fix for numerical runaway of rounding errors
due to turbine-pipeline interatction via a convergence method in the turbine and a "damping" trick on the reservoir velocity plus: code cleanup with consistent naming of variables
This commit is contained in:
Brantegger Georg
168
Turbinen/old/convergence_turbine.py
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168
Turbinen/old/convergence_turbine.py
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import numpy as np
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#importing pressure conversion function
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import sys
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import os
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current = os.path.dirname(os.path.realpath(__file__))
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parent = os.path.dirname(current)
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sys.path.append(parent)
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from functions.pressure_conversion import pressure_conversion
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class Francis_Turbine_test:
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# units
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# make sure that units and print units are the same
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# units are used to label graphs and print units are used to have a bearable format when using pythons print()
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density_unit = r'$\mathrm{kg}/\mathrm{m}^3$'
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flux_unit = r'$\mathrm{m}^3/\mathrm{s}$'
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LA_unit = '%'
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pressure_unit = 'Pa'
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time_unit = 's'
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velocity_unit = r'$\mathrm{m}/\mathrm{s}$'
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volume_unit = r'$\mathrm{m}^3$'
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density_unit_print = 'kg/m³'
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flux_unit_print = 'm³/s'
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LA_unit_print = '%'
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pressure_unit_print = 'mWS'
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time_unit_print = 's'
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velocity_unit_print = 'm/s'
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volume_unit_print = 'm³'
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g = 9.81 # m/s² gravitational acceleration
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# init
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def __init__(self, Q_nenn,p_nenn,t_closing=-1.,timestep=-1.):
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self.Q_n = Q_nenn # nominal flux
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self.p_n = p_nenn # nominal pressure
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self.LA_n = 1. # 100% # nominal Leitapparatöffnung
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h = pressure_conversion(p_nenn,'Pa','MWs') # nominal pressure in terms of hydraulic head
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self.A = Q_nenn/(np.sqrt(2*self.g*h)*0.98) # Ersatzfläche
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self.dt = timestep # simulation timestep
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self.t_c = t_closing # closing time
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self.d_LA_max_dt = 1/t_closing # maximal change of LA per second
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# initialize for get_info() - parameters will be converted to display -1 if not overwritten
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self.p = pressure_conversion(-1,self.pressure_unit_print,self.pressure_unit)
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self.Q = -1.
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self.LA = -0.01
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# setter
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def set_LA(self,LA,display_warning=True):
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# set Leitapparatöffnung
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self.LA = LA
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# warn user, that the .set_LA() method should not be used ot set LA manually
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if display_warning == True:
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print('Consider using the .update_LA() method instead of setting LA manually')
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def set_timestep(self,timestep,display_warning=True):
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# set Leitapparatöffnung
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self.dt = timestep
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# warn user, that the .set_LA() method should not be used ot set LA manually
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if display_warning == True:
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print('WARNING: You are changing the timestep of the turbine simulation. This has implications on the simulated closing speed!')
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def set_pressure(self,pressure):
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# set pressure in front of the turbine
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self.p = pressure
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#getter
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def get_current_Q(self):
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# return the flux through the turbine, based on the current pressure in front
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# of the turbine and the Leitapparatöffnung
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if self.p < 0:
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self.Q = 0
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else:
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self.Q = self.Q_n*(self.LA/self.LA_n)*np.sqrt(self.p/self.p_n)
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return self.Q
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def get_current_pressure(self):
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return self.p
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def get_current_LA(self):
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return self.LA
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def get_info(self, full = False):
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new_line = '\n'
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p = pressure_conversion(self.p,self.pressure_unit,self.pressure_unit_print)
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p_n = pressure_conversion(self.p_n,self.pressure_unit,self.pressure_unit_print)
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if full == True:
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# :<10 pads the self.value to be 10 characters wide
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print_str = (f"Turbine has the following attributes: {new_line}"
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f"----------------------------- {new_line}"
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f"Type = Francis {new_line}"
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f"Nominal flux = {self.Q_n:<10} {self.flux_unit_print} {new_line}"
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f"Nominal pressure = {round(p_n,3):<10} {self.pressure_unit_print}{new_line}"
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f"Nominal LA = {self.LA_n*100:<10} {self.LA_unit_print} {new_line}"
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f"Closing time = {self.t_c:<10} {self.time_unit_print} {new_line}"
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f"Current flux = {self.Q:<10} {self.flux_unit_print} {new_line}"
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f"Current pipe pressure = {round(p,3):<10} {self.pressure_unit_print} {new_line}"
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f"Current LA = {self.LA*100:<10} {self.LA_unit_print} {new_line}"
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f"Simulation timestep = {self.dt:<10} {self.time_unit_print} {new_line}"
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f"----------------------------- {new_line}")
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else:
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# :<10 pads the self.value to be 10 characters wide
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print_str = (f"The current attributes are: {new_line}"
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f"----------------------------- {new_line}"
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f"Current flux = {self.Q:<10} {self.flux_unit_print} {new_line}"
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f"Current pipe pressure = {round(p,3):<10} {self.pressure_unit_print} {new_line}"
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f"Current LA = {self.LA*100:<10} {self.LA_unit_print} {new_line}"
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f"----------------------------- {new_line}")
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print(print_str)
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# methods
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def update_LA(self,LA_soll):
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# update the Leitappartöffnung and consider the restrictions of the closing time of the turbine
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LA_diff = self.LA-LA_soll # calculate the difference to the target LA
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LA_diff_max = self.d_LA_max_dt*self.dt # calculate the maximum change in LA based on the given timestep
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LA_diff = np.sign(LA_diff)*np.min(np.abs([LA_diff,LA_diff_max])) # calulate the correct change in LA
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LA_new = self.LA-LA_diff
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if LA_new < 0.:
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LA_new = 0.
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elif LA_new > 1.:
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LA_new = 1.
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self.set_LA(LA_new,display_warning=False)
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def set_steady_state(self,ss_flux,ss_pressure):
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# calculate and set steady state LA, that allows the flow of ss_flux at ss_pressure through the
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# turbine at the steady state LA
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ss_LA = self.LA_n*ss_flux/self.Q_n*np.sqrt(self.p_n/ss_pressure)
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if ss_LA < 0 or ss_LA > 1:
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raise Exception('LA out of range [0;1]')
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self.set_LA(ss_LA,display_warning=False)
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def converge(self,area_pipe,pressure_s2l_node,velocity_s2l_node,alpha,f_D,dt):
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eps = 1e-9
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error = 1.
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i = 0
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p = pressure_s2l_node
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v = velocity_s2l_node
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rho = 1000
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g = self.g
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c = 400
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D = area_pipe
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p_old = self.get_current_pressure()
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Q_old = self.get_current_Q()
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v_old = Q_old/area_pipe
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while error > eps:
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self.set_pressure(p_old)
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Q_new = self.get_current_Q()
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v_new = Q_new/area_pipe
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p_new = p-rho*c*(v_old-v)+rho*c*dt*g*np.sin(alpha)-f_D*rho*c*dt/(2*D)*abs(v)*v
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error = abs(Q_old-Q_new)
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Q_old = Q_new.copy()
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p_old = p_new.copy()
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v_old = v_new.copy()
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i = i+1
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if i == 1e6:
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print('did not converge')
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break
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self.Q = Q_new
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