RCAIDE.Library.Methods.Noise.Frequency_Domain_Buildup.Rotor.harmonic_noise_point

harmonic_noise_point

harmonic_noise_point(harmonics_blade, harmonics_load, conditions, coordinates, rotor, settings, Noise, cpt)

This computes the harmonic noise (i.e. thickness and loading noise) in the frequency domain of a rotor at any angle of attack having the loads act at a single point. This is a level 1 fidelity approach. The thickness source is however computed using the helicoidal surface theory.

Assumptions: 1) Acoustic compactness of loads along blade chord. 2) Acoustic compactness of loads along blade span. 3) Acoustic compactness of loads along blade thickness.

Source: 1) Hanson, D. B. (1995). Sound from a propeller at angle of attack: a new theoretical viewpoint. Proceedings - Royal Society of London, A, 449(1936). https://doi.org/10.1098/rspa.1995.0046

2) Hubbard, Harvey H., ed. Aeroacoustics of flight vehicles: theory and practice. Vol. 1. NASA Office of Management, Scientific and Technical Information Program, 1991.

Inputs:

harmonics_blade - blade harmonics [Unitless] harmonics_load - loading harmonics (modes within each blade harmonic mode) [Unitless] freestream - freestream data structure [m/s] angle_of_attack - aircraft angle of attack [rad] position_vector - position vector of aircraft [m] velocity_vector - velocity vector of aircraft [m/s] rotors - data structure of rotors [None] aeroacoustic_data - data structure of acoustic data [None] settings - accoustic settings [None] res - results data structure [None]

Outputs

res. acoustic data is stored and passed in data structures

SPL_prop_harmonic_bpf_spectrum - harmonic noise in blade passing frequency spectrum [dB] SPL_prop_harmonic_bpf_spectrum_dBA - dBA-Weighted harmonic noise in blade passing frequency spectrum [dbA] SPL_prop_harmonic_1_3_spectrum - harmonic noise in 1/3 octave spectrum [dB] SPL_prop_harmonic_1_3_spectrum_dBA - dBA-Weighted harmonic noise in 1/3 octave spectrum [dBA] p_pref_harmonic - pressure ratio of harmonic noise [Unitless] p_pref_harmonic_dBA - pressure ratio of dBA-weighted harmonic noise [Unitless]

Properties Used:

N/A

Code Convention - The number in front of a variable name indicates the number of dimensions of the variable.

For instance, m_6 is the 6 dimensional harmonic modes variable, m_5 is 5 dimensional harmonic modes variable