Canted Core Nozzle Layout for Unducted Exhaust-Flap Clearance
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Solution Overview
Problem
Aircraft engines with unducted thrust producing systems face challenges in efficiently directing core exhaust away from wing flaps while maintaining thrust alignment and minimizing efficiency penalties, particularly due to jet-flap interactions and potential impingement.
Innovation Solution
Implementing a canted, internal plug core nozzle with parallel flow between core exhaust and bypass streams, utilizing an elliptical outlet nozzle design to minimize impingement risks and enhance thrust efficiency through the eductor effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional core nozzle is used to direct core exhaust away from wing flaps, then jet-flap impingement is reduced, but thrust alignment is compromised and efficiency penalties increase
Solution Approach 1:
The outlet nozzle is segmented into multiple functional sections: a core nozzle for core exhaust, a bypass nozzle for bypass stream, and a mixing section where the streams interact. This segmentation allows each component to be optimized for its specific function while working together to resolve the contradiction between directing exhaust away from flaps and maintaining thrust efficiency.
Solution Approach 2:
The bypass stream acts as an intermediary that interacts with the core exhaust stream in the mixing section. The bypass stream serves as a mediator to control the core exhaust flow direction and reduce impingement on wing flaps while maintaining thrust efficiency through the eductor effect.
2Reliability
If core exhaust is directed away from wing flaps using a canted nozzle, then impingement risks are reduced, but thrust alignment and performance are compromised
Solution Approach 1:
The outlet nozzle incorporates adjustable components including a movable core nozzle and variable geometry in the mixing section that can dynamically adapt to different operating conditions. This dynamic capability allows the system to optimize both impingement avoidance and thrust alignment across varying flight regimes.
Solution Approach 2:
The system utilizes variable parameters including adjustable nozzle angles, changing flow rates through the bypass and core streams, and variable mixing section geometry to optimize performance. These parameter changes enable the system to maintain thrust alignment while directing exhaust away from wing flaps.
3Loss of energy
If an unducted fan configuration is used to reduce drag, then efficiency is improved, but control over exhaust stream direction and interaction with wing flaps is reduced
Solution Approach 1:
The outlet nozzle design incorporates features that respond to flow conditions and operating parameters to automatically adjust exhaust stream direction and control the interaction between core and bypass streams. This feedback mechanism enables the unducted fan configuration to maintain exhaust control while minimizing drag.
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 effectively directs core exhaust away from wing flaps, reduces impingement risks, and enhances thrust efficiency by optimizing the interaction between core and bypass streams, resulting in improved performance and reduced drag.
Implementation Method 1
the bypass or third exhaust stream scrubbing the aft core cowl entrains a core exhaust stream expelled through the core nozzle
Data Source
AI summary
A thrust producing system for an aircraft includes a turbomachine; a fan rotatably driven by the turbomachine; and a downward and/or laterally outward canted outlet nozzle. The outlet nozzle includes a core nozzle with a core nozzle segment with a decreasing cross-sectional area in an axial direction toward an exhaust end of the outlet nozzle; and an aft core cowl, positioned radially outward with respect to and surrounding the core nozzle segment. The aft core cowl comprises an aft core cowl segment with a decreasing cross-sectional area in the axial direction. Surfaces of the core nozzle segment and the aft core cowl segment transition together into surfaces that are parallel with respect to each other along the axial direction, such that during operation of the thrust producing system, a bypass or third exhaust stream scrubbing the aft core cowl entrains a core exhaust stream expelled through the core nozzle.