def __defaults__(self):
"""This sets the default values at breaks in the atmosphere.
Assumptions:
None
Source:
U.S. Standard Atmosphere (1976 version)
Inputs:
None
Outputs:
None
Properties Used:
None
"""
self.tag = ' U.S. Standard Atmosphere (1976)'
# break point data:
self.fluid_properties = Air()
self.planet = Earth()
self.breaks = Data()
self.breaks.altitude = np.array( [-2.00 , 0.00, 11.00, 20.00, 32.00, 47.00, 51.00, 71.00, 84.852]) * Units.km # m, geopotential altitude
self.breaks.temperature = np.array( [301.15 , 288.15, 216.65, 216.65, 228.65, 270.65, 270.65, 214.65, 186.95]) # K
self.breaks.pressure = np.array( [127774.0 , 101325.0, 22632.1, 5474.89, 868.019, 110.906, 66.9389, 3.95642, 0.3734]) # Pa
self.breaks.density = np.array( [1.47808e0, 1.2250e0, 3.63918e-1, 8.80349e-2, 1.32250e-2, 1.42753e-3, 8.61606e-4, 6.42099e-5, 6.95792e-6]) # kg/m^3
def __defaults__(self):
"""This sets the default values at breaks in the atmosphere.
Assumptions:
Constant temperature
Source:
U.S. Standard Atmosphere (1976 version)
Inputs:
None
Outputs:
None
Properties Used:
None
"""
self.fluid_properties = Air()
self.planet = Earth()
self.breaks = Data()
self.breaks.altitude = np.array( [-2.00 , 0.00, 11.00, 20.00, 32.00, 47.00, 51.00, 71.00, 84.852]) * Units.km # m, geopotential altitude
self.breaks.temperature = np.array( [301.15 , 301.15, 301.15, 301.15, 301.15, 301.15, 301.15, 301.15, 301.15]) # K
self.breaks.pressure = np.array( [127774.0 , 101325.0, 22632.1, 5474.89, 868.019, 110.906, 66.9389, 3.95642, 0.3734]) # Pa
self.breaks.density = np.array( [1.545586 , 1.2256523,.273764, .0662256, 0.0105000 , 1.3415E-03, 8.0971E-04, 4.78579E-05, 4.51674E-06]) #kg/m^3
def __defaults__(self):
self.fluid_properties = Air()
self.planet = Earth()
self.breaks = Data()
self.breaks.altitude = np.array( [-2.00 , 0.00, 11.00, 20.00, 32.00, 47.00, 51.00, 71.00, 84.852]) * Units.km # m, geopotential altitude
self.breaks.temperature = np.array( [301.15 , 301.15, 301.15, 301.15, 301.15, 301.15, 301.15, 301.15, 301.15]) # K
self.breaks.pressure = np.array( [127774.0 , 101325.0, 22632.1, 5474.89, 868.019, 110.906, 66.9389, 3.95642, 0.3734]) # Pa
self.breaks.density = np.array( [1.545586 , 1.2256523,.273764, .0662256, 0.0105000 , 1.3415E-03, 8.0971E-04, 4.78579E-05, 4.51674E-06]) #kg/m^3
def compute_values(self,altitude,temperature_deviation=0.0,var_gamma=False):
"""Computes atmospheric values.
Assumptions:
US 1976 Standard Atmosphere
Source:
U.S. Standard Atmosphere, 1976, U.S. Government Printing Office, Washington, D.C., 1976
Inputs:
altitude [m]
temperature_deviation [K]
Output:
atmo_data.
pressure [Pa]
temperature [K]
speed_of_sound [m/s]
dynamic_viscosity [kg/(m*s)]
kinematic_viscosity [m^2/s]
thermal_conductivity [W/(m*K)]
prandtl_number [-]
Properties Used:
self.
fluid_properties.gas_specific_constant [J/(kg*K)]
planet.sea_level_gravity [m/s^2]
planet.mean_radius [m]
breaks.
altitude [m]
temperature [K]
pressure [Pa]
"""
# unpack
zs = altitude
gas = self.fluid_properties
planet = self.planet
grav = self.planet.sea_level_gravity
Rad = self.planet.mean_radius
R = gas.gas_specific_constant
delta_isa = temperature_deviation
# check properties
if not gas == Air():
warn('US Standard Atmosphere not using Air fluid properties')
if not planet == Earth():
warn('US Standard Atmosphere not using Earth planet properties')
# convert input if necessary
zs = atleast_2d_col(zs)
# get model altitude bounds
zmin = self.breaks.altitude[0]
zmax = self.breaks.altitude[-1]
# convert geometric to geopotential altitude
zs = zs/(1 + zs/Rad)
# check ranges
if np.amin(zs) < zmin:
print("Warning: altitude requested below minimum for this atmospheric model; returning values for h = -2.0 km")
zs[zs < zmin] = zmin
if np.amax(zs) > zmax:
print("Warning: altitude requested above maximum for this atmospheric model; returning values for h = 86.0 km")
zs[zs > zmax] = zmax
# initialize return data
zeros = np.zeros_like(zs)
p = zeros * 0.0
T = zeros * 0.0
rho = zeros * 0.0
a = zeros * 0.0
mu = zeros * 0.0
z0 = zeros * 0.0
T0 = zeros * 0.0
p0 = zeros * 0.0
alpha = zeros * 0.0
# populate the altitude breaks
# this uses >= and <= to capture both edges and because values should be the same at the edges
for i in range( len(self.breaks.altitude)-1 ):
i_inside = (zs >= self.breaks.altitude[i]) & (zs <= self.breaks.altitude[i+1])
z0[ i_inside ] = self.breaks.altitude[i]
T0[ i_inside ] = self.breaks.temperature[i]
p0[ i_inside ] = self.breaks.pressure[i]
alpha[ i_inside ] = -(self.breaks.temperature[i+1] - self.breaks.temperature[i])/ \
(self.breaks.altitude[i+1] - self.breaks.altitude[i])
# interpolate the breaks
dz = zs-z0
i_isoth = (alpha == 0.)
i_adiab = (alpha != 0.)
p[i_isoth] = p0[i_isoth] * np.exp(-1.*dz[i_isoth]*grav/(R*T0[i_isoth]))
p[i_adiab] = p0[i_adiab] * ( (1.-alpha[i_adiab]*dz[i_adiab]/T0[i_adiab]) **(1.*grav/(alpha[i_adiab]*R)) )
T = T0 - dz*alpha + delta_isa
rho = gas.compute_density(T,p)
a = gas.compute_speed_of_sound(T,p,var_gamma)
mu = gas.compute_absolute_viscosity(T)
K = gas.compute_thermal_conductivity(T)
Pr = gas.compute_prandtl_number(T)
atmo_data = Conditions()
atmo_data.expand_rows(zs.shape[0])
atmo_data.pressure = p
atmo_data.temperature = T
atmo_data.density = rho
atmo_data.speed_of_sound = a
atmo_data.dynamic_viscosity = mu
atmo_data.kinematic_viscosity = mu/rho
atmo_data.thermal_conductivity = K
atmo_data.prandtl_number = Pr
return atmo_data
def compute_values(self,altitude,temperature_deviation = 0):
""" Computes values from the International Standard Atmosphere
Inputs:
altitude : geometric altitude (elevation) (m)
can be a float, list or 1D array of floats
temperature_deviation : delta_isa
Outputs:
list of conditions -
pressure : static pressure (Pa)
temperature : static temperature (K)
density : density (kg/m^3)
speed_of_sound : speed of sound (m/s)
dynamic_viscosity : dynamic_viscosity (kg/m-s)
Example:
atmosphere = SUAVE.Attributes.Atmospheres.Earth.USStandard1976()
atmosphere.ComputeValues(1000).pressure
"""
# unpack
zs = altitude
gas = self.fluid_properties
planet = self.planet
grav = self.planet.sea_level_gravity
Rad = self.planet.mean_radius
gamma = gas.gas_specific_constant
delta_isa = temperature_deviation
# check properties
if not gas == Air():
warn('US Standard Atmosphere not using Air fluid properties')
if not planet == Earth():
warn('US Standard Atmosphere not using Earth planet properties')
# convert input if necessary
zs = atleast_2d_col(zs)
# get model altitude bounds
zmin = self.breaks.altitude[0]
zmax = self.breaks.altitude[-1]
# convert geometric to geopotential altitude
zs = zs/(1 + zs/Rad)
# check ranges
if np.amin(zs) < zmin:
print "Warning: altitude requested below minimum for this atmospheric model; returning values for h = -2.0 km"
zs[zs < zmin] = zmin
if np.amax(zs) > zmax:
print "Warning: altitude requested above maximum for this atmospheric model; returning values for h = 86.0 km"
zs[zs > zmax] = zmax
# initialize return data
zeros = np.zeros_like(zs)
p = zeros * 0.0
T = zeros * 0.0
rho = zeros * 0.0
a = zeros * 0.0
mew = zeros * 0.0
z0 = zeros * 0.0
T0 = zeros * 0.0
p0 = zeros * 0.0
alpha = zeros * 0.0
# populate the altitude breaks
# this uses >= and <= to capture both edges and because values should be the same at the edges
for i in range( len(self.breaks.altitude)-1 ):
i_inside = (zs >= self.breaks.altitude[i]) & (zs <= self.breaks.altitude[i+1])
z0[ i_inside ] = self.breaks.altitude[i]
T0[ i_inside ] = self.breaks.temperature[i]
p0[ i_inside ] = self.breaks.pressure[i]
alpha[ i_inside ] = -(self.breaks.temperature[i+1] - self.breaks.temperature[i])/ \
(self.breaks.altitude[i+1] - self.breaks.altitude[i])
# interpolate the breaks
dz = zs-z0
i_isoth = (alpha == 0.)
i_adiab = (alpha != 0.)
p[i_isoth] = p0[i_isoth] * np.exp(-1.*dz[i_isoth]*grav/(gamma*T0[i_isoth]))
p[i_adiab] = p0[i_adiab] * ( (1.-alpha[i_adiab]*dz[i_adiab]/T0[i_adiab]) **(1.*grav/(alpha[i_adiab]*gamma)) )
T = T0 - dz*alpha + delta_isa
rho = gas.compute_density(T,p)
a = gas.compute_speed_of_sound(T)
mew = gas.compute_absolute_viscosity(T)
atmo_data = Conditions()
atmo_data.expand_rows(zs.shape[0])
atmo_data.pressure = p
atmo_data.temperature = T
atmo_data.density = rho
atmo_data.speed_of_sound = a
atmo_data.dynamic_viscosity = mew
return atmo_data
def compute_values(self,altitude,temperature=288.15):
"""Computes atmospheric values.
Assumptions:
Constant temperature atmosphere
Source:
U.S. Standard Atmosphere, 1976, U.S. Government Printing Office, Washington, D.C., 1976
Inputs:
altitude [m]
temperature [K]
Outputs:
atmo_data.
pressure [Pa]
temperature [K]
speed_of_sound [m/s]
dynamic_viscosity [kg/(m*s)]
Properties Used:
self.
fluid_properties.gas_specific_constant [J/(kg*K)]
planet.sea_level_gravity [m/s^2]
planet.mean_radius [m]
breaks.
altitude [m]
pressure [Pa]
"""
# unpack
zs = altitude
gas = self.fluid_properties
planet = self.planet
grav = self.planet.sea_level_gravity
Rad = self.planet.mean_radius
R = gas.gas_specific_constant
# check properties
if not gas == Air():
warn('Constant_Temperature Atmosphere not using Air fluid properties')
if not planet == Earth():
warn('Constant_Temperature Atmosphere not using Earth planet properties')
# convert input if necessary
zs = atleast_2d_col(zs)
# get model altitude bounds
zmin = self.breaks.altitude[0]
zmax = self.breaks.altitude[-1]
# convert geometric to geopotential altitude
zs = zs/(1 + zs/Rad)
# check ranges
if np.amin(zs) < zmin:
print "Warning: altitude requested below minimum for this atmospheric model; returning values for h = -2.0 km"
zs[zs < zmin] = zmin
if np.amax(zs) > zmax:
print "Warning: altitude requested above maximum for this atmospheric model; returning values for h = 86.0 km"
zs[zs > zmax] = zmax
# initialize return data
zeros = np.zeros_like(zs)
p = zeros * 0.0
T = zeros * 0.0
rho = zeros * 0.0
a = zeros * 0.0
mu = zeros * 0.0
z0 = zeros * 0.0
T0 = zeros * 0.0
p0 = zeros * 0.0
alpha = zeros * 0.0
# populate the altitude breaks
# this uses >= and <= to capture both edges and because values should be the same at the edges
for i in range( len(self.breaks.altitude)-1 ):
i_inside = (zs >= self.breaks.altitude[i]) & (zs <= self.breaks.altitude[i+1])
z0[ i_inside ] = self.breaks.altitude[i]
T0[ i_inside ] = temperature
p0[ i_inside ] = self.breaks.pressure[i]
self.breaks.temperature[i+1]=temperature
alpha[ i_inside ] = -(temperature - temperature)/ \
(self.breaks.altitude[i+1] - self.breaks.altitude[i])
# interpolate the breaks
dz = zs-z0
i_isoth = (alpha == 0.)
p = p0* np.exp(-1.*dz*grav/(R*T0))
T = temperature
rho = gas.compute_density(T,p)
a = gas.compute_speed_of_sound(T)
mu = gas.compute_absolute_viscosity(T)
atmo_data = Conditions()
atmo_data.expand_rows(zs.shape[0])
atmo_data.pressure = p
atmo_data.temperature = T
atmo_data.density = rho
atmo_data.speed_of_sound = a
atmo_data.dynamic_viscosity = mu
return atmo_data