Ribbed Composite Fan Inlet Containment for Blade-Out Events

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Solution Overview

Problem

Existing gas turbine engine fan inlets face challenges in containing blade fragments ejected from damaged fan blades, leading to potential damage to composite materials and compromising the structural integrity and stability of the nacelle, especially during blade-out events, which can result in fiber breakage, delamination, and secondary failures during coast down and windmilling phases.

Innovation Solution

A ribbed composite shell with an annular grid of thick crack arresting ribs embedded in a thin annular shell, surrounded by thin panels and thick adjoining ribs, is used in the composite fan inlet casing to dissipate kinetic energy and contain impact damage, maintaining structural integrity and stability even after a blade-out event.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metallic casing shell is used to contain blade fragments, then the containment capability and structural stiffness are improved, but the weight of the engine and airframe increases

Engineering Contradiction:

Improveblade fragment containment capabilityVSAvoidengine and airframe weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent applies composite materials consisting of a metallic outer shell and an inner liner made of noise-absorbing material (such as honeycomb paneling or foam). This composite structure provides effective blade fragment containment while reducing the overall weight compared to a solid metallic casing, as the inner liner material offers energy absorption and damage containment properties without the full weight penalty of solid metal construction throughout the entire casing.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If the inlet is made of composite material to reduce weight, then the weight is reduced, but the damage resistance and structural integrity under blade-out impact are worsened

Engineering Contradiction:

Improveinlet weightVSAvoidimpact damage resistance

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The inlet structure employs a composite construction with an outer composite skin and an inner liner of energy-absorbing material (honeycomb paneling or foam). This composite design maintains lightweight properties while the inner liner provides enhanced impact resistance by absorbing blade fragment kinetic energy and preventing direct transmission to the composite skin, thereby maintaining structural integrity during blade-out events.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The inner liner made of noise-absorbing material (honeycomb or foam) serves as a pre-positioned cushioning layer between the blade fragments and the composite inlet structure. This beforehand cushioning absorbs impact energy and prevents direct damage to the composite material, allowing the lightweight inlet to withstand blade-out events without compromising structural integrity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a second blade containment structure with titanium ring is added to capture blade fragments, then the containment effectiveness is improved, but the device complexity and weight increase

Engineering Contradiction:

Improveblade fragment containment effectivenessVSAvoidcontainment structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of the fan casing and the blade containment structure into a single integrated assembly. The inner liner of noise-absorbing material is incorporated directly within the fan casing structure, eliminating the need for a separate second containment structure. This integration maintains effective blade fragment containment while reducing overall device complexity and weight compared to having multiple separate containment components.

Inventive Principle:

Principle #5Merging (Combining)

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 ribbed composite shell effectively contains blade fragment impacts, preventing further damage propagation and maintaining the nacelle's structural and aerodynamic stability, supporting the aircraft's fly-home capability by dissipating energy through delamination and capturing impact objects within a few panels.

Implementation Method 1

dissipate kinetic energy and contain impact damage

Methodology Applied

Scientific EffectKinetic energy dissipation: Damping

Implementation Method 2

dissipating energy through delamination

Methodology Applied

Scientific EffectDelamination:

Data Source

PatentUS10385870B2Composite fan inlet blade containment

Publication Date: 2019.08.20 GENERAL ELECTRIC CO

AI summary

A ribbed composite shell includes an annular grid of relatively thick crack arresting ribs embedded in a relatively thin annular shell and relatively thin panels in thin annular shell between arresting ribs wherein each of panels are completely surrounded by a set of relatively thick adjoining ones of ribs. A shell forward flange may extend radially inwardly from thin annular shell. Arresting ribs may include radially stacked layers of strips between radially stacked annular layers of shell. Annular grid may include a rectangular grid pattern, a diamond grid pattern, or a hexagonal grid pattern. A nacelle inlet may have the ribbed composite shell within one or both of radially spaced apart composite inner and outer skins of an inner barrel. Nacelle inlet may be part of attached to a fan casing and axially disposed forward of fan blades circumscribed by the casing. The inlet may be on an engine nacelle.