Aircraft Fuselage Bilge Vacuum Chamber for Lower Deck Thermal Insulation

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Solution Overview

Problem

In aircraft fuselages with an intermediate floor dividing the upper deck (passenger area) and lower deck (freight area), the ventilation system operates under excess pressure, leading to low flow speeds and temperature gradients in the lower deck, resulting in cold spots due to insufficient insulation against the fuselage wall, causing inefficient heat distribution and discomfort.

Innovation Solution

Sealing the bilge area against the freight area to create a vacuum chamber connected via small cross-section flow orifices between the lower floor and fuselage wall, creating a film flow that acts as insulation, and using perforated sheets aligned with the fuselage frames to enhance this flow and retain heat.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the ventilation system operates under excess pressure with large cross-sectional faces in the lower floor areas, then air exchange is achieved, but flow speeds become low and temperature gradients occur in the lower deck

Engineering Contradiction:

Improveair exchangeVSAvoidtemperature distribution

Core Design Contradiction:

Quantity of substanceVSTemperature

Solution Approach 1:

The lower deck is divided into two separate zones: the freight area and the bilge area. The bilge area is sealed to form a vacuum chamber, while the freight area remains connected to the ventilation system. This segmentation allows different pressure conditions to be maintained in different zones, resolving the contradiction between achieving air exchange and maintaining temperature uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different pressure conditions are applied to different parts of the lower deck. The bilge area is maintained under vacuum conditions to prevent cold air formation, while the freight area maintains excess pressure for ventilation. This local differentiation of pressure quality allows each zone to function optimally for its specific purpose.

Inventive Principle:

Principle #3Local quality

2Productivity

If the bilge area is left open for ventilation access, then air flow is maintained, but heat energy is lost to the fuselage wall

Engineering Contradiction:

Improveair flowVSAvoidheat energy loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

A vacuum chamber is introduced as an intermediary structure between the bilge area and the freight area. This vacuum chamber acts as a thermal barrier that prevents heat transfer from the freight area to the fuselage wall, while still allowing the ventilation system to function through controlled openings in the intermediate floor.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bilge area is transformed into a vacuum environment, which serves as a thermal barrier. The vacuum condition prevents convection and conduction of heat from the freight area to the fuselage wall, effectively creating an inert thermal environment that preserves heat energy.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Temperature

If small cross-section flow orifices are used in the abutment area, then film flow is achieved for insulation, but manufacturing complexity increases

Engineering Contradiction:

Improvetemperature uniformityVSAvoidflow orifice configuration

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

Perforated sheets are used to create the flow orifices in the abutment area between the lower floor and fuselage wall. These perforated sheets provide a standardized way to create numerous small cross-section openings that generate the required film flow for insulation, while simplifying the manufacturing process compared to custom-shaped orifices.

Inventive Principle:

Principle #31Porous materials

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 ensures even temperature distribution in the lower deck, minimizing energy loss and heating the freight area to a level comparable to the passenger area, preventing cold spots and optimizing heat utilization.

Implementation Method 1

the bilge area is sealed against the freight area to form a vacuum chamber

Methodology Applied

Scientific EffectPressure difference: Pressure Gradient

Implementation Method 2

a film flow is achieved tangentially over the fuselage wall from the intermediate floor to the bilge area

Methodology Applied

Scientific EffectFilm flow: Laminar Flow

Implementation Method 3

This film flow forms a very good insulation layer between the lower floor freight area and the fuselage wall

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 4

a ventilation installation with compressed air ducts through which fresh air can be fed into the upper deck

Methodology Applied

Scientific EffectCompressed air flow: Pressure Gradient

Implementation Method 5

the flow orifices are formed in the abutment area between the lower floor and the fuselage wall by perforated sheets running in the longitudinal direction of the fuselage

Methodology Applied

Scientific EffectPerforated flow distribution:

Data Source

PatentUS7766276B2Aircraft fuselage with upper and lower deck

Publication Date: 2010.08.03 AIRBUS OPERATIONS GMBH

AI summary

Aircraft fuselage with an upper deck, constructed as a passenger area, and a lower deck, including a freight area, and with a ventilation installation for the upper deck and lower deck, wherein a bilge area is constructed as a vacuum chamber against the freight area and is connected to the lower deck solely via flow orifices in the abutment area between a lower floor and the fuselage wall.