Wind-Turbine Trailing-Edge Noise Reduction by Means of Boundary-Layer Suction

Arnold, Benjamin; Lutz, Thorsten; Krämer, Ewald; Rautmann, Christof

doi:10.2514/1.j056633

Cited by 28 publications

(16 citation statements)

References 23 publications

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“…Many attentions are focused to increase the heat transfer rate of the systems which include power stations, chemical plants, air conditioning and petrochemical industry. Suction is one of the boundary layer control methods, which is traditionally used in drag reduction of bodies in an external flow or energy losses in channels [ 1 , 2 , 3 , 4 ]. The imposition of suction on the boundary layer flow due to a shrinking sheet was initially explored by Miklavčič and Wang [ 5 ] for a viscous fluid.…”

Section: Introductionmentioning

confidence: 99%

Mixed Convective Flow and Heat Transfer of a Dual Stratified Micropolar Fluid Induced by a Permeable Stretching/Shrinking Sheet

Khashi’ie

Arifin

Nazar

et al. 2019

Entropy

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The present study accentuates the magnetohydrodynamics (MHD) flow and heat transfer characteristics of a dual stratified micropolar fluid over a permeable stretching/shrinking sheet. Thermal and solutal buoyancy forces are also included to incorporate with the stratification effect. Similarity, transformation is applied to reduce the governing model (partial differential equations) into a set of nonlinear ordinary differential equations (ODEs) due to its complexity. Using bvp4c solver in the MATLAB software, numerical results for some limiting cases are in favorable agreement with the earlier published results. Both assisting and opposing buoyancy flows have dual similarity solutions within specific range of suction and stretching/shrinking parameters, whereas only a distinctive solution is observed for pure forced convective flow. The micropolar fluid shows a disparate pattern of flow, heat and mass transfer characteristics between stretching and shrinking cases. Unlike the shrinking flow, the surface velocity gradient, local Nusselt and Sherwood numbers for stretching flow intensify with the increment of the material parameter. The result from stability analysis reveals that the first solution is the real solution, whereas the second solution is virtual.

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Section: Introductionmentioning

confidence: 99%

Mixed Convective Flow and Heat Transfer of a Dual Stratified Micropolar Fluid Induced by a Permeable Stretching/Shrinking Sheet

Khashi’ie

Arifin

Nazar

et al. 2019

Entropy

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show abstract

“…The wall suction is among the first techniques applied to control the structure of the boundary layer. Most suction investigations concentrate on pure flow subject to active control by applying homogeneous suction boundaries [11][12][13][14][15][16]. Only a few studies are carried out concerning detonation combustion.…”

Section: Nomenclature Fmentioning

confidence: 99%

Detonation Stabilization in Supersonic Flow: Effects of Suction Boundaries

et al. 2020

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“…Sound generated by turbulence around an airfoil represents one of the dominant sources of noise from airplanes, turbomachines, and wind farms [1][2][3][4] . Brooks et al 2 identified the turbulent boundary layer trailing edge (TE) noise as one of the dominating component of airfoil self noise.…”

Section: Introductionmentioning

confidence: 99%

Uniform flow injection into a turbulent boundary layer for trailing edge noise reduction

2020

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The hydrodynamic effects of inclined uniform continuous blowing on a turbulent boundary layer are investigated experimentally. A laminar flow is introduced into the boundary layer through a fence on a flat plate at a distance of 3.38δ 0 upstream of the trailing edge. The effects of this open-loop technique of flow control are examined at different angles of injection and at different blowing rates. Surface pressure fluctuations acquired from flushmounted microphones are used to estimate the trailing edge noise. Injection angles of 70 • and 90 • in combination with strong blowing rates enable a noise reduction of up to 15 dB at mid and high frequencies, f > 300 Hz. Similar aeroacoustic performances are obtained at a blowing angle of 50 • , but at lower blowing rates. At low frequencies a penalty is expected, with the trailing edge noise increasing for all the injection angles and blowing rates under analysis. Mean velocity profiles from hot-wire anemometry reveal that high injection angles and strong blowing rates induce a flow separation which is expected to deteriorate the aerodynamic performances. When applying a uniform blowing at 50 • , however, no flow separation occurs. From an aeroacoustic and aerodynamic point of view, uniform blowing applied at 50 • and at intermediate blowing rates is found to be the most promising setting.

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Wind-Turbine Trailing-Edge Noise Reduction by Means of Boundary-Layer Suction

Cited by 28 publications

References 23 publications

Mixed Convective Flow and Heat Transfer of a Dual Stratified Micropolar Fluid Induced by a Permeable Stretching/Shrinking Sheet

Mixed Convective Flow and Heat Transfer of a Dual Stratified Micropolar Fluid Induced by a Permeable Stretching/Shrinking Sheet

Detonation Stabilization in Supersonic Flow: Effects of Suction Boundaries

Uniform flow injection into a turbulent boundary layer for trailing edge noise reduction

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