# -*- coding: utf-8 -*-
"""
Created on Tue Mar 24 10:54:09 2026

@author: Grabow
"""
import numpy as np
import matplotlib.pyplot as plt

# -----------------------------
# Lüfterparameter (identisch)
# -----------------------------
dp0 = 500.0        # Pa (Sperrdruck bei V=0)
R_fan = 2000.0     # Pa / (m^3/s)

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

def fan_pressure(V):
    return dp0 - R_fan * V

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

# -----------------------------
# Kombinationen
# -----------------------------

# 1. Einzellüfter
def single_fan(V):
    return fan_pressure(V)

# 2. Reihenschaltung (Drücke addieren sich)
def series_fans(V):
    return 2 * fan_pressure(V)

# 3. Parallelschaltung (Volumenströme addieren sich)
# -> Druck gleich, aber jeder Lüfter liefert V/2
def parallel_fans(V):
    return fan_pressure(V / 2)

# -----------------------------
# Arbeitspunkt finden
# -----------------------------
def find_operating_point(fan_func):
    V = np.linspace(0, 1.0, 1000)
    dp_fan = fan_func(V)
    dp_sys = system_pressure(V)
    
    idx = np.argmin(np.abs(dp_fan - dp_sys))
    return V[idx], dp_fan[idx]

# -----------------------------
# Berechnung
# -----------------------------
V_single, dp_single = find_operating_point(single_fan)
V_series, dp_series = find_operating_point(series_fans)
V_parallel, dp_parallel = find_operating_point(parallel_fans)

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, 1.0, 500)

plt.figure()
plt.plot(V, single_fan(V), label="Einzellüfter (ideal)")
plt.plot(V, series_fans(V), label="2 Lüfter in Reihe")
plt.plot(V, parallel_fans(V), label="2 Lüfter parallel")
plt.plot(V, system_pressure(V), label="System", linestyle="--")

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