def execute(self):
fs_tube = self.fs_tube = FlowStation()
tube_rad = self.radius_tube*0.0328084 #convert to ft
inlet_rad = self.radius_inlet*0.0328084
self._tube_area = pi*(tube_rad**2) #ft**2
self._bypass_area = pi*(tube_rad**2-inlet_rad**2)
self._Ts = self.Ts_tube*1.8 #convert to R
self._Ps = self.Ps_tube*0.000145037738 #convert to psi
area_ratio_target = self._tube_area/self._bypass_area
def f(m_guess):
fs_tube.setStaticTsPsMN(self._Ts, self._Ps , m_guess)
gam = fs_tube.gamt
g_exp = (gam+1)/(2*(gam-1))
ar = ((gam+1)/2)**(-1*g_exp)*((1+ (gam-1)/2*m_guess**2)**g_exp)/m_guess
return ar - area_ratio_target
self.limit_Mach = secant(f, .3, x_min=0, x_max=1)
self.limit_speed = fs_tube.Vflow*0.3048 #convert to meters
#excess mass flow calculation
fs_tube.setStaticTsPsMN(self._Ts, self._Ps, self.Mach_pod)
self.W_tube = fs_tube.rhos*fs_tube.Vflow*self._tube_area*0.45359
fs_tube.Mach = self.Mach_bypass #Kantrowitz flow is at these total conditions, but with Mach 1
self.W_kant = fs_tube.rhos*fs_tube.Vflow*self._bypass_area*0.45359
#print "test", fs_tube.rhos, fs_tube.Vflow, self._bypass_area, self.W_kant
self.W_excess = self.W_tube - self.W_kant
def execute(self):
fs_tube = self.fs_tube = FlowStation()
tube_rad = cu(self.radius_tube, 'cm', 'ft') #convert to ft
inlet_rad = cu(self.radius_inlet, 'cm', 'ft')
#A = pi(r^2)
self._tube_area = pi * (tube_rad**2) #ft**2
self._inlet_area = pi * (inlet_rad**2) #ft**2
self._bypass_area = self._tube_area - self._inlet_area
self._Ts = cu(self.Ts_tube, 'degK', 'degR') #convert to R
self._Ps = cu(self.Ps_tube, 'Pa', 'psi') #convert to psi
area_ratio_target = self._tube_area / self._bypass_area
#iterate over pod speed until the area ratio = A_tube / A_bypass
def f(m_guess):
fs_tube.setStaticTsPsMN(
self._Ts, self._Ps, m_guess
) #set the static conditions iteratively until correct (Ts, Ps are known)
gam = fs_tube.gamt
g_exp = (gam + 1) / (2 * (gam - 1))
ar = ((gam + 1) / 2)**(-1 * g_exp) * (
(1 + (gam - 1) / 2 * m_guess**2)**g_exp) / m_guess
return ar - area_ratio_target
#Solve for Mach where AR = AR_target
self.limit_Mach = secant(
f, .3, x_min=0, x_max=1
) #value not actually needed, fs_tube contains necessary flow information
self.limit_speed = cu(fs_tube.Vflow, 'ft',
'm') #convert to meters/second
#excess mass flow calculation
fs_tube.setStaticTsPsMN(self._Ts, self._Ps, self.Mach_pod)
self.W_tube = cu(fs_tube.rhos * fs_tube.Vflow * self._tube_area, 'lbm',
'kg') #convert to kg/sec
fs_tube.Mach = self.Mach_bypass #Kantrowitz flow is at these total conditions, but with Mach 1
self.W_kant = cu(fs_tube.rhos * fs_tube.Vflow * self._bypass_area,
'lbm', 'kg') #convert to kg/sec
#print "test", fs_tube.rhos, fs_tube.Vflow, self._bypass_area, self.W_kant
self.W_excess = self.W_tube - self.W_kant
def execute(self):
fs_tube = self.fs_tube = FlowStation()
tube_rad = cu(self.radius_tube,'cm','ft') #convert to ft
inlet_rad = cu(self.radius_inlet,'cm','ft')
#A = pi(r^2)
self._tube_area = pi*(tube_rad**2) #ft**2
self._inlet_area = pi*(inlet_rad**2) #ft**2
self._bypass_area = self._tube_area - self._inlet_area
self._Ts = cu(self.Ts_tube,'degK','degR') #convert to R
self._Ps = cu(self.Ps_tube,'Pa','psi') #convert to psi
area_ratio_target = self._tube_area/self._bypass_area
#iterate over pod speed until the area ratio = A_tube / A_bypass
def f(m_guess):
fs_tube.setStaticTsPsMN(self._Ts, self._Ps , m_guess) #set the static conditions iteratively until correct (Ts, Ps are known)
gam = fs_tube.gamt
g_exp = (gam+1)/(2*(gam-1))
ar = ((gam+1)/2)**(-1*g_exp)*((1+ (gam-1)/2*m_guess**2)**g_exp)/m_guess
return ar - area_ratio_target
#Solve for Mach where AR = AR_target
self.limit_Mach = secant(f, .3, x_min=0, x_max=1) #value not actually needed, fs_tube contains necessary flow information
self.limit_speed = cu(fs_tube.Vflow,'ft','m') #convert to meters/second
#excess mass flow calculation
fs_tube.setStaticTsPsMN(self._Ts, self._Ps, self.Mach_pod)
self.W_tube = cu(fs_tube.rhos*fs_tube.Vflow*self._tube_area,'lbm','kg') #convert to kg/sec
fs_tube.Mach = self.Mach_bypass #Kantrowitz flow is at these total conditions, but with Mach 1
self.W_kant = cu(fs_tube.rhos*fs_tube.Vflow*self._bypass_area,'lbm','kg') #convert to kg/sec
#print "test", fs_tube.rhos, fs_tube.Vflow, self._bypass_area, self.W_kant
self.W_excess = self.W_tube - self.W_kant
def execute(self):
Fl_I = self.Fl_I
Fl_O = self.Fl_O
Fl_ref = self.Fl_ref
fs_throat = CanteraFlowStation()
fs_exitIdeal = CanteraFlowStation()
fs_throat.W = Fl_I.W
fs_throat.setTotalTP( Fl_I.Tt, Fl_I.Pt )
fs_throat.Mach = 1.0
Athroat_dmd = fs_throat.area
fs_exitIdeal.W = Fl_I.W
fs_exitIdeal.setTotalTP( Fl_I.Tt, Fl_I.Pt )
fs_exitIdeal.Ps = Fl_ref.Ps
Fl_O.W = Fl_I.W
Fl_O.setTotalTP( Fl_I.Tt, Fl_I.Pt )
Fl_O.Mach = fs_exitIdeal.Mach
if self.run_design:
# Design Calculations at throat
self.Athroat_des = fs_throat.area
# Design calculations at exit
self.Aexit_des = fs_exitIdeal.area
self.switchRegime = "PERFECTLY_EXPANDED"
else:
# Find subsonic solution, curve 4
Fl_O.sub_or_super = "sub"
Fl_O.area = self.Aexit_des
MachSubsonic = Fl_O.Mach
if MachSubsonic > 1:
print "invalid nozzle subsonic solution"
PsSubsonic = Fl_O.Ps
# Find supersonic solution, curve 5
Fl_O.sub_or_super = "super"
PsOut = Fl_ref.Ps
def F( Ps ):
Fl_O.Ps = Ps
return Fl_O.area - self.Aexit_des
Fl_O.Ps = secant( F, PsOut )
MachSupersonic = Fl_O.Mach
PsSupersonic = Fl_O.Ps
# normal shock at nozzle exit, curve c
Fl_O.sub_or_super = "sub"
Msuper = MachSupersonic
PtExit = self.shockPR( Msuper, fs_throat.gams ) * fs_throat.Pt
Fl_O.setTotalTP( fs_throat.Tt, PtExit )
Fl_O.area = self.Aexit_des
PsShock = Fl_O.Ps
# find correct operating regime
# curves 1 to 4
if Fl_ref.Ps >= PsSubsonic:
self.switchRegime = "UNCHOKED"
fs_throat.sub_or_super = "sub"
Fl_O.sub_or_super = "sub"
fs_throat.area = self.Athroat_des
Fl_O.setTotalTP( fs_throat.Tt, fs_throat.Pt )
Fl_O.area = self.Aexit_des
# between curves 4 and c
elif Fl_ref.Ps < PsSubsonic and Fl_ref.Ps >= PsShock:
self.switchRegime = "NORMAL_SHOCK"
Msuper = 1.5
def F( MN ):
PtExit = self.shockPR( MN, fs_throat.gams) * fs_throat.Pt
Fl_O.setTotalTP( fs_throat.Tt, PtExit )
Fl_O.sub_or_super = "sub"
Fl_O.area = self.Aexit_des
return (Fl_O.Ps - Fl_ref.Ps)/Fl_ref.Ps
Fl_O.Mach = secant( F, Msuper )
# between curves c and 5
elif Fl_ref.Ps < PsShock and Fl_ref.Ps > PsSupersonic:
self.switchRegime = "OVEREXPANDED"
Fl_O.sub_or_super = "super"
Fl_O.setTotalTP( fs_throat.Tt, fs_throat.Pt )
Fl_O.area = self.Aexit_des
# between curves 5 and e
elif Fl_ref.Ps <= PsSupersonic:
self.switchRegime = "UNDEREXPANDED"
Fl_O.sub_or_super = "super"
Fl_O.setTotalTP( fs_throat.Tt, fs_throat.Pt )
Fl_O.area = self.Aexit_des
if abs(Fl_ref.Ps - PsSupersonic)/Fl_ref.Ps < .001:
self.switchRegime = "PERFECTLY_EXPANDED"
