasing axial cross-sectional areas and a partially surrounding surge plenum, both with fluid inlets and outlets, optimized for compactness and alignment within the aircraft tail cone, allowing for efficient gas flow and maintenance access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If tandem plenum configuration is used, then oil cooler and surge flow functions are achieved, but the system becomes too long and bulky to fit within converging aircraft tail cones
Solution Approach 1:
The patent merges the oil cooler plenum and surge flow plenum into a single integrated assembly where the surge flow plenum is positioned within the oil cooler plenum structure. This consolidation eliminates the need for separate tandem plena, reducing the overall length while maintaining both oil cooler and surge flow functions, thereby enabling installation within converging blade tail cones.
Solution Approach 2:
The surge flow plenum is nested within the oil cooler plenum structure, with the surge flow plenum positioned inside the radial envelope of the oil cooler plenum. This nesting arrangement allows both plena to occupy overlapping spatial volumes, significantly reducing the external dimensions and enabling compact installation within the blade tail cone.
2Volume of moving object
If tandem plena are arranged to fit within blade tail, then space utilization is improved, but interference with tail cone walls occurs
Solution Approach 1:
The patent applies different geometric characteristics to different sections of the plenum assembly. The oil cooler plenum includes a first section with larger cross-sectional area and a second section with smaller cross-sectional area, creating a tapered configuration. This local variation in geometry allows the plenum to fit within the converging blade tail cone while maintaining sufficient internal volume for oil cooling, preventing interference with the tail cone walls.
3Area of stationary object
If APU is moved forward to accommodate plena in wider tail cone portion, then plenum installation space is improved, but distance between firewall and APU becomes insufficient for LRU removal
Solution Approach 1:
Instead of moving the APU forward in the axial direction, the patent resolves the space conflict by transitioning to a radial arrangement where the surge flow plenum is positioned within the radial envelope of the oil cooler plenum. This dimensional change from axial to radial arrangement allows both plena to be accommodated in the available tail cone space without requiring the APU to be positioned too close to the firewall, thereby maintaining accessibility for LRU removal.
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 compact design fits within the aircraft tail cone, maintaining system functionality while allowing sufficient space for maintenance, enhancing operational efficiency and reducing interference with the tail cone structure.
Implementation Method 1
an eductor system that uses the APU exhaust gas to draw and direct other gases through the aircraft
Implementation Method 2
a first plenum is used to draw gas across an oil cooler
Data Source
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AI summary
An eductor assembly (104) is provided that includes a primary nozzle (114), a cooler plenum (120), and a surge plenum (122). In one embodiment, and by way of example only, the primary nozzle (114) is configured to accelerate and discharge turbine exhaust gas therefrom and the cooler plenum (120) surrounds the primary nozzle (114) and includes at least a fluid inlet (134) and a fluid outlet (136). The surge plenum (122) partially surrounds the primary nozzle (114) and the cooler plenum (120) and includes at least a fluid inlet (154) and a fluid outlet (156). The surge plenum fluid outlet (156) axially aligns and is coterminous with the cooler plenum fluid outlet (136).