Source code for RCAIDE.Library.Methods.Aeroacoustics.Semi_Empirical.Turbofan.external_plug_effect
# RCAIDE/Methods/Aeroacoustics/Semi_Empirical/Engine/external_plug_effect.py
#
#
# Created: Jul 2023, M. Clarke
# ----------------------------------------------------------------------------------------------------------------------
# IMPORT
# ----------------------------------------------------------------------------------------------------------------------
# RCAIDE imports
from RCAIDE.Framework.Core import Data
# Python package imports
import numpy as np
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# External Plug Effect
# ----------------------------------------------------------------------------------------------------------------------
[docs]
def external_plug_effect(Velocity_primary, Velocity_secondary, Velocity_mixed, Diameter_primary,
Diameter_secondary, Diameter_mixed, Plug_diameter, sound_ambient, theta_p, theta_s, theta_m):
"""
This function calculates the adjustments, in decibels, to be added to the predicted jet noise levels due to external plugs in coaxial jets.
Parameters
----------
Velocity_primary : float
Velocity of the primary jet [m/s].
Velocity_secondary : float
Velocity of the secondary jet [m/s].
Velocity_mixed : float
Velocity of the mixed jet [m/s].
Diameter_primary : float
Diameter of the primary jet [m].
Diameter_secondary : float
Diameter of the secondary jet [m].
Diameter_mixed : float
Diameter of the mixed jet [m].
Plug_diameter : float
Diameter of the external plug [m].
sound_ambient : float
Ambient sound level [dB].
theta_p : float
Angle for the primary jet [rad].
theta_s : float
Angle for the secondary jet [rad].
theta_m : float
Angle for the mixed jet [rad].
Returns
-------
jet_plug_effects : Data
Contains the noise adjustments for each jet component.
- PG_p : float
Adjustment for the primary jet [dB].
- PG_s : float
Adjustment for the secondary jet [dB].
- PG_m : float
Adjustment for the mixed jet [dB].
Notes
-----
The function assumes that the external plug effect is significant for coaxial jets and calculates the noise adjustments accordingly.
**Definitions**
'PG'
Plug Gain, the adjustment in decibels due to the presence of an external plug.
References
----------
[1] SAE ARP876D: Gas Turbine Jet Exhaust Noise Prediction (original)
[2] de Almeida, Odenir. "Semi-empirical methods for coaxial jet noise prediction." (2008). (adapted)
"""
# Primary jet
PG_p = 0.1*(Velocity_primary/sound_ambient)*(10-(18*theta_p/np.pi))*Plug_diameter/Diameter_primary
# Secondary jet
PG_s = 0.1*(Velocity_secondary/sound_ambient)*(6-(18*theta_s/np.pi))*Plug_diameter/Diameter_secondary
# Mixed jet
PG_m = 0.1*(Velocity_primary*Velocity_mixed/(sound_ambient**2))*(9-(18*theta_m/np.pi))*Plug_diameter/Diameter_mixed
# Pack Results
jet_plug_effects = Data()
jet_plug_effects.PG_p = PG_p
jet_plug_effects.PG_s = PG_s
jet_plug_effects.PG_m = PG_m
return jet_plug_effects
