TY - JOUR
T1 - Unsteady aerodynamics analysis and modelling of a Slingsby Firefly aircraft
T2 - Detached-Eddy Simulation model and flight test validation
AU - Neves, A. F.
AU - Lawson, N. J.
AU - Bennett, C. J.
AU - Khanal, B.
AU - Hoff, R. I.
PY - 2020/11
Y1 - 2020/11
N2 - This paper presents unsteady stall characteristics of a Slingsby T67M260 Firefly light aircraft from both a computational fluid dynamics (CFD) half model and flight tests. Initial results from the steady CFD, based on a RANS k−ω SST turbulence model, established the critical angle of attack of the stall to be αstall=16∘, with a maximum lift coefficient of CLmax=1.2. Comparisons with straight and level flight test data were comparable up to α=12∘ – 14∘, with the increasing deviation at higher α attributed to the effect of the propeller slipstream under these flight conditions. The RANS CFD model was then extended to an unsteady Detached-Eddy Simulation (DES) model for three angles of attack at pre-stall and stall condition (α=14∘, 16∘, 18∘), with analysis of the vortex shedding frequency. Further comparisons were then made with flight test data taken using on-board accelerometers and wing tuft surface flow visualization, at a stalled condition at equivalent α. These unsteady CFD data established a dominant shedding frequency ranging from 11.7 Hz – 8.74 Hz with increasing α and a Strouhal number based on wing chord of St = 0.11, which when compared to flight test accelerometer spectra matched within 2.9% of the measured frequency.
AB - This paper presents unsteady stall characteristics of a Slingsby T67M260 Firefly light aircraft from both a computational fluid dynamics (CFD) half model and flight tests. Initial results from the steady CFD, based on a RANS k−ω SST turbulence model, established the critical angle of attack of the stall to be αstall=16∘, with a maximum lift coefficient of CLmax=1.2. Comparisons with straight and level flight test data were comparable up to α=12∘ – 14∘, with the increasing deviation at higher α attributed to the effect of the propeller slipstream under these flight conditions. The RANS CFD model was then extended to an unsteady Detached-Eddy Simulation (DES) model for three angles of attack at pre-stall and stall condition (α=14∘, 16∘, 18∘), with analysis of the vortex shedding frequency. Further comparisons were then made with flight test data taken using on-board accelerometers and wing tuft surface flow visualization, at a stalled condition at equivalent α. These unsteady CFD data established a dominant shedding frequency ranging from 11.7 Hz – 8.74 Hz with increasing α and a Strouhal number based on wing chord of St = 0.11, which when compared to flight test accelerometer spectra matched within 2.9% of the measured frequency.
KW - Buffet frequency
KW - CFD
KW - Detached-Eddy Simulation
KW - Flight test
KW - Stall
KW - Strouhal number
UR - http://www.scopus.com/inward/record.url?scp=85091649833&partnerID=8YFLogxK
U2 - 10.1016/j.ast.2020.106179
DO - 10.1016/j.ast.2020.106179
M3 - Article
AN - SCOPUS:85091649833
VL - 106
JO - Aerospace Science and Technology
JF - Aerospace Science and Technology
SN - 1270-9638
M1 - 106179
ER -