On aerodynamic noise generation from vortex shedding in rotating blades

1992 ◽  
Vol 155 (2) ◽  
pp. 317-324 ◽  
Author(s):  
B.T. Martin ◽  
D.A. Bies
Keyword(s):  
Vortex Shedding ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Rotating Blades

Advanced Numerical Methods for the Prediction of Tonal Noise in Turbomachinery—Part I: Implicit Runge–Kutta Schemes

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Graham Ashcroft ◽  
Christian Frey ◽  
Kathrin Heitkamp ◽  
Christian Weckmüller
Keyword(s):  
Stokes Equations ◽  
Temporal Integration ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Noise Generation ◽  
Academic Problems ◽  
Tonal Noise ◽  
Navier Stokes Equations ◽  
Runge Kutta ◽  
The Stability

This is the first part of a series of two papers on unsteady computational fluid dynamics (CFD) methods for the numerical simulation of aerodynamic noise generation and propagation. In this part, the stability, accuracy, and efficiency of implicit Runge–Kutta schemes for the temporal integration of the compressible Navier–Stokes equations are investigated in the context of a CFD code for turbomachinery applications. Using two model academic problems, the properties of two explicit first stage, singly diagonally implicit Runge–Kutta (ESDIRK) schemes of second- and third-order accuracy are quantified and compared with more conventional second-order multistep methods. Finally, to assess the ESDIRK schemes in the context of an industrially relevant configuration, the schemes are applied to predict the tonal noise generation and transmission in a modern high bypass ratio fan stage and comparisons with the corresponding experimental data are provided.

scholarly journals Aeroacoustics of Silent Owl Flight

2020 ◽  
Vol 52 (1) ◽  
pp. 395-420 ◽  
Author(s):  
Justin W. Jaworski ◽  
N. Peake
Keyword(s):  
Mathematical Modeling ◽  
Noise Reduction ◽  
Current Knowledge ◽  
Foraging Strategies ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Reduction Strategies ◽  
Noise Measurements ◽  
Modeling And Experiments ◽  
Review Current

The ability of some species of owl to fly in effective silence is unique among birds and provides a distinct hunting advantage, but it remains a mystery as to exactly what aspects of the owl and its flight are responsible for this dramatic noise reduction. Crucially, this mystery extends to how the flow physics may be leveraged to generate noise-reduction strategies for wider technological application. We review current knowledge of aerodynamic noise from owls, ranging from live owl noise measurements to mathematical modeling and experiments focused on how owls may disrupt the standard routes of noise generation. Specialized adaptations and foraging strategies are not uniform across all owl species: Some species may not have need for silent flight, or their evolutionary adaptations may not be effective for useful noise reduction for certain species. This hypothesis is examined using mathematical models and borne out where possible by noise measurements and morphological observations of owl feathers and wings.

Noise generation by rotating blades in a riding lawnmower

2001 ◽  
Vol 109 (5) ◽  
pp. 2402-2402
Author(s):  
Christian Skinner ◽  
Courtney B. Burroughs
Keyword(s):  
Noise Generation ◽  
Rotating Blades

On the Modelling of Noise Generation in Corrugated Pipes

2009 ◽  
Author(s):  
Hugh Goyder
Keyword(s):  
Vortex Shedding ◽  
Oil And Gas ◽  
Natural Frequencies ◽  
Oil And Gas Industry ◽  
Noise Generation ◽  
Noise Levels ◽  
Eigenvalue Approach ◽  
Gas Industry ◽  
Offshore Oil And Gas ◽  
Offshore Oil

The offshore oil and gas industry uses pipes which are made flexible by means of a corrugated construction. Those pipes that run from a platform to the seabed are known as risers while those that connect two pipes on the seabed are known as jumpers. Gas flowing within the pipe interacts with the corrugations and generates noise. This noise is of concern because it is of sufficient amplitude to cause pipework vibration with the threat of fatigue and pipe breakages. This paper examines the conditions that give rise to the large noise levels. The conditions for the onset of noise are investigated using an eigenvalue approach which involves the effect of damping due to losses from the pipe boundaries and pipe friction. The investigation which is conducted in terms of reflection conditions shows why only few of the very many possible natural frequencies are selected. The conditions for maximum noise response are also investigated using a non-linear model of vortex shedding. Here an approach is developed in which the net power generated along a single wavelength is calculated.

Active Control of Vortex Shedding Behind a Bluff Body and Aerodynamic Noise by Micro-Excitation Sidewall Surfaces

2003 ◽  
Vol 2003.56 (0) ◽  
pp. 63-64
Author(s):  
Manabu ODA ◽  
Yoshihisa YAMAMOTO ◽  
Atsushi TAKAKI ◽  
Yasutake HARAMOTO ◽  
Masato FURUKAWA ◽  
...  
Keyword(s):  
Active Control ◽  
Vortex Shedding ◽  
Bluff Body ◽  
Aerodynamic Noise

On the Modelling of Noise Generation in Corrugated Pipes

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Hugh Goyder
Keyword(s):  
Vortex Shedding ◽  
Oil And Gas ◽  
Natural Frequencies ◽  
Oil And Gas Industry ◽  
Noise Generation ◽  
Noise Levels ◽  
Eigenvalue Approach ◽  
Gas Industry ◽  
Offshore Oil And Gas ◽  
Offshore Oil

The offshore oil and gas industry uses corrugated pipes because of their flexibility. Gas flowing within these pipes interacts with the corrugations and generates noise. This noise is of concern because it is of sufficient amplitude to cause pipework vibration with the threat of fatigue and pipe breakages. This paper examines the conditions that give rise to the large noise levels. These conditions, for the occurrence of noise, are investigated using an eigenvalue approach, which involves the effect of damping due to losses from the pipe boundaries and pipe friction. The investigation is conducted in terms of reflection conditions and shows why only few of the very many possible natural frequencies are selected. The conditions for maximum noise response are also investigated by means of a nonlinear model of vortex shedding. Here, an approach is developed in which the net power generated by each wavelength is calculated.

scholarly journals BVI-noise generation by wing-shaped helicopter blade

2020 ◽  
Keyword(s):  
Calculated Data ◽  
Low Noise ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
High Frequency Region ◽  
Helicopter Blade ◽  
Sound Fields ◽  
Helicopter Flight ◽  
Natural Forms ◽  
Mach Numbers

Aerodynamic noise includes a number of noise components, among which rotational noise and vortex noise (BVI-noise) make the largest contribution to the overall noise generated. Rotation noise depends on the magnitude of the velocity of the incoming blade and prevails over other noise components at significant Mach Mach numbers. Unlike rotation noise, vortex noise is evident at low helicopter flight speeds, moderate Mach numbers. In the formation of this type of noise,an important role is played by the longitudinal geometry. Therefore, recently the shape of the helicopter blade is chosen close to existing natural forms, which are as balanced as possible. One of these may be a wing-shaped blade. In this work, the problem of generating BVI noise by the wing shaped blade of a helicopter is posed and solved. The mathematical model of the problem is constructed on the previously proposed by the author and successfully tested system of aeroacoustic equations for the general case. Estimated features in this system are pulsations of sound pressure and sound potential. The calculated data of these quantities, as well as their derivatives, were used to study near and far sound fields. In particular, the dependence of the density ripple distribution is revealed from the blade geometry, the angle of attack and the blade angle to the oncoming flow. Increasing flow velocity contributes to the emergence of transverse ripples on the surface blades that dominate the longitudinal ripples by level. An interesting feature noticed in the calculations is that there are calculations for moderate Mach numbers M=0.2,0.3 situations, at certain angles of blade placement to the stream and angles of attack where rotation noise dominates eddy noise. For values Mach numbers M>0.4 rotation noise plays a major role in blade noise generation. The noise level generated is in the range 50dB≤L≤60dB, which is lower by 5-6dB for the Blue Edge blade, as well as the rounded blade. In addition, activation of the high-frequency region in the frequency spectrum of noise was observed f≈840Hz. The results of the calculations show that the blade of the wing-shaped is low-noise in the mode of maneuvers at small flight speeds.

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