from pressure_conversion import pressure_conversion import numpy as np class Druckrohrleitung_class: # units acceleration_unit = r'$\mathrm{m}/\mathrm{s}^2$' angle_unit = '°' area_unit = r'$\mathrm{m}^2$' density_unit = r'$\mathrm{kg}/\mathrm{m}^3$' flux_unit = r'$\mathrm{m}^3/\mathrm{s}$' length_unit = 'm' pressure_unit = 'Pa' time_unit = 's' velocity_unit = r'$\mathrm{m}/\mathrm{s}$' # for flux and pressure propagation volume_unit = r'$\mathrm{m}^3$' # init def __init__(self,total_length,diameter,number_segments,pipeline_angle,Darcy_friction_factor,rho=1000,g=9.81): self.length = total_length self.dia = diameter self.n_seg = number_segments self.angle = pipeline_angle self.f_D = Darcy_friction_factor # = Rohrreibungszahl oder flow coefficient self.density = 1000 self.g = g self.dx = total_length/number_segments self.l_vec = np.arange(0,(number_segments+1)*self.dx,self.dx) # workaround for try-except construct in set_number_of_timesteps self.c = 0 # setter def set_pressure_propagation_velocity(self,c): self.c = c self.dt = self.dx/c def set_number_of_timesteps(self,number_timesteps): self.nt = number_timesteps if self.c == 0: raise Exception('Please set the pressure propagation velocity before setting the number of timesteps.') else: self.t_vec = np.arange(0,self.nt*self.dt,self.dt) def set_initial_pressure(self,pressure,input_unit = 'Pa'): p,_ = pressure_conversion(pressure,input_unit,target_unit=self.pressure_unit) if np.size(p) == 1: self.p0 = np.full_like(self.l_vec,p) elif np.size(p) == np.size(self.l_vec): self.p0 = p else: raise Exception('Unable to assign initial pressure. Input has to be of size 1 or' + np.size(self.l_vec)) #initialize the vectors in which the old and new pressures are stored for the method of characteristics self.p_old = self.p0.copy() self.p_new = np.empty_like(self.p_old) def set_initial_flow_velocity(self,velocity): if np.size(velocity) == 1: self.v0 = np.full_like(self.l_vec,velocity) elif np.size(velocity) == np.size(self.l_vec): self.v0 = velocity else: raise Exception('Unable to assign initial velocity. Input has to be of size 1 or' + np.size(self.l_vec)) #initialize the vectors in which the old and new velocities are stored for the method of characteristics self.v_old = self.v0.copy() self.v_new = np.empty_like(self.v_old) def set_boundary_conditions_next_timestep(self,v_reservoir,p_reservoir,v_turbine,input_unit_pressure = 'Pa'): rho = self.density c = self.c f_D = self.f_D dt = self.dt D = self.dia p_old = self.p_old[-2] # @ second to last node (the one before the turbine) v_old = self.v_old[-2] # @ second to last node (the one before the turbine) self.v_boundary_res = v_reservoir self.v_boundary_tur = v_turbine self.p_boundary_res,_ = pressure_conversion(p_reservoir,input_unit_pressure,target_unit=self.pressure_unit) self.p_boundary_tur = p_old+rho*c*v_old-rho*c*f_D*dt/(2*D)*abs(v_old)*v_old self.v_new[0] = self.v_boundary_res.copy() self.v_new[-1] = self.v_boundary_tur.copy() self.p_new[0] = self.p_boundary_res.copy() self.p_new[-1] = self.p_boundary_tur.copy() # getter def get_pipeline_geometry(self): print('The total length of the pipeline is', '\n', \ self.length, self.length_unit, '\n', \ 'The diameter of the pipeline is', '\n', \ self.dia, self.length_unit, '\n', \ 'The pipeline is divided into', self.n_seg , 'segments of length', '\n', \ round(self.dx,1), self.length_unit, '\n', \ 'The pipeline has an inclination angle of', '\n', \ self.angle, self.angle_unit) def get_other_pipeline_info(self): print('The Darcy-friction factor of the pipeline is', '\n', \ self.f_D, '\n', \ 'The pipeline is filled with a liquid with density', '\n', \ self.density, self.density_unit, '\n', \ 'The gravitational acceleration is set to', '\n', \ self.g, self.acceleration_unit) def get_pressure_propagation_velocity(self): print('The pressure propagation velocity in the pipeline is', '\n', \ self.c, self.velocity_unit) def get_number_of_timesteps(self): print(self.nt, 'timesteps are performed in the simulation') def get_initial_pressure(self,target_unit='bar'): print('The inital pressure distribution in is', '\n', \ pressure_conversion(self.p0,self.pressure_unit,target_unit)) def get_initial_flow_velocity(self): print('The inital velocity distribution is', '\n', \ self.v0, self.velocity_unit) def get_boundary_conditions_next_timestep(self,target_unit_pressure ='bar'): print('The pressure at the reservoir for the next timestep is', '\n', \ pressure_conversion(self.p_boundary_res,self.pressure_unit,target_unit_pressure), '\n', \ 'The velocity at the reservoir for the next timestep is', '\n', \ self.v_boundary_res, self.velocity_unit, '\n', \ 'The pressure at the turbine for the next timestep is', '\n', \ pressure_conversion(self.p_boundary_tur,self.pressure_unit,target_unit_pressure), '\n', \ 'The velocity at the turbine for the next timestep is', '\n', \ self.v_boundary_tur, self.velocity_unit) def timestep_characteristic_method(self): #number of nodes nn = self.n_seg+1 rho = self.density c = self.c f_D = self.f_D dt = self.dt D = self.dia for i in range(1,nn-1): self.v_new[i] = 0.5*(self.v_old[i-1]+self.v_old[i+1])+0.5/(rho*c)*(self.p_old[i-1]-self.p_old[i+1]) \ -f_D*dt/(4*D)*(abs(self.v_old[i-1])*self.v_old[i-1]+abs(self.v_old[i+1])*self.v_old[i+1]) self.p_new[i] = 0.5*rho*c*(self.v_old[i-1]-self.v_old[i+1])+0.5*(self.p_old[i-1]+self.p_old[i+1]) \ -rho*c*f_D*dt/(4*D)*(abs(self.v_old[i-1])*self.v_old[i-1]-abs(self.v_old[i+1])*self.v_old[i+1]) self.p_old = self.p_new.copy() self.v_old = self.v_new.copy()