A new calibration and data reduction method for turbulence measurement by multihotwire probes

Lemonis, G.; Dracos, Themistocles

doi:10.1007/bf00211387

Cited by 21 publications

(12 citation statements)

References 8 publications

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“…In a recent analytical work Vukoslavčević et al [68] extend the theoretical uniqueness limit for sensor arrays similar to those used in the present study to 39 • when the data reduction algorithm is taking into account signals from all four wires of an array, whereas the use of three wires limited the uniqueness domain to 26 • in a certain direction. Lemonis and Dracos [38] have investigated the uniqueness domain of a 4-wire probe in conjunction with present data reduction method, described above, by means of reverse computation of calibration data. Several data points within the cone [α, β] ∈ [±40, ±40] have been always recovered correctly along with a significant percentage of data points extending outside this range.…”

Section: The Experiments Setupmentioning

confidence: 99%

“…The jet nozzle is rotatable about the pitch and yaw directions, its motion being automatically controlled with an accuracy of better than 0.01 • . The calibration as well as the data reduction techniques are refinements of those used by Lemonis and Dracos [38], based on the lookup-table method, which is considered to be one of the best alternative for processing hot -wire measurements (Van Dijk and Nieuwstadt [67]). Velocity estimates are obtained assuming that the velocity does not change substantially across a four wire array.…”

Section: The Experiments Setupmentioning

confidence: 99%

“…Values between the equidistant grid points are interpolated by means of 3D Bezier polynomials. Calibration methodology is extensively described in Lemonis and Dracos [38], Cavo et al [9].…”

Section: The Experiments Setupmentioning

confidence: 99%

“…3), measures simultaneously the three dimensional velocity vector at three locations on a cross plane of the flow field. The design and construction of the probe as well as the measurement and data reduction techniques rely upon the work of Lemonis [39] and Lemonis and Dracos [38], who established the accuracy, sensitivity and reliability of the technique in grid turbulence and boundary layer measurements. The concept was further improved and refined at the University of Patras.…”

Section: The Experiments Setupmentioning

confidence: 99%

“…The four different sub-array solutions are used for the estimation of the velocity vector at the centroid of each four wire array. The technique has been described extensively and tested by Lemonis [39] and Lemonis and Dracos [37,38]). …”

Section: The Experiments Setupmentioning

confidence: 99%

See 4 more Smart Citations

Multisensor Hot Wire Vorticity Probe Measurements of the Formation Field of Two Corotating Vortices

Romeos

Lemonis

Papailiou

2009

Flow Turbulence Combust

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Experimental evidence is reported, regarding the formation of a pair of co-rotating tip vortices by a split wing configuration, consisting of two half wings at equal and opposite angles of attack. Simultaneous measurements of the threedimensional vector fields of velocity and vorticity were conducted on a cross plane at a downstream distance corresponding to 0.3 cord lengths (near wake), using an in-house constructed 12-sensor hot wire anemometry vorticity probe. The probe consists of three closely separated orthogonal 4-wire velocity sensor arrays, measuring simultaneously the three-dimensional velocity vector at three closely spaced locations on a cross plane of the flow filed. This configuration makes possible the estimation of spatial velocity derivatives by means of a forward difference scheme of first order accuracy. Velocity measurements obtained with an X-wire are also presented for comparison. In this near wake location, the flow field is dictated by the pressure distribution established by the flow around the wings, mobilizing large masses of air and leading to the roll up of fluid sheets. Fluid streams penetrating between the wings collide, creating on the cross plane flow a stagnation point and an "impermeable" line joining the two vortex centres. Along this line fluid is directed towards the two vortices, expanding their cores and increasing their separation distance. This feeding process generates a dipole of opposite sign streamwise mean vorticity within each vortex. The rotational flow within the vortices obligates an adverse streamwise pressure gradient leading to a significant streamwise velocity deficit characterizing the vortices. The turbulent flow field is the result of temporal changes in the intensity of the vortex formation and changes in the position of the cores (wandering).

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Section: The Experiments Setupmentioning

confidence: 99%

Section: The Experiments Setupmentioning

confidence: 99%

“…Values between the equidistant grid points are interpolated by means of 3D Bezier polynomials. Calibration methodology is extensively described in Lemonis and Dracos [38], Cavo et al [9].…”

Section: The Experiments Setupmentioning

confidence: 99%

Section: The Experiments Setupmentioning

confidence: 99%