def two_phase_single_channel(T_wall,
w_channel,
Nu_func_gas,
Nu_func_liquid,
T_inlet,
T_chamber,
p_ref,
m_dot,
h_channel,
fp: FluidProperties,
print_info=True):
""" Function that calculates the total power consumption of a specific chamber, in order to optimize the chamber
Args:
T_wall (K): Wall temperature
w_channel (m): Channel width
Nu_func_gas (-): Nusselt function for gas phase
Nu_func_liquid (-) Nusselt function for liquid phase
T_inlet (K): Chamber inlet temperature
T_chamber (K): Chamber outlet temperature (same as T_c in IRT)
p_ref (Pa): Reference pressure for the Nusselt relation and flow similary parameters (same as inlet pressure as no pressure drop is assumed)
m_dot (kg/s): Mass flow
h_channel (m): Channel height
w_channel_margin (m): The amount of margin around the chamber for structural reasons. Important because it also radiates heat
fp (- ): [description]
print_info(Bool): for debugging purposes
"""
# Calculate saturation temperature, to determine where transition from gas to liquid occurs
T_sat = fp.get_saturation_temperature(p=p_ref) # [K]
# Sanity check on input
assert (T_chamber > T_sat)
assert (T_wall > T_chamber)
# Calculate the two reference temperatures for the separated phases
T_bulk_gas = (T_sat + T_chamber) / 2 # [K] Bulk temperature gas phase
T_bulk_liquid_multi = (
T_inlet +
T_sat) / 2 # [K] Bulk temperature of liquid and multi-phase flow
# Calculate the density at these reference points
rho_bulk_gas = fp.get_density(T=T_bulk_gas, p=p_ref) # [kg/m^3]
rho_bulk_liquid_multi = fp.get_density(T=T_bulk_liquid_multi,
p=p_ref) # [kg/m^3]
# Channel geometry
A_channel = w_channel * h_channel # [m^2] Area through which the fluid flows
wetted_perimeter = wetted_perimeter_rectangular(
w_channel=w_channel, h_channel=h_channel
) # [m] Distance of channel cross-section in contact with fluid
D_hydraulic = hydraulic_diameter_rectangular(
w_channel=w_channel, h_channel=h_channel) # [m] Hydraulic diameter
# Flow similarity parameters (for debugging and Nu calculatoin purposes)
Re_bulk_gas = fp.get_Reynolds_from_mass_flow(
m_dot=m_dot, p=p_ref, T=T_bulk_gas, L_ref=D_hydraulic,
A=A_channel) # [-] Bulk Reynolds number in the gas phase
Re_bulk_liquid_multi = fp.get_Reynolds_from_mass_flow(
m_dot=m_dot,
p=p_ref,
T=T_bulk_liquid_multi,
L_ref=D_hydraulic,
A=A_channel) # [-] Bulk Reynolds number in the liquid/multi-phase
Pr_bulk_gas = fp.get_Prandtl(
T=T_bulk_gas, p=p_ref) # [-] Prandtl number in the gas phase
Pr_bulk_liquid_multi = fp.get_Prandtl(
T=T_bulk_liquid_multi,
p=p_ref) # [-] Prandtl number in liquid/multi-phase
Bo_sat = fp.get_Bond_number(
p_sat=p_ref, L_ref=D_hydraulic
) # [-] Bond number at saturation pressure (assumed to be p_ref)
# Calculate Nusselt number in both sections
args_gas = {
'Re': Re_bulk_gas, # Arguments for Nusselt function (gas phase)
'Pr': Pr_bulk_gas,
'Bo': Bo_sat,
}
args_liquid_multi = { # Arguments for Nusselt function (liquid/multi phase)
'Re': Re_bulk_liquid_multi,
'Pr': Pr_bulk_liquid_multi,
'Bo': Bo_sat,
}
Nu_gas = Nu_func_gas(args=args_gas)
Nu_liquid_multi = Nu_func_liquid(args=args_liquid_multi)
# Calculate Stanton number in both sections
St_gas = Stanton_from_Nusselt_and_velocity(
Nu=Nu_gas,
T_ref=T_bulk_gas,
p_ref=p_ref,
L_ref=D_hydraulic,
m_dot=m_dot,
A=A_channel,
fp=fp) # [-] Stanton number in gas phase
St_liquid_multi = Stanton_from_Nusselt_and_velocity(
Nu_liquid_multi,
T_ref=T_bulk_liquid_multi,
p_ref=p_ref,
L_ref=D_hydraulic,
m_dot=m_dot,
A=A_channel,
fp=fp) # [-] Stanton number in liquid phase
# Calculate velocity for convection parameter (bulk temp used as reference for phase)
u_bulk_gas = velocity_from_mass_flow(
A=A_channel, m_dot=m_dot,
rho=rho_bulk_gas) # [m/s] Velocity at the gas bulk reference state
u_bulk_liquid_multi = velocity_from_mass_flow(
A=A_channel, m_dot=m_dot, rho=rho_bulk_liquid_multi
) # [m/s] Velocity at the liquid/multi-phase bulk reference state
# Convective parameter
h_conv_gas = h_conv_from_Stanton(
Stanton=St_gas, u=u_bulk_gas, T_ref=T_bulk_gas, p_ref=p_ref, fp=fp
) # [W/(m^2*K)] Convective heat transfer coefficient at bulk gas state
h_conv_liquid_multi = h_conv_from_Stanton(
Stanton=St_liquid_multi,
u=u_bulk_liquid_multi,
T_ref=T_bulk_liquid_multi,
p_ref=p_ref,
fp=fp
) # [W/(m^2*K)] Convective heat transfer coefficient at bulk liquid/multi-phase state
# Required specific enthalpy change for heating the separate sections
h_outlet = fp.get_enthalpy(
T=T_chamber, p=p_ref) # [J/kg] Specific enthalpy at the outlet
h_sat_gas = fp.get_saturation_enthalpy_gas(
p=p_ref) # [J/kg] Specific enthalpy of saturated gas
h_inlet = fp.get_enthalpy(T=T_inlet, p=p_ref) # [J/kg]
# Required specific enthalpy increases
delta_h_gas = h_outlet - h_sat_gas # [J/kg] Enthalpy increase needed to go from saturated gas to outlet enthalpy
delta_h_liquid_multi = h_sat_gas - h_inlet # [J/k] Enthalpy increase needed to go from inlet enthalpy to saturated gas
# Required power for those enthalpy changes at the given mass flow
Q_dot_gas = required_power(m_dot=m_dot, delta_h=delta_h_gas) # [W]
Q_dot_liquid_multi = required_power(m_dot=m_dot,
delta_h=delta_h_liquid_multi) # [W]
# Required heater area to achieve the required power
A_heater_gas = required_heater_area(Q_dot=Q_dot_gas,
h_conv=h_conv_gas,
T_wall=T_wall,
T_ref=T_bulk_gas) # [m^2]
A_heater_liquid_multi = required_heater_area(
Q_dot=Q_dot_liquid_multi,
h_conv=h_conv_liquid_multi,
T_wall=T_wall,
T_ref=T_bulk_liquid_multi) # [m^2]
# Required length to achieve desired area
L_channel_gas = A_heater_gas / wetted_perimeter # [m] Length of channel after gas is saturated
L_channel_liquid_multi = A_heater_liquid_multi / wetted_perimeter # [m] Length of channel after heater
L_channel = L_channel_gas + L_channel_liquid_multi # [m]
L_hydrodynamic_entrance = D_hydraulic * Re_bulk_liquid_multi * 0.04 # [m] Hydrodynamic entrance to estimate if the flow is fully developed
assert (h_outlet > h_sat_gas)
assert (h_sat_gas > h_inlet)
if (print_info):
print("\n--- SPECIFIC ENTHALPY AT DIFFERENT STATIONS ---")
print("h_outlet: {:4.3f} J/kg".format(h_outlet))
print("h_sat_gas: {:4.3f} J/kg".format(h_sat_gas))
print("h_inlet: {:4.3f} J/kg".format(h_inlet))
print("\n --- REQUIRED POWER ---")
print("Q_dot_gas: {:2.5f} W".format(Q_dot_gas))
print("Q_dot_liquid_multi: {:2.5f} W".format(Q_dot_liquid_multi))
print("\n --- BULK GAS PHASE PARAMETERS --- ")
print("u: {:3.2f} m/s".format(u_bulk_gas))
print("Nu: {}".format(Nu_gas))
print("Re: {}".format(Re_bulk_gas))
print("Pr: {}".format(Pr_bulk_gas))
print("St: {}".format(St_gas))
print("Bo_sat: {}".format(Bo_sat))
print("\n --- BULK LIQUID/MULTI-PHASE PARAMETERS ---")
print("u: {:3.4f} m/s".format(u_bulk_liquid_multi))
print("Nu: {}".format(Nu_liquid_multi))
print("Re: {}".format(Re_bulk_liquid_multi))
print("Pr: {}".format(Pr_bulk_liquid_multi))
print("St: {}".format(St_liquid_multi))
print("\n --- CHARACTERISTIC GEOMETRIC VALUES --- ")
print("Hydrodynamic entance length: {:3.3f} micron".format(
L_hydrodynamic_entrance * 1e6))
print("Hydraulic diameter: {:3.3f} micron".format(D_hydraulic * 1e6))
print("L/D: {:4.2f} ".format(L_channel / D_hydraulic))
print("L/X_T {:4.2f}".format(L_channel / L_hydrodynamic_entrance))
print("\n --- RESULTING GEOMETRY ---")
print("Total length: {:3.3f} mm".format(L_channel * 1e3))
print("Length (liquid/multi): {:3.3f} mm".format(
L_channel_liquid_multi * 1e3))
print("Length (gas): {:3.4f} mm".format(L_channel_gas * 1e3))
print("Relative length (gas) {:3.3f} \%".format(L_channel_gas /
L_channel * 100))
## Return a dictionary with results and interesting intermediate values
res = {
"L_channel": L_channel, # [m] Total length of channel
"D_hydraulic": D_hydraulic, # [m] Hydraulic diameter of channel
"Nu_liquid_multi":
Nu_liquid_multi, # [-] Nusselt number of liquid/multi-phase flow
"Pr_bulk_liquid_multi":
Pr_bulk_liquid_multi, # [-] Prandlt number of liquid/multi-phase flow
"Re_bulk_liquid_multi":
Re_bulk_liquid_multi, # [-] Reynolds number of liquid/multi-phase flow
"St_liquid_multi":
St_liquid_multi, # [-] Stanton number of liquid/multi-phase flow
"h_conv_liquid_multi":
h_conv_liquid_multi, # [W/(m^2*K)] Heat transfer coefficient
"A_heater_liquid_multi":
A_heater_liquid_multi, # [m^2] Required heater area for liquid/multi-phase flow
"L_channel_liquid_multi":
L_channel_liquid_multi, # [m] Length of channel to get required heater area
"u_bulk_liquid_multi":
u_bulk_liquid_multi, # [m/s] Bulk flow velocity of liquid/multi-phase flow
"rho_bulk_liquid_multi":
rho_bulk_liquid_multi, # [kg/m^3] Bulk density of liquid/multi-phase flow
"T_bulk_liquid_multi":
T_bulk_liquid_multi, # [K] Bulk temperature of liquid/multi-phase flow
"delta_h_liquid_multi":
delta_h_liquid_multi, # [J/kg] Enthalpy change from inlet to saturated gas
"Q_dot_liquid_multi":
Q_dot_liquid_multi, # [W] Power required for enthalpy change
## Same thing but for gas values
"Nu_gas": Nu_gas, # [-]
"Pr_bulk_gas": Pr_bulk_gas, # [-]
"Re_bulk_gas": Re_bulk_gas, # [-]
"St_gas": St_gas, # [-]
"h_conv_gas": h_conv_gas, # [W/(m^2*K)]
"A_heater_gas": A_heater_gas, # [m^2]
"L_channel_gas": L_channel_gas, # [m]
"u_bulk_gas": u_bulk_gas, # [m/s]
"rho_bulk_gas": rho_bulk_gas, # [kg/m^3]
"T_bulk_gas": T_bulk_gas, # [K]
"delta_h_gas": delta_h_gas, # [J/kg]
"Q_dot_gas": Q_dot_gas, # [W]
}
return res
def chamber_performance_from_Nu(Nu_func, T_inlet, T_chamber, T_ref, T_wall,
p_ref, m_dot, A_channel, L_ref,
fp: FluidProperties):
""" Function that calculates the power consumption and heating area for a specific chamber
Args:
Nu_func (-): Nusselt function, that implement the emperical relation of choice
T_inlet (K): Chamber inlet temperature
T_chamber (K): Chamber outlet temperature (same as T_chamber for IRT)
T_ref (K): Reference temperature for the Nusselt relation and flow similary parameters
T_wall (K): Wall temperature
p_ref (Pa): Chamber pressure (no pressure drop assumed)
m_dot (kg/s): Mass flow
A_channel (m^2): Cross-sectional area of the chamber, through which the fluid flows
L_ref (m): Reference length for Nusselt relation and flow similarty parameters
fp (FluidProperties): Object from which Fluid Properties are determined
Returns:
dictionary with heater area, power required to heat up flow and Nusselt number
"""
## Make sure all parameters are calculated at the same reference state (including velocity!)
# Pr and Re parameters needed for most Nusselt relation
rho_ref = fp.get_density(T=T_ref, p=p_ref) # [kg/m^3] Reference density
u_ref = velocity_from_mass_flow(
A=A_channel, m_dot=m_dot,
rho=rho_ref) # [m/s] Speed at reference state
print("u_ref {} m/s".format(u_ref))
Re_ref = fp.get_Reynolds_from_mass_flow(
T=T_ref, p=p_ref, L_ref=L_ref, m_dot=m_dot,
A=A_channel) # [-] Reynolds number at reference state
Pr_ref = fp.get_Prandtl(T=T_ref,
p=p_ref) # [-] Prandtl number at reference state
# Now the Nusselt can be determined
Nusselt = Nu_func(args={
'Re': Re_ref,
'Pr': Pr_ref
}) # [-] Nusselt number at given state (used for plotting purposes)
Stanton = Stanton_from_Nusselt_func_and_velocity(
Nu_func=Nu_func,
m_dot=m_dot,
A=A_channel,
T_ref=T_ref,
p_ref=p_ref,
L_ref=L_ref,
fp=fp) # [-] Stanton number at reference state
h_conv = h_conv_from_Stanton(Stanton=Stanton,
u=u_ref,
T_ref=T_ref,
p_ref=p_ref,
fp=fp)
# Now determine how much energy must be convected
delta_h = ideal_enthalpy_change(T_inlet=T_inlet,
p_inlet=p_ref,
T_outlet=T_chamber,
p_outlet=p_ref,
fp=fp) # [J/kg]
Q_dot = required_power(
m_dot=m_dot, delta_h=delta_h) # [W] Required power to achieve delta_h
A_heater = required_heater_area(Q_dot=Q_dot,
h_conv=h_conv,
T_wall=T_wall,
T_ref=T_ref) # [m^2]
assert (A_heater > 0)
# Return a dictionary with interesting values
return {
'A_heater': A_heater,
'Q_dot': Q_dot,
'Nusselt': Nusselt,
'Re_ref': Re_ref,
'Pr_ref': Pr_ref
}
p_outlet = p_inlet # [Pa] Outlet pressure (assumed roughly equal to inlet)
T_inlet = td['T_inlet'] # [K]
# Geometry calculations
D_h = hydraulic_diameter_rectangular(
w_channel=w_channel, h_channel=h_channel) # [m] Hydraulic diameter
A_channel = w_channel * h_channel
# Inlet conditions
rho_inlet = fp.get_density(T=T_inlet, p=p_inlet) # [kg/m^3]
u_inlet = velocity_from_mass_flow(A=A_channel, m_dot=m_dot, rho=rho_inlet)
# Outlet conditions
rho_outlet = fp.get_density(T=T_outlet, p=p_outlet)
u_outlet = velocity_from_mass_flow(A=A_channel, m_dot=m_dot, rho=rho_outlet)
Re_outlet = fp.get_Reynolds_from_mass_flow(T=T_outlet,
p=p_outlet,
L_ref=D_h,
m_dot=m_dot,
A=A_channel)
print("\n\nTHRUSTER NAME: {}".format(td['name']))
print("\n --- GEOMETRY ---")
print("Channel length: {:4.3f} mm".format(L_channel * 1e3))
print("Hydraulic diameter: {:4.3f} um".format(D_h * 1e6))
print("L/D: {:3.2f} ".format(L_channel / D_h))
print("\n --- INLET FLOW CONDITIONS --- ")
print("Density: {:3.2f} kg/m^3".format(rho_inlet))
print("\n --- OUTLET FLOW CONDITIONS ---")
print("Mass flow: {:1.3f} mg/s".format(m_dot * 1e6))
print("Density: {:1.3f} kg/m^3".format(rho_outlet))
T_liquid = 300 # [K]
T_gas = 500 # [K]
m_dot = 1e-6 # [kg/s] For Kandlikar relation.
#h_c = 100e-6 # [m] Channel depth/height
# Density is needed to reverse calculate the reference length for Re, so it can be applied in other flow similarity parameters
rho_liquid = fp.get_density(T=T_liquid, p=p)
mu_liquid = fp.get_viscosity(T=T_liquid, p=p)
# Range of Reynolds numbers to consider
Reynolds = np.logspace(start=0, stop=2.8)
D_hydraulic = np.logspace(start=-4.93, stop=-2.93)
A_channel = D_hydraulic**2
Reynolds_2 = fp.get_Reynolds_from_mass_flow(T=T_liquid,
p=p,
L_ref=D_hydraulic,
m_dot=m_dot,
A=A_channel)
# Range of hydraulic diameter that fit this Reynolds number
#w_channel = 2*m_dot/( Reynolds_100 * mu_liquid ) - h_c # [m]
#A_channel = h_c * w_channel # [m^2]
#D_hydraulic = basic.chamber.hydraulic_diameter_rectangular(w_channel=w_channel,h_channel=h_c) # [m]
#Reynolds_check = fp.get_Reynolds_from_mass_flow(T=T_liquid, p=p, L_ref=D_hydraulic, m_dot=m_dot, A=A_channel) # [-]
Bond = fp.get_Bond_number(p_sat=p, L_ref=D_hydraulic) # [m]
# Prandtl number in both reference states
Pr_liquid = fp.get_Prandtl(T=T_liquid, p=p) # [-]
Pr_gas = fp.get_Prandtl(T=T_gas, p=p) # [-]
# Conductivity in reference state
conductivity_liquid = fp.get_thermal_conductivity(T=T_liquid, p=p)
it_T = np.nditer(T_wall,
flags=['c_index']) # [K] To iterate over all T_chamber values
for T in it_T:
## Make sure all parameters are calculated at the same reference state (including velocity)
# Calculate all the bulk conditions required to determine the Nusselt number relation
T_bulk = (T_inlet + T_chamber) / 2 # [K] Bulk temperature as reference
rho_bulk = fp.get_density(
T=T_bulk, p=p_inlet
) # [kg/m^3] Bulk density is required to get the correct velocity at the reference temperature
u_bulk[it_T.index, :] = velocity_from_mass_flow(
m_dot=m_dot, rho=rho_bulk,
A=A_channel) # [m/s] The velocity at the bulk reference state
Re_bulk[it_T.index, :] = fp.get_Reynolds_from_mass_flow(T=T_bulk,
p=p_inlet,
L_ref=Dh_channel,
m_dot=m_dot,
A=A_channel) # [-]
Pr_bulk[it_T.index, :] = fp.get_Prandtl(T=T_bulk, p=p_inlet) # [-]
# Now the convection parameters can be determined, taking care that the reference temperature and flow conditions are evaluated in the same location
Nusselt[it_T.index, :] = Nu_func(args={
'Re': Re_bulk[it_T.index, :],
'Pr': Pr_bulk[it_T.index, :]
}) # [-] Not necessary, but useful for plots
Stanton[it_T.index, :] = Stanton_from_Nusselt_func_and_velocity(
Nu_func=Nu_func,
m_dot=m_dot,
A=A_channel,
T_ref=T_bulk,
p_ref=p_inlet,
L_ref=Dh_channel,
def optim_P_total(channel_amount, w_channel, h_channel, inlet_manifold_length_factor, inlet_manifold_width_factor, l_exit_manifold, w_channel_spacing, w_outer_margin, T_wall, p_ref, m_dot, \
prepared_values, Nusselt_relations, pressure_drop_relations, convergent_half_angle, divergent_half_angle, F_desired, p_back, AR_exit, w_throat, emissivity_top, fp: FluidProperties, wall_args=None):
# First calculate area ratio at entrance so it can be provided to contraction pressure drop function
w_inlet_manifold = chamber.inlet_manifold_width(\
channel_amount=channel_amount,
w_channel=w_channel,
w_channel_spacing=w_channel_spacing,
inlet_manifold_width_factor=inlet_manifold_width_factor) # [m] Total width of inlet manifold
area_ratio_contraction = chamber.area_ratio_contraction(\
w_inlet_manifold=w_inlet_manifold,
w_channel=w_channel,
channel_amount=channel_amount) # [-] Area ratio of sudden contraction
def x(T):
wall_args[
'T_wall_bottom'] = T # [K] Add the bottom wall temperature in the wall argument dictionary
# Calculate heat transfer to determine channel length
res = oneD.rectangular_multi_channel_homogenous_calculation(\
channel_amount=channel_amount,
prepared_values=prepared_values,
Nusselt_relations=Nusselt_relations,
pressure_drop_relations=pressure_drop_relations,
w_channel=w_channel,
h_channel=h_channel,
m_dot=m_dot,
T_wall=T_wall,
p_inlet=p_ref,
fp=fp,
area_ratio_contraction=area_ratio_contraction,
wall_args=wall_args)
#print(res['Q_total_bottom_plane_heat_balance'])
return res['Q_total_bottom_plane_heat_balance']
## ROOT FINDING PROBLEM FOR T_WALL_BOTTOM
# The proper bounds for the optimization are very sensitive to wall temperature and chamber temperature
# It is hard to pick bounds that are valid for a wide range of those parameters
# The problem is that that a too low lower bound results in model results that are wholly invalid and break the optimization
# Too high a lower bound results in the solution not being within the bounds at all.
# The quick and dirty solution here is to stepwise move the bounds down until the valid solution is between it.
# The stepsize must be small enough to reliably avoid the scenario where the calculations are completely incorrect.
delta_T_bounds = 25 # [K] The size of the bound shift could determine how low the bounds can go to the final chamber temperature without resulting into incorrection calculations
## The resultant channel length, pressure drops, etc, depends on bottom wall temperature. It must be iterated towards here.
T_wall_bottom_min = T_wall - delta_T_bounds # [K] Minimum temperature is in practice probably not lower than chamber temperature (not impossible, though)
T_wall_bottom_max = T_wall
bounds_are_correct = False # [bool] Is False until a solution has been found
# The bounds are correct once they get the opposite sign
while not bounds_are_correct:
a = x(T_wall_bottom_max)
b = x(T_wall_bottom_min)
# If the solutions have the same sign, subtract delta_T_bounds
if np.sign(a) == np.sign(b):
T_wall_bottom_min -= delta_T_bounds
T_wall_bottom_max -= delta_T_bounds
else:
bounds_are_correct = True
root_result = root_scalar(x,
bracket=([T_wall_bottom_min, T_wall_bottom_max]))
if root_result.converged:
T_wall_bottom = root_result.root # [m^2]
wall_args['T_wall_bottom'] = T_wall_bottom
#print(" T_wall_bottom: {:3.2f} K".format(T_wall_bottom))
else:
raise Exception("No solution found for given temperature")
res = oneD.rectangular_multi_channel_homogenous_calculation(\
channel_amount=channel_amount,
prepared_values=prepared_values,
Nusselt_relations=Nusselt_relations,
pressure_drop_relations=pressure_drop_relations,
w_channel=w_channel,
h_channel=h_channel,
m_dot=m_dot,
T_wall=T_wall,
p_inlet=p_ref,
fp=fp,
area_ratio_contraction=area_ratio_contraction,
wall_args=wall_args)
# Check if these solutions are eventually valid
assert (np.all(res['res_l']['delta_L'] >= 0))
assert (np.all(res['res_tp']['delta_L'] >= 0))
assert (np.all(res['res_g']['delta_L'] >= 0))
l_channel = res['L_total'] # [m] Channel length
p_chamber = res[
'p_chamber'] # [Pa] Pressure out channel outlet/inlet of nozzle according to IRT
T_chamber = res['T_chamber']
# Nozzle performance must be recalculated, if pressure drop occured
assert (pressure_drop_relations
is not None) # Just check is one was calculated
if p_chamber <= 0: # If pressure drop was so large p_chamber was negative, the solution is invalid, and NaNs must be returned
# Return the same dictionary, but all NaN.
return {
'P_loss': np.nan, # [W] Current approximation of heat loss
'l_channel': np.nan, # [m] Channel length
'pressure_drop': np.nan, # [Pa] Total pressure drop
'dP_contraction': np.nan, # [Pa] Pressure drop de to contraction
'w_total': np.nan, # [m] Total chip width
'l_total': np.nan, # [m] Total chip length
'is_channel_choked': np.nan,
'Re_channel_exit': np.nan, # [-] Reynolds number at channel exit
}
# This only runs if pressure drop was not too large.
# In that case the throat area must be recalculated still
else:
ep = engine_performance_from_F_and_T(F_desired=F_desired,
p_chamber=p_chamber,
T_chamber=T_chamber,
AR_exit=AR_exit,
p_back=p_back,
fp=fp)
# New throat widtl_inlet_manifoldmined from desired performance parameter
w_throat_new = ep['A_throat'] / h_channel # [m]
# Check if new pressure, does not cause choked heating channels
is_channel_choked = (
w_channel * h_channel * channel_amount < ep['A_throat']
) # [bool] If combined channel area is smaller than throat, they are choked.
# Check new Reynolds number at channel exit for laminar/turbulent flow assumptions
hydraulic_diameter = chamber.hydraulic_diameter_rectangular(
w_channel=w_channel, h_channel=h_channel)
Re_channel_exit = fp.get_Reynolds_from_mass_flow(
T=T_chamber,
p=p_chamber,
L_ref=hydraulic_diameter,
m_dot=m_dot,
A=h_channel * w_channel)
l_outlet = chamber.outlet_length(\
w_channel=w_channel,
w_channel_spacing=w_channel_spacing,
channel_amount=channel_amount,
convergent_half_angle=convergent_half_angle,
w_throat=w_throat_new,
divergent_half_angle=divergent_half_angle,
AR_exit=AR_exit,
l_exit_manifold=l_exit_manifold
)
l_inlet_manifold = chamber.inlet_manifold_length(
w_inlet_manifold=w_inlet_manifold,
inlet_manifold_length_factor=inlet_manifold_length_factor)
l_total = chamber.total_chip_length(l_inlet_manifold=l_inlet_manifold,
l_channel=l_channel,
l_outlet=l_outlet)
w_total = chamber.total_chip_width(\
w_inlet_manifold=w_inlet_manifold,
w_outer_margin=w_outer_margin,
w_throat=w_throat_new,
AR_exit=AR_exit)
A_chip = l_total * w_total # [m^2]
P_rad_loss_top = chamber.radiation_loss(
T=T_wall, A=A_chip, emmisivity=emissivity_top
) # [W] Radiation loss through top of chip
P_rad_loss_bottom = chamber.radiation_loss(
T=wall_args['T_wall_bottom'],
A=A_chip,
emmisivity=wall_args['emissivity_chip_bottom']
) # Radiation loss through bottom of chip
P_loss = P_rad_loss_top + P_rad_loss_bottom # [W] Total heat loss
return {
'P_loss': P_loss, # [W] Current approximation of heat loss
'l_channel': l_channel, # [m] Channel length
'pressure_drop': res['dP_total'], # [Pa] Total pressure drop
'dP_contraction':
res['dP_contraction'], # [Pa] Pressure drop due to contraction
'w_total': w_total, # [m] Total chip width
'l_total': l_total, # [m] Total chip length
'is_channel_choked':
is_channel_choked, # [bool] 0 and 1 in this case, to check if channels are not too small
'Re_channel_exit':
Re_channel_exit, # [-] Check Reynolds number to see if laminar flow assumptions still hold
}