Numerical simulation of maneuvering combat aircraft

Folie 1 > HLRS 2005 > A. Schütte14. Oktober 2005

Andreas Schütte

DLR - German Aerospace CenterInstitute of Aerodynamics and Flow Technology

Oct. 14th 2005, Stuttgart

Numerical simulation of maneuvering combat aircraft


Gunnar Einarsson, Britta Schöning, Axel Raichle,Wulf Mönnich, Thomas Alrutz, Jens Neumann, Jörg Heinecke

DLR - German Aerospace CenterInstitute of Aerodynamics and Flow Technology

Oct. 14th 2005, Stuttgart

Numerical simulation of maneuvering combat aircraft


OverviewMotivation

Objectives

Simulation Environment

Experimental Simulation

Numerical Results

HPC Requirements and Resources

Summary and Outlook


HPC – RequirementsInstitut of Aerodynamics and

Flow TechnologyBraunschweig /Göttingen


Motivation

Source: Cenaero


Objectivesof the DLR Project SikMa

Prediction of the unsteady behavior of maneuvering aircraft.

Development of a numerical simulation environment for calculating maneuvers of a free flying elastic combat aircraft.

Realized a by multi disciplinary time-accurate coupling of CFD, Structure Dynamics and Flight Mechanics within the framework TENT.

SikMa is a multidisciplinary project were several DLR Institutes are involved:

Institute of Aerodynamics and Flow TechnologyInstitute of AeroelasticityInstitute of Flight SystemsDLR Sistec


Simulation Environment TENTCodes are implemented in TENT via wrappers. TENT carries out data transfers and communication between codes.TENT can distribute applications over different platforms

SimBrowser:Definition of grid hierarchies for CHIMERA gridsdefinition of all movements of parts and grids relative to each otheranimation and test of movements creation of “motion” and “hierarchy” files for the CFD-Code-TAU


DLR TAU-CodeCFD-Code

solution of RANS equations for arbitrarily moving bodies on unstructured meshes hybrid meshes (hex., prisms, tetra., pyram.)FV using dual grid approach, MG acceleratedunsteady via dual time stepping state-of-the-art turbulence modelsgrid adaptation (refinement & de-refinement)CHIMERA techniquedeforming mesh capability designed for massively parallel computersvalidated for a large number of test cases


DLR TAU-Code Chimera approach

Chimera boundary of the flap

Chimera boundary of the wing

Realized soon: Automatic hole-cutting approach


Stream lines & Total pressure distribution

DLR TAU-Code Mesh adaptation (unsteady calc.)

History of mesh adaptation


SIMULAFlight mechanics library

Simulation environment SIMULA delivers the solutions of the flight mechanics equations

Trimming calculationAnalyze stabilityManeuver simulations with 6 DoF and control devices

Coupling of Aerodynamics/Flight mechanicsImplicit time integration schemeClose coupling within each pseudo time-step

Implemented models for SikMaRolling delta-wing with trailing-edge flapsGeneric 6-DoF model (e.g. X-31)


CSM-CodeStructural mechanics simulation

Two approachesDiscrete approach: Coupling with the overall FE-ModelModal approach: Coupling with characteristic Eigenmodes

CharacteristicsCoupling Aerodynamics/Structure: Loose/weak coupling scheme –coupling within each physical time stepSolving the CSM-equations: Implicit Newmark integration-schemeSpatial coupling: Scattered data interpolation methods for force and deformation transferCoupling in time: Conventional Serial Staggered-algorithm with predictor- /corrector step for the CSM calculationDetermination of the system matrices: Reduced system matrices MAA and KAA imported from NASTRAN


Experimental SimulationWind tunnel experiments

ObjectivesGenerating a validation data base for the numerical simulation.Knowledge approach of the aerodynamic behavior of configurations with vortex dominated flow fields

Configurations1. Delta-wing-configuration with movable trailing-edge flaps

2. X-31 CFRP and Remote-Control-Model with remote controlled flaps, rudder and canard for maneuver simulations on the Model-Positioning-Mechanism (MPM) at NWB


Experimental SimulationWind tunnel facilities

Transonic Wind Tunnel Göttingen (TWG)

Test section 1x1mMach number range: 0.3 ÷1.2 (with perf. walls)Re = 1.8 × 106 (based on 0.1√s)

Low Speed Wind Tunnel Braunschweig (NWB)

Test section 3.25 × 2.8mMach number range: 0 ÷0.26 (for open test section)Re = 1.8 x 106 (based on 0.1√s)


Experimental SimulationWind tunnel models

Delta-wing-configuration with trailing-edge flaps

Internal 6-component piezo-balancePiezo-resistive pressure sensors at 60% and 80% chord lengthControl device velocity up to 300°/s

X-31 configuration with remote controlled control devices

CFRP fuselage, steel wing and aluminum made control devices8 internal servo engines for control device movementInternal 6-component strain gauge Pressure sensors for measuring the unsteady pressure distribution at 60% and 70% chord length Internal 64 channel 16 bit telemetric system for data transfer


MPM - ”Model Positioning Mechanism”Maneuver simulation in the wind tunnel

Synchronized, dynamic similarmovement of model and control devices in comparison to flight tests

Parallel kinematicsSteward platform connected to electromagnetic linear motors by 6 rods of constant length


Numerical Results

Guided coupled simulation of CFD and CSM

Coupled free-to-roll maneuver simulation of CFD, CSM and Flight Mechanics

Coupled free-to-roll maneuver of delta-wing-configuration with movable trailing-edge flaps (CFD-FM-Coupling)

X-31: first steady calculations


FE-Model of delta-wing andrear sting support

Numerical Results (1)Delta wing guided rolling motion around longitudinal axisCSM-TAU-Coupling


Numerical Results (1)Delta wing guided rolling motion around longitudinal axisCSM-TAU-Coupling


Numerical Results (2)Delta wing guided rolling motion around longitudinal axisCSM-TAU-FM-Coupling


Numerical Results (3)Delta wing free-to-roll motion around longitudinal axisTAU-FM-Coupling

Ma = 0.5Re = 3.8MioΘ = 17°Φ0 = 0°η = ±5°



12 3

4



Flap down

Flap up

O clO Φ


α=14°α=18°α=22°

Numerical Results (4)Flow simulation around X-31 configuration (clean wing)


separation line

attachement line

Tau-CalculationOil Flow Picture

Numerical Results (4)Flow topology of X-31 (clean wing)

Ma=0.12Re=1.0Mioa=18°


Numerical Results (4)Flow simulation around X-31 configuration

TAU-Calculation:Re = 2.07Mioα =18°

PSP-Measurement:Re = 2.07Mioα =18°


HPC Requirements and Resources (1)Calculation times and resources today


Herbstmaneuver: 10 s

HPC Requirements and Resources (2)Requirements on HPC Cluster-HardwareManeuver Simulation

X-31 configuration, movable control devices~30 Million grid pointsunsteady simulation with DLR-TAU-CodeCFD / CSD / FMManeuver simulation of 2 seconds real timeAim: 2 weeks

Approximation on target platformHWW-Cluster Strider (64 Proc, 64 Bit): 30 Mio. grid points2 s real time, 2000 physical time steps,600 inner Iterations ~ 950 h wall clock~ 40 days on HWW-Cluster Strider (64 Proz)~ 14 days on Cluster with > 256 Processors


Summary

Development strategy for the prediction of the behavior of maneuvering aircraft

Simulation environment and its elements

Experimental simulation for validation data base

First results showing the capability of time-accurate coupling of CFD/FM- and CFD/CSD/FM-Coupling

First CFD results of the complex flow topology over the X-31 configuration

Need for HPC resources were demanded

Numerical simulation of maneuvering combat aircraft

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