Seven hole probe measurement of leading edge vortex flows
TL;DR: In this paper, the use of a seven-hole probe on measurements of leading edge vortices of highly sweep delta wing planforms was compared with nonintrusive measurements made with laser Doppler anemometry system.
Abstract: This paper discusses the use of a seven-hole probe on measurements of leading edge vortices of highly sweep delta wing planforms. Intrusive probe data taken with the pressure probe were compared with nonintrusive measurements made with laser Doppler anemometry system. In addition to probe size, the natural position of breakdown and the sweep angle of the wing are also factors in determining sensitivity of the flow to probe interference. At low angles of attach vortex breakdown does not occur in the vicinity of the model and the seven hole probe was found to yield reasonably accurate measurements. When the angle of attack of the model was increased so that vortex breakdown was near the trailing edge, introducing the probe over the wing would cause the breakdown position to move ahead of the probe. However, when breakdown naturally occurred ahead of the mid-chord of the wing the vortices were found to be less sensitive to a probe placed behind the breakdown point. Vortex breakdown on a lower swept wing is found to be more sensitive to interference. Near the breakdown region, seven hole probe measurement is less accurate due to a combination of probe interference and flow reversal.
Citations
More filters
TL;DR: In this article, cross-wire measurements of the flow field above a 75-deg flat-plate delta wing have yielded distributions of velocity, axial vorticity, and circulation which exhibit strongly conical behavior upstream of the breakdown region and away from the apex and trailing edge regions.
Abstract: The present cross-wire measurements of the flowfield above a 75-deg flat-plate delta wing have yielded distributions of velocity, axial vorticity, and circulation which exhibit strongly conical behavior upstream of the breakdown region and away from the apex and trailing edge regions. The conical character of these properties is most pronounced over the central portion of the planform, away from the apex and trailing-edge regions. This behavior is further documented by the roughly linear increase in vortex strength with distance from the apex over the forward area of the wing.
101 citations
TL;DR: In this article, an overview of experimental investigations on a 65 deg swept delta wing as part of the International Vortex Flow Experiment 2 (VFE-2) is presented, with details of the delta wing vortex structure and breakdown phenomenon are discussed and analyzed.
48 citations
42 citations
TL;DR: In this article, the interaction of vortex breakdown with an oscillating e n was investigated by visualization and velocity measurements to understand the effects of aeroelastic dee ections on buffeting.
Abstract: The interaction of vortex breakdown with an oscillating e n was investigated by e ow visualization and velocity measurements to understand the effects of aeroelastic dee ections on e n buffeting. For frequencies lower than a cutoff frequency, the response of vortex breakdown location is quasi periodic, and the amplitude of the variations of breakdown location decreases with increasing frequency. For frequencies higher than the cutoff frequency, vortex breakdown does not respond to the e n oscillations. These observations suggest that the dynamic response of breakdown location to an oscillating e n is similar to that of a low-pass e lter. For different locations of the e n with respect to the vortex, similar amplitude responses were found. This result can be used in the design of e ns to prevent a feedback effect and coupling between the vortex breakdown and e n structure. A theoretical explanation of the experimental observations based on the wave propagation characteristics of the vortex e ows is presented.
37 citations
TL;DR: In this article, the growth and eventual breakdown of the leading-edge vortices of a delta wing were investigated in a wind tunnel at Reynolds numbers of order 10 5, where the flowfield along the trailing edge was mapped out via a seven-hole probe designed, constructed and calibrated to general time-resolved information.
Abstract: The transient flowfield over a delta wing during pitch-up motions to very large angles of attack was investigated. Emphasis was directed at the growth and the eventual breakdown of the leading-edge vortices. Delta wing models were tested in a wind tunnel at Reynolds numbers of order 10 5 . The flowfield along the trailing edge was mapped out via a seven-hole probe designed, constructed, and calibrated to general time-resolved information. Instantaneous surface pressure measurements were also obtained. Earlier qualitative evidence of hysteresis in the development of the flow was confirmed. Moreover, the present data indicate significant differences of vorticity content between the steady and the steady motions, for reduced frequencies as low as 0.01
32 citations
References
More filters
TL;DR: Vortex breakdown on slender sharp edged and modified delta wings with varying sweep angles investigated in wind tunnel using schlieren system for flow visualization as discussed by the authors, using Schlieren-based flow visualization.
Abstract: Vortex breakdown on slender sharp edged and modified delta wings with varying sweep angles investigated in wind tunnel using schlieren system for flow visualization
282 citations
"Seven hole probe measurement of lea..." refers background in this paper
...It has been pointed out by Wentz and Kohlman (1971) that since the adverse pressure gradient is maximum near the trailing edge of a delta wing the breakdown location is most unstable there....
[...]
01 Jan 1979
106 citations
TL;DR: In this article, a method for calibrating seven-hole probes to measure local total and static pressures and relative flow angles of up to 70 degrees in subsonic compressible flows is presented.
Abstract: This paper illustrates a method for calibrating seven-hole probes to measure local total and static pressures and relative flow angles of up to 70 degrees in subsonic compressible flows. The method of Latin Squares was used to statistically sample a large and otherwise unmanageable data set, thereby reducing to a minimum the number of data points required to construct a polynomial curve fit to the data. Calibration produces three-variable third order polynomials which permit all of the desired flow properties to be found explicitly from probe measured pressures. This method determines the flow angles to within 2 degrees and Mach number to within 0.04 with 95 percent certainty.
47 citations
01 Jun 1987
TL;DR: In this paper, a combination of flow visualization, seven-hole pressure probe surveys and laser velocimeter measurements were used to study the leading edge vortex formation and breakdown for a set of delta wings.
Abstract: An experimental study of the leading edge vortices on delta wings at large angles of incidence is presented. A combination of flow visualization, seven-hole pressure probe surveys and laser velocimeter measurements were used to study the leading edge vortex formation and breakdown for a set of delta wings. The delta wing models were thin flat plates with sharp leading edges having sweep angles of 70, 75, 80, and 85 degrees. The flow structure was examined for angles of incidence from 10 to 40 degrees and chord Reynolds numbers from 85,000 to 640,000. Vortex breakdown was observed on all the wings tested. Both bubble and spiral modes of breakdown were observed. The visualization and wake survey data shows that when vortex breakdown occurs the core flow transforms abruptly from a jet-like flow to a wake-like flow. The result also revealed that probe induced vortex breakdown was more steady than the natural breakdown.
35 citations