A far-field approximation for high-speed impulsive noise prediction

1996 ◽  
Author(s):  
Peter Holland
Keyword(s):  
High Speed ◽  
Impulsive Noise ◽  
Field Approximation ◽  
Noise Prediction ◽  
Far Field

scholarly journals Jet-Surface Interaction Test: Far-Field Noise Results

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Clifford A. Brown
Keyword(s):  
High Speed ◽  
Radial Distance ◽  
Jet Noise ◽  
Surface Interaction ◽  
Shielding Effect ◽  
Noise Prediction ◽  
Far Field ◽  
Wide Range ◽  
Field Noise ◽  
Surface Length

Many configurations proposed for the next generation of aircraft rely on the wing or other aircraft surfaces to shield the engine noise from the observers on the ground. However, the ability to predict the shielding effect and any new noise sources that arise from the high-speed jet flow interacting with a hard surface is currently limited. Furthermore, quality experimental data from jets with surfaces nearby suitable for developing and validating noise prediction methods are usually tied to a particular vehicle concept and, therefore, very complicated. The Jet-Surface Interaction Tests are intended to supply a high quality set of data covering a wide range of surface geometries and positions and jet flows to researchers developing aircraft noise prediction tools. The initial goal is to measure the noise of a jet near a simple planar surface while varying the surface length and location in order to: (1) validate noise prediction schemes when the surface is acting only as a jet noise shield and when the jet-surface interaction is creating additional noise, and (2) determine regions of interest for future, more detailed, tests. To meet these objectives, a flat plate was mounted on a two-axis traverse in two distinct configurations: (1) as a shield between the jet and the observer and (2) as a reflecting surface on the opposite side of the jet from the observer. The surface length was varied between 2 and 20 jet diameters downstream of the nozzle exit. Similarly, the radial distance from the jet centerline to the surface face was varied between 1 and 16 jet diameters. Far-field and phased array noise data were acquired at each combination of surface length and radial location using two nozzles operating at jet exit conditions across several flow regimes: subsonic cold, subsonic hot, underexpanded, ideally expanded, and overexpanded supersonic. The far-field noise results, discussed here, show where the jet noise is partially shielded by the surface and where jet-surface interaction noise dominates the low frequency spectrum as a surface extends downstream and approaches the jet plume.

scholarly journals A time-domain method for prediction of noise radiated from supersonic rotating sources in a moving medium

2018 ◽  
Vol 474 (2210) ◽  
pp. 20170089 ◽  
Author(s):  
Zhongjie Huang ◽  
Leonidas Siozos-Rousoulis ◽  
Tim De Troyer ◽  
Ghader Ghorbaniasl
Keyword(s):  
Time Domain ◽  
High Speed ◽  
Impulsive Noise ◽  
Time Domain Method ◽  
Special Treatment ◽  
Noise Prediction ◽  
Moving Medium ◽  
Domain Method ◽  
Emission Surface ◽  
Flow Effects

This paper presents a time-domain method for noise prediction of supersonic rotating sources in a moving medium. The proposed approach can be interpreted as an extensive time-domain solution for the convected permeable Ffowcs Williams and Hawkings equation, which is capable of avoiding the Doppler singularity. The solution requires special treatment for construction of the emission surface. The derived formula can explicitly and efficiently account for subsonic uniform constant flow effects on radiated noise. Implementation of the methodology is realized through the Isom thickness noise case and high-speed impulsive noise prediction from helicopter rotors.

In‐Flight Far‐Field Measurement of Helicopter Impulsive Noise

1976 ◽  
Vol 21 (4) ◽  
pp. 2-16
Author(s):  
F. H. Schmitz ◽  
D. A. Boxwell
Keyword(s):  
High Speed ◽  
Impulsive Noise ◽  
Operating Conditions ◽  
Tape Recording ◽  
Far Field ◽  
Recording Equipment ◽  
Radiation Characteristics ◽  
Acoustic Data ◽  
Noise Radiation ◽  
The Subject

A new and highly successful method of collecting far‐field acoustic data radiated by helicopters in forward flight has been developed, utilizing a quiet aircraft flying in formation ahead of the subject helicopter. The lead aircraft, flown as an acoustic probe, was equipped with tape‐recording equipment and an external microphone. Spatial orientation of the helicopter with respect to the monitoring aircraft was achieved through visual flight reference. Far‐field acoustic data defining the impulsive noise radiation characteristics of the UH‐1H helicopter during high‐speed flight and partial ‐power descents have been gathered with this technique. Three distinct types of impulsive waveforms have been identified and correlated with helicopter steady operating conditions.

HELICOPTER NOISE PREDICTIONS USING KIRCHHOFF METHODS

1996 ◽  
Vol 04 (03) ◽  
pp. 321-339 ◽  
Author(s):  
ROGER C. STRAWN ◽  
RUPAK BISWAS ◽  
ANASTASIOS S. LYRINTZIS
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
High Speed ◽  
Impulsive Noise ◽  
Near Field ◽  
Rotor Blades ◽  
Far Field ◽  
Computationally Efficient ◽  
Efficient Manner ◽  
Helicopter Noise

This paper presents two methods for predicting the noise from helicopter rotors in forward flight. Aerodynamic and acoustic solutions in the near field are computed with a finite-difference solver for the Euler equations. Two different Kirchhoff acoustics methods are then used to propagate the acoustic signals to the far field in a computationally-efficient manner. One of the methods uses a Kirchhoff surface that rotates with the rotor blades. The other uses a nonrotating Kirchhoff surface. Results from both methods are compared to experimental data for both high-speed impulsive noise and blade-vortex interaction noise. Agreement between experimental data and computational results is excellent for both cases. The rotating and nonrotating Kirchhoff methods are also compared for accuracy and efficiency. Both offer high accuracy with reasonable computer resource requirements. The Kirchhoff integrations efficiently extend the near-field finite-difference results to predict the far field helicopter noise.

Advanced open rotor noise prediction

2014 ◽  
Vol 118 (1208) ◽  
pp. 1125-1135 ◽  
Author(s):  
M. J. Kingan
Keyword(s):  
High Speed ◽  
Broadband Noise ◽  
Current Status ◽  
Prediction Methods ◽  
Noise Prediction ◽  
Acoustic Data ◽  
Rotor Noise ◽  
Future Challenges ◽  
Open Rotor ◽  
Development And Validation

Abstract The purpose of this paper is to describe the current status of open rotor noise prediction methods and to highlight future challenges in this area. A number of analytic and numerical methods are described which can be used for predicting ‘isolated’ and ‘installed’ open rotor tonal noise. Broadband noise prediction methods are also described and it is noted that further development and validation of the current models is required. The paper concludes with a discussion of the analytical methods which are used to assess the acoustic data collected during the high-speed wind-tunnel testing of a model scale advanced open rotor rig.

scholarly journals A fast computational model for near- and far-field noise prediction due to offshore pile driving

2021 ◽  
Vol 149 (3) ◽  
pp. 1772-1790
Author(s):  
Yaxi Peng ◽  
Apostolos Tsouvalas ◽  
Tasos Stampoultzoglou ◽  
Andrei Metrikine
Keyword(s):  
Computational Model ◽  
Pile Driving ◽  
Noise Prediction ◽  
Far Field ◽  
Field Noise
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