Compressibility effects on the vortical flow over a 65° sweep delta wing

Abstract

Dynamically stretching and retracting wingspan has been widely observed in the flight of birds and bats, and its effects on the aerodynamic performance particularly lift generation are intriguing. The rectangular flat-plate flapping wing with a sinusoidally stretching and retracting wingspan is proposed as a simple model for biologically inspired dynamic morphing wings. Numerical simulations of the low-Reynolds-number flows around the flapping morphing wing are conducted in a parametric space by using the immersed boundary method. It is found that the instantaneous and time-averaged lift coefficients of the wing can be significantly enhanced by dynamically changing wingspan in a flapping cycle. The lift enhancement is caused by both changing the lifting surface area and manipulating the flow structures responsible to the vortex lift generation. The physical mechanisms behind the lift enhancement are explored by examining the three-dimensional flow structures around the flapping wing. C 2014 AIP Publishing LLC. [http://dx.

Compressibility effects for the AGARD-B model

“…In contrast to Riou et al (9) and Kalkhoran et al (25) , the vortex breakdown is not triggered by a streamwise normal shock because no such shock exists for this configuration. Given that vortex breakdown occurs at similar angles for low speeds (17) and transonic speeds, the cause for the vortex breakdown has been attributed to the adverse pressure gradient of the flow over the circular arc profile.…”

“…Given that vortex breakdown occurs at similar angles for low speeds (17) and transonic speeds, the cause for the vortex breakdown has been attributed to the adverse pressure gradient of the flow over the circular arc profile. Similar to Riou et al (9) is the 'kidney' shaped vortex rather than the circular vortex of incompressible speeds.…”

“…The primary region of interest in this paper is the lower angle-of-attack leading edge separation region with a secondary vortex. Riou et al (9) studied the centreline shock region and identified a complex lambda shock structure in the region of the secondary vortex rather than a simple normal shock.…”

Zones of Influence and Shock Motion in a Shock/Boundary-Layer Interaction

“…in the recent years to analyze successfully compressible flows either by DES, LES and DNS [15][16][17]. The numerical scheme is designed to be able to capture the shock while meeting the LES requirement of very low dissipation in the turbulent region [18].…”

Control of Separated Flow over Swept Missile Fin Using Pitching Oscillations

“…The agreement of the results with the existing experimental data was very satisfactory since, for example, the errors on the lift and drag coefficients were found equal to 3 and 1.3%, respectively. Furthermore, this hybrid Reynoldsaveraged Navier-Stokes/large-eddy simulation approach has been successfully applied to the study of compressibility effects on the vortical flow over a highly swept wing [13] and to its control [14]. The grid is composed of 21 10 6 points.…”