Turbofan Nacelle Convex Surface Coanda Thrust Amplification
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Solution Overview
Problem
Existing turbofan gas turbine engine and nacelle arrangements fail to maximize thrust and thrust efficiency while minimizing weight and noise radiation.
Innovation Solution
The arrangement features a fan by-pass duct within the nacelle with a radially oriented outlet and an aft section with a convex surface that decreases in curvature, utilizing the Coanda effect to deflect and amplify the by-passed air, increasing thrust and efficiency with minimal weight increase and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the by-pass air is ejected directly without deflection, then the structure is simple, but the thrust and thrust efficiency are not maximized
Solution Approach 1:
The patent employs a convex surface in the aft section of the nacelle that curves the by-pass air flow. This curved surface deflects the jet flow rearward, generating additional thrust through the Coanda effect while maintaining a relatively simple integrated structure rather than adding separate complex components
Solution Approach 2:
The convex surface acts as an intermediary element between the by-pass duct outlet and the external environment. It mediates the interaction between the high-velocity by-pass jet and the surrounding air, enabling thrust amplification through flow deflection and entrainment without requiring direct mechanical intervention
2Productivity
If the by-pass duct outlet is oriented axially, then the structure is conventional, but the thrust vectoring and efficiency are limited
Solution Approach 1:
The patent employs asymmetric outlet configuration where the by-pass duct outlet is oriented radially rather than axially. This asymmetric arrangement, combined with the convex surface positioning, creates optimized flow deflection patterns that enhance thrust generation while distributing structural requirements across the nacelle assembly
3Productivity
If the nacelle aft section has high curvature throughout, then the flow deflection is strong, but the jet amplification and noise reduction are compromised
Solution Approach 1:
The patent applies varying curvature characteristics at different locations along the aft section. The convex surface provides localized high curvature adjacent to the outlet for strong initial flow deflection, while the curvature decreases toward the rear end to allow jet amplification and proper flow development, creating optimal local conditions at each position
4Object-affected harmful factors
If the by-pass air is not deviated, then the structure is simple, but the noise radiation is increased
Solution Approach 1:
The convex curved surface gradually deflects the by-pass air flow rearward, promoting smoother flow transitions and reducing turbulent mixing noise compared to abrupt deflection methods. The curved geometry naturally guides the flow while minimizing shock waves and separation-induced noise
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 enhances thrust and thrust efficiency with minimal weight increase and reduces noise radiation by leveraging the Coanda effect for air deflection and amplification.
Implementation Method 1
deviating the by-passed air along a convex surface having a decreasing curvature and becoming concave towards a rear end of the engine
Data Source
AI summary
The arrangement comprises a fan by-pass duct located within the nacelle and having an inlet and an outlet. The outlet is generally oriented substantially radially and at an intermediary location along the nacelle. The nacelle has an aft section with an initially convex and substantially outwardly extending surface adjacent to the outlet of the fan by-pass duct. The surface of the aft section decreases in curvature and becomes concave towards a rear end of the engine.