Parasite Drag Functions¶

This group of API functions is supplemental to performing a Paraste Drag analysis through the Analysis Manager. They include functions to write out Parasite Drag Tool equations, calculate atmospheric properties, and control excrescences.

`AddExcrescence`(excresName, excresType, excresVal)	Add an Excresence to the Parasite Drag Tool
`GetNumExcrescences`()	Delete an Excresence from the Parasite Drag Tool
`DeleteAllExcrescences`()	Delete all Excresences from the Parasite Drag Tool
`DeleteExcrescence`(index)	Delete one excrescence from the Parasite Drag tool, by index.
`UpdateParasiteDrag`()	Update any reference geometry, atmospheric properties, excressences, etc.
`ExportParasiteDragToCSV`(file_name)	Write the Parasite Drag Tool buildup table out to a CSV file, the way the Export CSV button on the tool does.
`WriteAtmosphereCSVFile`(file_name, atmos_type)	Calculate the atmospheric properties determined by a specified model for a preset array of altitudes ranging from 0 to 90000 m and write the results to a CSV output file
`CalcAtmosphere`(alt, delta_temp, atmos_type)	Calculate the atmospheric properties determined by a specified model at input altitude and temperature deviation.
`WriteBodyFFCSVFile`(file_name)	Calculate the form factor from each body FF equation (i.e. Hoerner Streamlined Body) and write the results to a CSV output file.
`WriteWingFFCSVFile`(file_name)	Calculate the form factor from each wing FF equation (i.e. Schemensky 4 Series Airfoil) and write the results to a CSV output file.
`WriteCfEqnCSVFile`(file_name)	Calculate the coefficient of friction from each Cf equation (i.e. Power Law Blasius) and write the results to a CSV output file.
`WritePartialCfMethodCSVFile`(file_name)	Calculate the partial coefficient of friction and write the results to a CSV output file

Details¶

openvsp.AddExcrescence(excresName, excresType, excresVal)[source]¶

Add an Excresence to the Parasite Drag Tool

AddExcrescence( "Miscellaneous", EXCRESCENCE_COUNT, 8.5 )

AddExcrescence( "Cowl Boattail", EXCRESCENCE_CD, 0.0003 )

# Each excrescence gets its own row, so deleting them one at a time has to
# empty the table and then start being rejected.  The error queue is reached
# through the error manager singleton in Python.
err_mgr = ErrorMgrSingleton.getInstance()

DeleteExcrescence( 1 )
DeleteExcrescence( 0 )

assert err_mgr.GetNumTotalErrors() == 0, "the two excrescences were not both added"

DeleteExcrescence( 0 )

assert err_mgr.GetNumTotalErrors() > 0, "more excrescences were added than asked for"

# That error was raised deliberately, so take it back off the queue.
while err_mgr.GetNumTotalErrors() > 0 :
    err = err_mgr.PopLastError()

See also: EXCRES_TYPE :param [in]: excresName string Name of the Excressence :param [in]: excresType int Excressence type enum (i.e. EXCRESCENCE_PERCENT_GEOM) :param [in]: excresVal double Excressence value

openvsp.GetNumExcrescences()[source]¶

Delete an Excresence from the Parasite Drag Tool

AddExcrescence( "Miscellaneous", EXCRESCENCE_COUNT, 8.5 )

AddExcrescence( "Cowl Boattail", EXCRESCENCE_CD, 0.0003 )

AddExcrescence( "Percentage Example", EXCRESCENCE_PERCENT_GEOM, 5 )

DeleteExcrescence( 2 ) # Last Index

# Three were added and one was deleted, so index 2 no longer exists and
# asking for it again has to be rejected.  The error queue is reached through
# the error manager singleton in Python.
err_mgr = ErrorMgrSingleton.getInstance()

DeleteExcrescence( 2 )

assert err_mgr.GetNumTotalErrors() > 0, "DeleteExcrescence accepted an index past the end"

# That error was raised deliberately, so take it back off the queue.
while err_mgr.GetNumTotalErrors() > 0 :
    err = err_mgr.PopLastError()

Parameters:: [in] – index int Index of the Excressence to delete

Get the number of Excresences in the Parasite Drag Tool

assert GetNumExcrescences() == 0, "a new model starts with excrescences"

AddExcrescence( "Miscellaneous", EXCRESCENCE_COUNT, 8.5 )

AddExcrescence( "Cowl Boattail", EXCRESCENCE_CD, 0.0003 )

assert GetNumExcrescences() == 2, "GetNumExcrescences did not count what was added"

DeleteExcrescence( 1 )

assert GetNumExcrescences() == 1, "GetNumExcrescences did not follow DeleteExcrescence"

See also: AddExcrescence, DeleteExcrescence, DeleteAllExcrescences :rtype: int :return: int Number of excrescences

openvsp.DeleteAllExcrescences()[source]¶

Delete all Excresences from the Parasite Drag Tool

AddExcrescence( "Miscellaneous", EXCRESCENCE_COUNT, 8.5 )

AddExcrescence( "Cowl Boattail", EXCRESCENCE_CD, 0.0003 )

AddExcrescence( "Percentage Example", EXCRESCENCE_PERCENT_GEOM, 5 )

DeleteAllExcrescences()

assert GetNumExcrescences() == 0, "DeleteAllExcrescences left excrescences behind"

# Clearing an empty table is not an error.
err_mgr = ErrorMgrSingleton.getInstance()

DeleteAllExcrescences()

assert err_mgr.GetNumTotalErrors() == 0, "DeleteAllExcrescences complained about an empty table"

See also: AddExcrescence, DeleteExcrescence, GetNumExcrescences

openvsp.DeleteExcrescence(index)[source]¶

Delete one excrescence from the Parasite Drag tool, by index.

AddExcrescence( "TestExcrescence", EXCRESCENCE_COUNT, 2.0 )

DeleteExcrescence( 0 )

assert GetNumExcrescences() == 0, "DeleteExcrescence did not delete the excrescence"

See also: AddExcrescence, GetNumExcrescences :param [in]: index int Index of the excrescence to delete

openvsp.UpdateParasiteDrag()[source]¶

Update any reference geometry, atmospheric properties, excressences, etc. in the Parasite Drag Tool

pid = AddGeom( "POD" )

Update()

UpdateParasiteDrag()

openvsp.ExportParasiteDragToCSV(file_name)[source]¶

Write the Parasite Drag Tool buildup table out to a CSV file, the way the Export CSV button on the tool does. The same table is also placed in the Results Manager under the name “Parasite_Drag”, so the returned ID gives access to it without going through the file.

pod_id = AddGeom( "POD", "" )

Update()

# The table is filled in by running the buildup, so do that first.
ExecAnalysis( "ParasiteDrag" )

res_id = ExportParasiteDragToCSV( "ParasiteDragExample.csv" )

assert len( res_id ) > 0, "ExportParasiteDragToCSV returned no results"

# The buildup carries one row per Geom, so the Pod has to be in there.
labels = GetStringResults( res_id, "Comp_Label" )

assert len( labels ) > 0, "the buildup table is empty"

See also: UpdateParasiteDrag :param [in]: file_name string Name of the CSV file to write :rtype: string :return: string Results ID for the buildup table

openvsp.WriteAtmosphereCSVFile(file_name, atmos_type)[source]¶

Calculate the atmospheric properties determined by a specified model for a preset array of altitudes ranging from 0 to 90000 m and write the results to a CSV output file

print( "Starting USAF Atmosphere 1966 Table Creation. \n" )

WriteAtmosphereCSVFile( "USAFAtmosphere1966Data.csv", ATMOS_TYPE_HERRINGTON_1966 )
# The call above should have produced a file with content in it.
import os
assert os.path.getsize( "USAFAtmosphere1966Data.csv" ) > 0, "WriteAtmosphereCSVFile wrote no file"

See also: ATMOS_TYPE :param [in]: file_name string Output CSV file :param [in]: atmos_type int Atmospheric model enum (i.e. ATMOS_TYPE_HERRINGTON_1966)

openvsp.CalcAtmosphere(alt, delta_temp, atmos_type)[source]¶

Calculate the atmospheric properties determined by a specified model at input altitude and temperature deviation. This function may not be used for any manual atmospheric model types (i.e. ATMOS_TYPE_MANUAL_P_T). This function assumes freestream units are metric, temperature units are Kelvin, and pressure units are kPA.

alt = 4000

delta_temp = 0

temp, pres, pres_ratio, rho_ratio = CalcAtmosphere( alt, delta_temp, ATMOS_TYPE_US_STANDARD_1976)

# The ratios are against sea level standard day, so asking at sea level with
# no temperature offset has to return the sea level standard itself.
sl_temp, sl_pres, sl_pres_ratio, sl_rho_ratio = CalcAtmosphere( 0.0, 0.0, ATMOS_TYPE_US_STANDARD_1976 )

assert abs( sl_temp - 288.15 ) < 1e-2, "sea level is not the standard day temperature"

# The density ratio carries a little rounding from the model constants.
assert abs( sl_pres_ratio - 1.0 ) < 1e-9, "the sea level ratios are not one"
assert abs( sl_rho_ratio - 1.0 ) < 1e-4, "the sea level ratios are not one"

# The atmosphere thins with altitude.
assert temp < sl_temp, "the atmosphere did not thin with altitude"
assert pres < sl_pres, "the atmosphere did not thin with altitude"
assert pres_ratio < 1.0, "the atmosphere did not thin with altitude"
assert rho_ratio < 1.0, "the atmosphere did not thin with altitude"

# The pressure ratio is the pressure against sea level.
assert abs( pres_ratio - pres / sl_pres ) < 1e-6, "the pressure ratio does not match the pressure"

See also: ATMOS_TYPE :param [in]: alt double Altitude :param [in]: delta_temp double Deviation in temperature from the value specified in the atmospheric model :param [in]: atmos_type int Atmospheric model enum (i.e. ATMOS_TYPE_HERRINGTON_1966) :param [out]: temp double output Temperature :param [out]: pres double output Pressure :param [out]: pres_ratio double Output pressure ratio :param [out]: rho_ratio double Output density ratio

openvsp.WriteBodyFFCSVFile(file_name)[source]¶

Calculate the form factor from each body FF equation (i.e. Hoerner Streamlined Body) and write the results to a CSV output file

print( "Starting Body Form Factor Data Creation. \n" )
WriteBodyFFCSVFile( "BodyFormFactorData.csv" )
# The call above should have produced a file with content in it.
import os
assert os.path.getsize( "BodyFormFactorData.csv" ) > 0, "WriteBodyFFCSVFile wrote no file"

Parameters:: [in] – file_name string Output CSV file

openvsp.WriteWingFFCSVFile(file_name)[source]¶

Calculate the form factor from each wing FF equation (i.e. Schemensky 4 Series Airfoil) and write the results to a CSV output file

print( "Starting Wing Form Factor Data Creation. \n" )
WriteWingFFCSVFile( "WingFormFactorData.csv" )
# The call above should have produced a file with content in it.
import os
assert os.path.getsize( "WingFormFactorData.csv" ) > 0, "WriteWingFFCSVFile wrote no file"

Parameters:: [in] – file_name string Output CSV file

openvsp.WriteCfEqnCSVFile(file_name)[source]¶

Calculate the coefficient of friction from each Cf equation (i.e. Power Law Blasius) and write the results to a CSV output file

print( "Starting Turbulent Friciton Coefficient Data Creation. \n" )
WriteCfEqnCSVFile( "FrictionCoefficientData.csv" )
# The call above should have produced a file with content in it.
import os
assert os.path.getsize( "FrictionCoefficientData.csv" ) > 0, "WriteCfEqnCSVFile wrote no file"

Parameters:: [in] – file_name string Output CSV file

Write a CSV file of the skin friction coefficient equations over a range of Reynolds numbers.

WriteCfEqnCSVFile( "TestCfEqn.csv" )

See also: WritePartialCfMethodCSVFile :param [in]: file_name string Name of the CSV file to write

openvsp.WritePartialCfMethodCSVFile(file_name)[source]¶

Calculate the partial coefficient of friction and write the results to a CSV output file

print( "Starting Partial Friction Method Data Creation. \n" )
WritePartialCfMethodCSVFile( "PartialFrictionMethodData.csv" )
# The call above should have produced a file with content in it.
import os
assert os.path.getsize( "PartialFrictionMethodData.csv" ) > 0, "WritePartialCfMethodCSVFile wrote no file"

Parameters:: [in] – file_name string Output CSV file

Write a CSV file of the partial turbulence skin friction methods.

WritePartialCfMethodCSVFile( "TestPartialCf.csv" )

See also: WriteCfEqnCSVFile :param [in]: file_name string Name of the CSV file to write

Parasite Drag Functions¶

Details¶

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