# -*- coding: utf-8 -*-
"""
Created on Tue Mar 24 10:56:58 2026

@author: Grabow
"""
import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import fsolve

# -----------------------------
# Lüfterparameter
# -----------------------------
dp0 = 500.0        # Pa (Sperrdruck)
Vmax = 1.0         # m^3/s (freier Volumenstrom)

# -----------------------------
# System
# -----------------------------
R_sys = 3000.0     # Pa / (m^3/s)^2

def fan_pressure(V):
    return dp0 * (1 - (V / Vmax)**2)

def system_pressure(V):
    return R_sys * V**2

# -----------------------------
# Kombinationen
# -----------------------------
def single_eq(V):
    return fan_pressure(V) - system_pressure(V)

def series_eq(V):
    return 2 * fan_pressure(V) - system_pressure(V)

def parallel_eq(V):
    return fan_pressure(V / 2) - system_pressure(V)

# -----------------------------
# Arbeitspunkte berechnen
# -----------------------------
V_single = fsolve(single_eq, 0.3)[0]
V_series = fsolve(series_eq, 0.4)[0]
V_parallel = fsolve(parallel_eq, 0.6)[0]

dp_single = system_pressure(V_single)
dp_series = system_pressure(V_series)
dp_parallel = system_pressure(V_parallel)

print("Einzellüfter:      V = %.3f m³/s, Δp = %.1f Pa" % (V_single, dp_single))
print("Reihenschaltung:   V = %.3f m³/s, Δp = %.1f Pa" % (V_series, dp_series))
print("Parallelschaltung: V = %.3f m³/s, Δp = %.1f Pa" % (V_parallel, dp_parallel))

# -----------------------------
# Plot
# -----------------------------
V = np.linspace(0, Vmax, 500)

plt.figure()
plt.plot(V, fan_pressure(V), label="Einzellüfter (real)")
plt.plot(V, 2 * fan_pressure(V), label="2 Lüfter in Reihe")
plt.plot(V, fan_pressure(V / 2), label="2 Lüfter parallel")
plt.plot(V, system_pressure(V), '--', label="System")

plt.xlabel("Volumenstrom [m³/s]")
plt.ylabel("Druck [Pa]")
plt.legend()
plt.grid()
plt.show()