Compact Thrust Reverser Nacelle Design
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Solution Overview
Problem
Existing cascade thrust reversers for turbojet engines occupy a large volume, limiting the optimization of aerodynamic shapes and soundproofing in the annular flow path due to their design, which includes tie rods below the cascades describing curves in an axial plane.
Innovation Solution
A thrust reverser design featuring movable cascades and tilting flaps connected by rear pivots, where the cascades and flaps are stored outside a fixed casing in the closed position, utilizing slides and telescopic rods to control the movement and tilting of the flaps, allowing for a shorter nacelle length and reduced aerodynamic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tie rods are disposed below the cascades describing curves in an axial plane, then the thrust reverser can be actuated, but the volume below the cascades increases which prevents optimization of aerodynamic shapes and soundproofing
Solution Approach 1:
The patent moves the tie rods from a horizontal arrangement (below the cascades in the axial plane) to a vertical arrangement (above the cascades in the radial direction). This dimensional change relocates the actuation mechanism from the axial dimension to the radial dimension, freeing up the space below the cascades for aerodynamic optimization and soundproofing while maintaining the thrust reverser actuation function.
2Loss of energy
If the nacelle length is reduced by storing cascades and flaps outside the fixed casing, then aerodynamic losses are minimized, but the mechanism complexity increases with slides and telescopic rods
Solution Approach 1:
The patent employs nesting by placing the slides within the telescopic rods, and the cascades and flaps within the movable cowl assembly. This nested arrangement allows multiple components to occupy overlapping spatial envelopes, enabling compact storage of the thrust reverser components outside the fixed casing when retracted, thereby minimizing nacelle length and reducing aerodynamic losses while managing the inherent complexity through efficient spatial organization.
Data Source
AI summary
A thrust reverser for a turbojet engine nacelle includes thrust reversal cascade vanes arranged about an annular flow duct having a stationary front casing, at least one movable cover moving backwards into a thrust reversal open position, and tilting flaps connected by rear pivots to the movable cover, which, in an open position, tilt and thereby at least partially close the annular flow duct. The cascade vanes move backwards with the movable cover, in that, in the closed position, the tilting flaps and the cascade vanes are arranged outside the stationary casing, and each tilting flap is connected to the stationary casing by slides which cause the tilting flaps to tilt when the movable cover moves backwards.