def set_NPR(NPR):
if NPR < NPR0:
_Ms = Is.Mach_PiPs(NPR, gamma=self.model.gamma)
self._M = mf.MachSub_Sigma(self.AsoAc * mf.Sigma_Mach(Ma_col) /
self.AsoAc[-1],
gamma=self.model.gamma)
self._Pt = 0. * coord_x + 1.
self._Ps = _Pt / Is.PiPs_Mach(self._M, gamma=self.model.gamma)
elif NPR < NPRsw:
_M = mf.Mach_Sigma(Noz_AoAc, Mach=_Minit)
#
# analytical solution for Ms, losses and upstream Mach number of shock wave
Ms = nz.Ms_from_AsAc_NPR(target_AoAc, NPR)
Ptloss = Is.PiPs_Mach(Ms) / NPR
Msh = sw.Mn_Pi_ratio(Ptloss)
#
# redefine curves starting from 'ish' index (closest value of Msh in supersonic flow)
ish = np.abs(_M - Msh).argmin()
_M[ish:] = mf.MachSub_Sigma(Noz_AoAc[ish:] * mf.Sigma_Mach(Ms) /
target_AoAc)
_Pt[ish:] = Ptloss
_Ps = _Pt / Is.PiPs_Mach(_M)
def set_NPR(self, NPR):
""" Define Nozzle Pressure Ratio (inlet Ptot over outlet Ps) for this case
:param NPR: NPR value (>1)
"""
self.NPR = NPR
defg.set_gamma(self._gam)
if NPR < self.NPR0: # flow is fully subsonic
_Ms = Is.Mach_PiPs(NPR)
_M = mf.MachSub_Sigma(self.section * mf.Sigma_Mach(_Ms) /
self.section[-1])
_Pt = 0. * _M + NPR
_Ps = _Pt / Is.PiPs_Mach(_M)
else:
# compute Mach, assumed to be subsonic before throat, supersonic after
_Minit = 0. * self.section + .5
_Minit[self.ithroat:] = 2.
_M = mf.Mach_Sigma(self.section / self.section[self.ithroat],
Mach=_Minit)
_Pt = NPR + 0. * _M
# CHECK, there is a shock
# analytical solution for Ms, losses and upstream Mach number of shock wave
Ms = nz.Ms_from_AsAc_NPR(self.AsoAc, NPR)
Ptloss = Is.PiPs_Mach(Ms) / NPR
Msh = sw.Mn_Pi_ratio(Ptloss)
#
if NPR < self.NPRsw: # throat is choked, there may be a shock
# redefine curves starting from 'ish' index (closest value of Msh in supersonic flow)
ish = np.abs(_M - Msh).argmin()
_M[ish:] = mf.MachSub_Sigma(
self.section[ish:] * mf.Sigma_Mach(Ms) / self.section[-1])
_Pt[ish:] = Ptloss * NPR
_Ps = _Pt / Is.PiPs_Mach(_M)
#
self._M = _M
self._Pt = _Pt
self._Ps = _Ps
return
def test_stagnation_i2t():
assert Is.TtTs_Mach(2.) == Is.TiTs_Mach(2.)
assert Is.PtPs_Mach(2.) == Is.PiPs_Mach(2.)
assert Is.Mach_PiPs(3.) == Is.Mach_PtPs(3.)
assert Is.Mach_TiTs(3.) == Is.Mach_TtTs(3.)
assert Is.Velocity_MachTi(.8, 300.) == Is.Velocity_MachTt(.8, 300.)