Ground Based Fuel Tank Inerting

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FAA Inerting System Flight Testing on an Airbus
A320
William CavageAAR-440 Fire Safety
ResearchFederal Aviation Administration
Systems Fire Protection Working Group DTA -
Grenoble, France June 21-22, 2003
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Outline

• Goals and Objectives
• OBIGGs
• Instrumentation
• System
• Center Wing Tank
• OBOAS
• Additional Parameters
• Analysis
• Data
• System Performance
• Fuel Tank Inerting
• Summary

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Testing Goals and Objectives

• Validate the simplified inerting concept and
  develop/expand upon existing system performance
  models
• Examine system sizing requirements
• Validate in flight inert gas distribution
  assumptions
• Examine potential operational effects on the
  ability of a system to maintain inert conditions
  in a fuel tank

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OBIGGS - System Architecture

• Uses Air Separation Modules based on HFM
  technology
• Excepts hot air from aircraft bleed system
• Cools, filters, and conditions air
• Air is separated by ASMs and NEA is plumbed to
  output valves to control flow
• OEA is dumped overboard, H/X cooling air
  deposited in cargo bay near outflow valve
• System configured to operate in high and low
  flow modes
• Prototype system controlled by control box in
  cabin that is connected to system with cable
• Install system in test aircraft cargo bay for
  simplicity sake

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FAA OBIGGs Installation Drawing
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FAA OBIGGs Installation Drawing
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FAA OBIGGS Installation
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Instrumentation and Data Acquisition

• Various thermocouples and pressure transducers
  used to evaluate system performance
• OBIGGS system flow meter and 2-channel oxygen
  analyzer for NEA and OEA analysis
• Eight sample locations within the Center-Wing
  Tank (CWT)
• FAA Onboard Oxygen Analysis System (OBOAS)
  utilized
• Aircraft parameters measured
• Airbus data acquisition system utilized
• Full-up flight worthy DAS

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System Instrumentation Diagram
Spare O2
Temperature
Static Pressure
Static Pressure
Temperature
NEA O2
Static Pressure
Temperature
OEA O2
Temperature
Static Pressure
Temperature
Temperature (FAA Reader)
Penetration Hole
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Flow Meter
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CWT Instrumentation
Vent Location
NEA Deposit
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OBOAS Mounted in A320 Test Aircraft
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Test Plan

• Operated system in two flow mode for a series of
  tests with a 39,000 ft cruise altitude and a high
  rate of descent (4k ft/min)
• Descended to 3,000 feet for operational purposes
• Nine total tests, 6 relative to FAA testing goals
  and objectives
• Used OBIGGS in both a single ASM configuration
  and a 2-membrane configuration to evaluate sizing
  requirements
• Testing proved the FAA system concept, acquired
  system sizing data, and examined the effects of
  several operational conditions
• Studied effect of fuel on an inert ullage
• Studied effect of the high flow mode on the inert
  ullage
• Studied effect of bleed air on the membrane
  performance

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Table of Airbus Flight Tests
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Data Analysis

• Calculation of bleed air consumed

With NEA Oxygen Concentration
OEA Oxygen Concentration

• Model of Ullage gas Oxygen Concentration

Mass of oxygen in tank at time t
Mass flow rate of inerting gas (in terms of
t) IGOF Fraction of oxygen in inerting
gas ?? Change in Ullage Density due to
Altitude Change VTank Volume of Tank
Ullage mTank Mass of Gas in Tank mair
Mass of air entering tank
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Results - System Performance

• System performed as expected with predictable ASM
  dynamic charactaristics
• Easily predicted with static measurements
• 2-membrane system configuration gave
  approximately double the NEA
• Less at altitude probably due to OEA back
  pressure
• Bleed air consumption greater then expected
• Aircraft bleed air pressures were higher then
  expected at altitude
• ASM degraded during the ground and flight testing
  ( 100 hours) giving about a 14 reduction in
  productivity
• Not much more then normal expected break-in of
  ASM

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System Performance Data
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One vs. Two ASM Performance Data
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Bleedair Consumption Data
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Results - Tank Inerting

• CWT inerting accomplished easily
• No stratification observed, ullage acted in a
  very homogenous manner
• Two ASM inerting gave very little benefit
  compared to a single ASM
• Different system tuning could change that
• High flow mode effective at helping maintain a
  low resulting ullage oxygen concentration during
  descent
• Fuel load had very little effect on measured
  ullage oxygen concentrations for both static and
  consumed fuel loads
• Simple model effective at predicting resulting
  ullage oxygen concentration given a system
  performance and mission profile

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CWT Inerting Oxygen Concentration Data
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One vs. Two ASM Tank Inerting Data
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High Flow Mode Benefit Tank Inerting Data
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Effects of Fuel Tank Inerting Data
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System Performance Data
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Summary

• FAA simplified OBIGGS concept validated
• System performance predictable
• Bleed air consumption significant
• ASM performance degradation needs to be studied
  further
• Fuel tank inerting
• Inert gas distribution accomplished easily
• System tuning needs to be studied further to say
  true benefit of 2 ASMs versus 1
• Two flow mode beneficial
• Fuel load effected resulting ullage oxygen
  concentration very little
• Ullage inerting easily modeled given a system
  performance