Propulsion System Architecture with Radially Inward Inlet
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Solution Overview
Problem
Contra-rotating rotor assemblies in open rotor propulsion systems face challenges in power transmission and design complexity, leading to increased weight and length, which complicates achieving propulsive efficiency comparable to conventional ducted engine designs.
Innovation Solution
A propulsion system with a rotating element, a stationary element, and an inlet that passes radially inward, leading to an inlet duct dividing into separate ducts, where a ducted fan generates thrust and a gas turbine core stream is directed into the engine core, reducing complexity and weight while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contra-rotating rotor assemblies are used to improve propulsive efficiency, then propulsive efficiency is improved, but device complexity and weight increase
Solution Approach 1:
The propulsion system is segmented into distinct functional components: an unducted fan for primary thrust generation and a ducted fan for secondary thrust and core stream management. This segmentation allows each component to be optimized independently, reducing overall system complexity while maintaining high propulsive efficiency through specialized function distribution.
Solution Approach 2:
The ducted fan acts as an intermediary component between the gas turbine core and the external environment. It manages the core stream separately from the bypass air, enabling efficient heat exchange and thrust generation without requiring complex contra-rotating mechanisms. This intermediary structure simplifies the power transmission system while preserving propulsive efficiency.
2Productivity
If contra-rotating rotor assemblies are used to improve propulsive efficiency, then propulsive efficiency is improved, but weight increases
Solution Approach 1:
The complex power transmission mechanisms required for contra-rotating assemblies are extracted and replaced with a simpler architecture. The unducted fan is driven directly by the gas turbine core, eliminating the need for intermediate gear systems and contra-rotating drive mechanisms, thereby significantly reducing system weight while maintaining propulsive efficiency.
Solution Approach 2:
Complex mechanical power transmission systems are replaced with a simplified direct-drive configuration. The ducted fan utilizes the core stream's kinetic energy and pressure differential to generate thrust, reducing reliance on heavy mechanical drive systems and decreasing overall component weight.
3Productivity
If contra-rotating rotor assemblies are used to improve propulsive efficiency, then propulsive efficiency is improved, but length increases
Solution Approach 1:
The ducted fan is nested within the engine nacelle structure, with the core stream duct positioned concentrically within the overall engine assembly. This nested configuration allows the ducted fan to occupy space within the existing engine envelope, avoiding the need for additional axial length that would be required by extended contra-rotating rotor assemblies.
4Device complexity
If a ducted fan configuration is used to reduce complexity and weight, then device complexity and weight are reduced, but propulsive efficiency must be maintained
Solution Approach 1:
The propulsion system merges two fan configurations (ducted and unducted) into a single integrated architecture. The unducted fan handles the majority of bypass air for high efficiency, while the ducted fan manages core stream extraction and supplementary thrust. This merging allows the system to achieve comparable propulsive efficiency to contra-rotating designs through coordinated operation of simplified components.
Solution Approach 2:
The system optimizes operational parameters of the ducted fan, including blade geometry, rotational speed, and duct configuration, to maximize thrust generation from the core stream. By carefully adjusting these parameters, the ducted fan compensates for its smaller size and simpler construction, maintaining overall propulsive efficiency despite reduced mechanical complexity.
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 system achieves reduced weight and length with comparable propulsive efficiency to contra-rotating designs, incorporating a ducted fan and unducted fan configuration to optimize thrust, fuel burn, and acoustic performance.
Implementation Method 1
a ducted fan having an axis of rotation and a plurality of blades
Implementation Method 2
directing the core stream into a gas turbine engine core
Data Source
AI summary
A propulsion system, the propulsion system comprising a rotating element, a stationary element, and an inlet between the rotating element and the stationary element, wherein the inlet passes radially inward of the stationary element; wherein the inlet passes radially inward of the stationary element; wherein the inlet leads to an inlet duct containing a ducted fan having an axis of rotation and a plurality of blades; and wherein the inlet duct divides into a first duct and a second duct, separate from the first duct. A method of operating a propulsion system, comprising the steps of: operating a first rotating fan assembly to produce a first stream of air; directing a portion of the first stream of air into a second ducted rotating fan assembly; operating the second ducted rotating fan assembly to produce a second stream of air; dividing the second stream of air into a core stream and a fan stream; and directing the core stream into a gas turbine engine core.