Syamir Alihan Showkat Ali
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Syamir Alihan Showkat Ali
Official Name
Syamir Alihan, Showkat Ali
Alternative Name
Alihan Showkat Ali, Syamir
Showkat Ali, Syamir A.
Ali, Syamir Alihan Showkat
Showkat Ali, S.A
Showkat Ali, Syainir Alihan
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Scopus Author ID
57190746528

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  • Publication
    Aeroacoustic performance of high-lift airfoil with serrated slat cusp
    ( 2020-01-01)
    Jawahar H.K.
    ;
    Syamir Alihan Showkat Ali
    ;
    Azarpeyvand M.
    ;
    da Silva C.R.I.
    Experimental measurements to assess the aeroacoustic capabilities of 30P30N airfoil fitted with two different types of serrated slat cusps were carried out at the aeroacoustic wind tunnel at the University of Bristol. The results from the simultaneous surface pressure measurement within and close to the slat cove region and far-field noise measurements above the slat trailing edge are presented to gain a deeper understanding of the noise generation mechanism of the slat and other presented configurations. The far-field noise measurement results showed that significant noise reduction at the vortex shedding frequency can be achieved by the use of serration-2 and No-Cusp configuration. The coherence results for all the frequencies are almost zero for the No-Cusp configuration and the coherence was notably reduced for the Serration-2 configuration. Further higher order statistical and spectral analysis showed that even the serration-1 with small serrations reduces the energy within the norrowband peaks to some level.
  • Publication
    Aerodynamic and aeroacoustic performance of high-lift airfoil fitted with slat cove fillers
    ( 2020-08-04)
    Kamliya Jawahar H.
    ;
    Syamir Alihan Showkat Ali
    ;
    Azarpeyvand M.
    ;
    Ilário da Silva C.R.
    Experimental measurements were carried out to assess the aerodynamic and aeroacoustic performance of an MDA 30P30N airfoil fitted with two different types of slat cove fillers. The aerodynamic results are presented for lift and drag measurements and mean surface pressure measurements, while the aeroacoustic results are presented for the near-field surface pressure fluctuations and far-field noise measurement. The flow measurement results show that there is no significant difference in the aerodynamic lift and drag between the tested cases, however, the slat cove filler configurations exhibit a much better lift-to-drag performance. The pressure coefficient results show that the use of slat cove fillers lead to a slight decrease in the suction peak over the main-element of the airfoil. In order to better understand the flow-field and the noise generation mechanism of the airfoil with slat cove fillers, simultaneous near-field and far-field noise measurements were carried out. The result shows that the use of the slat cove filler can generally lead to a significant reduction of the broadband noise and eliminate the characteristic tonal noise generated by the slat. The directivity pattern and the overall sound pressure level of the radiated noise have shown that a significant noise reduction can be achieved with the applications of the slat cove fillers. The multiple tonal phenomena generated by the slat were also analyzed using the continuous wavelet transform method and higher order spectral analysis methods.
  • Publication
    Turbulent flow interaction with a circular cylinder
    ( 2020-01-01)
    Maryami R.
    ;
    Syamir Alihan Showkat Ali
    ;
    Azarpeyvand M.
    ;
    Afshari A.
    This paper presents a comprehensive experimental study on the unsteady pressure exerted on the surface of a round cylinder in smooth and turbulent flows. A highly instrumented cylinder with several static pressure taps and dynamic pressure transducers at different spanwise and peripheral locations was used, enabling extensive dynamic surface pressure, coherence, and turbulence length-scale analysis. The effects of the free-stream turbulence and turbulent length scale are investigated by placing the turbulent-generating grids within the wind tunnel duct. For both the laminar and turbulent incident flows, the surface pressure results show the emergence of the fundamental, first and second harmonics at most peripheral angles, while at the cylinder base, the surface pressure spectra are dominated by the first harmonic. It has also been observed that an increase in the level of the turbulence intensity results in an increase in the energy level of unsteady pressure acting on the cylinder. An increase in the length scale of the incoming flow structures is shown to result in an increase in the energy level of the tonal frequencies and the broadband content of the surface pressure spectra. The spanwise coherence results have also shown that an increase in the length scale of the flow structures increases the spanwise correlation length of the flow structures at the vortex shedding frequency at the stagnation point, while at the cylinder base, the spanwise correlation length decreases at the vortex shedding frequency.
  • Publication
    Trailing edge bluntness noise reduction using porous treatments
    ( 2020-05-26)
    Syamir Alihan Showkat Ali
    ;
    Azarpeyvand, Mahdi
    ;
    Ilário da Silva, Carlos R.
    This paper provides an experimental investigation of the noise generated from a blunt flat plate and the possibility of the control of noise at source using porous trailing edges. The noise generation characteristics have been examined using a flat plate equipped with surface pressure transducers and far-field microphones and was performed in an anechoic open jet wind tunnel. Two types of porous materials with different porosities and permeability constants were tested. Simultaneous near-field and far-field noise measurements, as well as the boundary layer and wake flow measurements, have been carried out to better understand the effects of the porous treatment to the flow-field and the noise generation mechanism of the plate. Results have shown that the use of porous trailing edges can generally lead to the effective suppression of both the tonal noise, due to the vortex shedding from the blunt trailing edge and also the broadband noise of the plate. The level of the noise reduction was also found to be dependent on the porosity and permeability of the porous materials. The directivity patterns of the radiated noise have shown significant noise reduction at the vortex shedding frequencies. The flow measurement results have shown that the use of porous trailing edges leads to the reduction of flow acceleration over the blunt edges, and subsequently the delay and weakening of the vortex shedding. The results presented in this paper provide an impetus for further experimental and numerical studies on the use of porous treatments for the suppression of aerodynamically generated noise at source.
      2  2
  • Publication
    Control of flows around bluff bodies mediated by porous materials
    ( 2020-06-01)
    Sadeghipour, Sakineh
    ;
    Syamir Alihan Showkat Ali
    ;
    Liu, Xiao
    ;
    Azarpeyvand, Mahdi
    ;
    Thorpe, Graham R.
    There is evidence that the application of porous media to the surfaces of bluff bodies immersed in turbulent fluid flows has a profound effect on the associated aerodynamic phenomena. This idea is explored by performing a series of experiments on cylinders that have circular, square and rectangular cross sections. The flow fields were established around circular cylinders that had been encased in porous media, and which retained the same dimensions of the bare cylinder. The square and rectangular bluff bodies were modified so that their upstream and downstream halves consisted of solid and porous materials respectively. It is found that the porous media applied to the circular cylinder had the most effect on the wake, and the largest effect was observed in the wake generated by the most permeable material. The principal effect of the porous media was to cause the eyes of the recirculation region to be located further downstream. The effect of the permeability is increasingly diminished in the square and rectangular geometries. The presence of the porous media also had a significant effect on the Reynolds stresses. The effect of the porous media applied is to damp the normal stresses further downstream of the bluff bodies.
      2  2