Aircraft Propulsion Pylon Stiffness and Weight Trade-off
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Solution Overview
Problem
Existing aircraft propulsion systems face challenges in maximizing stiffness while minimizing weight and reducing drag, particularly in managing 1P moment loads and optimizing pitch throughout the flight envelope, which affects fuel efficiency and operating costs.
Innovation Solution
The proposed system features a core engine with a nacelle and free power turbines driving rotor modules, mounted on pylons that are strategically positioned to maximize stiffness and minimize weight, with a tripod configuration allowing for pitch adjustment to optimize thrust alignment and reduce drag, and includes a gearbox for counter-rotation of rotors to mitigate 1P loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pylons are positioned to maximize stiffness, then the structural strength is improved, but the weight increases
Solution Approach 1:
The patent applies local quality by positioning pylons at specific locations on the nacelle where structural stiffness is most needed, rather than uniformly distributing support structures. This allows the system to achieve maximum stiffness with minimum weight by concentrating structural reinforcement only where aerodynamic and gravitational loads are highest.
Solution Approach 2:
The pylons are strategically positioned in advance during the design phase to preemptively handle 1P moment loads and thrust alignment issues. By pre-positioning the support structures to account for anticipated flight envelope conditions, the system achieves optimal stiffness-to-weight ratio without requiring additional weight for adaptive adjustments during flight.
2Weight of moving object
If the pylons are positioned to minimize weight, then the weight is reduced, but the stiffness decreases
Solution Approach 1:
The patent applies local quality by positioning pylons at specific locations on the nacelle where structural stiffness is most needed, rather than uniformly distributing support structures. This allows the system to achieve maximum stiffness with minimum weight by concentrating structural reinforcement only where aerodynamic and gravitational loads are highest.
3Use of energy by moving object
If the pitch is adjusted to optimize thrust alignment, then the fuel efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent applies dynamics by enabling pitch adjustment of the rotor modules to optimize thrust alignment with the aircraft's center of gravity throughout the flight envelope. The system transitions from a fixed pitch configuration to a dynamic one where pitch angles can be adjusted based on flight conditions, improving fuel efficiency without requiring complex active control systems.
Solution Approach 2:
The pitch adjustment mechanism serves multiple functions: optimizing thrust alignment for fuel efficiency, managing 1P moment loads, and adapting to different flight phases. This multi-functionality reduces the need for separate systems for each purpose, thereby limiting the increase in device complexity.
4Manufacturing precision
If the rotor inlet distortion is reduced, then the airflow quality is improved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the airflow management into distinct zones around the rotor inlet. By segmenting the nacelle structure and pylon positioning to specifically address airflow distortion patterns, the system improves rotor inlet quality without requiring complex active flow control systems across the entire inlet area.
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
This configuration achieves optimal trade-offs between weight, stiffness, and rotor inlet distortion, leading to reduced fuel consumption, lower operating costs, and emissions, while also addressing the challenges of 1P loads and thrust alignment during various flight phases.
Implementation Method 1
at least one free power turbine driven to rotate by exhaust gases exiting the turbine section
Implementation Method 2
at least one rotor module driven to rotate by the at least one free power turbine
Data Source
AI summary
An aircraft propulsion system is disclosed herein. The aircraft propulsion system includes a core engine having an intake, a compressor section, a combustor section, and a turbine section arranged along a centerline axis. The aircraft propulsion system also includes a nacelle surrounding the core engine. The aircraft propulsion system also includes at least one free power turbine driven to rotate by exhaust gases exiting the turbine section. The aircraft propulsion system also includes at least one rotor module driven to rotate by at least one free power turbine. The aircraft propulsion system also includes first and second pylons extending away from the nacelle and operable to mount the core engine to an aircraft. The first and second pylons are spaced from one another on opposite sides of at least one plane containing the centerline axis and mirror one another across the at least one plane.