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Spanwise vortex dislocation in the wake of segmented blunt trailing edge

DSpace at IIT Bombay

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Title Spanwise vortex dislocation in the wake of segmented blunt trailing edge
 
Creator DESHPANDE, PJ
SHARMA, SD
 
Subject Vortex dislocation
Spanwise flow
Streamwise vortices
Vortex shedding
BLUFF-BODY
BASE DRAG
3-DIMENSIONAL INSTABILITIES
VORTICAL STRUCTURES
CIRCULAR-CYLINDER
TRANSITION
FLOW
REDUCTION
PATTERNS
BODIES
 
Description Dislocation of the Karman vortex is forced in the near wake behind a two dimensional blunt trailing edge aerofoil to induce strong three dimensionality to weaken the Karman vortex and inhibit its periodic shedding by segmenting the trailing edge in a novel way, different from a rectangular segmented trailing edge tried in the past. Symmetrical trapezoidal prismatic blocks, with the major and the minor sides being equal to 4 and 2 base heights, respectively, are attached to the base at regular intervals along the span which could be varied in order to render multiple wavelengths of spanwise discontinuity to ensure that at least one of the modes of dislocation is triggered independent of the Reynolds number. Hot-wire measurements confirm effectiveness of the trailing edge configurations with trapezoidal prismatic blocks in creating controlled dislocation along the span which annihilates the Karman vortices and suppresses their periodic shedding completely. Flow visualization in a water tunnel reinforces the hot-wire results and clearly shows that the classical Karman vortex street, seen behind the plain base model, disappears when segmented trailing edge is used. In comparison, the rectangular segmented trailing edge is found to attenuate the Karman vortex strength only partially. However, the base pressure measurements have shown improvement in reducing the associated base drag only by 3-4%. The segmented trailing edges designed for the present study are found to generate strong streamwise vortices that effectively transfer energy from the Karman vortices resulting in suppression of the unsteadiness but, perhaps, lower pressures in their core may be restricting the further rise in the base pressure due to the induced effect. (C) 2012 Elsevier Ltd. All rights reserved.
 
Publisher ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
 
Date 2014-10-16T14:39:48Z
2014-10-16T14:39:48Z
2012
 
Type Article
 
Identifier JOURNAL OF FLUIDS AND STRUCTURES, 34202-217
http://dx.doi.org/10.1016/j.jfluidstructs.2012.04.004
http://dspace.library.iitb.ac.in/jspui/handle/100/15807
 
Language en