Analysis and Correlation of Data on Pressure Fluctuations in Separated Flow

Mabey, D. G.

doi:10.2514/3.59053

Cited by 134 publications

(60 citation statements)

References 6 publications

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“…This maximum is located just upstream of the mean reattachment point location. This is coherent both with the present experimental measurements and the data collected from a numerous con¦gurations of separated §ows [11]. Nevertheless, noticeable discrepancies appear in the second part of the recirculation region where the levels are overestimated by a factor 2 at the end of the afterbody.…”

Section: Pressure Fluctuations Levelssupporting

confidence: 78%

Simulation of afterbody transonic flows using partially-averaged navier stokes model for turbulence

Deprés¹,

Brenner²

2012

Progress in Flight Physics

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This investigation is dedicated to the elaboration of a numerical strategy to simulate accurately and at a reasonable cost the main unsteady features of high Reynolds separated §ows. Within this framework, the Partially-Averaged Navier Stokes (PANS) turbulence model has been used. In this hybrid approach, the modeled-to-resolved scale ratio (the level of physical resolution) is introduced and set explicitly in the closure model of the unresolved scales which is based on the ReynoldsAveraged Navier Stokes (RANS) paradigm. The §ow separation behind an axisymmetric afterbody has been simulated. The large-scale coherent structures are captured and the comparison of the results with wallpressure measurements shows that the §ow physics simulated is relevant. Nevertheless, these encouraging results need to be con¦rmed by deeper investigations on the model behavior and its sensitivity to physical as well as numerical parameters. This step of validation is mandatory before considering an extensive use of the approach at an industrial level.

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Section: Pressure Fluctuations Levelssupporting

confidence: 78%

Simulation of afterbody transonic flows using partially-averaged navier stokes model for turbulence

Deprés¹,

Brenner²

2012

Progress in Flight Physics

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“…zone. Gurbacki points out that the location of the peak RMS C p is consistent with RMS pressures observed in backward facing step flows [39][40][41][42] and flows over blunt flat plates. 43,44 Instabilities in the shear layer eventually generate spanwise vortices, which amalgamate to form larger vortical structures.…”

Section: Horn-ice Flowfieldsupporting

confidence: 50%

Experimental Study of Full-Scale Iced Airfoil Aerodynamic Performance Using Sub-Scale Simulations

Busch

Bragg

2009

1st AIAA Atmospheric and Space Environments Conference

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Determining the aerodynamic effects of ice accretion on aircraft surfaces is an important step in aircraft design and certification. The goal of this work was to develop a complete sub-scale wind tunnel simulation methodology based on knowledge of the detailed iced-airfoil flowfield that allows the accurate measurement of aerodynamic penalties associated with the accretion of ice on an airfoil and to validate this methodology using full-scale iced-airfoil performance data obtained at near-flight Reynolds numbers. In earlier work, several classifications of ice shape were developed based on key aerodynamic features in the iced-airfoil flowfield: ice roughness, streamwise ice, horn ice, and tall and short spanwise-ridge ice. Castings of each of these classifications were acquired on a full-scale NACA 23012 airfoil model and the aerodynamic performance of each was measured at a Reynolds number of 12.0 x 10 6 and a Mach number = 0.20. In the current study, sub-scale simple-geometry and 2-D smooth simulations of each of these castings were constructed based on knowledge of iced-airfoil flowfields. The effects of each simulation on the aerodynamic performance of an 18-inch chord NACA 23012 airfoil model was measured in the University of Illinois 3 x 4 ft. wind tunnel at a Reynolds number of 1.8 x 10 6 and a Mach number of 0.18 and compared with that measured for the corresponding full-scale casting at high Reynolds number. Geometrically-scaled simulations of the horn-ice and tall spanwise-ridge ice castings modeled C l,max to within 2% and C d,min to within 15%. Good qualitative agreement in the C p distributions suggests that important geometric features such as horn and ridge height, surface location, and angle with respect to the airfoil chordline were appropriately modeled. Geometrically-scaled simulations of the ice roughness, streamwise ice, and short-ridge ice tended to have conservative C l,max and C d . The aerodynamic performance of simulations of these types of accretion was found to be sensitive to roughness height and concentration. Scaled roughness heights smaller than those ii found on the casting were necessary to improve simulation accuracy, resulting in C l,max and C d,min within 3% and 5% of the casting, respectively.iii

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“…The predicted amplitude of pressure fluctuations in the present case is higher than the peak r.m.s. fluctuation in Cp of 0.06 previously measured near the reattachment downstream of a backward facing step [52]. Certainly, a part of the difference in Cp' magnitudes may be related to the inherent differences between the respective flow configurations and the larger than expected spanwise coherence in the computational simulations (see subsection 3. below); however, it will be very useful to have future measurements of slat pressure fluctuations near the reattachment region to help resolve this important issue.…”

Section: Pressure Fluctuationsmentioning

confidence: 99%

Slat Cove Unsteadiness: Effect of 3D Flow Structures

Choudhari

Khorrami

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

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Our previous studies have indicated that 2D, time accurate computations based on a pseudo-laminar zonal model of the slat cove region (within the framework of the Reynolds-Averaged Navier-Stokes equations) are inadequate for predicting the full unsteady dynamics of the slat cove flow field. Even though such computations could capture the large-scale, unsteady vorticity structures in the slat cove region without requiring any external forcing, the simulated vortices were excessively strong and the recirculation zone was unduly energetic in comparison with the PIV measurements for a generic high-lift configuration. To resolve this discrepancy and to help enable physics based predictions of slat aeroacoustics, the present paper is focused on 3D simulations of the slat cove flow over a computational domain of limited spanwise extent. Maintaining the pseudo-laminar approach, current results indicate that accounting for the threedimensionality of flow fluctuations leads to considerable improvement in the accuracy of the unsteady, nearfield solution. Analysis of simulation data points to the likely significance of turbulent fluctuations near the reattachment region toward the generation of broadband slat noise. The computed acoustic characteristics (in terms of the frequency spectrum and spatial distribution) within short distances from the slat resemble the previously reported, subscale measurements of slat noise.

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Analysis and Correlation of Data on Pressure Fluctuations in Separated Flow

Cited by 134 publications

References 6 publications

Simulation of afterbody transonic flows using partially-averaged navier stokes model for turbulence

Simulation of afterbody transonic flows using partially-averaged navier stokes model for turbulence

Experimental Study of Full-Scale Iced Airfoil Aerodynamic Performance Using Sub-Scale Simulations

Slat Cove Unsteadiness: Effect of 3D Flow Structures

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