MULTI-PHYSICS MODELING
PSAAP Center, Stanford University
V. Terrapon, R. Pecnik, J. Larsson, B. Morgan, A. Irvine, F. Ham, I. Boyd, G. Iaccarino, H. Pitsch, S. Lele, P. Moin
Shock-turbulence interaction
Complex physical phenomena are involved
Canonical shock/turbulence interaction
Flamelet-based combustion model
Shock
Train
(M ~ 2.5)
Motivation and objectives
•Drastic changes in structure and
statistics of turbulence and in
shock structure
•Need to elucidate underlying
physics and dynamics, and to
devise novel and more physicsbased turbulence models
Approach
•DNS simulation of interaction
between isotropic turbulence and
shock
•Solution-adaptive high-order
central/WENO method with
minimal numerical dissipation
•Run on up to 65,536 cores on the
BG/P machine
Flow
Mach ~8
Heat
Losses
Work performed by B. Morgan
Motivation and objectives
•Heat release model is critical to
accurately predict unstart by thermal
choking
Fuel
Injection
Turbulent
Boundary Layer
Heat
Losses
Laminar/Turbulent
Boundary Layer
Forebody Ramp
Isotropic turbulence passing through
a nominally normal shock wave. The
figure shows the shock as a
transparent sheet and eddies colored
by the vorticity magnitude. Note the
increased vorticity, decreased size,
and predominant alignment in the
shock-plane of the post-shock
eddies.
Inlet/Isolator
Combustor
Nozzle/Afterbody
Approach
•Flamelet-based approach with
tabulated chemistry
•Temperature computed from energy
and not looked up from table
•3 additional transport equation for
mixture fraction and progress variable
• Accurate chemistry mechanism
(improved GRI-3.0)
Temperature in [K]
OH mass fraction
Water mass fraction (progress variable)
Unfueled side
inside walls
Full-system simulation
Fueled side
RANS simulation of the DLR HyShot II ground
experiment: contours along combustor bottom wall,
along symmetry planes and at different crosssections. Mass flow rate of H2 injected corresponds to
an equivalence ratio of ϕ=0.3.
Isolator bottom
wall / side wall
corner, pressure
contour plot
indicates induced
bow shocks
Shock / turbulent boundary layer interaction
LES
of
SWTBLI:
turbulent
structures visualized by the
second invarient of the velocity
gradient tensor (Q) and colored
by the streamwise vorticity
Mixing and
combustion
(M > 1)
Bow Shock
Work performed by J. Larsson
LES of SWTBLI: contours of instantaneous
density gradient magnitude at half span and
instantaneous streamwise velocity contours
near the wall (y/δ = 0.05, y+ = 24)
Injection, mixing and combustion
Comparison with DLR HyShot II ground
experiment: normalized pressure along
the inside walls at the symmetry plane of
the unfueled and fueled sides, pressure
normalized by the static pressure at the
isolator/combustor inlet.
Motivation and objectives
•Oblique shock/boundary layer
interaction common in scramjet
shock train
•Limits scramjet inlet/isolator
operability
•Difficult to predict using RANS
•Need to quantify modeling errors
and develop improved reduced
order models.
Work performed by V. Terrapon
Radiation
Pressure contour plots
for unfueled and fueled
combustor of the Hyshot
II scramjet simulation
Approach
•LES of oblique shock/boundary
layer interaction
•High-order compact differencing
scheme
•Localized Artificial Diffusivity
(LAD) for shock capturing with
dilatation-based switching
function
•Rescale/Reintroduction with
spanwise shifting used to
generate inflow BCs
H2 injectors, wall
streak lines and
pressure contours of
scramjet combustor
Pressure contour of
bow shock at forebody
leading edge
Full system RANS simulation
• Cold: 3D with side walls, Spalart-Allmaras
• Hot: FPVA with H2 injection, no side walls,
Spalart-Allmaras
Motivation and
objectives
•Quantify uncertainty in
wall heating of
combustor/nozzle from
Radiative Thermal
Transport (RTT)
Comparison of Monte Carlo RTT
code with Fleck and Cummings
results (J. Comp. Phys. Vol. 8, 1971)
for cold slab heated by a blackbody.
Approach
•RTT code using
implicit MC method
•Spectral modeling of
hydrogen scramjet
species
Work performed by R. Pecnik and V. Terrapon
Acknowledgments
This work was supported by the United States Department of Energy under the Predictive Science Academic Alliance Program (PSAAP) at Stanford University
Comparison of spectral code with
Nelson results (J. Thermophysics
and Heat Transfer, Vol. 11, 1997)
for model combustor at M=14.
Emitting species are H2O and OH.
Work performed by A. Irvine