Source code for RCAIDE.Library.Methods.Aeroacoustics.Semi_Empirical.Airframe.clean_wing_noise
# RCAIDE/Methods/Aeroacoustics/Semi_Empirical/Airframe/clean_wing_noise.py
#
#
# Created: Jul 2023, M. Clarke
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# IMPORT
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import numpy as np
from RCAIDE.Framework.Core import Units
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# Clean Wing Noise
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[docs]
def clean_wing_noise(S, b, ND, IsHorz, velocity, viscosity, M, phi, theta, distance, frequency):
"""
This computes the 1/3 octave band sound pressure level and the overall sound pressure level from the clean wing.
Parameters
----------
S : float
Wing area [sq.ft].
b : float
Wing span [ft].
ND : int
Constant from the method, set to 0 for clean wings and 1 for others.
IsHorz : int
Constant from the method, set to 1 for horizontal components.
velocity : float
Aircraft speed [kts].
viscosity : float
Dynamic viscosity.
M : float
Mach number.
phi : float
Azimuthal angle [rad].
theta : float
Polar angle [rad].
distance : float
Distance from airplane to observer, evaluated at retarded time [ft].
frequency : array_like
Frequency array [Hz].
Returns
-------
SPL : array_like
Sound Pressure Level of the clean wing [dB].
Notes
-----
The function uses correlation-based methods to compute the noise levels from the clean wing.
**Definitions**
'SPL'
Sound Pressure Level, a measure of the sound intensity.
References
----------
Fink, Martin R. "Noise component method for airframe noise." Journal of aircraft 16.10 (1979): 659-665.
"""
distance_ft = distance /Units.ft
delta = 0.37*(S/b)*(velocity*S/(b*viscosity))**(-0.2)
if IsHorz==1:
DIR = np.cos(phi)
elif IsHorz==0:
DIR = np.sin(phi)
if DIR==0:
SPL = np.zeros(24)
else:
fmax = 0.1*velocity / delta # eqn 7
OASPL = 50*np.log10((velocity*Units.ft/Units.kts)/100.0) + 10*np.log10(delta*Units.ft*b*Units.ft/((distance*Units.ft)**2.0)) * (DIR ** 2) * (np.cos(theta/2)) ** 2 + 101.3
SPL = OASPL + 10.0*np.log10( 0.613* (frequency/fmax)**4 * ((frequency/fmax)**1.5 + 0.5)**(-4)) # eqn 5
Delta_SPL = -0.03* (distance_ft/500 ) * np.abs(((frequency/fmax)-1))**1.5 # eqn 6
SPL += Delta_SPL
return SPL
