Noise Generation Mechanisms in Single and Coaxial Jets

2006 ◽  
Author(s):  
Elmar Gröschel ◽  
Wolfgang Schröder ◽  
Matthias Meinke
Keyword(s):  
Noise Generation ◽  
Coaxial Jets ◽  
Generation Mechanisms

scholarly journals Exterior Noise Due to Interaction of Tyre-Thermoplastic Transverse Rumble Strips

2017 ◽  
Vol 42 (3) ◽  
pp. 449-457 ◽  
Author(s):  
Zaiton Haron ◽  
Mohd Hanifi Othman ◽  
Lim Meng Hee ◽  
Khairulzan Yahya ◽  
Mohd Rosli Hainin ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Surface Texture ◽  
Sound Level ◽  
Vehicle Speed ◽  
Noise Generation ◽  
Octave Band ◽  
Trade Off ◽  
Low Speed ◽  
The Public ◽  
Generation Mechanisms

AbstractTransverse rumble strips (TRS) are a common choice to reduce vehicle speed and increase driver alertness on roadways. However, there is a potential trade-off using them on rural roadway due to the noise problem created when vehicles go over the strips. The present study investigated the noise level, spectral analysis, and the possible noise generation mechanism when the TRS is hit by a vehicle. Tenraised- rumbler (RR) and three-layer-overlapped (TLO) TRS were selected in this study as they have received complaints from the public. Results showed that RR generated a relatively higher noise and impulse at a low speed, and increased sound level in each octave band. Based on these results, RR may irritate human ears even when the vehicle travels at a low speed. It was found that RR increased all noise generation mechanisms of tyre-pavement interaction whilst TLO increased structural resonance, sidewall and surface texture vibration.

Investigation of Centrifugal Blower Noise

1999 ◽  
Author(s):  
Christopher L. Banks ◽  
Sean F. Wu
Keyword(s):  
Radiation Pattern ◽  
Free Field ◽  
Sound Radiation ◽  
Noise Generation ◽  
Centrifugal Blower ◽  
Noise Radiation ◽  
Passenger Vehicles ◽  
Generation Mechanisms ◽  
Semi Empirical ◽  
Noise Spectra

Abstract This paper presents the results of an ongoing investigation of noise radiation from centrifugal blowers used in passenger vehicles. The semi-empirical formulation previously derived by the authors (1998) for predicting noise spectra of centrifugal blowers running in a free field is extended to centrifugal blowers installed in a HVAC scroll housing. Because of the presence of the scroll and cutoff, the flow fields are different from those in a free field. Accordingly, the noise generation mechanisms become much more difficult to analyze and model. The previous model assumed a monopole type sound radiation pattern, and predicted the broadband component of the noise spectra well. This model is extended to include the contributions of both monopole and directional dipole sound radiation. It is this complex radiation that is characteristic of a centrifugal blower situated inside a scroll housing with a cutoff. Comparisons of the calculated and measured noise spectra were demonstrated, and good agreements were obtained in all cases.

scholarly journals Numerical study of eigenmode forcing effects on jet flow development and noise generation mechanisms

2009 ◽  
Vol 21 (4) ◽  
pp. 045106 ◽  
Author(s):  
Felix Keiderling ◽  
Leonhard Kleiser ◽  
Christophe Bogey
Keyword(s):  
Numerical Study ◽  
Jet Flow ◽  
Noise Generation ◽  
Flow Development ◽  
Generation Mechanisms

An Experimental Investigation of Sunroof Buffeting Characteristics of a Sedan

2012 ◽  
Vol 226-228 ◽  
pp. 247-251 ◽  
Author(s):  
Yin Zhi He ◽  
Zhi Gang Yang
Keyword(s):  
Experimental Investigation ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Resonance Frequency ◽  
Test Point ◽  
Noise Generation ◽  
Short Introduction ◽  
Wind Speeds ◽  
Operating Modes ◽  
Generation Mechanisms

After a short introduction about vehicle wind buffeting noise generation mechanisms, sunroof buffeting characteristics of a production sedan under different wind speeds and operating modes are investigated through full-scale aeroacoustic wind tunnel tests. As sunroof fully open, the severest buffeting effect occurs at wind speed 50kph, with the peak SPL 122dB and the corresponding resonance frequency 18Hz for the test point at the front row. From ca. 60kph it seems that the buffeting effect disappeared. As sunroof tilt, the severest buffeting effect occurs at wind speed equal or less than 30kph, the resonance frequency equal or less than 15Hz. From ca. 40kph the buffeting effect almost disappeared. Whether sunroof fully open or tilt, the resonance frequency increases all along as wind speed goes up till the buffeting effect disappeared (less than 20Hz). Different test positions at the front row or back row show very similar buffeting characteristics.

scholarly journals Aeroacoustic Analysis of the Tonal Noise of a Large-Scale Radial Blower

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Aurélien Marsan ◽  
Stéphane Moreau
Keyword(s):  
Numerical Simulations ◽  
Large Scale ◽  
Navier Stokes ◽  
Noise Generation ◽  
Tonal Noise ◽  
Radiated Noise ◽  
Rotating Blades ◽  
Reynolds Averaged Navier Stokes ◽  
Generation Mechanisms ◽  
Made In

Large-scale radial blowers are widely used in factories and are one of the main sources of noise. The present study aims at identifying the noise generation mechanisms in such a radial blower in order to suggest simple modifications that could be made in order to reduce the noise. The flow in a representative large-scale radial blower is investigated thanks to unsteady Reynolds-averaged Navier–Stokes (URANS) numerical simulations. The radiated noise is calculated, thanks to an in-house propagation code based on the Ffowcs Williams Hawkings' (FWH) analogy, SherFWH. The results highlight the main noise generation mechanisms, in particular the interaction between the rotating blades and the tongue, and the interaction between the rotating blades and the trapdoors located on the volute sidewall. Some modifications of the geometry are suggested.

Sign in / Sign up

Export Citation Format

Share Document