Turboreactor Nacelle Air Intake Circulation Ducts for Reverse Thrust
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Solution Overview
Problem
Conventional thrust reversal systems in high-bypass turbojet engines are cumbersome and reduce performance due to the generation of local depressions at the air inlet lip, which opposes the thrust reversal phase and decreases efficiency.
Innovation Solution
The air inlet incorporates circulation pipes that open at the air inlet lip and on the interior and exterior walls to deflect the reverse air flow, reducing local depressions and enhancing thrust reversal performance without affecting the thrust phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional thrust reversal system is integrated into the nacelle, then thrust reversal capability is achieved, but mass and size are significantly increased
Solution Approach 1:
The invention extracts the thrust reversal function from the conventional complex mechanical system and integrates it into the existing air inlet structure through circulation pipes. The air inlet lip and circulation pipes are used to deflect exhaust gases forward, achieving thrust reversal without adding separate mechanical reversal components, thus reducing mass while maintaining capability
Solution Approach 2:
The air inlet structure is given multiple functions: it serves both as the normal air intake during thrust phase and as the thrust reversal mechanism during braking. The circulation pipes and air inlet lip are used for both airflow intake and exhaust gas deflection, eliminating the need for dedicated reversal hardware and reducing overall system mass
2Adaptability or versatility
If a conventional thrust reversal system is integrated into the nacelle, then thrust reversal capability is achieved, but device complexity is significantly increased
Solution Approach 1:
The invention merges the thrust reversal system with the existing air inlet structure. The circulation pipes are integrated into the air inlet, and the air inlet lip serves dual purposes. This consolidation eliminates separate reversal mechanisms, flaps, and complex mechanical assemblies, significantly reducing device complexity while achieving thrust reversal capability
Solution Approach 2:
The same structural components (air inlet lip, circulation pipes) are used for both normal operation and thrust reversal, eliminating the need for separate dedicated reversal hardware. This multi-functionality approach simplifies the overall device architecture by reducing the number of distinct components and systems required
3Productivity
If the reverse airflow bypasses the air intake lip in radial direction, then thrust reversal is achieved, but local low pressure area generates upstream suction force opposing thrust reversal
Solution Approach 1:
The invention applies local quality by creating a specific circulation pattern through the circulation pipes that directs exhaust gases along the air inlet lip in an axial direction rather than radially. This localized flow control at the air inlet lip region prevents the formation of low pressure areas that would create adverse suction forces, thereby improving thrust reversal efficiency
Solution Approach 2:
The circulation pipes act as intermediaries that guide and control the exhaust gas flow path. Instead of allowing direct radial bypass of the air intake lip, the circulation pipes mediate the flow, directing gases along the lip in an axial direction. This intermediary flow path prevents adverse pressure gradients and suction forces while maintaining effective thrust reversal
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 solution improves thrust reversal efficiency by minimizing opposing forces and maintaining the performance of the turbojet during the thrust phase, with a design that reduces mass, size, and energy consumption.
Implementation Method 1
The air inlet comprises at least one circulation duct in the annular cavity opening, on the one hand, at the level of the air inlet lip and, on the other hand, at the level of the inner wall and/or the outer wall so as to promote a thrust reversal phase
Implementation Method 2
Part of the reverse airflow F-INV bypasses the aerodynamic profile of the air intake 200 in a substantially radial direction, resulting in a local low-pressure area P near the air intake lip 203. This local low pressure P generates an upstream suction force, which opposes thrust reversal.
Data Source
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AI summary
An aircraft turbojet engine (1) comprising a fan (11) configured to provide a reverse thrust and a nacelle comprising an air intake (2), the air intake (2) comprising at least one circulation duct (3) in the annular cavity (20) opening, on the one hand, at the air intake lip (23) and, on the other hand, at the inner wall (21) and/or the outer wall (22) so as to promote a reverse thrust phase, the air intake (2) comprising at least one cover member (31, 32) mounted to move between a covered position, in which the cover member (31, 32) closes the circulation duct (3) at the air intake lip (23) and an uncovered position, in which the cover member (31, 32) opens the circulation duct (3) at the air intake lip (23).