NEA Ullage Washing Testing
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NEA Ullage Washing Testing With a Vented Fuel Tank. December 11th-12th, 2000 International Aircraft Systems Fire Protection Working Group. Outline. Background Ullage Washing Data Model Validation Hydrocarbon Effects Data Temperature Effects Data. Background.

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NEA Ullage Washing Testing

With a Vented Fuel Tank

December 11th-12th, 2000International Aircraft Systems FireProtection Working Group

AAR-422 Fire Safety R&D


Outline

  • Background

  • Ullage Washing Data

  • Model Validation

  • Hydrocarbon Effects Data

  • Temperature Effects Data

AAR-422 Fire Safety R&D


Background

  • Obtained Nitrogen Supply System from Air Liquide to Examine Fuel Tank Ullage Washing

  • Utilized Existing Test Article

  • Primary Task is to Characterize the Ability of Nitrogen to Inert an Empty Fuel Tank

    • Effective of Nitrogen Purity, Flow Rate

    • Effective Ullage Temperature / Hydrocarbon Concentration

    • Develop Empirical Relationships and Varify Existing Models

AAR-422 Fire Safety R&D




Nondimensional Time

  • Want to Express Time in Terms of Volume Delivered

  • Volumetric Tank Exchange = Time * Volume Flow Rate / Total Tank Volume

  • Should Allow for Comparison of Data with Different Parameters, Regardless of Volume Flow Rate

AAR-422 Fire Safety R&D




Nondimensional Oxygen Concentration

  • Want to Express [O2] in Terms of Purity Delivered. Consider that Gas is Slowly Changing the Ullage to Gas Purity

  • Tank Inertion Ratio = Air[O2] - Tank[O2] / Air[O2] - NEA[O2]

  • Should Allow for Comparison of Data with Different Parameters, Regardless of Purity

AAR-422 Fire Safety R&D



Comparison of Data with Solutions

  • Empirical Equation (fourth order polynomial) Based on Previous Graph

  • ANM-100 Model (Ivor Thomas)

    • Based on O2 Volume Exchange

    • Gives One Nondimensional Solution

  • Exact Solution Based on Perfect Mixing Model (y = 1 - e-λt )

  • Results Compare Well

AAR-422 Fire Safety R&D




Effects of Ullage Temperature / [THC]

  • Performed Several Tests Varying Tank Ullage Temperature and Total Hydrocarbon Concentration

  • Used Hot Plate Element, Kerosene Heater, and Liquid CO2

  • Final Results Show Little Effect on Time to Inert

AAR-422 Fire Safety R&D




Future Work

  • Continue with Re-circulate and Replace Work and Quantify Benefit

  • Extrapolate Requirements for an On-Aircraft System and Determine Preliminary Cost/Ben

  • Work with Manufacturers to Develop Innovative Designs to Cut Cost/Weight/Size

AAR-422 Fire Safety R&D


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