scholarly journals Measurements of near-wall pressure fluctuations for trailing-edge serrations and slits

2018 ◽  
Vol 60 (1) ◽  
Author(s):  
D. Ragni ◽  
F. Avallone ◽  
W. C. P. van der Velden ◽  
D. Casalino
Keyword(s):  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Trailing Edge ◽  
Wall Pressure Fluctuations ◽  
Trailing Edge Serrations ◽  
Near Wall

scholarly journals Near-wall pressure fluctuations over noise reduction add-ons

2017 ◽  
Author(s):  
Francesco Avallone ◽  
Wouter C. van der Velden ◽  
Roberto Merino Martinez ◽  
Daniele Ragni
Keyword(s):  
Noise Reduction ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Wall Pressure Fluctuations ◽  
Near Wall

Active Control Methods of Flow-Induced-Vibrations: Near-Wall-Turbulent-Pressure-Fluctuation Measurements

2002 ◽  
Author(s):  
Efim B. Kudashev ◽  
Leonid R. Yoblonik
Keyword(s):  
Turbulent Flows ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Control Methods ◽  
Flow Induced Vibration ◽  
Active Method ◽  
Wall Pressure Fluctuations ◽  
Turbulent Pressure ◽  
Flow Induced Vibrations ◽  
Near Wall

Near-wall pressure fluctuations in turbulent flows are of considerable interest in many engineering applications. We shall concentrate on a number of specific questions related to the resolution of components of wall pressure spectra. Our emphasis shall be on outstanding problems of experiment and theory and their relationship to one another. A study on pressure fluctuations transducer’s interaction with wall vibration resulting from near-wall turbulent flows has been performed. Piezoelectric pressure transducer generates the signal also on vibration influence. Algorithm of assign of turbulent surface pressure in conditions of flow-induced-vibration is suggested. An active method of vibration control has been developed.

scholarly journals Influence of Surface Roughness Geometry on Trailing Edge Wall Pressure Fluctuations and Noise

2021 ◽  
Author(s):  
Fernanda Leticia dos Santos ◽  
Nikolaj A. Even ◽  
Laura Botero ◽  
Cornelius Venner ◽  
Leandro D. de Santana
Keyword(s):  
Surface Roughness ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Trailing Edge ◽  
Wall Pressure Fluctuations

Wall-Layer Scale Electromagnetic Turbulence Control in an Axisymmetric Body

Volume 1 ◽  
2004 ◽  
Author(s):  
Promode R. Bandyopadhyay ◽  
John M. Castano ◽  
Daniel P. Thivierge
Keyword(s):  
Boundary Layer ◽  
Large Diameter ◽  
Pressure Fluctuations ◽  
Axisymmetric Body ◽  
Wall Pressure ◽  
Wall Region ◽  
Turbulence Control ◽  
Wall Pressure Fluctuations ◽  
Surface Normal ◽  
Near Wall

The progress made with the control of turbulence in a boundary layer developing over a small axisymmetric body in saltwater at moderate Reynolds numbers is briefly described. A resonance-interference mechanism of control by means of a small periodic Lorenz force confined to the near-wall region, designed to overcome the issue of low efficiency of electromagnetic turbulence control in general, is attempted to alter surface normal turbulence near-wall. At a low momentum thickness Reynolds number of 2300, drag is reduced by 15–25% at a freestream speed of 5.12 m/s with an efficiency of 2–3.4%. Bi-polar pulsing succeeds in lowering surface-normal turbulence intensity near wall. It also makes wall pressure fluctuations less spiky. Positive uni-polar pulsing is found to weaken the sources of wall-pressure fluctuations residing in the logarithmic region of the boundary layer. Further confirmatory work is needed with robust electrodes and drag measurements on a large diameter axisymmetric body.

LES Prediction of Wall-Pressure Fluctuations and Noise of a Low-Speed Airfoil

2009 ◽  
Vol 8 (3) ◽  
pp. 177-197 ◽  
Author(s):  
Meng Wang ◽  
Stephane Moreau ◽  
Gianluca Iaccarino ◽  
Michel Roger
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Transition To Turbulence ◽  
Trailing Edge ◽  
Frequency Spectra ◽  
Potential Core ◽  
Low Speed ◽  
Wall Pressure Fluctuations

This paper discusses the prediction of wall-pressure fluctuations and noise of a low-speed flow past a thin cambered airfoil using large-eddy simulation (LES). The results are compared with experimental measurements made in an open-jet anechoic wind-tunnel at Ecole Centrale de Lyon. To account for the effect of the jet on airfoil loading, a Reynolds-averaged Navier-Stokes calculation is first conducted in the full wind-tunnel configuration, and the mean velocities from this calculation are used to define the boundary conditions for the LES in a smaller domain within the potential core of the jet. The LES flow field is characterized by an attached laminar boundary layer on the pressure side of the airfoil and a transitional and turbulent boundary layer on the suction side, in agreement with experimental observations. An analysis of the unsteady surface pressure field shows reasonable agreement with the experiment in terms of frequency spectra and spanwise coherence in the trailing-edge region. In the nose region, characterized by unsteady separation and transition to turbulence, the wall-pressure fluctuations are highly sensitive to small perturbations and thus diffcult to predict or measure with certainty. The LES, in combination with the Ffowcs Williams and Hall solution to the Lighthill equation, also predicts well the radiated trailing-edge noise. A finite-chord correction is derived and applied to the noise prediction, which is shown to improve the overall agreement with the experimental sound spectrum.

scholarly journals Wall pressure fluctuations induced by a single stream jet over a semi-finite plate

2020 ◽  
Vol 19 (3-5) ◽  
pp. 240-253 ◽  
Author(s):  
Stefano Meloni ◽  
Jack LT Lawrence ◽  
Anderson R Proença ◽  
Rod H Self ◽  
Roberto Camussi
Keyword(s):  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Trailing Edge ◽  
Statistical Characterization ◽  
Pressure Transducers ◽  
Finite Plate ◽  
Wall Pressure Fluctuations ◽  
Time Domains ◽  
Subsonic Regime ◽  
The University

This work provides an experimental investigation into the interaction between a jet flow and a semi-finite plate parallel to the jet. Wall pressure fluctuations have been measured in a high compressible subsonic regime and for different distances between the jet and the plate trailing edge. The experiment has been carried out in the ISVR anechoic Doak Laboratory at the University of Southampton, using wall pressure transducers flush mounted on the plate surface. Signals were acquired in the stream-wise direction along the jet centreline and in the span-wise direction in a region close to the trailing edge. The radial position of the flat plate was fixed very close to the jet axis to simulate a realistic jet–wing configuration. The plate was moved axially in order to investigate four different jet-trailing edge distances and to include measurements upstream of the nozzle exhaust. The acquired database was analyzed in both the frequency and the time domains providing an extensive statistical characterization in terms of spectral uni– and multi–variate quantities as well as high order statistical moments. A wavelet analysis was performed as well to investigate the time evolution of the wall pressure events.

Space–time characteristics of a compliant wall in a turbulent channel flow

2014 ◽  
Vol 756 ◽  
pp. 30-53 ◽  
Author(s):  
Euiyoung Kim ◽  
Haecheon Choi
Keyword(s):  
Channel Flow ◽  
Wall Motion ◽  
Pressure Fluctuations ◽  
Turbulent Channel Flow ◽  
Space Time ◽  
Wall Pressure ◽  
Wall Displacement ◽  
Wall Pressure Fluctuations ◽  
Compliant Wall ◽  
Near Wall

AbstractThe space–time characteristics of a compliant wall in a turbulent channel flow are investigated using direct numerical simulation (DNS). The compliant wall is modelled as a homogeneous plane supported by spring-and-damper arrays and is passively driven by wall-pressure fluctuations. The frequency/wavenumber spectra and convection velocities of the wall-pressure fluctuations, wall displacement and wall velocity are obtained from the present simulation. As the spring, damping, and tension coefficients decrease, the wall becomes softer and the wall displacement and velocity fluctuations increase. For a relatively stiff compliant wall (i.e. large spring, damping and streamwise tension coefficients), there are few changes in the skin-friction drag and near-wall turbulence structures. However, when a compliant wall is soft (i.e. small spring, damping and streamwise tension coefficients), the wall moves in the form of a large-amplitude quasi-two-dimensional wave travelling in the downstream direction. This wave is generated by the resonance of the wall property and the near-wall flow is significantly activated by this wall motion. The power spectra of wall variables show distinct peaks near the resonance frequencies. The convection velocities of the wall motion and wall-pressure fluctuations become smaller with a softer wall.

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