Hypersonic Morphing for a Cabin Escape System Aerothermodynamics analysis of the Spaceliner Cabin Escape System modified via a morphing system E. Laroche, Y. Prevereaud, J.L. Vérant, F. Sourgen, ONERA D. Bonetti, DEIMOS.
HYPMOCES : Objectives of the aerothermodynamics analysis ONERA responsible of the Aerothermodynamis DataBase of HYPMOCES program Build the general aerothermodynamic environment of the escape vehicle at different characteristic flight points and for several configurations of the wings and flaps. Analyse the microaerothermodynamic phenomena at the most critical points involving the morphing structures. Analyse transient effects during morphing process. Provide the detailed aerodynamics during morphing to update the AEDB at system level (WP2, 3), as well Provide the heat fluxes distribution to be used for structural design in WP4 and for flight corridor computation in WP3.
Outline of the talk Modelling strategy Flow topology analysis Pressure coefficients results / analysis Heat transfer issues Conclusions
Modelling strategy AETDB constructed with 2 tools combined CEDRE detailed NS solver, In-house ONERA s platform dedicated to the simulation of energetics flows, with general unstructured capabilty FAST, Aerothermodynamics Design code based on modified Newton s law Detailed aerothermodynamics calculations : CEDRE Variation of angle of attack, systematic comparison between configurations when detailed calculations not available : FAST Question : What kind of confidence for simplified methos (FAST)?
CEDRE Calculation matrix Matrix of CFD cases available from Design Loop 1 ID Vehicle AoA Elevator AoS Aileron Scope Phase Deliv. Date 1 Undeployed 35 15 0 0 First run DL1 31-ago 2 Undeployed 35-10 0 0 Elevator DL1 31-ago 3 Baseline 35 15 0 0 First run DL1 31-ago 4 Baseline 35 15-5 0 Sideslip DL1 31-ago 5 Backup 35 15 0 0 First run DL1 31-ago Matrix of CFD cases to be run in Design Loop 2 ID Vehicle AoA Elevator AoS Aileron Scope Phase Deliv. Date 1 Baseline 35 15-10 0 Sideslip Pre-Loop 2 10-oct 2 Baseline 35-10 0 0 Elevator Pre-Loop 2 17-oct 3 Baseline 10 15 0 0 AoA Pre-Loop 2 24-oct 4 Baseline 20 0 0 5 Aileron DL2 5-feb 5 Baseline 20 0-10 0 Sideslip DL2 17-feb 6 Baseline Evo3 10 15 0 0 Heat Flux DL2 7 Baseline 35 15 0 0 Flaps sizing DL2 Micro Aetd Transient Aetd Next Steps (2015) Start by February 2015 (Availability of "worst" vehicle geometry OML, from DLR/AVS) Start by May 2015 (Availability of variable geometry during morphing, from DLR/AVS)
Geometries considered Undeployed Baseline Geometries provided by DLR Simplified shape at flap hinges Back-up
Example of 3D mesh : -10 configuration
Navier-Stokes modelling Laminar flow Chemical non-equilibrium, Park s kinetics Wall assumed totally catalytic, recombining to upstream values, partial catalycity also possible Wall assumed to be at radiative equilibrium Worst point conditions V=6314 m/s, P=29.5 Pa, T=253 K Reference point AoA = 35
NS convergence process Around 25 000 iterations to get convergence, starting from rest Progressive increase in CFL number from 0.1 to 1 Calculations on ONERA s own supercomputer (SGI) Performed on 256 cores Restitution time for 1 calculation around 100 000 s, so depending on availability of cores, around 3 to 4 days to get converged calculation (not the first calculation where parameters are tuned up) Not the same as FAST where return time ranges from a few minutes to half an hour!
Flow topology for the baseline configuration High pressure level behind the bow shock, especially in the stagnation point area Flow separation upstream of the flaps related to shock/shock interaction, and reattachment on the flaps : high pressure level Unsteady behavior in the flaps area (cf separation) Large recirculation zone behind the capsule (wake) No shock/rudder interaction
Flow topology in flap area
Analysis of pressure coefficients Comparison of results obtained with FAST and CEDRE to determine key points/differences Basis : comparison between undeployed, baseline (and backup) configurations
Analysis of pressure coefficients : undeployed a) Cp CEDRE b) Cp FAST c) Δ Cp / Cp CEDRE (%) Figure 1: Comparison of pressure coefficient distributions obtained with CEDRE and FAST on undeployed configuration for the worst case and = 15, = 35, = 0.
Analysis of pressure coefficients : baseline a) Cp CEDRE b) Cp FAST c) Δ Cp / Cp CEDRE (%) Comparison of pressure distributions obtained with CEDRE and FAST on baseline configuration for the worst case and = 15, = 35, = 0.
Analysis of pressure coefficients : undeployed -10 a) Cp CEDRE b) Cp FAST c) Δ Cp / Cp CEDRE (%) Comparison of pressure distributions obtained with CEDRE and FAST on undeployed configuration for the worst case and = -10, = 35, = 0.
Pressure coefficients partial conclusions Fairly good agreement between FAST and CEDRE, except in flap region At stagnation, maximum pressure overestimated by FAST by 10% Pressure maximum at stagnation point, but also on the flap for the 15 case, due to separation of the boundary layer + reattachment Expected effect on moment, not necessarily on forces Coming to aerodynamics coefficients, baseline better by 11% wrt undeployed : downrange increased by more than 10%
Heat transfer issues : baseline a) Φ CEDRE b) Φ FAST c) Δ Φ / Φ CEDRE (%) Comparison of heat flux distribution obtained with CEDRE and FAST on baseline configuration for the worst case and = 15, = 35, = 0
Heat transfer issues : undeployed, flaps -10 a) Φ CEDRE b) Φ FAST c) Δ Φ / Φ CEDRE (%) Comparison of heat flux distribution obtained with CEDRE and FAST on undeployed configuration for the worst case for = -10, = 35, = 0.
Heat flux distribution on morphing structures : baseline configuration Side view of the capsule Zoom on the rudder
Heat flux distribution on morphing structures : configuration effect Baseline Back-up
Heat transfer : partial conclusions Highest heat flux at stagnation points, but also on flaps for large deflections. A value around 800 kw/m2 is expected Probably sizing, because of the full recombination assumption at the wall Heat flux distribution evaluated on the basis of CEDRE NS solver : available input for thermomechanical analysis
Conclusions The AETDB was generated with a NS solver and compared with a design tool to identify major differences Major differences exist on the flaps, especially for large deflections. This can lead to a wrong estimation of the moment coefficients Heat transfer was analysed and is available for thermo-mechanical analysys. The differences can be sizing in the flap region The heat fluxes predicted on morphing systems are just at the acceptable limit from a thermomechanical point of view
BACK-UP
Perspectives The AETDB will be completed by extra-calculations defined during PM1 with the other partners The transient calculation corresponding to the deployment of morphing structures will be tackled in the coming months
FAST platform Design code based on modified Newton s law Input mesh : STL Allows to calculate the arodynamic coefficients + heat transfer Specific model for heat transfer (Vérant Sagnier + innovative propagation law Return time between a few minutes and half an hour depending on mesh size Use not planned at the beginning of program but finally used at CEF
CEDRE platform In-house ONERA s platform dedicated to the simulation of energetics flows General unstructured capabilty Different coupled solvers to model various physical phenomena CHARME : Navier-Stokes (used here) SPIREE, SPARTE : 2-phase flows ASTRE, REA : radiative heat transfer ACACIA : conduction..
Some elements about meshing Generated with CentaurSoft Unstructured (Tetras, prisms, pyramids, hexaedra) Between 7 and 12 M cells depending on the configuration Creation + generation of the mesh First time : one week Now : about 1 day (starting from a new geometry) Prisms near the wall to capture heat transfer properly
Flow topology for the baseline configuration
Nomenclature C A Axial coefficient [-] C Y Side force coefficient [-] C N Normal coefficient [-] C D Drag coefficient [-] C L Lift coefficient [-] L/D Lift to drag ratio [-] C l Rolling moment coefficient [-] C m Pitching moment coefficient [-] C n Yawing moment coefficient [-]
Aerodynamic coefficients : baseline C A C Y C N C l C m C n Pressure 1.329 0.002 6.849 0.000-0.434 0.000 CEDRE Friction 0.000 0.000 0.016 0.000 0.002 0.000 Baseline = 15 Total 1.329 0.002 6.865 0.000-0.436 0.000 = 35 Pressure 1.330 0.000 6.679 0.000-0.277 0.000 = 0 FAST Friction 0.000 0.000 0.000 0.000 0.000 0.000 Total 1.330 0.000 6.679 0.000-0.277 0.000
Aerodynamic coefficients : main conclusions Good estimate of force coefficients using FAST or equivalent tools Moment coefficients to be confirmed, but Fairly poor estimate of the pitching coefficient, due to the bad prediction of the flap pressure distribution. Effect is amplified for large deflections In the presence of yawing, the pitching and yawing moments are not predicted very satisfactorily, for the same reasons Discrepancies can probably reach 50% for large flap deflections
Baseline surface mesh