The exact numerical calculation of propeller noise

Development and Application of Open Rotor Discrete Noise Prediction Program Using Time-Domain Methods

“…To validate code a2, the prediction example of the forward flight propeller noise provided by Farassat and Brown [11] is selected, in which the experimental and theoretical results for overall noise, encompassing acoustic pressure time histories and spectra, are presented. Separately, Woan and Gregorek [15] presented theoretical results, including the acoustic pressure time histories and spectra, for the overall noise as well as for its thickness and loading noise components. In this paper, the acoustic pressure time history and spectrum of the overall noise at the observer point O 1 (0, 7.28 m, 0) are calculated using code a2.…”

An approximation model for the performance and acoustic predictions of counterrotating propeller configurations

“…where the loading noise, P L ' observed at time t emanating from blade element n is given by: (9) and the thickness noise, PT' is given by:…”

“…The terms in Eqs. (9) and 10 The fundamental idea behind a strip analysis method is to calculate the performance of a three-dimensional propeller by modeling the blades as two-dimensional airfoil sections placed about a pitch-change axis. By accounting for three-dimensional effects in the calculation of the radial velocity and angle of attack distributions, twodimensional lift and drag data can be used to obtain the radial variations of thrust and torque which are integrated to obtain the total thrust and torque of the propeller.…”

“…The volumes, velocities, and aerodynamic loads on each of these segments are then used with Eqs. (8), (9), and (10) to obtain the acoustic pressure at the observer time created by a given blade segment. This calculation is repeated for each compact source on the propeller for a given observer time t to obtain the total acoustic pressure.…”

An Inverse Aeroacoustic Problem with Aerodynamic Constraint for a Helicopter Rotor

“…High speed rotating blades have many applications in industry, including rotor, propeller, compressor, and turbine et al [1][2][3][4][5]. This kind of rotating blade has a high speed in the tip region, its loading is larger but its thickness is thinner.…”