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getCv.py
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# -*- coding: cp936 -*-
import urllib2,urllib
import oneVariableCubicEquation
from numpy import *
'''
#计算线圈内气体的比体积
def calv0(pressure,temp):
a = 0.0324*10**6
b = 23.4
R = 8.31451
s1 = pressure
s2 = -(pressure*b+R*temp)
s3 = a
s4 = -a*b
ans = oneVariableCubicEquation.getCubicRoot(s1,s2,s3,s4)
return ans
print calv0(0.41,4.2)
'''
'''
v = 33.336 # cm3/mol
#通过状态方程以及温度 T ， 计算压强 p
def pressure(temp,v):
R = 83.1451
a = -0.0005808
A0 = 0.0414945
b = -0.00000019727
B0 = 0.023661
C = -0.005592
alpha = -0.0000072673
C0 = -0.00000164379
gama = 0.00077942
p1 = R*temp/v + (B0*R*temp-A0-C0/(temp**2))/(v**2)
p2 = (b*R*temp-a)/(v**3) + a*alpha/(v**6)
p3 = (C*(1+gama/(v**2))*exp(-alpha/(v**2)))/((temp**2)*(v**3))
p = p1 + p2 + p3
return p
print pressure(5.2,v)
'''
#从网上获得氦气的定压比热容
#temp = 34.5
#pressure = 0.3
'''
def getCv(temp, pressure):
#从http://webbook.nist.gov获得地址
heliumurl = "http://webbook.nist.gov/cgi/fluid.cgi?Action=Load&ID=C7440597&Type=IsoTherm&Digits=5&PLow="+str(pressure)+"&PHigh="+str(pressure)+"&PInc=0&T="+str(temp)+"&RefState=DEF&TUnit=K&PUnit=MPa&DUnit=mol%2Fl&HUnit=kJ%2Fmol&WUnit=m%2Fs&VisUnit=uPa*s&STUnit=N%2Fm"
#heliumdlurl = "http://webbook.nist.gov/cgi/fluid.cgi?Action=Data&Wide=on&ID=C7440597&Type=IsoTherm&Digits=5&PLow="+str(pressure)+"&PHigh="+str(pressure)+"&PInc=0&T="+str(temp)+"&RefState=DEF&TUnit=K&PUnit=MPa&DUnit=mol%2Fl&HUnit=kJ%2Fmol&WUnit=m%2Fs&VisUnit=uPa*s&STUnit=N%2Fm"
url = heliumurl
up = urllib2.urlopen(url)
cont = up.read()
#print cont
head = '<td align="right">'
rd = 0
ph = 0
while(rd<8):
ph = cont.find(head,ph+10,len(cont))
rd = rd+1
#print rd,ph
Cv = cont[ph+len(head):ph+len(head)+6]
return Cv
#print getCv(temp,pressure)
'''
def getVandCv(temp,pressure):
#从http://webbook.nist.gov获得地址
heliumurl = "http://webbook.nist.gov/cgi/fluid.cgi?Action=Load&ID=C7440597&Type=IsoTherm&Digits=5&PLow="+str(pressure)+"&PHigh="+str(pressure)+"&PInc=0&T="+str(temp)+"&RefState=DEF&TUnit=K&PUnit=MPa&DUnit=mol%2Fl&HUnit=kJ%2Fmol&WUnit=m%2Fs&VisUnit=uPa*s&STUnit=N%2Fm"
#heliumdlurl = "http://webbook.nist.gov/cgi/fluid.cgi?Action=Data&Wide=on&ID=C7440597&Type=IsoTherm&Digits=5&PLow="+str(pressure)+"&PHigh="+str(pressure)+"&PInc=0&T="+str(temp)+"&RefState=DEF&TUnit=K&PUnit=MPa&DUnit=mol%2Fl&HUnit=kJ%2Fmol&WUnit=m%2Fs&VisUnit=uPa*s&STUnit=N%2Fm"
url = heliumurl
up = urllib2.urlopen(url)
cont = up.read()
#print cont
head = '<td align="right">'
rd = 0
vh = 0
ph = 0
while(rd<4):
vh = cont.find(head,vh+10,len(cont))
rd = rd +1
ph = vh
while(rd<8):
ph = cont.find(head,ph+10,len(cont))
rd = rd+1
#print rd,ph
v = float(cont[vh+len(head):vh+len(head)+6])
Cv = float(cont[ph+len(head):ph+len(head)+6])
return v,Cv
#test part
print 'temp ','pressure ','v ',' Cv'
attempts = 0
for i in range(100):
for j in range(10):
temp = 4.5+i*0.1
pressure = 0.30+j*0.01
#print temp , pressure
try:
v,Cv = getVandCv(temp,pressure)
success = True
except:
attempts +=1
if attempts == 10:
print temp, ' ',pressure,' output wrong'
print temp,' ',pressure,' ',v,' ',Cv
'''
# 筛选比体积v= 时的 p 和 T 的值
T0 = 4.5 #起点
p0 = 0.41
v0,Cv0 = getVandCv(T0,p0)
def choosePandCv(T1,T0,p0):
#v,Cv = getVandCv(T1,p0)
try:
v,Cv = getVandCv(T1,p0)
success = True
except:
attempts +=1
if attempts == 10:
print temp,' ',pressure,' output wrong'
p = p0
#print v,v0
#print Cv,Cv0
while(v>v0):
vhigh = v
Cvhigh = Cv
pbegin = p
p=p+0.01
v,Cv = getVandCv(T1,p)
#print v,Cv
vlow = v
Cvlow = Cv
pend = p
ratelow = (vhigh-v0)/((vhigh-v0) + (v0-vlow))
ratehigh = (v0-vlow)/((vhigh-v0) + (v0-vlow))
#print ratelow+ratehigh
p1 = pbegin*ratehigh + pend*ratelow
Cv1 = Cvhigh*ratehigh+Cvlow*ratelow
v1 = vhigh*ratehigh+vlow*ratelow
return p1,v1,Cv1
#print choosePandCv(4.6,4.5,0.41)
'''
'''
for i in range(50):
T1= T0 + 0.1
p1,v1,Cv1 = choosePandCv(T1,T0,p0)
print T1,p1,v1,Cv1
T0 = T1
p0 = p1
'''