예제 #1
0
    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
예제 #2
0
    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
예제 #3
0
    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
예제 #4
0
    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