Source code for RCAIDE.Library.Methods.Geometry.Airfoil.import_airfoil_polars
# RCAIDE/Library/Methods/Geometry/Two_Dimensional/Airfoil/import_airfoil_polars.py
#
#
# Created: Jul 2024, M. Clarke
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# IMPORT
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from RCAIDE.Framework.Core import Data , Units
import numpy as np
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# import_airfoil_polars
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[docs]
def import_airfoil_polars(airfoil_polar_files,angel_of_attack_discretization = 89):
"""This imports airfoil polars from a text file output from XFOIL or Airfoiltools.com
Assumptions:
Input airfoil polars file is obtained from XFOIL or from Airfoiltools.com
Source:
http://airfoiltools.com/
Inputs:
airfoil polar files <list of strings>
Outputs:
data numpy array with airfoil data
Properties Used:
N/A
"""
# number of airfoils
num_polars = 0
n_p = len(airfoil_polar_files)
if n_p < 3:
raise AttributeError('Provide three or more airfoil polars to compute surrogate')
num_polars = max(num_polars, n_p)
# create empty data structures
airfoil_data = Data()
AoA = np.zeros((num_polars,angel_of_attack_discretization))
CL = np.zeros((num_polars,angel_of_attack_discretization))
CD = np.zeros((num_polars,angel_of_attack_discretization))
Re = np.zeros(num_polars)
Ma = np.zeros(num_polars)
AoA_interp = np.linspace(-6,16,angel_of_attack_discretization)
for j in range(len(airfoil_polar_files)):
# Open file and read column names and data block
f = open(airfoil_polar_files[j])
data_block = f.readlines()
f.close()
# Ignore header
for header_line in range(len(data_block)):
line = data_block[header_line]
if 'Re =' in line:
Re[j] = float(line[25:40].strip().replace(" ", ""))
if 'Mach =' in line:
Ma[j] = float(line[7:20].strip().replace(" ", ""))
if '---' in line:
data_block = data_block[header_line+1:]
break
# Remove any extra lines at end of file:
last_line = False
while last_line == False:
if data_block[-1]=='\n':
data_block = data_block[0:-1]
else:
last_line = True
data_len = len(data_block)
airfoil_aoa= np.zeros(data_len)
airfoil_cl = np.zeros(data_len)
airfoil_cd = np.zeros(data_len)
# Loop through each value: append to each column
for line_count , line in enumerate(data_block):
airfoil_aoa[line_count] = float(data_block[line_count][0:8].strip())
airfoil_cl[line_count] = float(data_block[line_count][10:17].strip())
airfoil_cd[line_count] = float(data_block[line_count][20:27].strip())
AoA[j,:] = AoA_interp
CL[j,:] = np.interp(AoA_interp,airfoil_aoa,airfoil_cl)
CD[j,:] = np.interp(AoA_interp,airfoil_aoa,airfoil_cd)
airfoil_data.aoa_from_polar = AoA*Units.degrees
airfoil_data.re_from_polar = Re
airfoil_data.mach_number = Ma
airfoil_data.lift_coefficients = CL
airfoil_data.drag_coefficients = CD
return airfoil_data
