Source code for RCAIDE.Library.Methods.Aeroacoustics.Semi_Empirical.Turbofan.primary_noise_component
# RCAIDE/Methods/Aeroacoustics/Semi_Empirical/Engine/primary_noise_component.py
#
#
# Created: Jul 2023, M. Clarke
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# IMPORT
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# Python package imports
import numpy as np
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# Primary Noise Component
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[docs]
def primary_noise_component(Velocity_primary, Temperature_primary, R_gas, theta_p, DVPS, sound_ambient,
Velocity_secondary, Velocity_aircraft, Area_primary, Area_secondary, DSPL_p, EX_p, Str_p):
"""
This function calculates the noise contribution of the primary jet component.
Parameters
----------
Velocity_primary : float
Velocity of the primary jet [m/s].
Temperature_primary : float
Temperature of the primary jet [K].
R_gas : float
Specific gas constant [J/(kg·K)].
theta_p : float
Angle for the primary jet [rad].
DVPS : float
Design velocity parameter for the primary jet.
sound_ambient : float
Ambient sound level [SPL].
Velocity_secondary : float
Velocity of the secondary jet [m/s].
Velocity_aircraft : float
Velocity of the aircraft [m/s].
Area_primary : float
Area of the primary jet [m^2].
Area_secondary : float
Area of the secondary jet [m^2].
DSPL_p : float
Decibel Sound Pressure Level for the primary jet [SPL].
EX_p : float
Excess noise level for the primary jet.
Str_p : float
Strouhal number for the primary jet.
Returns
-------
SPL_p : float
Sound Pressure Level for the primary jet component [dB].
Notes
-----
The function uses empirical methods to calculate the noise contribution of the primary jet component.
**Definitions**
'SPL_p'
Sound Pressure Level for the primary jet component.
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)
"""
# Flow parameters of the primary jet
sound_primary = np.sqrt(1.4*R_gas*Temperature_primary)
Mach_primary_jet = Velocity_primary/sound_primary
# Calculation of the velocity exponent
velocity_exponent = 1.5*np.exp(-10*(theta_p - 2.2)**2)
velocity_exponent[theta_p <= 2.2] = 1.56
# Calculation of the Source Strengh Function (FV)
FV = Mach_primary_jet*(DVPS/sound_ambient)**0.6*((Velocity_primary+Velocity_secondary)/sound_ambient)**0.4* (np.abs(Velocity_primary-Velocity_aircraft)/Velocity_primary)**velocity_exponent
# Determination of the noise model coefficients
Z1 = -18*((1.8*theta_p/np.pi)-0.6)**2
Z2 = -18-18*((1.8*theta_p/np.pi)-0.6)**2
Z3 = 0.0
Z4 = -0.1 - 0.75*((Velocity_primary-Velocity_secondary-Velocity_aircraft)/sound_ambient) * ((1.8*theta_p/np.pi)-0.6)**3. + 0.8*(0.6-np.log10(1+Area_secondary/Area_primary))
Z5 = 50 + 20*np.exp(-(theta_p-2.6)**2.)
Z6 = 94 + 46*np.exp(-(theta_p-2.5)**2.) - 26.*(0.6-np.log10(1+Area_secondary/Area_primary))/ np.exp(5*(theta_p-2.3)**2) + DSPL_p + EX_p
# Determination of Sound Pressure Level for the primary jet component
SPL_p = (Z1*np.log10(FV)+Z2) * (np.log10(Str_p)-Z3*np.log10(FV)-Z4)**2 + Z5*np.log10(FV) + Z6
return SPL_p
