Effects of Spanwise Geometric Disturbances on a Bluff Body Wake

2006 ◽  
Author(s):  
Tat Loon Chng ◽  
Her Mann Tsai
Keyword(s):  
Bluff Body ◽  
Bluff Body Wake

Open Loop Transient Forcing of an Axisymmetric Bluff Body Wake

2008 ◽  
Author(s):  
Stefan Siegel ◽  
Jürgen Seidel ◽  
Kelly Cohen ◽  
Selin Aradag ◽  
Thomas McLaughlin
Keyword(s):  
Bluff Body ◽  
Open Loop ◽  
Transient Forcing ◽  
Bluff Body Wake

Control of vortex shedding in an axisymmetric bluff body wake

2000 ◽  
Vol 19 (5) ◽  
pp. 789-812 ◽  
Author(s):  
Ansgar Weickgenannt ◽  
Peter A. Monkewitz
Keyword(s):  
Vortex Shedding ◽  
Bluff Body ◽  
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.

0319 Optimizing driving conditions of plasma actuators for bluff-body wake control

2009 ◽  
Vol 2009 (0) ◽  
pp. 187-188
Author(s):  
Takashi Matsuno ◽  
Kentaro Ota ◽  
Takashi Kanatani ◽  
Hiromitsu Kawazoe
Keyword(s):  
Bluff Body ◽  
Plasma Actuators ◽  
Driving Conditions ◽  
Bluff Body Wake

scholarly journals Investigation of the dissipation in the wake of a wind turbine array

2021 ◽  
Author(s):  
Ingrid Neunaber ◽  
Joachim Peinke ◽  
Martin Obligado
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Bluff Body ◽  
Wind Farms ◽  
Energy Transition ◽  
Mean Velocity ◽  
Maintenance Time ◽  
Bluff Body Wake ◽  
Turbine Wake ◽  
Wind Turbine Wake

Abstract. Within the energy transition, more and more wind turbines are clustered in big wind farms, often offshore. Therefore, an optimal positioning of the wind turbines is crucial to optimize both the annual power production and the maintenance time. Good knowledge of the wind turbine wake and the turbulence within is thus important. However, although wind turbine wakes have been subject to various studies, they are still not fully understood. One possibility to improve the comprehension is to look into the modeling of bluff body wakes. These wakes have been the subject of intensive study for decades, and by means of the scaling behavior of the centerline mean velocity deficit, the nature of the turbulence inside a wake can be classified. In this paper, we introduce the models for equilibrium and non-equilibrium turbulence from classical wake theory as introduced by A. Townsend and W. George, and we test whether the requirements are fulfilled in the wake of a wind turbine. Finally, we apply the theory to characterize the wind turbine wake, and we compare the results to the Jensen and the Bastankhah-Porté-Agel model. We find that the insight into the classical bluff body wake can be used to further improve the wind turbine wake models. Particularly, the classical bluff body wake models perform better than the wind turbine wake models due to the presence of a virtual origin in the scalings, and we demonstrate the possibility of improving the wind turbine wake models by implementing this parameter. We also see how the dissipation changes across the wake which is important to model wakes within wind farms correctly.

Sign in / Sign up

Export Citation Format

Share Document