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From ARUP, ARA, Willams F1

Abstract¶

This document summarizes some initial results obtained within the second order benchmarking of a new CFD software. The zCFD code was used for the DLR F11 high lift configuration in order to compute the flow field using the k-ω SST turbulence model. The results consist of high Reynolds number computations for the simplified (Case 1) and complex (Case 2B) configurations at \(7^\circ\) angle of attack. The results were validated against the numerical solutions obtained using CFD++ and ANSYS FLUENT and showed a good agreement with the experimental data.

Introduction¶

The zCFD code is a GPU accelerated high performance computational fluid dynamic software. The zCFD solver is an unstructured cell centered finite volume code which solves explicitly the compressible Navier-Stokes equations. The solution is preconditioned and the convergence is accelerated using the Multigrid technique along with a dual time stepping method.

The results consist in high Reynolds number computations using k-ω SST turbulence model for the simplified (Case 1) and complex (Case 2B) configurations at \(7^\circ\) angle of attack. The zCFD solutions were compared with wind tunnel data and other CFD codes such as Metacomp CFD++ and Ansys FLUENT. These codes were selected since they use the same cell-centered approach in combination with k-ω SST model.

Results¶

Case 1, Coarse mesh (9.5M cells), \(Mach=0.175\), \(Re=15e6\), \(\alpha=7^\circ\)

Case 2b, Solar mesh (50M cells), \(Mach=0.175\), \(Re=15e6\), \(\alpha=7^\circ\)

DLR F11 High Lift Configuration; Locations of Pressure Sections. For the full definition of cutting planes refer to workshop website.

Configuration ( Wing-Body no Tail ) , L3 mesh unstructured hexahedral - 5.1 x 106 cells - Match CL = 0.5¶

NASA Common Research Model

Conditions¶

Reynolds number = 5.0 x e06 based on MAC

Mach = 0.85

Angle of attack = 2.217

Reference static pressure = 101325 Pa

Reference static temperature = 310.928 K

RANS steady state

k-W SST model

Preconditioned

MUSCL scheme for

Results¶

\(\circ\) Isosurfaces of Mach number

\(\circ\) CL match for L3 mesh unstructured hexahedral mesh

\(\circ\) Code to code validation

Abstract¶

In the present study the flow field around \(65^\circ\) delta wing is investigated using the unstructured density based solver zCFD. The simulations were carried out by solving the steady state RANS equations using the k-ω SST turbulence model at :math:‘13.3^circ’ flow angle for :math: ‘Re=6.0e06’ (NASA) and :math:’Re=3.0e06’ based on MAC. Within this analysis the numerical solutions are compared against wind tunnel results performed at NASA and DLR.

Geometry Specification¶

The geometry has been generated using the analytical definition available in the reference (Chu and Luckring). For the present study two sets of simulations were performed: (1) Comparison against the experiment performed at NASA and (2) Comparison against the experiment performed at DLR as part of the VFE 2 project.

Delta wing geometry

Results¶

Steady state RANS, SOLAR - octree mesh (30M cells), \(Mach=0.4\), \(Re=6.0e06\) (based on MAC = 0.3268 m)

\(\circ\) Large Radius - Validation against NASA Wind Tunnel Experiment

\(\circ\) Sharp Radius - Validation against NASA Wind Tunnel Experiment

\(\circ\) Large (right) and Sharp radius (left)

Abstract¶

In this section the flow field around DARPA SUBOFF geometry is computed using the unstructured cell centered finite volume density based solver zCFD. For this study the AFF8 configuration was employed due to complex flow features such as boundary layer - vortex and vortex-vortex interactions. The Reynolds number for this test case is \(Re=1.2e07\) and the employed turbulence model is k-ω SST. The steady state solutions are validated against wind tunnel data (see Reference) and have shown agreement.

Configuration (Axisymmetric hull + Fairwater + Stern appendages )¶

SUBOFF Configuration

Results¶

Steady state RANS, SOLAR - octree mesh (14 and 30 M cells), \(Mach=0.0179\), \(Re=1.2e7\) (model length based)

Coefficient of pressure in the symmetry plane

Coefficient of pressure contours

Wake development ( Left – Coarse Mesh ; Right – Fine Mesh )

x/L = 0.3

x/L = 0.4

x/L = 0.5

x/L = 0.978 (Propeller Plane)

Comparison against zCFD, experimental data and Bhushan et al (2013) (FLUENT)

x/L = 0.978 (Propeller Plane)

Abstract¶

Geometry and Mesh Generation (SMC-006 Nozzle)¶

SMC006 chevron type nozzle. Left (Model) and Right (Domain Topology ) (Xia et. al. (2009))

SMC006 mesh on x-y plane. Multiblock Stuctured Mesh (19M cells) (Xia H. and Tucker P. (2009))

Initial Conditions (Steady-State RANS)¶

Ambient Conditions

Jet Conditions

Results¶

Jet velocity profiles in the Tip-to-Tip plane at different stations

Jet velocity profiles in the Notch plane at different stations

Comparison between LES study of Xia et. al. (2009) (top) and present RANS study (bottom) at different stations

Isosurfaces of Q criterion (present study)

• Note

The Reynolds number is based on the jet diameter and reference velocity

Abstract¶

Geometry and Mesh Generation (NASA ROTOR37)¶

Parameters¶

Initial Conditions (Steady-State RANS)¶

Ambient Conditions

Inflow Total Conditions.

Results¶

Note that the map has been initially generated by varying the static pressure ratio on the outflow from 0.7 to 1.8 in order to determine the chocked and stalled conditions.

Cp distribution on the rotor blades

Mach number in the flow field and pressure contours.

Turbulent eddy viscosity and pressure contours

More results will be publised in the following weeks.

References¶