| 1. |
- Bourgoin, M., et al.
(författare)
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Investigation of the small-scale statistics of turbulence in the Modane S1MA wind tunnel
- 2018
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Ingår i: CEAS Aeronautical Journal. - : Springer. - 1869-5582 .- 1869-5590. ; 9:2, s. 269-281
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Tidskriftsartikel (refereegranskat)abstract
- This article describes the planning, set-up, turbulence characterization and analysis of measurements of a passive grid turbulence experiment that was carried out in the S1MA wind-tunnel from ONERA in Modane, in the context of the ESWIRP European project. This experiment aims at a detailed investigation of the statistical properties of turbulent flows at large Reynolds numbers. The primary goal is to take advantage of the unequaled large-scale dimensions of the ONERA S1MA wind-tunnel facility, to make available to the broad turbulence community high-quality experimental turbulence data with unprecendented resolution (both spatial and temporal) and accuracy (in terms of statistical convergence). With this goal, we designed the largest grid-generated turbulence experiment planned and performed to date. Grid turbulence is a canonical flow known to produce almost perfectly homogeneous and isotropic turbulence (HIT) which remains a unique framework to investigate fundamental physics of turbulent flows. Here, we present a brief description of the measurements, in particular those based on hot-wire diagnosis. By comparing results from classical hot-wires and from a nano-fabricated wire (developed at Princeton University), we show that our goal of resolving down to the smallest dissipative scales of the flow has been achieved. We also present the full characterization of the turbulence here, in terms of turbulent energy dissipation rate, injection and dissipation scales (both spatial and temporal) and Reynolds number.
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| 2. |
- Coudert, S., et al.
(författare)
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Double large field stereoscopic PIV in a high Reynolds number turbulent boundary layer
- 2011
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Ingår i: Experiments in Fluids. - : Springer Science and Business Media LLC. - 1432-1114 .- 0723-4864. ; 50:1, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- An experiment on a flat plate turbulent boundary layer at high Reynolds number has been carried out in the Laboratoire de Mecanique de Lille (LML, UMR CNRS 8107) wind tunnel. This experiment was performed jointly with LEA (UMR CNRS 6609) in Poitiers (France) and Chalmers University of Technology (Sweden), in the frame of the WALLTURB European project. The simultaneous recording of 143 hot wires in one transverse plane and of two perpendicular stereoscopic PIV fields was performed successfully. The first SPIV plane is 1 cm upstream of the hot wire rake and the second is both orthogonal to the first one and to the wall. The first PIV results show a blockage effect which based on both statistical results (i.e. mean, RMS and spatial correlation) and a potential model does not seem to affect the turbulence organization.
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| 3. |
- Delville, J., et al.
(författare)
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The WALLTURB joined experiment to assess the large scale structures in a high reynolds number turbulent boundary layer
- 2011
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Ingår i: ERCOFTAC Series. - Dordrecht : Springer Netherlands. - 1382-4309 .- 2215-1826. - 9789048196029 ; 14, s. 64-73
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Konferensbidrag (refereegranskat)abstract
- Experiments, involving the joint effort of three European teams and aiming at using the state-of-the-art techniques to study the dynamics of the high Reynolds turbulent boundary layer, have been performed in June 2006 in the LML large wind tunnel. A set of four stereoscopic PIV systems and a rake of 143 hot wires were used to provide synchronised measurements. This paper summarises these ex-periments, presents sample results of both PIV and hot-wire rake data and illustrates the complementarity of such a coupled approach that combines the advantages of each technique.
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| 4. |
- Foucaut, J. M., et al.
(författare)
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Spatial correlation from the SPIV database of the WALLTURB experiment
- 2011
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Ingår i: ERCOFTAC Series. - Dordrecht : Springer Netherlands. - 1382-4309 .- 2215-1826. - 9789048196029 ; 14, s. 85-93
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Konferensbidrag (refereegranskat)abstract
- An original experiment has been performed in the frame of the WALLTURB EC project. In this experiment a specific set-up of SPIV allows to compute the full 3D tensor of velocity spatial correlation by using the homogeneity of the flow. The two-point correlations are tools to study the coherence of a flow. Stanislas et al. (C. R. Acad. Sci. Paris 2b 327:55–61, 1999) and Kahler (Exp. Fluids 36:114–130, 2004) showed that double spatial correlations, computed from Particle Image Velocimetry (PIV) fields, allow a better understanding of the turbulent flow organization.
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| 5. |
- Stanislas, M., et al.
(författare)
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Calibration of the WALLTURB experiment hot wire rake with help of PIV
- 2011
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Ingår i: ERCOFTAC Series. - Dordrecht : Springer Netherlands. - 1382-4309 .- 2215-1826. - 9789048196029 ; 14, s. 75-84
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Konferensbidrag (refereegranskat)abstract
- In the WALLTURB LML experiment presented in Delville et al. (Stanislas, M., Jimenez, J., Marusic, I. (eds.) Progress in Wall Turbulence: Understanding and Modeling. Proceedings of the WALLTURB International Workshop Held in Lille, France, April 21–23, 2009. ERCOFTAC Series, vol. 14. Springer, Dordrecht, 2011), the calibration of the hot wire rake had to be performed on site, due to the large number of wires on the rake (143). For that purpose, the position of the wires with respect to the wall was carefully measured using two complementary techniques. The blockage effect due to the rake was characterized using StereoPIV and modeled using a simple potential flow model. The results show that the blockage affects mostly the mean flow and not the turbulence itself. Finally, the calibration data were built using the StereoPIV data in a plane located 1 cm upstream of the wires plane. The mean velocity, the second and third moments were provided. The calibration was checked on the fourth moment of the fluctuating velocity. © Springer Science+Business Media B.V. 2011.
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| 6. |
- Tutkun, Murat, 1977, et al.
(författare)
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In situ calibration of hot wire probes in turbulent flows
- 2009
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Ingår i: Experiments in Fluids. - : Springer Science and Business Media LLC. - 1432-1114 .- 0723-4864. ; 46:4, s. 617-629
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Tidskriftsartikel (refereegranskat)abstract
- A method for in situ calibration of hot-wires in a turbulent flow is presented. The method is particularly convenient (even necessary) for calibrating large probe arrays, like the 143-wire boundary layer rake of the WALLTURB experiment. It is based on polynomial expansion of the velocity statistics in terms of voltage statistics as originally described by George et al. [Exp Ther Fluid Sci 2(2):230-235, 1989]. Application of the method requires knowing reference mean velocity and higher order central moments (with the array in place) of the turbulent velocity at the probe location at only one freestream velocity. These were obtained in our experiment by a stereo PIV plane just upstream of the probe array. Both the procedure for implementing the method and sample results are presented in the article.
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| 7. |
- Tutkun, Murat, 1977, et al.
(författare)
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Two-point correlations and POD analysis of the WALLTURB experiment using the hot-wire rake database
- 2011
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Ingår i: ERCOFTAC Series. - Dordrecht : Springer Netherlands. - 1382-4309 .- 2215-1826. - 9789048196029 ; 14, s. 95-102
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Konferensbidrag (refereegranskat)abstract
- We use the novel hot-wire rake of 143 single wire probes to measure 30 cm thick boundary layer of the large LML wind tunnel at Reynolds number based on momentum thickness of 9800 and 19 100. Multiple-point cross-correlation analysis using the data from the hot-wire rake show that the physical length of the correlation contour in the streamwise direction is about 7 boundary layer thickness. In addition, the shape of the correlations maps obtained from two-point correlations on the streamwise–wall-normal plane retains its shape approximately throughout the entire boundary layer. The data is also used for POD analysis of the boundary layer using only the streamwise turbulent fluctuations. The normalized eigenvalue distribution shows that the first POD mode has more than 40% of the turbulence kinetic energy, while the second one has about 20% of the total turbulence kinetic energy for both of the Reynolds number tested here. It is possible to recover about 90% of the kinetic energy only using the first four POD modes. The reconstructed velocity fluctuations on the spanwise–wall-normal plane show how organized motions of turbulence with significant amounts of energy interact with each other across the boundary layer. It is also possible to observe the strength of the interaction between the inner and outer layer using these reconstructed velocity fields.
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| 8. |
- Tutkun, Murat, 1977, et al.
(författare)
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Two-point correlations in high Reynolds number flat plate turbulent boundary layers
- 2009
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Ingår i: Journal of Turbulence. - : Informa UK Limited. - 1468-5248. ; 10:21, s. 1-23
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Tidskriftsartikel (refereegranskat)abstract
- Two-point correlations of turbulent boundary layer are presented for Re. of 9800 and 19,100. The results are based on wind tunnel measurements performed in the 30 cm thick boundary layer of the 21.6 m long LML (Laboratoire de Mecanique de Lille) boundary layer research facility. Simultaneous hot-wire probe measurements of the entire boundary layer at 143 different points on an array are used for computation of the two-point correlations. The two-point correlations in the streamwise-spanwise plane at 11 different wall-normal positions covering one boundary layer thickness in the spanwise direction show that the maximal extension of the correlations in the streamwise direction is bounded within +/- 3.5 delta for both of the Reynolds number tested. The shapes of the positive correlations in the streamwise-spanwise plane at different wall-normal positions are similar throughout the boundary layer from nearly the freestream to the wall. The correlations in the streamwise-wall-normal plane for 11 different wall-normal reference positions also show that the correlations in some cases cover the entire boundary layer. The streamwise extent of the correlations in the streamwise-wall-normal plane is about 7-8 boundary layer thicknesses. Two-point correlation maps for the streamwise-wall-normal plane reveal the existence of non-zero correlations between even the intermittent region and near-wall region.
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