Experimental investigation of a three-dimensional bluff-body wake

AIAA Journal ◽  
1993 ◽  
Vol 31 (3) ◽  
pp. 559-563 ◽  
Author(s):  
A. Ahmed ◽  
M. J. Khan ◽  
B. Bays-Muchmore
Keyword(s):  
Experimental Investigation ◽  
Bluff Body ◽  
Three Dimensional ◽  
Bluff Body Wake

scholarly journals Stochastic modelling and feedback control of bistability in a turbulent bluff body wake

2016 ◽  
Vol 802 ◽  
pp. 726-749 ◽  
Author(s):  
R. D. Brackston ◽  
J. M. García de la Cruz ◽  
A. Wynn ◽  
G. Rigas ◽  
J. F. Morrison
Keyword(s):  
Reynolds Number ◽  
Feedback Control ◽  
Symmetry Breaking ◽  
Large Scale ◽  
Bluff Body ◽  
Three Dimensional ◽  
Power Saving ◽  
Stochastic Modelling ◽  
Bluff Body Wake ◽  
Modelling Approach

A specific feature of three-dimensional bluff body wakes, flow bistability, is a subject of particular recent interest. This feature consists of a random flipping of the wake between two asymmetric configurations and is believed to contribute to the pressure drag of many bluff bodies. In this study we apply the modelling approach recently suggested for axisymmetric bodies by Rigaset al.(J. Fluid Mech., vol. 778, 2015, R2) to the reflectional symmetry-breaking modes of a rectilinear bluff body wake. We demonstrate the validity of the model and its Reynolds number independence through time-resolved base pressure measurements of the natural wake. Further, oscillating flaps are used to investigate the dynamics and time scales of the instability associated with the flipping process, demonstrating that they are largely independent of Reynolds number. The modelling approach is then used to design a feedback controller that uses the flaps to suppress the symmetry-breaking modes. The controller is successful, leading to a suppression of the bistability of the wake, with concomitant reductions in both lateral and streamwise forces. Importantly, the controller is found to be efficient, the actuator requiring only 24 % of the aerodynamic power saving. The controller therefore provides a key demonstration of efficient feedback control used to reduce the drag of a high-Reynolds-number three-dimensional bluff body. Furthermore, the results suggest that suppression of large-scale structures is a fundamentally efficient approach for bluff body drag reduction.

Response of a Rod Stabilized, Premixed Flame to Longitudinal Acoustic Forcing

2006 ◽  
Author(s):  
Santosh J. Shanbhogue ◽  
Tim C. Lieuwen
Keyword(s):  
Experimental Investigation ◽  
Flame Front ◽  
Coherent Structures ◽  
Large Scale ◽  
Bluff Body ◽  
Premixed Flame ◽  
Longitudinal Acoustic ◽  
Harmonic Response ◽  
Flame Sheet ◽  
Bluff Body Wake

This paper describes an experimental investigation of the flame sheet dynamics of an acoustically forced bluff body flame over a range of perturbation frequencies and amplitudes. When acoustically excited, the flame sheet displays well defined, periodic corrugations, presumably due to flame sheet perturbations created at its attachment point that convect downstream, as well as the rollup of shear layer instabilities into large scale coherent structures. The dynamics of the flame front response, such as its growth and decay in the bluff body wake, disturbance convection velocity, sub-harmonic response, and total flame area is discussed.

scholarly journals On three-dimensional bluff body wake symmetry breaking with free-stream turbulence and residual asymmetry

2020 ◽  
Vol 348 (6-7) ◽  
pp. 509-517
Author(s):  
Olivier Cadot ◽  
Maha Almarzooqi ◽  
Antoine Legeai ◽  
Vladimir Parezanović ◽  
Luc Pastur
Keyword(s):  
Symmetry Breaking ◽  
Bluff Body ◽  
Free Stream ◽  
Three Dimensional ◽  
Free Stream Turbulence ◽  
Bluff Body Wake

WAVELET-BASED INVESTIGATION OF THE HIGH REYNOLDS NUMBER BLUFF BODY WAKE TOPOLOGY

2006 ◽  
Vol 04 (02) ◽  
pp. 321-332
Author(s):  
ADRIAN DOBRE ◽  
HORIA HANGAN
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Bluff Body ◽  
Three Dimensional ◽  
Square Prism ◽  
Wavelet Techniques ◽  
High Reynolds ◽  
Bluff Body Wake ◽  
Topological Models ◽  
Recognition Technique

The high Reynolds number wake topology of a square prism is experimentally investigated using wavelet analysis. It is shown that a systematic application of one-dimensional continuous wavelet techniques, including a relatively new wavelet pattern recognition technique can reveal important three-dimensional features of the flow, assessing the validity of previously proposed wake topological models. Present results suggest that the high Reynolds number turbulent wakes are topologically similar, but not identical, to their laminar counterparts.

Two-dimensionalization of a three-dimensional bluff body wake

2019 ◽  
Vol 31 (1) ◽  
pp. 017104 ◽  
Author(s):  
Li-Hao Feng ◽  
Guo-Peng Cui ◽  
Li-Yang Liu
Keyword(s):  
Bluff Body ◽  
Three Dimensional ◽  
Bluff Body Wake
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