From 5091eea2cce8e4ea7f76feda6ae46efa5cdc9686 Mon Sep 17 00:00:00 2001
From: Robin Tamburrini <robin.tamburrini@student.uliege.be>
Date: Thu, 29 Feb 2024 14:09:37 +0100
Subject: [PATCH] small script that runs XFOIL to generate polars
---
src/airfoil_data/calc_polar.py | 14 +++
src/airfoil_data/xfoil.py | 156 +++++++++++++++++++++++++++++++++
2 files changed, 170 insertions(+)
create mode 100644 src/airfoil_data/calc_polar.py
create mode 100644 src/airfoil_data/xfoil.py
diff --git a/src/airfoil_data/calc_polar.py b/src/airfoil_data/calc_polar.py
new file mode 100644
index 0000000..2b985e0
--- /dev/null
+++ b/src/airfoil_data/calc_polar.py
@@ -0,0 +1,14 @@
+# -*- coding: utf-8 -*-
+
+import numpy as np
+from xfoil import calc_polar
+
+NACA = "0021"
+REYNOLDS = [re * 1000000 for re in [0.02, 0.1, 0.2, 0.5, 1, 2, 5, 10]]
+
+
+for re in REYNOLDS:
+
+ filename = f"polar_{re}.txt"
+
+ calc_polar(NACA, re, filename, alfaseq= np.arange(-20,30,0.5), clseq=[], refine=False, max_iter=500, n=None)
diff --git a/src/airfoil_data/xfoil.py b/src/airfoil_data/xfoil.py
new file mode 100644
index 0000000..03109f7
--- /dev/null
+++ b/src/airfoil_data/xfoil.py
@@ -0,0 +1,156 @@
+# -*- coding: utf-8 -*-
+
+import os
+import numpy as np
+import subprocess as sp
+import re
+
+
+def polar(afile, re, *args,**kwargs):
+ """calculate airfoil polar and load results
+
+ Parameters
+ ----------
+ afile: string
+ path to aifoil dat file
+ re: float
+ fixed reynoldsnumber for polar calculation
+ *args, **kwargs
+ have a look at calcpolar for further information
+
+ Returns
+ -------
+ dict
+ airfoil polar
+ """
+ calc_polar(afile, re,'polar.txt', *args, **kwargs)
+ data = read_polar('polar.txt')
+ delete_polar('polar.txt')
+ return data
+
+
+def calc_polar(afile, re, polarfile, alfaseq=[], clseq=[], refine=False, max_iter=200, n=None):
+ """run xfoil to generate polar file
+
+ Parameters
+ ----------
+ afile: string
+ path to airfoil dat file
+ re: float
+ fixed reynoldsnumber
+ alfaseq: iterateable, optional
+ sequence of angles of attack
+ clseq: iterateable, optional
+ sequence of lift coefficients (either those or alfaseq must be defined)
+ refine: bool
+ shall xfoil refine airfoil
+ maxiter: int
+ maximal number of boundary layer iterations
+ n: int
+ boundary layer parameter
+ """
+
+ import subprocess as sp
+ import numpy as np
+ import sys,os
+
+ if(os.name == 'posix'):
+ xfoilbin = 'xfoil'
+ elif(os.name == 'nt'):
+ xfoilbin = 'xfoil.exe'
+ else:
+ print('Betriebssystem %s wird nicht unterstützt'%os.name)
+
+
+ pxfoil = sp.Popen([xfoilbin], stdin=sp.PIPE, stdout=None, stderr=None)
+
+ def write2xfoil(string):
+ if(sys.version_info > (3,0)):
+ string = string.encode('ascii')
+
+ pxfoil.stdin.write(string)
+
+ if(afile.isdigit()):
+ write2xfoil('NACA ' + afile + '\n')
+ else:
+ write2xfoil('LOAD ' + afile + '\n')
+
+ if(refine):
+ write2xfoil('GDES\n')
+ write2xfoil('CADD\n')
+ write2xfoil('\n')
+ write2xfoil('\n')
+ write2xfoil('\n')
+ write2xfoil('X\n ')
+ write2xfoil('\n')
+ write2xfoil('PANEL\n')
+
+ write2xfoil('OPER\n')
+ if n != None:
+ write2xfoil('VPAR\n')
+ write2xfoil('N '+str(n)+'\n')
+ write2xfoil('\n')
+ write2xfoil('ITER '+str(max_iter)+'\n')
+ write2xfoil('VISC\n')
+ write2xfoil(str(re) + '\n')
+ write2xfoil('PACC\n')
+ write2xfoil('\n')
+ write2xfoil('\n')
+ for alfa in alfaseq:
+ write2xfoil('A ' + str(alfa) + '\n')
+ for cl in clseq:
+ write2xfoil('CL ' + str(cl) + '\n')
+ write2xfoil('PWRT 1\n')
+ write2xfoil(polarfile + '\n')
+ write2xfoil('\n')
+
+ pxfoil.communicate(str('quit').encode('ascii'))
+
+def read_polar(infile):
+ """read xfoil polar results from file
+
+ Parameters
+ ----------
+ infile: string
+ path to polar file
+
+ Returns
+ -------
+ dict
+ airfoil polar splitted up into dictionary
+ """
+
+ regex = re.compile('(?:\s*([+-]?\d*.\d*))')
+
+ with open(infile) as f:
+ lines = f.readlines()
+
+ a = []
+ cl = []
+ cd = []
+ cdp = []
+ cm = []
+ xtr_top = []
+ xtr_bottom = []
+
+
+ for line in lines[12:]:
+ linedata = regex.findall(line)
+ a.append(float(linedata[0]))
+ cl.append(float(linedata[1]))
+ cd.append(float(linedata[2]))
+ cdp.append(float(linedata[3]))
+ cm.append(float(linedata[4]))
+ xtr_top.append(float(linedata[5]))
+ xtr_bottom.append(float(linedata[6]))
+
+ data = {'a': np.array(a), 'cl': np.array(cl) , 'cd': np.array(cd), 'cdp': np.array(cdp),
+ 'cm': np.array(cm), 'xtr_top': np.array(xtr_top), 'xtr_bottom': np.array(xtr_bottom)}
+
+ return data
+
+
+def delete_polar(infile):
+ """ deletes polar file """
+ os.remove(infile)
+
--
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