An efficient and robust method for predicting helicopter rotor high-speed impulsive noise

Research output: Contribution to conferencePaper

5 Citations (Scopus)

Abstract

A new formulation for the Ffowcs Williams- Hawkings quadrupole source, which is valid for a far-field in-plane observer, is presented. The far-field approximation is new and unique in that no further approximation of the quadrupole source strength is made and integrands with r-2 and r-3 dependence are retained. This paper focuses on the development of a retarded-time formulation in which time derivatives are analytically taken inside the integrals to avoid unnecessary computational work when the observer moves with the rotor. The new quadrupole formulation is similar to Farassat's thickness and loading formulation 1A. Quadrupole noise prediction is carried out in two parts: a preprocessing stage in which the previously computed flow field is integrated in the direction normal to the rotor disk, and a noise computation stage in which quadrupole surface integrals are evaluated for a particular observer position. Preliminary predictions for hover and forward flight agree well with experimental data. The method is robust and requires computer resources comparable to thickness and loading noise prediction.

Original languageEnglish (US)
StatePublished - Jan 1 1996
Event34th Aerospace Sciences Meeting and Exhibit, 1996 - Reno, United States
Duration: Jan 15 1996Jan 18 1996

Other

Other34th Aerospace Sciences Meeting and Exhibit, 1996
CountryUnited States
CityReno
Period1/15/961/18/96

Fingerprint

rotary wings
rotor speed
Helicopter rotors
Impulse noise
quadrupoles
high speed
formulations
noise prediction
Rotors
prediction
far fields
turbine wheels
flow field
Flow fields
flight
Derivatives
preprocessing
approximation
rotors
resource

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Aerospace Engineering

Cite this

Brentner, K. S. (1996). An efficient and robust method for predicting helicopter rotor high-speed impulsive noise. Paper presented at 34th Aerospace Sciences Meeting and Exhibit, 1996, Reno, United States.
Brentner, Kenneth Steven. / An efficient and robust method for predicting helicopter rotor high-speed impulsive noise. Paper presented at 34th Aerospace Sciences Meeting and Exhibit, 1996, Reno, United States.
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Brentner, KS 1996, 'An efficient and robust method for predicting helicopter rotor high-speed impulsive noise' Paper presented at 34th Aerospace Sciences Meeting and Exhibit, 1996, Reno, United States, 1/15/96 - 1/18/96, .

An efficient and robust method for predicting helicopter rotor high-speed impulsive noise. / Brentner, Kenneth Steven.

1996. Paper presented at 34th Aerospace Sciences Meeting and Exhibit, 1996, Reno, United States.

Research output: Contribution to conferencePaper

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N2 - A new formulation for the Ffowcs Williams- Hawkings quadrupole source, which is valid for a far-field in-plane observer, is presented. The far-field approximation is new and unique in that no further approximation of the quadrupole source strength is made and integrands with r-2 and r-3 dependence are retained. This paper focuses on the development of a retarded-time formulation in which time derivatives are analytically taken inside the integrals to avoid unnecessary computational work when the observer moves with the rotor. The new quadrupole formulation is similar to Farassat's thickness and loading formulation 1A. Quadrupole noise prediction is carried out in two parts: a preprocessing stage in which the previously computed flow field is integrated in the direction normal to the rotor disk, and a noise computation stage in which quadrupole surface integrals are evaluated for a particular observer position. Preliminary predictions for hover and forward flight agree well with experimental data. The method is robust and requires computer resources comparable to thickness and loading noise prediction.

AB - A new formulation for the Ffowcs Williams- Hawkings quadrupole source, which is valid for a far-field in-plane observer, is presented. The far-field approximation is new and unique in that no further approximation of the quadrupole source strength is made and integrands with r-2 and r-3 dependence are retained. This paper focuses on the development of a retarded-time formulation in which time derivatives are analytically taken inside the integrals to avoid unnecessary computational work when the observer moves with the rotor. The new quadrupole formulation is similar to Farassat's thickness and loading formulation 1A. Quadrupole noise prediction is carried out in two parts: a preprocessing stage in which the previously computed flow field is integrated in the direction normal to the rotor disk, and a noise computation stage in which quadrupole surface integrals are evaluated for a particular observer position. Preliminary predictions for hover and forward flight agree well with experimental data. The method is robust and requires computer resources comparable to thickness and loading noise prediction.

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Brentner KS. An efficient and robust method for predicting helicopter rotor high-speed impulsive noise. 1996. Paper presented at 34th Aerospace Sciences Meeting and Exhibit, 1996, Reno, United States.