Compact Thrust Reverser Deflecting Primary Flow
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Solution Overview
Problem
Conventional thrust reversers for turbojet engines are complex, heavy, and costly, with large dimensions that hinder aerodynamic nacelle profiles and increase mass balance, leading to high manufacturing and operational costs, and prevent size reduction for performance improvement.
Innovation Solution
A compact thrust reverser that deflects all or part of the primary flow gases downstream of the nacelle, redirecting them against the secondary flow to reduce rearward ejection velocity, using a simple and lightweight structure that fits within the primary nozzle fairing, thereby minimizing interaction with the secondary flow and allowing a smaller diameter design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thrust reversers are used to redirect exhaust flow for reverse thrust, then reverse thrust function is achieved, but the device becomes heavy and complex with large dimensions
Solution Approach 1:
The thrust reverser system is segmented into multiple independent elements: a circumferential array of individual gates, each capable of independent operation. This segmentation allows the system to achieve the same reverse thrust function with smaller, lighter individual components distributed around the engine nacelle, rather than requiring a single large heavy mechanism.
Solution Approach 2:
The invention transitions from traditional lateral deflection of exhaust flow to rearward deflection by orienting gates at angles between 0-90 degrees relative to the engine axis. This dimensional change in flow redirection approach enables compact gate structures that are lighter while still achieving effective reverse thrust through the rearward component of the deflected flow.
2Reliability
If conventional thrust reversers with large dimensions are used, then reverse thrust is generated, but the nacelle profile becomes less aerodynamic and mass balance increases
Solution Approach 1:
The circumferential array of segmented gates allows the thrust reverser to be integrated into the existing nacelle structure without requiring large external protrusions. Each gate element is compact and can be positioned within or near the nacelle contour, preserving the aerodynamic profile while collectively providing the necessary reverse thrust function.
Solution Approach 2:
The gate structures are designed to be nested within or adjacent to the nacelle structure, with gates positioned to utilize the existing nacelle volume and contour. This nesting approach allows the thrust reverser components to be accommodated within the overall nacelle envelope without significantly increasing its external dimensions or disrupting its aerodynamic shape.
3Reliability
If conventional thrust reversers are used, then exhaust flow is redirected, but manufacturing cost and operational cost increase
Solution Approach 1:
The segmented gate design allows for modular manufacturing and assembly, where identical or similar gate elements can be produced using the same tooling and processes. This standardization across multiple gate elements reduces manufacturing complexity and cost compared to conventional designs that require large custom-formed structures.
Solution Approach 2:
The invention uses multiple copies of the same basic gate element arranged circumferentially around the engine. This repetitive use of identical components simplifies manufacturing by allowing batch production with standardized processes, reducing both initial manufacturing cost and maintenance costs through parts interchangeability.
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 results in a more compact, lightweight, and cost-effective thrust reverser that reduces the nacelle's size, enabling additional space for maneuver and improved performance by acting on all outgoing flows without significant mechanical interaction with the secondary flow, thus enhancing the turbojet engine's efficiency and aerodynamics.
Implementation Method 1
the deflected primary flow gases encountering the secondary flow reduce the rearward ejection velocity of the latter, and thus generate a reverse thrust effect
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A turbofan engine comprising a thrust reverser (18). The latter includes deflection means (20) for deflecting all or part of the primary flow gases (32) such that the deflected primary flow gases, upon encountering the secondary flow, reduce the rearward ejection velocity of the latter, thus generating the reverse thrust effect. The secondary flow escapes behind the nacelle. In the thrust reverser position, the deflection means are radially positioned substantially within the cross-section (45) of the primary nozzle fairing at the rear end (11) of the nacelle (10). Such a thrust reverser proves to be particularly simple in design, economical, and eliminates the need for moving parts on the external part of the nacelle, simplifying the turbofan engine design.