Articles with tag: "analysis tools"

1. Anti-Ice Heat Required Calculations with LEWICE

   
   Public domain image by Donald Cook.

   Prerequisites

   You need to have completed Anti-Ice Heat Required Calculations.

   Introduction

   Here, we will see that the values calculated by a multi-node analysis in LEWICE are comparable to the values calculated previously.

   Running LEWICE for anti-icing calculations involves (necessarily) more complex inputs. The user has to select which set of external heat transfer assumptions to use. The detailed output files require post-processing to extract the total heat required value.

   Discussion

   The LEWICE manual describes "deicer" cases that also may be used for anti-ice heat requirement analysis.
   An input is the "IDEICE" value in the case.inp file. By default, this is 0, and an unheated surface ice analysis is performed. However, with IDEICE > 0, ice protection analysis is performed, as detailed in a cased.inp file. A key input in that file is ievap, which for the cases below is set to ievap=1 …

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2. Anti-Ice Heat Required Calculations

   
   Public domain image by Donald Cook.

   Prerequisites

   You need to have completed Anti-Ice Heating Calculations Theory.

   Introduction

   For this we will use "Engineering Summary of Airframe Icing Technical Data", ADS-4, as the anti-ice examples are more detailed than those in the "Aircraft Icing Handbook", DOT/FAA/CT-88/8-1.

   The ADS-4 analysis method uses NACA-TN-2799, from 1952, for the heat and mass balance calculations. This method implements solutions as nomographs (for more details, see the post NACA-TN-2799). We will not be using the nomographs. The heat balance equations are similar to the Standard Computational Model, which we will use.

   The calculations are implemented in the file "aircraft_a_ads4.py" (and associated files) available at github.com/icinganalysis/icinganalysis.github.io. Readers are encouraged to run the analysis to the duplicate results.

   Discussion

   "Aircraft Icing", AC 20-73A, briefly mentions the terms Qa and Qr:

   Qa Heat available
   Qr Heat required

   Heat required is …

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3. Anti-Ice Heating Calculations Theory

   
   From ADS-4 apps.dtic.mil.

   Prerequisites

   You need to have completed Aircraft Icing Handbook Energy Balance Examples.

   Introduction

   We will review "Engineering Summary of Airframe Icing Technical Data", ADS-4 apps.dtic.mil, as the anti-ice examples are more detailed than those in the "Aircraft Icing Handbook", DOT/FAA/CT-88/8-1 apps.dtic.mil.

   We will also look at "Ice, Frost, and Rain Protection", SAE AIR1168/4 sae.org, for practical guidance for analysis.

   The ADS-4 and SAE AIR 1168/4 analysis methods use nomographs to implement graphical solutions. We will not be using the nomographs. While the notation is different, the analysis method from ADS-4 is very similar to the Standard Computational Model in the Aircraft Icing Handbook Merged Sections which we will use here.

   The energy balance equation is:

   Q"Source + Q"Sink = 0  
   

   Define Q"Sink by:
   

   Q"Sink = Q"conv + Q"DropWarm + Q"Evap  
   

   Define Q"Source …

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4. Analysis Toolset

   
   Figure 15 of NACA-TN-2904 ntrs.nasa.gov.

   Summary

   You will have to choose a toolset to perform the example analyses.

   Example calculations are provided in the Python programming language, and using the NASA-provided LEWICE code.

   Introduction

   You are highly encouraged to perform the analysis described in the examples (and not just read the examples). Some examples can be accomplished with hand calculations, while other require computational capabilities.

   You need to select your toolset.

   Consider your current and future uses

   A toolset is an investment of your time and resources. By performing the calculation of the examples used here, you will build your personal and software capabilities and skills.

   Your toolset at a particular time may not be entirely your choice. Your company, institution, or customer may have policies on which kinds of software are required, encouraged, discouraged, or prohibited. Some codes have by-country use restrictions. You may have signed an …

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