![IXV numerical model
STRUCTURE MODELING
CONFIGURATION ASSUMPTIONS
External dimensions taken
Fuselage into account
components
Bidimensional rapresentation
of surfaces
Flaps assembly Rigid body description
RIGID BODY INERTIAL PROPERTIES
Mass Jxx Jyy Jzz
[kg]
27,82 1,17 4,52 4,31
4/17](https://image.slidesharecdn.com/presentazionetesialtairupdated-120529035226-phpapp02/85/Study-on-structural-behavior-of-an-atmospheric-reentry-vehicle-during-ditching-6-320.jpg)
![Fluid numerical model
HORIZONTAL EXTENSION
• LimitedZ Acceleration -to
front dimensions Accelerometer T1064-63 (COG)
avoid wave reflection
VERTICAL EXTENSION
• Limited in-deep dimensions
to lighten fluid model
WATER BASIN COMPARISON
Deep water model Shallow water model
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
Horizontal 1,22 x 2,14 [m] 1,22 x 2,14 [m]
Vertical Time [s]
0,8 [m] 0,4 [m]
N Elements 335265 Deep Water Model 189317
Shallow Water Model
CPU Time 8413 [s] 5077 [s]
6/17](https://image.slidesharecdn.com/presentazionetesialtairupdated-120529035226-phpapp02/85/Study-on-structural-behavior-of-an-atmospheric-reentry-vehicle-during-ditching-8-320.jpg)
![Characteristic elements dimension
Finest mesh Sensitivity
normal to analysis
phenomenon
2D ELEMENTS 3D ELEMENTS 3D ELEMENTS
(VEHICLE) (AIR) (WATER)
HEIGHT 20 [mm] 20 [mm] 20 [mm]
WIDTH 20 [mm] 20 [mm] 20 [mm]
DEPTH / 10 [mm] 10 [mm]
N ELEMENTS 3564 78324 287188
7/17](https://image.slidesharecdn.com/presentazionetesialtairupdated-120529035226-phpapp02/85/Study-on-structural-behavior-of-an-atmospheric-reentry-vehicle-during-ditching-9-320.jpg)
![First Loadcase
0.2
AX - COG
0.1
0
-0.1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
-0.2
-0.3
-0.4
-0.5
t [s]
0.6
AZ - COG
0.4
0.2
0
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
-0.2
t [s]
Numerical
Experimental
11/17 All curves normalized to 1](https://image.slidesharecdn.com/presentazionetesialtairupdated-120529035226-phpapp02/85/Study-on-structural-behavior-of-an-atmospheric-reentry-vehicle-during-ditching-13-320.jpg)
![Second Loadcase
0.1
AX - COG
0
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
-0.1
-0.2
-0.3
-0.4
t [s]
0.8
AZ - COG
0.6
0.4
0.2
0
-0.2 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
-0.4
t [s]
Numerical
Experimental
12/17 All curves normalized to 1](https://image.slidesharecdn.com/presentazionetesialtairupdated-120529035226-phpapp02/85/Study-on-structural-behavior-of-an-atmospheric-reentry-vehicle-during-ditching-14-320.jpg)
![Third Loadcase
0.3
AX - COG
0.2
0.1
0
-0.1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
-0.2
-0.3
-0.4
t [s]
0.4
AZ - COG
0.3
0.2
0.1
0
-0.1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
-0.2
t [s]
Numerical
Experimental
13/17 All curves normalized to 1](https://image.slidesharecdn.com/presentazionetesialtairupdated-120529035226-phpapp02/85/Study-on-structural-behavior-of-an-atmospheric-reentry-vehicle-during-ditching-15-320.jpg)
![Third Loadcase
19 deg Sensor
0.40
0.30
0.20
0.10
0.00
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
-0.10
t [s]
Numerical Experimental
35 deg Sensor
0.80
0.60
0.40
0.20
0.00
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
-0.20
t [s]
Numerical Experimental
1.00
51 deg Sensor
0.80
0.60
0.40
0.20
0.00
-0.20 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
t [s]
14/17](https://image.slidesharecdn.com/presentazionetesialtairupdated-120529035226-phpapp02/85/Study-on-structural-behavior-of-an-atmospheric-reentry-vehicle-during-ditching-16-320.jpg)
Study on structural behavior of an atmospheric reentry vehicle during ditching
- 1. POLITECNICO OF TURIN MASTER DEGREE THESIS IN AEROSPACE ENGINEERING Study on structural behavior of an atmospheric reentry vehicle during ditching Supervisors: • Prof. Giulio Romeo – Politecnico of Turin • Ing. Roberto Ullio – Thales Alenia Space Candidate • Maurizio Coltro
- 2. Thesis activity Part of ESA’s Future Launchers Preparatory Programme has been devoted to optimizing a long-term European roadmap for in-flight experimentation with atmospheric re-entry enabling systems and technologies. The Intermediate eXperimental Vehicle (IXV) project is the next core step of this effort. This work has been developed within the IXV project and with closed collaboration of TAS-I and ESA. Many thanks to ESA and TAS for their support. Thanks also to Altair Engineering for providing the software suite for the analysis.
- 3. The IXV Project Technology platform • Intermediate element of technology-effective and cost efficient European roadmap • Prepare future ambitious operational system developments with limited risks for Europe Project objectives • Design, development, manufacturing, on-ground and in-flight verification of autonomous European lifting and controlled re-entry system Critical technologies of interest • Advanced instrumentation for aerodynamics and aerothermodynamics • Thermal protection and hot-structures solutions • Guidance, navigation and flight control Success of IXV mission • Correct performance of re-entry • Safe landing and recovery with its experimental data 1/17
- 4. Experimental measurements Mockup • representative of external shape • inertial properties • scale factors Physical quantities • accelerations • pressures Test facility • electromagnets to release vehicle • high frequency cameras • high pool dimension to perform impact 2/17
- 5. Modeling methodology Solver • Hyperview • Hypermesh • Radioss • Hypercrash BLOCK V10 Preprocessor Postprocessor Explicit Suited for solution Drawbacks problems tecnique • short duration • high velocity • highly nonlinear nature 3/17
- 6. IXV numerical model STRUCTURE MODELING CONFIGURATION ASSUMPTIONS External dimensions taken Fuselage into account components Bidimensional rapresentation of surfaces Flaps assembly Rigid body description RIGID BODY INERTIAL PROPERTIES Mass Jxx Jyy Jzz [kg] 27,82 1,17 4,52 4,31 4/17
- 7. Fluid numerical model MODELING FLUID DESCRIPTION ASSUMPTIONS Gas volume extension LAW37 Biphas ALE approach Liquid volume extension 5/17
- 8. Fluid numerical model HORIZONTAL EXTENSION • LimitedZ Acceleration -to front dimensions Accelerometer T1064-63 (COG) avoid wave reflection VERTICAL EXTENSION • Limited in-deep dimensions to lighten fluid model WATER BASIN COMPARISON Deep water model Shallow water model 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 Horizontal 1,22 x 2,14 [m] 1,22 x 2,14 [m] Vertical Time [s] 0,8 [m] 0,4 [m] N Elements 335265 Deep Water Model 189317 Shallow Water Model CPU Time 8413 [s] 5077 [s] 6/17
- 9. Characteristic elements dimension Finest mesh Sensitivity normal to analysis phenomenon 2D ELEMENTS 3D ELEMENTS 3D ELEMENTS (VEHICLE) (AIR) (WATER) HEIGHT 20 [mm] 20 [mm] 20 [mm] WIDTH 20 [mm] 20 [mm] 20 [mm] DEPTH / 10 [mm] 10 [mm] N ELEMENTS 3564 78324 287188 7/17
- 10. Fluid-structure interface FLUID STRUCTURE INTERFACE TYPE18 SENSITIVITY STFAC GAP ANALYSIS Interface Activation PERFORMED stiffness distance PRESSURE PROBES • Single TYPE18 interface to INTERFACE represent sensors separately 8/17
- 11. Boundary-initial conditions • Atmospheric pressure to water free surface WATER • DYREL dynamic relaxation for convergence BOUNDARY • Gravity load to water volume CONDITIONS • Lateral/bottom surfaces locked • FLRD = 1 upper surface • Initially locked in all DOFs VEHICLE • Gravity load to master node BOUNDARY CONDITIONS • Initial velocity to master node • Initial distance from free surface 9/17
- 12. Numerical - Experimental Correlation All loadcases computed from 0 to 200 ms FOURTH SECOND THIRD FIRST • Impact angle 51 deg 19 35 deg • Flaps position 21deg 0 deg LOADCASE • Vertical velocity 3,4 m/s 10/17
- 13. First Loadcase 0.2 AX - COG 0.1 0 -0.1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 -0.2 -0.3 -0.4 -0.5 t [s] 0.6 AZ - COG 0.4 0.2 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 -0.2 t [s] Numerical Experimental 11/17 All curves normalized to 1
- 14. Second Loadcase 0.1 AX - COG 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 -0.1 -0.2 -0.3 -0.4 t [s] 0.8 AZ - COG 0.6 0.4 0.2 0 -0.2 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 -0.4 t [s] Numerical Experimental 12/17 All curves normalized to 1
- 15. Third Loadcase 0.3 AX - COG 0.2 0.1 0 -0.1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 -0.2 -0.3 -0.4 t [s] 0.4 AZ - COG 0.3 0.2 0.1 0 -0.1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 -0.2 t [s] Numerical Experimental 13/17 All curves normalized to 1
- 16. Third Loadcase 19 deg Sensor 0.40 0.30 0.20 0.10 0.00 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 -0.10 t [s] Numerical Experimental 35 deg Sensor 0.80 0.60 0.40 0.20 0.00 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 -0.20 t [s] Numerical Experimental 1.00 51 deg Sensor 0.80 0.60 0.40 0.20 0.00 -0.20 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 t [s] 14/17
- 17. Correlation results summary model updating activity • improvement of modelling Correlation approaches process • correction of individual parameters Main outcomes from acceleration results • very good correlation at COG in X and Z directions • satisfactory correlation at NOSE and REAR parts Main outcomes from pressure results • good correlation • impact event chronology • pressure time history signature • satisfactory correlation • pressure peak values 15/17
- 18. Remarks and further developments Experimental numerical results deviation Flexible body Statistic data Exposed impact areas and behaviour dispersion mathematical model Alternative modeling methodology Structure Deformable body Fluid LAW51 Multimaterial with SPH method outlet treatment 16/17
- 19. Thanks for your attention 17/17