Analysis of Unsteadiness in Afterbody Transonic Flows

Deprés, David; Reijasse, Philippe; Dussauge, Jean‐Paul

doi:10.2514/1.7000

Cited by 95 publications

(131 citation statements)

References 13 publications

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“…Comparison of the wall pressure coe©cient distribution computed via zonal RANS/LES (1) to experimental data [16] (2) from the base shoulder corresponding to 5 boundary layer thicknesses, which is su©cient for the RANS/LES transition. Additional mesh re¦ne-ments are realized in the regions with high gradients, e. g., along the boundary and shear layers as well as near the base shoulder.…”

Section: Figurementioning

confidence: 99%

Combined experimental and numerical investigation of a transonic space launcher wake

Scharnowski

Statnikov

Meinke

et al. 2015

Progress in Flight Physics – Volume 7

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Combined experimental und numerical investigations of the turbulent wake of a generic space launcher at transonic free stream conditions (Ma ∞ = 0.7 and Re D = 1.0 · 10 6 ) are performed to gain a better understanding of intricate phenomena of the wake §ow physics and to validate new methods for its analysis. The experiments are conducted at the Bundeswehr University Munich using a high-repetition-rate particle image velocimetry (PIV) system, while the numerical investigation is performed by the Institute of Aerodynamics of RWTH Aachen University using a zonal Reynolds-averaged NavierStokes (RANS) / large-eddy simulation (LES) approach. After a characterization of the wake §ow topology, two applied methodologies are compared to each other with respect to the spatial and temporal resolution stressing their strengths and shortcomings. It is shown that both methods are well suitable for the prediction of the mean and instantaneous values of the turbulent velocity ¦eld, whereas for a reliable statistical analysis of the velocity §uctuations, the PIV approach is more appropriate due to the computational time limitations of the LES. On the other hand, the high spatial and temporal resolution of the LES allows for an accurate detection of relevant coherent structures as well as tracking their motion in time without any signi¦cant arti¦cial vortex agglomeration that can be critical in the case of PIV. Furthermore, the in §uence of di¨erent model assumptions, e. g., the level of incoming turbulence and model vibrations, is discussed in order to emphasize the importance of a side-by-side combination of both investigation techniques.

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Section: Figurementioning

confidence: 99%

Combined experimental and numerical investigation of a transonic space launcher wake

Scharnowski

Statnikov

Meinke

et al. 2015

Progress in Flight Physics – Volume 7

View full text Add to dashboard Cite

show abstract

“…18, originate from the image resection markers. In the case of M 1 ¼ 0:7; the line plots of c p and c p,rms are compared to data from Deprés et al (2004), whose data were acquired with unsteady pressure transducers at M 1 ¼ 0:85 on a comparable geometry, equipped with a cylindrical nozzle of length 1.2 D instead of a rearsting mounting. The good agreement in both c p and c p,rms validates the fact that a high-resolution estimation of pressure fluctuations with small amplitudes is possible by using fast-responding pressure-sensitive paints.…”

Section: Pressure Distributionmentioning

confidence: 99%

Characterization of pressure dynamics in an axisymmetric separating/reattaching flow using fast-responding pressure-sensitive paint

et al. 2012

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This collaborative work discusses the results of time-resolved pressure-sensitive paint measurements performed on a model of a generic spacecraft under sub-and transonic test conditions. It is shown that optical pressure measurements using an active layer from platinumporphyrin complexes (PtTFPP) in combination with a polymer-ceramic base layer are able to measure dynamic flow phenomena in the trisonic wind tunnel facility up to sampling rates of 2 kHz. Low amplitude fluctuations in the order of 0.1 kPa were determined by means of this measurement technique. The buffet dynamics, as well as the spatial extent of the recirculation area in the near-wake, compare well with numerical predictions and PIV measurements. Furthermore, characteristic coherent pressure modes on the base were resolved, which were predicted by large-eddy simulations.

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“…1-3 For the higher Reynolds numbers found at lower altitudes, vortex shedding persists as a coherent large-scale phenomenon superimposed on the turbulent flow field, [4][5][6] which suggests that the present results rigorously derived at moderate Reynolds numbers can carry over as a first step toward the control of the turbulent flow.…”

Section: Introductionmentioning

confidence: 66%

Open-loop control of compressible afterbody flows using adjoint methods

Méliga¹,

Sipp²,

Chomaz

2010

Physics of Fluids

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International audienceThe flow past an axisymmetric body is generically unstable to a steady and a time-periodic global instability, the latter being thought to lead the low-frequency unsteadiness of the wake even at larger Reynolds numbers. The present paper examines how the growth rate of the oscillatory unstable mode developing in the wake of bullet-shaped objects can be reduced by a steady forcing, whose effect is to modify the base flow. The use of the compressible Navier-Stokes equations allows to consider control through steady mass, momentumheat forcing applied in the bulk and at the wall. To do so, we extend to compressible flows and axisymmetric geometries the method first proposed by Hill (NASA Technical Report No. 103858, 1992) to analyze the control of the two-dimensional mode of the incompressible cylinder wake. This method aims at evaluating the sensitivity of one particular eigenvalue to forcing by resolution of adjoint equations. Considering control at the wall, it allows to compute directly the eigenvalue gradient with respect to the wall variables. We show that the oscillating mode can be stabilized by a steady blowing at the wall (the so-called base-bleed control). Expressing the gradient as a sum of production, streamwise advectioncross-stream advection terms, we show that this stabilizing effect is due to cross-stream advection, in contradiction with the up to now accepted interpretation based on the local absolute and convective instability analysis of parallel profiles. The same technique allows to compute the gradient of the oscillatory eigenvalue to bulk mass, momentumheat sources. Momentum control can be achieved by placing a small ring in the lee of the afterbody. Similar to the two-dimensional case studied by Hill, the effect of such a ring is twofold, as it induces a steady drag force which modifies the base flow and a fluctuating drag force proportional to the perturbation momentum at the ring location. We show that the efficiency of the control can be improved by heating the ring, which then acts as an additional heat source. © 2010 American Institute of Physics

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Analysis of Unsteadiness in Afterbody Transonic Flows

Cited by 95 publications

References 13 publications

Combined experimental and numerical investigation of a transonic space launcher wake

Combined experimental and numerical investigation of a transonic space launcher wake

Characterization of pressure dynamics in an axisymmetric separating/reattaching flow using fast-responding pressure-sensitive paint

Open-loop control of compressible afterbody flows using adjoint methods

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