Ram Air Turbine Generator Housing with Variable Wall Thickness
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Solution Overview
Problem
Ram air turbines face extreme loads during high-level, short-duration events and windmilling vibrations, which reduce the fatigue life of components, and existing designs struggle to accommodate thermal variations and stress concentrations effectively.
Innovation Solution
A generator housing with radially thickened contacting and spaced portions, swiveling with the generator between stowed and deployed positions, and a consistent radial thickness ratio to the stator diameter, allowing for thermal flexibility and load distribution, while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the RAT housing is strengthened to endure HLSD events, then the structural strength improves, but the weight and complexity increase
Solution Approach 1:
The patent applies local quality by varying the wall thickness in specific regions of the housing. The wall includes a first portion with a first thickness and a second portion with a second thickness greater than the first thickness. This localized thickening provides additional strength where needed to endure HLSD events while avoiding unnecessary weight and complexity in other regions.
2Strength
If the wall thickness is increased to withstand extreme loads, then the structural integrity improves, but the thermal flexibility decreases
Solution Approach 1:
The patent resolves this contradiction by applying different wall thicknesses in different regions. The thinner first portion maintains thermal flexibility to accommodate dimensional changes due to thermal variations, while the thicker second portion provides the structural integrity needed to withstand extreme loads.
Solution Approach 2:
The housing wall is segmented into distinct portions with different thicknesses. This segmentation allows each portion to be optimized for its specific function - the first portion for thermal flexibility and the second portion for load bearing - thereby resolving the contradiction between thermal adaptability and structural strength.
3Object-affected harmful factors
If the RAT components are designed to avoid resonance frequencies, then the vibration loads reduce, but the design flexibility is limited
Solution Approach 1:
The patent changes the physical parameters of the housing by varying wall thickness in different regions. This parameter change modifies the structural characteristics and natural frequencies of the housing, helping to avoid resonance with HLSD vibration frequencies while maintaining design flexibility through the localized approach.
4Ease of manufacture
If the housing is designed with uniform wall thickness, then the manufacturing is simplified, but the stress concentration is increased
Solution Approach 1:
The patent applies local quality by designing the wall with different thicknesses in different regions rather than using a uniform thickness. The second portion has a greater thickness to specifically address stress concentration issues in high-load areas, while improving stress resistance without significantly complicating the overall manufacturing process.
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 enhances the ram air turbine's ability to withstand extreme loads and thermal variations, extending its fatigue life and maintaining structural integrity under high vibration conditions.
Implementation Method 1
A generator housing of the ram air turbine needs to withstand these loads while accommodating changes in part dimensions due to thermal variations.
Data Source
AI summary
An example ram air turbine generator assembly includes a generator housing that holds a generator in axial alignment with a hydraulic pump. The generator housing includes a wall having contacting portions that contact a stator of the generator and spaced portions that are radially spaced from the stator. The generator wall is designed to be strong enough to withstand HLSD and windmilling vibrations, while flexible enough to accommodate thermal expansion.