This paper presents compact forms for the monopole term of several of Farassat’s formulations. When the physical surface is elongated, such as in the case of a high aspect ratio rotorcraft blade, one can derive compact forms that are shown to be a function of the blade cross-sectional area by reducing the computation from a surface integral to a line integral. The compact forms of all formulations are applied to two example cases: a short span wing with constant airfoil cross-section moving at three forward flight Mach numbers and a rotor at two advance ratios. Acoustic pressure time histories and power spectral densities predicted from the compact forms are shown to resemble very closely the predictions from their noncompact counterparts. A study on the influence of the rotorcraft blade shape on the high-frequency content shows that there is a direct correlation between the aspect ratio of the airfoil and the error incurred. Finally, a prediction of the pressure gradient from the noncompact and compact forms of the thickness term of formulation G1A shows that using the compact forms results in a 99.6% improvement in computation time, which will be critical when noise is incorporated in a design environment.
Compact Assumption Applied to Monopole Term of Farassat’s Formulations
Journal of Aircraft ; 54 , 5 ; 1649-1663
2017-03-10
15 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Compact Assumption Applied to Monopole Term of Farassat’s Formulations
Online Contents | 2017
|Investigations on compact UWB monopole antenna
IEEE | 2017
|Exploiting the Generic Viewpoint Assumption
British Library Online Contents | 1996
|