Thrust Reverser Cowl Cut-Outs for Wing Slat Interference

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing thrust reverser systems for aircraft nacelles with large diameters near wings face interference issues between movable cowls and leading edge slats during deployment, leading to reduced braking thrust due to fixed cowls that do not open, thereby limiting airflow and thrust reversal efficiency.

Innovation Solution

The design incorporates a cut-out in the movable cowl that avoids physical contact with the leading edge slat, maintaining aerodynamic continuity and structural simplicity, with a closure panel that reestablishes the nacelle's outer surface, allowing increased uncovered surface area for cascades and improved thrust reversal effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fixed cowls are added to prevent interference with leading edge slats, then interference is avoided, but airflow is reduced and braking thrust is limited

Engineering Contradiction:

Improveinterference avoidanceVSAvoidbraking thrust

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The cowl is designed to be movable rather than fixed, allowing it to adapt its position based on operational requirements. During normal flight, the cowl remains in a retracted position to maintain aerodynamic flow, while during thrust reversal, it moves to a deployed position to redirect airflow effectively, thus avoiding the need for permanent fixed structures that would continuously obstruct flow.

Inventive Principle:

Principle #15Dynamics

2Productivity

If movable cowls are used for thrust reversal, then braking thrust is improved, but interference with leading edge slats occurs during deployment

Engineering Contradiction:

Improvebraking thrustVSAvoidinterference avoidance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The cowl is divided into multiple independent segments or panels that can move and position themselves separately. This segmentation allows different portions of the cowl to be deployed at different times and to different extents, enabling the system to achieve effective thrust reversal while avoiding collision with leading edge slats by coordinating the movement of individual segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A control system or mechanical linkage acts as an intermediary between the thrust reversal actuation and the cowl movement, mediating the deployment sequence to ensure that the cowl reaches its operational position without interfering with the leading edge slats. This intermediary mechanism coordinates the timing and extent of cowl movement with the position of the slats.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the cowl structure is modified to avoid slat interference, then interference is prevented, but aerodynamic quality and structural simplicity are reduced

Engineering Contradiction:

Improveinterference avoidanceVSAvoidstructural modifications

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The design modifies operational parameters such as the range of motion, deployment timing, and positioning coordinates of the cowl rather than fundamentally changing its structural configuration. By adjusting these parameters, the system achieves interference avoidance while preserving the basic aerodynamic shape and structural integrity of the cowl, thus minimizing the need for complex structural modifications.

Inventive Principle:

Principle #35Parameter changes

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 reversal efficiency by minimizing structural modifications and maintaining aerodynamic quality, reducing drag, and allowing the secondary rail to remain aligned with the nacelle beam, while preventing interference and increasing the uncovered surface area of the cascades for enhanced braking performance.

Implementation Method 1

rear movable cowls axially sliding downstream under the effect of cylinders, while deploying flaps in the annular flow path

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

These flaps return the cold air flow radially outwards while passing through uncovered cascades during the sliding, comprising blades which direct this flow forwards

Methodology Applied

Scientific EffectFluid Flow:

Implementation Method 3

a thrust reverser system which closes at least partially the cold air annular flow path, and discharges the secondary flow forwards in order to generate a braking reverse thrust

Methodology Applied

Scientific EffectFluid Flow:

Data Source

PatentUS10458362B2Turbojet nacelle provided with a thrust reverser, including cut-outs to avoid the movable slat of an aircraft wing

Publication Date: 2019.10.29 SAFRAN NACELLES

AI summary

The disclosure relates to a turbofan nacelle including a thrust reverser, the thrust reverser including a movable cover moving back from a closed position in which the thrust is not reversed to an open position for uncovering cascades that reverse the direction of the flow of cold air which is diverted from the annular stream of secondary air, the movable cover including a radially outer portion intended for being adjacent to a leading edge of a wing of an aircraft. The movable cover includes on the radially outer portion at least one cut-out intended for avoiding interference with a movable slat of the leading edge of the wing of the aircraft, as well as a panel for closing the cut-out, the closing panel including a stationary portion at least partially covered by an upstream portion of the movable cover when the movable cover is in the open position.