Propulsion Pylon Secondary Air Flow Homogenization

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Solution Overview

Problem

The proximity of longitudinally aligned elements in a propulsion unit's secondary air flow duct, such as OGV blades, structural arms, and ancillary passage arms, causes significant aerodynamic disturbances and angular distortion, negatively impacting the unit's performance.

Innovation Solution

A pylon with a profiled cross-section is introduced, featuring an upstream blade, a downstream arm, and a fairing that connects them, optimizing the secondary air flow by defining specific distances and quotients to minimize disturbances, and ensuring a continuous external surface to reduce backflow interactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If elements (OGV blade, structural arm, ancillaries passage arm) are positioned longitudinally aligned to minimize disturbances, then the angular distortion of secondary air flow is reduced, but the proximity of consecutive arms causes significant aerodynamic backflow and wake interactions

Engineering Contradiction:

Improveangular distortion of secondary air flowVSAvoidaerodynamic backflow and wake interactions

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent merges the OGV blade, structural arm, and ancillaries passage arm into a single integrated pylon structure with a continuous external surface. This combination eliminates the gaps and discontinuities between separate elements, preventing aerodynamic backflow and wake interactions while maintaining longitudinal alignment to minimize angular distortion of the secondary air flow.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The pylon is designed with a streamlined, curved external surface that follows the flow direction of the secondary air. The continuous curved surface reduces flow separation and minimizes aerodynamic disturbances by guiding the air flow smoothly around the entire structure, eliminating sharp edges and discontinuities that would cause backflow.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Adaptability or versatility

If multiple separate elements are used in the secondary duct, then functional requirements are met, but the proximity of elements causes significant disturbances in secondary air flow

Engineering Contradiction:

Improvefunctional requirements fulfillmentVSAvoidsecondary air flow performance

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent combines multiple functional elements (OGV blade for flow straightening, structural arm for support, ancillaries passage arm for utilities) into a single pylon structure. This integration maintains all required functions while eliminating the performance penalties associated with having multiple separate elements in close proximity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The pylon structure serves multiple functions simultaneously: it provides flow straightening through its blade geometry, structural support through its arm configuration, and utility passage routing through integrated channels. This multi-functionality eliminates the need for separate elements while maintaining all required capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-generated harmful factors

If elements are joined to form a continuous surface pylon, then aerodynamic disturbances are reduced, but the design complexity increases

Engineering Contradiction:

Improveaerodynamic disturbancesVSAvoidpylon design complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

While the external surface is continuous, the pylon is designed with distinct functional segments (blade portion, arm portion, passage portion) that can be independently analyzed and optimized. This segmentation approach allows complex functionality to be achieved through modular design principles while maintaining aerodynamic continuity.

Inventive Principle:

Principle #1Segmentation

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 optimized pylon design significantly homogenizes the secondary air flow, reducing angular distortion and enhancing the propulsion unit's performance by minimizing pressure losses and preventing recirculation zones.

Implementation Method 1

an upstream blade straightening said air flow

Methodology Applied

Scientific EffectAerodynamic flow straightening:

Implementation Method 2

the fairing has at least one upstream segment so as to cover at least said leading edge of said structural arm

Methodology Applied

Scientific EffectAerodynamic flow optimization:

Data Source

PatentUS11047300B2Pylon of a propulsion unit

Publication Date: 2021.06.29 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A disclosed propulsion unit includes a pylon having a blade presenting a chord Cx and a downstream arm having a structural arm. The pylon has a first distance D between a trailing edge of a fan blade and a leading edge of the fan blade, a second distance d between said trailing edge of the blade and a leading edge of the structural arm, and a third distance L between the trailing edge of the blade and a mark located at a maximum thickness of the downstream arm. The pylon is dimensioned according to: a first quotient between D and Cx between 2.2 and 2.6, a second quotient between d and Cx between 1 and 1.2, and a third quotient between L and Cx between 4 and 7.