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D'Aguanno, A. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author)This study investigates the possibility of controlling transonic buffet by means of a Gurney Flap with an upward deflection at the trailing edge of the airfoil (UGF). Different geometries and dimensions of UGFs have been studied for their impact on the buffet behaviour. The effectiveness of the UGFs has been tested experimentally with Schlieren...conference paper 2019
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van Oudheusden, B.W. (author)Traditionally in aerospace research, pressure is measured with pressure probes or wall-mounted sensors, while integral loads are obtained by means of balance systems. Recent years have seen the emerging and development of an alternative approach, which exploits Particle Image Velocimetry (PIV) data as a source for the nonintrusive determination...other 2019
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Santiago Patterson, J. (author), Laguarda, L. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author), Hickel, S. (author)An experimental investigation of shock-shock interactions has been conducted with the aim of studying the transition between Regular (RI) and Mach (MI) interactions induced by a variation of the inflow Mach number. The experiments were conducted in the TST-27 wind tunnel at Delft University of Technology. For all cases, the wind tunnel runs were...conference paper 2019
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Laguarda, L. (author), Hickel, S. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author)The dynamic interaction of two planar and asymmetric shock waves at a free-stream Mach number M¥ = 3 is studied numerically in order to characterize the transition between the regular (RI) and Mach (MI) interaction patterns. Shock deflection disturbances are independently introduced in the form of a sinusoidal oscillation of the shock generator....conference paper 2019
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Hu, W. (author), Hickel, S. (author), van Oudheusden, B.W. (author)The unsteadiness of shock wave-boundary layer interactions is investigated in a transitional backward-facing step flow at Ma=1:7 and Red0 =13718 using large eddy simulation. The mean and instantaneous flow shows that the laminar inflow undergoes a laminar-to-turbulence transition in which Kelvin-Helmholtz vortices form, distort and eventually...conference paper 2019
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van Gent, P.L. (author), Payanda, Qais (author), Brust, S.G. (author), van Oudheusden, B.W. (author), Schrijer, F.F.J. (author)The effects of an exhaust plume and nozzle length on the flow organization of axisymmetric base flows have been studied experimentally at Mach numbers of 0.76 and 2.2 using particle image velocimetry. From the measured velocity data, the mean pressure field was computed. The application of different nozzle lengths resulted in flow cases in which...journal article 2019
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Karasek, M. (author), Perçin, M. (author), Cunis, Torbjørn (author), van Oudheusden, B.W. (author), de Wagter, C. (author), Remes, B.D.W. (author), de Croon, G.C.H.E. (author)Flow visualisations are essential to better understand the unsteady aerodynamics of flapping wing flight. The issues inherent to animal experiments, such as poor controllability and unnatural flapping when tethered, can be avoided by using robotic flyers that promise for a more systematic and repeatable methodology. Here, we present a new...journal article 2019
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Vanierschot, M. (author), Muller, Jens S. (author), Sieber, Moritz (author), Perçin, M. (author), van Oudheusden, B.W. (author), Oberleithner, Kilian (author)In this paper, we study the shape and dynamics of helical coherent structures found in the flow field of an annular swirling jet undergoing vortex breakdown. The flow field is studied by means of time-resolved tomographic particle image velocimetry measurements. The obtained flow fields are analysed using both classic and spectral proper...journal article 2019
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Hu, W. (author), Hickel, S. (author), van Oudheusden, B.W. (author)The path of laminar-to-turbulent transition behind a backward-facing step (BFS) in the supersonic regime at Ma = 1.7 and Re<sub>δ</sub><sub>0</sub> = 13718 is investigated using a very well-resolved large eddy simulation (LES). Five distinct stages are identified in the transition process by the visualisation of instantaneous flow. The...conference paper 2019
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van de Meerendonk, R. (author), Perçin, M. (author), van Oudheusden, B.W. (author)The flow field and fluid-dynamic loads of revolving low-aspect-ratio chordwise-flexible wings are studied experimentally at a Reynolds number of 10,000. The investigation involves phase-locked tomographic particle image velocimetry (PIV) complemented with force measurements. The pressure fields are reconstructed from the three-dimensional...journal article 2018
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Del Estal Herrero, A. (author), Perçin, M. (author), Karasek, M. (author), van Oudheusden, B.W. (author)Flow visualizations have been performed on a free flying, flapping-wing micro air vehicle (MAV), using a large-scale particle image velocimetry (PIV) approach. The PIV method involves the use of helium-filled soap bubbles (HFSB) as tracer particles. HFSB scatter light with much higher intensity than regular seeding particles, comparable to that...journal article 2018
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Giepman, R.H.M. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author)High-resolution particle image velocimetry measurements were performed on laminar and transitional oblique shock wave reflections for a range of Mach numbers (M D 1:6-2:3), Reynolds numbers (Re<sub>xsh</sub> D 1.4×10<sup>6</sup>-3.5×10<sup>6</sup>) and flow deflection angles (θ 1°-5° or p3=p1 D 1.11-1.64). The laminar interactions revealed a...journal article 2018
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van Gent, P.L. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author)The present study characterises the spatio-temporal filtering associated with pseudo-tracking. A combined theoretical and numerical assessment is performed that uses the relatively simple flow case of a two-dimensional Taylor vortex as analytical test case. An additional experimental assessment considers the more complex flow of a low-speed...journal article 2018
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van Gent, P.L. (author), Schrijer, F.F.J. (author), van Oudheusden, B.W. (author)Pseudo-tracking refers to the construction of imaginary particle paths from PIV velocity fields and the subsequent estimation of the particle (material) acceleration. In view of the variety of existing and possible alternative ways to perform the pseudo-tracking method, it is not straightforward to select a suitable combination of numerical...journal article 2018
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Vanierschot, M. (author), Perçin, M. (author), van Oudheusden, B.W. (author)In this paper, we report on the structure and dynamics of double helix vortex breakdown in a turbulent annular swirling jet. Double helix breakdown has been reported previously for the laminar flow regime, but this structure has rarely been observed in turbulent flow. The flow field is investigated experimentally by means of time-resolved...journal article 2018
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van Gent, P.L. (author), van Oudheusden, B.W. (author), Schrijer, F.F.J. (author)The feasibility of computing the flow pressure on the basis of PIV velocity data has been demonstrated abundantly for low-speed conditions. The added complications occurring for high-speed compressible flows have, however, so far proved to be largely inhibitive for the accurate experimental determination of instantaneous pressure. Obtaining...journal article 2018
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van Campenhout, O.W.G. (author), van Nesselrooij, M. (author), Veldhuis, L.L.M. (author), van Oudheusden, B.W. (author), Schrijer, F.F.J. (author)Although various experimental studies have confirmed the potential drag reducing effect of dimpled surfaces in a turbulent boundary layer, the working mechanism remains largely unresolved. An experimental investigation has been performed with the objective to strengthen the understanding of this aerodynamic surface and its interaction with...conference paper 2018
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Martinez Gallar, Blanca (author), van Oudheusden, B.W. (author), Sciacchitano, A. (author), Karasek, M. (author)The aim of this investigation is to provide an experimental volumetric visualization of the near wake topology of the vortex structures generated by a flapping-wing Micro Air Vehicle (MAV) by means of large-scale Robotic PIV. This novel technique implements coaxial illumination and imaging in combination with the use of Helium Filled Soap...conference paper 2018
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Del Estal Herrero, A. (author), Perçin, M. (author), Karasek, M. (author), van Oudheusden, B.W. (author)Flow visualizations have been performed on a free flying flapping-wing Micro Air Vehicle (MAV), using a large-scale particle image velocimetry (PIV) approach. The PIV method involves the use of helium filled soap bubbles (HFSB) as tracer particles. HFSB scatter light with much higher intensity than regular seeding particles and comparable to...conference paper 2018
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Terra, W. (author), Sciacchitano, A. (author), Scarano, F. (author), van Oudheusden, B.W. (author)The accuracy of the “PIV wake rake” method to measure the drag of transiting objects is evaluated. Tomographic Particle Image Velocimetry measurements are conducted on a sphere towed at different speeds, within a Reynolds number range where the drag coefficient is constant. In contrast to PIV wake rake application on steady models in wind...conference paper 2018