Organization of an axisymmetric turbulent wake in presence of a central protrusion

Organization of an axisymmetric turbulent wake in presence of a central protrusion

Gentile, V.
Schrijer, F.F.J.
Van Oudheusden, B.W.
Scarano, F.

Aerospace Engineering

Aerodynamics, Wind Energy & Propulsion

2015-07-15

Stereoscopic Particle Image Velocimetry (PIV) was used to study the wake of an ogive-cylinder with after-body at a diameter-based Reynolds number ReD = 6.7 · 104. The vertical fluctuations reduced from a maximum of 0.18 U? in absence of rear-protrusion, up to 0.12 U? and 0.1 U? when the main-body to after- body diameter ratio d/D was increased to 0.2 and 0.4 respectively. For d/D = 0.2 the trace of the backflow centroid motion reflected the occurrence of a random motion where no pattern associated with a consistent precession of the reverse flow region can be identified, whereas a preferred azimuthal direction could be detected for d/D = 0.4. Proper Orthogonal Decomposition showed that modes k = 1, 2 contribute up to 20% and 11% of the turbulent kinetic energy, for d/D = 0.2 and d/D = 0.4 respectively. For d/D = 0.2 the two modes were found to be paired and to feature a dipole organization which is linked to a displacement of the wake in all azimuthal directions. For d/D = 0.4 only the first mode exhibited such an arrangement, thus reflecting wake displacement occurring along a preferred azimuthal direction.

http://resolver.tudelft.nl/uuid:5e669455-da2b-4cf4-8338-6b4643984b2a

ICJWSF 2015: International Conference on Jets, Wakes and Separated Flows, Stockholm, Sweden, 15-18 July 2015

Institutional Repository

conference paper

(c) 2015 The Author(s)