Презентация на тему Simulation of wing-body junction flows with hybrid RANS/LES methods

an obstruction
At realistic large Reynolds number, the adverse pressure

gradient in the streamwise direction imposed by the wing often causes the upwind boundary layer on the body to separate and form multiple horseshoe vortices around the wing
Better understanding and accurate prediction of the junction flows can effectively help the design of lower drag and high-efficiency flight vehicles

a NACA 0020 tail model) – have experimental results
NASA

TN D-712 – has interference flows at high angles of attack with a low-Re two-equation k–g model which requires no parameterization of the distance to the wall

based on a compressible solver using a Roe flux-difference

splitting scheme with a 3rd order monotone upstream scheme
A modified fully implicit lower–upper symmetric Gaussian Seidel (LUSGS, Yoon and Jameson, 1987; Xiao et al., 2006) model with Newton-like sub-iteration in pseudo time is taken as the time marching method when solving the mean flow and the turbulence model equations
Global non-dimensional time stepping is implemented to capture the unsteady properties of the separation flows

method
The production terms are treated explicitly, lagged in time

while the dissipation and diffusion terms are treated implicitly
The advective terms are discretized using second order upwind scheme. The diffusive terms are discretized using a second-order central scheme.

(from experiment)
at x/T = 16: outflow (zero streamwise gradients)
at

y/T = 0, y/T = 7 and z/T = 3: symmetric
at z/T = 0: wall (no-slip)

k with the WD+ and SST

on two grids

on the symmetric plane

different streamwise positions (maximum thickness, middle and trailing edge

of the wing)

the wing-body junction (a) shear stress lines and vortex

in the wake; (b) upwind symmetry plane horseshoe vortex and (c) vortices near the trailing edge

kinetic energy and cross-streamwise normal stress near the trailing

edge (x/T = 3.95)

and the vertical flow vectors in the wake (x/T

= 6.38)

junction.

106 (based on halfspan)
Angle of attack is 12.5o
Computation

parameters

methods near the junction

wing with RANS, DES and DDES methods.

different AoAs (Left: 12.5; Right: 26.2)

streamwise positions by DDES. 2x/B = 1.667, 1.833, 2.167

and 2.500.