Variable Geometry Nozzle for Aircraft Wing Thermal Stress Reduction
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Solution Overview
Problem
Aircraft with wing-mounted turbofan engines face challenges of increased drag and thermal stress, leading to higher operational costs, weight penalties, and manufacturing costs due to the impingement of exhaust flow on wing surfaces, necessitating the use of titanium flaps and resulting in suboptimal performance.
Innovation Solution
An integrated engine exhaust system featuring a variable shape nozzle that adjusts the exit aperture to reduce drag and thermal loading, comprising an inner and outer nozzle configuration that can change shape to alter the exhaust flowfield, thereby minimizing drag and thermal stress on the wing assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If exhaust flow is directed onto wing surfaces to augment lift during low-speed operations, then short field takeoff and landing capabilities are improved, but thermal loading on wing surfaces increases requiring titanium flaps instead of aluminum
Solution Approach 1:
The nozzle incorporates a variable geometry mechanism that dynamically changes the exit aperture shape between a circular configuration (for thrust optimization) and a flattened configuration (for exhaust redirection onto the wing). This dynamic adaptability allows the system to optimize performance for different operational phases while managing thermal loads through controlled exhaust placement.
Solution Approach 2:
The invention changes the geometric parameters of the nozzle exit aperture by varying the ratio of vertical to horizontal dimensions. This parameter transformation enables the exhaust flow to be redirected onto the wing surface at specific phases, achieving augmented lift and shorter takeoff/landing distances while controlling the distribution and intensity of thermal loading through optimized flow patterns.
2Strength
If titanium flaps are used to withstand thermal loads from exhaust impingement, then thermal stress resistance is improved, but aircraft weight and manufacturing costs increase
Solution Approach 1:
The variable geometry nozzle creates a localized concentration of exhaust flow onto specific regions of the wing surface, particularly the flap area. This local quality approach concentrates thermal energy where needed for lift augmentation while limiting the spread of thermal loading, thereby reducing the overall thermal stress burden on the wing structure and enabling the use of lighter materials.
Solution Approach 2:
The invention converts the harmful thermal impingement effect into a beneficial aerodynamic force. By directing the hot exhaust flow onto the wing surface, the system generates both thermal pressure and momentum-based lift augmentation, transforming what would normally be a harmful thermal load into a useful propulsive and aerodynamic assistance during critical low-speed phases.
3Productivity
If variable geometry nozzle is implemented to reduce drag and thermal loading, then aerodynamic performance is improved, but device complexity increases
Solution Approach 1:
The nozzle is segmented into distinct functional zones including an inner circular nozzle and an outer annular nozzle with variable geometry. This segmentation allows independent optimization of each zone's function while simplifying the control mechanism, as the variable portion can be actuated separately to achieve the desired flattened configuration without requiring complete redesign of the entire nozzle structure.
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 takeoff and landing distances, lower aircraft weight, reduced fuel consumption, lower production and maintenance costs, and lower noise levels by optimizing the exhaust flowfield to distribute pressure and temperature more uniformly across the wing, allowing for the potential use of lighter materials and smaller engines.
Implementation Method 1
The nozzle includes a variable portion configured to vary an exit aperture of the nozzle from a first shape to a second shape to change the flowfield shape of at least a portion of the exhaust flowfield proximate the wing assembly
Data Source
AI summary
Integrated engine exhaust systems and methods for reducing drag and thermal loads are disclosed. In one embodiment, a propulsion system includes an engine installation configured to be mounted on a wing assembly of an aircraft. The engine installation includes an engine, and an exhaust system operatively coupled to the engine. The exhaust system includes at least one nozzle configured to exhaust an exhaust flow from the engine. The nozzle includes a variable portion configured to vary an exit aperture of the nozzle from a first shape to a second shape to change a flowfield shape of at least a portion of the nozzle flowfield proximate the wing assembly, thereby reducing at least one of drag and thermal loading on the wing assembly. In a further embodiment, the exhaust system includes an inner nozzle that exhausts a core exhaust flow, and an outer nozzle that exhausts a secondary exhaust flow, the outer nozzle having the variable portion configured to vary the exit aperture of the outer nozzle.