Variable Airflow Capture Propulsion for Supersonic Noise Control
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Solution Overview
Problem
Supersonic passenger aircraft using low bypass ratio turbojet engines face excessive noise levels during take-off and landing, exceeding acceptable noise standards, while maintaining efficiency at high speeds is challenging due to trade-offs between noise and drag considerations.
Innovation Solution
A propulsion system with a variable airflow capture area that includes a main propulsion source (low bypass ratio turbojet engines) and an auxiliary propulsion source (auxiliary thrust fans) that can be deployed or stowed to manage airflow capture area, reducing noise at lower speeds without compromising high-speed efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low bypass ratio turbojet engines are used for high-speed cruise, then fuel efficiency at supersonic speeds is improved, but noise output during take-off and landing exceeds acceptable levels
Solution Approach 1:
The patent employs a variable geometry intake system with movable capture area boundaries that dynamically adjust the airflow capture area based on flight conditions. During take-off and landing, the capture area is reduced to lower noise output, while during supersonic cruise, the capture area is optimized for fuel efficiency. This dynamic adaptation resolves the contradiction by allowing the engine to operate efficiently at different flight regimes without consistently generating excessive noise.
Solution Approach 2:
The patent changes the operational parameters of the engine by varying the airflow capture area. By adjusting the capture area parameter according to flight phase, the engine can maintain optimal fuel efficiency during supersonic cruise while reducing noise during low-speed operations. This parameter change enables the system to satisfy both efficiency and noise requirements under different operating conditions.
2Object-generated harmful factors
If larger airflow capture area is used to reduce noise at low speeds, then noise levels are reduced, but drag increases during high-speed cruise
Solution Approach 1:
The variable geometry intake system dynamically adjusts the airflow capture area based on flight conditions. During take-off and landing, the capture area is enlarged to reduce noise levels by increasing mass flow. During supersonic cruise, the capture area is reduced to minimize drag and maintain high-speed efficiency. This dynamic adjustment resolves the contradiction by optimizing the capture area for each flight phase rather than using a fixed large area.
Solution Approach 2:
The intake system is segmented into movable boundaries that can independently adjust the capture area. This segmentation allows the system to modify the effective capture area without changing the physical size of the entire intake structure, enabling noise reduction at low speeds while maintaining aerodynamic efficiency at high speeds by preventing excessive drag during cruise.
3Object-generated harmful factors
If variable geometry intake system is implemented, then both noise reduction and efficiency are achieved, but device complexity increases
Solution Approach 1:
The patent implements a variable geometry intake system with movable capture area boundaries that automatically adjust based on flight conditions. While this increases device complexity compared to a fixed intake, it enables simultaneous achievement of noise reduction during low-speed operations and fuel efficiency during supersonic cruise. The complexity is justified by the system's ability to resolve the fundamental noise-efficiency contradiction through dynamic adaptation.
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 reduces noise output during low-speed operations by augmenting airflow capture area with auxiliary thrust fans, while preserving efficiency during high-speed cruise, thus meeting commercial aviation noise standards.
Implementation Method 1
power extracted from the main propulsion source
Implementation Method 2
mitigate adverse change aligned with the 'but' side
Data Source
AI summary
An aircraft propulsion system having a variable airflow capture area is provided. The propulsion system includes a main propulsion source and an auxiliary propulsion source. In a first mode, the auxiliary propulsion source is stowed within an aerodynamic profile of the aircraft, and the main propulsion source provides all of the propulsion force for powering flight of the aircraft. In a second mode, the auxiliary propulsion source is deployed to augment the airflow capture area of the main propulsion source and increase an overall airflow capture area of the propulsion system. In the second mode, the auxiliary power source is operated by power extracted from the main propulsion source. The main propulsion source may include one or more low bypass ratio engines. The auxiliary power source may include one or more auxiliary thrust fans coupled at a plurality of locations on the aircraft.