Ground Based Fuel Tank Inerting

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Scale Model InertingTesting with 1/4 Scale Boeing
747 SP Fuel Tank
July 17-18, 2001International Aircraft Systems
FireProtection Working GroupWilson, NC
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Background

• Inconsistent Comparisons of Test Data Created
  Questions of NEA Required to Inert an Aircraft
  Center Wing Tank
• Focus of the Testing is to Better Determine the
  Best Method to Inert a Compartmentalized Fuel
  Tank
• Study Equal NEA Distribution and Localized NEA
  Deposit
• Study Cross-Vented and Single Vent Configurations
• Develop Methods to Make Fair Comparisons.

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Test Article

• Quarter Scale Model of Boeing 747 SP CWT was
  Built from Plywood By Scaling Drawings from
  Shepherd Report
• 24 length Scale (1.2 Volume)
• Scaled all Bay-Bay Penetrations
• Variable Manifold Allows for Depositing NEA in
  Any and All Bays of the Tank at Different Rates
  to Support Inerting Times as Low as 10 Minutes
• Oxygen Sensor in Each Bay and in One Vent Channel

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Scale Model Bay Convention
Dry Bay
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2
3
4
5
6
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Preliminary Balanced Data

• Inerted Tank Several Times with NEA 95 and NEA
  98 with the Goal of Balancing the Flow into
  Inert Each Bay Equally for Standard
  Cross-Venting Configuration
• Acquired Data with a Stop Watch (1 reading per
  minute)
• Developed a Volumetric Average to Make
  Comparisons with Other Inerting Runs
• Results As Expected and Consistent with Previous
  Testing but New Numbers Point Toward a VTE of 1.6
  for 95 NEA
• VTE Very Sensitive to O2 Concentration at 8 for
  95 NEA

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Preliminary Balanced Inerting Data
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Preliminary Balanced Weighted Average Data
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Preliminary Unbalanced Data

• Inerted Tank Several Times with NEA 95 with the
  Goal of Minimizing the Volume Required to Inert
  the Tank with Standard Cross-Venting
  Configuration
• Acquired Data with a Stop Watch (1 reading per
  minute)
• Used the Volumetric Average Developed to Make
  Fair Comparisons with Other Inerting Runs
• Results Illustrated Very Little Improvement in
  VTE Required, but Allowed for Simpler Manifold
  Designs
• Smart Design as Good or Better then Well Balanced
  Manifold

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Preliminary Unbalanced Inerting Data
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Preliminary Unbalanced Weighted Average Data
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NEA Minimization Data

• Inerted Tank Several Times with NEA 95 to
  Minimizing the NEA Volume Required to Inert the
  Tank with Half Vent System Blocked (No Cross
  Venting)
• Acquired Data with Computer Data Acquisition
  System at a Rate of 1 Sample per Second
  (Approximate)
• First did Balanced Run to Give Baseline Used
  the Volumetric Average Developed to Make Fair
  Comparisons with Other Inerting Methods
• Results Illustrated Modest Improvement with
  Simplest Deposit Scheme

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NEA Minimization Data - Best Data
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Unbalanced Weighted Average Data
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Summary

• Model Results Consistent with Existing Knowledge
  Base But VTE Slightly Higher in These Experiments
• This is Believed to be due to Better Measurement
  Techniques Developed
• Depositing in an Efficient Manner Can Greatly
  Simplify Manifold Design and Even Improve
  Inerting Efficiency
• Still Need to Verify Results in Full-Scale Test
  Article