The purpose of a multi-element high lift device is to increase lift dramatically
while controlling the stall limit. The fluid flow over a multi-element high lift device
has been explored widely both experimentally and numerically at high Reynolds
numbers (O(10^6 )). The numerical simulations use turbulence models and hence
details of the flow are not yet available. Low Reynolds number (O(10^4 )) flows
over high lift devices have not been explored until recently. These lower Reynolds
number flows have applications in the development of small aerial vehicles. The
present work discusses both two-dimensional and three-dimensional direct numer-
ical simulations of fluid flow over a 30P30N three-element high lift system using a
high-order spectral element method code, Nek5000, that solves the incompressible
Navier-Stokes equations. The intricate geometry of the multi-element device poses
a challenge for the high-order spectral element method. We study the complex
flow physics in the slat cove region and the wake/shear layer interaction over a
30P30N three-element high lift device. The targeted cases are at Reynolds num-
bers based on stowed chord lengths (Rec ) of 8.32 × 10^3 , 1.27 × 10^4 , and 1.83 × 10^4 at angle of attack of 4. A critical interval for Rec has previously been found
between 1.27 × 10^4 and 1.38 × 10^4 in experiments. This divides the flow into
two types: when Rec is below the critical interval, no roll-up is observed in the
slat cove and Görtler vortices dominate the slat wake; however when the Rec is
above the critical interval, a roll-up is observed in the slat cove and co-existence
of streamwise and spanwise vortices is confirmed in the slat wake. We confirm
the presence of the critical interval from the simulations performed at three values of Rec . Lift and drag analysis is provided along with pressure coefficient plots
for each element of the multi-element airfoil. Different vortical structures are also
identified in the transition of flow from two dimensions to three dimensions. The
relevant validation is performed with the available experimental data.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/40964 |
| Date | 10 September 2020 |
| Creators | Vadsola, Mayank |
| Contributors | Mavriplis, Catherine, Agbaglah, Gbemeho Gilou |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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