Turbulence Kinetic Energy Balance in the Wake of a Sharp-edged Highly Swept Delta Wing

Abstract

Hot-wire measurements in the wake of a flat plate delta wing, at a fixed angle of attack, were carried-out in order to investigate its turbulence kinetic energy budget. The purpose of this study is to help acquire more information about the vortex structure formed in the wake region of the delta wing and to provide data for turbulence models' validation. Point measurements were conducted in five planes perpendicular to the flow, on a high spatial resolution two-dimensional measurement grid that allowed precise derivative calculations of the flow quantities needed for the derivation of the kinetic energy budget. The turbulence kinetic energy convection, production, viscous diffusion and turbulence diffusion terms were directly obtained from the experimental data, whereas dissipation and pressure diffusion terms were calculated indirectly using techniques presented and validated in previous studies. All of the terms of the turbulence kinetic energy budget, along with the velocity components and the Reynolds stresses, are presented and discussed.Keywords Delta wing · Hot-wire anemometry · Measurement · Turbulence kinetic energy balance · Vortex breakdown · Wake NomenclatureEnglish symbols C k convection term of the TKE budget D p pressure diffusion term of the TKE budget D t turbulence diffusion term of the TKE budget D v viscous diffusion term of the TKE budget e iso isotropic expression for the dissipation term of the TKE budget k turbulence kinetic energy per unit mass

Assessment of Computational Fluid Dynamic for Surface Combatant 5415 at Straight Ahead and Static Drift β = 20 deg

“…Both T and PT transport energy away from vortex core such that |T p /Pr p |$1.25 and |PT p /Pr p |$0.7. The TKE distribution in the core, peak Pr at the breakdown, and the role of C and T in TKE distribution are consistent with those observed in delta wing [42] and KVLCC2 flows. However, both the 5415 and KVLCC2 flows show high dissipation compared to the delta wing flow.…”

Aerodynamic efficiency and performance enhancement of fixed-wing unmanned aerial vehicles using novel configurations and techniques

“…All other experiments, including the surface oil flow visualizations, the LDA and the force balance measurements, were conducted with a freestream velocity of 13.4m/s at the test section, held constant within 1%, corresponding to Reynolds numbers of 33 x 10 3 and 25 x 10 4 , based on the tip and the root (centerline) chord of the models respectively. Those Reynolds numbers are in agreement with previously published studies related to wingtip vortices [28,30] and leading-edge separation [66,135]. The turbulence intensity was measured at 0.7%.…”

“…Even though the flow visualizations do not provide quantitative results, they can be used to identify any existing flow phenomena over, and around the examined configurations. Thus, valuable information about flow field the can be extracted, that velocity or force measurements cannot provide on their own, as noted in [66]. Moreover, the visualization results can help a long way in preparing other experiments, e.g.…”

“…Moreover, regarding the sampling time, both preliminary measurements and the corresponding literature [66,79,80] are considered. That way, an investigation of the apparent frequencies in the lower frequency range is made, ensuring that the acquisition time is adequately long for providing reliable mean values.…”