Aircraft Outflow Valve Flap Protrusions for Noise Reduction

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Solution Overview

Problem

Existing outflow valves for aircraft generate noticeable noise due to non-uniform fluid flow profiles caused by flap projections, leading to increased noise levels.

Innovation Solution

The design incorporates projections on the flaps that form diverging vortex braids, preventing the formation of uniform or stationary vortices, which are arranged and shaped to influence fluid flow effectively, allowing for adaptation to different flow rates and fluid properties without altering the valve's basic construction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If projections are added to the flaps to control fluid flow, then noise reduction is achieved through vortex formation, but device complexity increases due to additional structural elements

Engineering Contradiction:
ImprovenoiseVSAvoiddevice complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The flap surface is segmented into multiple projections (first projections and second projections) that are distributed across the flap. Each projection independently generates vortices that contribute to noise reduction, while the segmented structure allows for modular design and manufacturing

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The projections are designed with curved surfaces rather than sharp edges, with rounded tops and smooth transitions. This curvature promotes stable vortex formation while reducing turbulence and secondary noise sources, and also simplifies manufacturing compared to complex angular geometries

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Adaptability or versatility

If the shape and arrangement of projections are changed to adapt to different flow rates, then adaptability is improved, but manufacturing precision requirements increase

Engineering Contradiction:
ImproveadaptabilityVSAvoidmanufacturing precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The projections are designed with specific geometric parameters (height, width, spacing, curvature radius) that can be adjusted to optimize performance for different flow rates and fluid properties. By changing these parameters rather than the fundamental projection structure, the design achieves adaptability while maintaining manufacturability with standard tolerances

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The projection structure serves multiple functions simultaneously: it generates vortices for noise reduction, influences flow distribution across the valve opening, and can be adjusted for different operating conditions. This multi-functionality reduces the need for multiple specialized components, thereby lowering overall manufacturing precision requirements

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 significantly reduces noise pollution by ensuring that vortices interfere with each other, minimizing noise generation and allowing for flexible adaptation to various operational conditions.

Implementation Method 1

the flaps having protrusions which form vortices in the fluid flow to reduce noise

Methodology Applied
Scientific EffectVortex formation: Vortex Ring

Implementation Method 2

vortices form on the projections, which spread out in the flow direction in the form of vortex braids, diverging

Methodology Applied
Scientific EffectTurbulence: Turbulence

Data Source

PatentEP2185412B1Outflow valve for an aircraft
Publication Date: 2011.03.09 NORD MICRO AG & CO
  • EP2185412B1 patent drawingFigure 1~2
  • EP2185412B1 patent drawingFigure 3~4
  • EP2185412B1 patent drawingFigure 5~7

AI summary

The invention relates to a valve for controlling a fluid flow from a first environment to a second environment, having a frame for disposing a separating element in the region of an opening, said element separating the first environment from the second environment, and a first flap and a second flap for controlling the fluid flow through the opening between the first environment and the second environment, the flaps being movable in the frame. The flaps have protrusions designed to reduce noise generation in the fluid flow.