7506da8b2e
incline - not sure if code reproduces physical behavior because initial pressure seems to disipate way too quickly
172 lines
7.3 KiB
Python
172 lines
7.3 KiB
Python
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 Druckrohrleitung_class:
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# units
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acceleration_unit = r'$\mathrm{m}/\mathrm{s}^2$'
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angle_unit = '°'
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area_unit = r'$\mathrm{m}^2$'
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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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length_unit = 'm'
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pressure_unit = 'Pa'
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time_unit = 's'
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velocity_unit = r'$\mathrm{m}/\mathrm{s}$' # for flux and pressure propagation
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volume_unit = r'$\mathrm{m}^3$'
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acceleration_unit_print = 'm/s²'
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angle_unit_print = '°'
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area_unit_print = 'm²'
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density_unit_print = 'kg/m³'
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flux_unit_print = 'm³/s'
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length_unit_print = 'm'
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pressure_unit_print = 'Pa'
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time_unit_print = 's'
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velocity_unit_print = 'm/s' # for flux and pressure propagation
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volume_unit_print = 'm³'
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# init
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def __init__(self,total_length,diameter,number_segments,pipeline_angle,Darcy_friction_factor,rho=1000,g=9.81):
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self.length = total_length
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self.dia = diameter
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self.n_seg = number_segments
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self.angle = pipeline_angle
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self.f_D = Darcy_friction_factor # = Rohrreibungszahl oder flow coefficient
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self.density = 1000
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self.g = g
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self.dx = total_length/number_segments
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self.l_vec = np.arange(0,(number_segments+1)*self.dx,self.dx)
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# initialize for get_info method
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self.c = '--'
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self.dt = '--'
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# setter
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def set_pressure_propagation_velocity(self,c):
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self.c = c
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self.dt = self.dx/c
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def set_number_of_timesteps(self,number_timesteps):
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self.nt = number_timesteps
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if self.c == '--':
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raise Exception('Please set the pressure propagation velocity before setting the number of timesteps.')
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else:
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self.t_vec = np.arange(0,self.nt*self.dt,self.dt)
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def set_initial_pressure(self,pressure,input_unit = 'Pa'):
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p,_ = pressure_conversion(pressure,input_unit,target_unit=self.pressure_unit)
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if np.size(p) == 1:
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self.p0 = np.full_like(self.l_vec,p)
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elif np.size(p) == np.size(self.l_vec):
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self.p0 = p
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else:
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raise Exception('Unable to assign initial pressure. Input has to be of size 1 or' + np.size(self.l_vec))
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#initialize the vectors in which the old and new pressures are stored for the method of characteristics
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self.p_old = self.p0.copy()
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self.p = np.empty_like(self.p_old)
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def set_initial_flow_velocity(self,velocity):
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if np.size(velocity) == 1:
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self.v0 = np.full_like(self.l_vec,velocity)
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elif np.size(velocity) == np.size(self.l_vec):
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self.v0 = velocity
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else:
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raise Exception('Unable to assign initial velocity. Input has to be of size 1 or' + np.size(self.l_vec))
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#initialize the vectors in which the old and new velocities are stored for the method of characteristics
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self.v_old = self.v0.copy()
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self.v = np.empty_like(self.v_old)
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def set_boundary_conditions_next_timestep(self,v_reservoir,p_reservoir,v_turbine,input_unit_pressure = 'Pa'):
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rho = self.density
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c = self.c
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f_D = self.f_D
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dt = self.dt
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D = self.dia
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p_old = self.p_old[-2] # @ second to last node (the one before the turbine)
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v_old = self.v_old[-2] # @ second to last node (the one before the turbine)
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self.v_boundary_res = v_reservoir
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self.v_boundary_tur = v_turbine
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self.p_boundary_res,_ = pressure_conversion(p_reservoir,input_unit_pressure,target_unit=self.pressure_unit)
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self.p_boundary_tur = p_old+rho*c*v_old-rho*c*f_D*dt/(2*D)*abs(v_old)*v_old
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self.v[0] = self.v_boundary_res.copy()
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self.v[-1] = self.v_boundary_tur.copy()
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self.p[0] = self.p_boundary_res.copy()
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self.p[-1] = self.p_boundary_tur.copy()
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# getter
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def get_info(self):
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new_line = '\n'
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# :<10 pads the self.value to be 10 characters wide
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print_str = (f"The pipeline has the following attributes: {new_line}"
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f"----------------------------- {new_line}"
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f"Length = {self.length:<10} {self.length_unit_print} {new_line}"
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f"Diameter = {self.dia:<10} {self.length_unit_print} {new_line}"
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f"Number of segemnts = {self.n_seg:<10} {new_line}"
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f"Number of nodes = {self.n_seg+1:<10} {new_line}"
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f"Length per segment = {self.dx:<10} {self.length_unit_print} {new_line}"
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f"Pipeline angle = {self.angle:<10} {self.angle_unit_print} {new_line}"
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f"Darcy friction factor = {self.f_D:<10} {new_line}"
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f"Density of liquid = {self.density:<10} {self.density_unit_print} {new_line}"
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f"Pressure wave vel. = {self.c:<10} {self.velocity_unit_print} {new_line}"
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f"Simulation timesteps = {self.dt:<10} {self.time_unit_print } {new_line}"
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f"Number of timesteps = {self.nt:<10} {new_line}"
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f"----------------------------- {new_line}"
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f"Velocity and pressure distribution are vectors and are accessible by the .v and .p attribute of the pipeline object")
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print(print_str)
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def get_boundary_conditions_next_timestep(self,target_unit_pressure ='bar'):
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print('The pressure at the reservoir for the next timestep is', '\n', \
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pressure_conversion(self.p_boundary_res,self.pressure_unit_print,target_unit_pressure), '\n', \
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'The velocity at the reservoir for the next timestep is', '\n', \
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self.v_boundary_res, self.velocity_unit, '\n', \
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'The pressure at the turbine for the next timestep is', '\n', \
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pressure_conversion(self.p_boundary_tur,self.pressure_unit_print,target_unit_pressure), '\n', \
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'The velocity at the turbine for the next timestep is', '\n', \
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self.v_boundary_tur, self.velocity_unit)
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def timestep_characteristic_method(self):
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#number of nodes
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nn = self.n_seg+1
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rho = self.density
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c = self.c
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f_D = self.f_D
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dt = self.dt
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D = self.dia
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for i in range(1,nn-1):
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self.v[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]) \
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-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])
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self.p[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]) \
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-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])
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self.p_old = self.p.copy()
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self.v_old = self.v.copy()
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