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Presented By Lorenzo Andrioli

TFAWS Paper Session. Thermal Analysis in Support to Thermal Protection System Seals and Interface Design of IXV Lorenzo Andrioli, Massimo Antonacci Thales Alenia Space – Turin, Italy Alessandro Mannarelli SSE Sofiter System Engineering – Turin, Italy. Presented By Lorenzo Andrioli.

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Presented By Lorenzo Andrioli

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  1. TFAWS Paper Session Thermal Analysis in Support to Thermal Protection System Seals and Interface Design of IXVLorenzo Andrioli, Massimo AntonacciThales Alenia Space – Turin, ItalyAlessandro MannarelliSSE Sofiter System Engineering – Turin, Italy Presented ByLorenzo Andrioli Thermal & Fluids Analysis WorkshopTFAWS 2011August 15-19, 2011 NASA Langley Research CenterNewport News, VA

  2. Outline • Introduction • Analysis Approach • Interfaces (I/F) Thermal Mathematical Models (TMMs) general description • Thermal network basic concept • Environment simulation • Analysis work logic • Model example • New approach for Thermal Protection System (TPS) thermal analysis • Summary & Conclusions TFAWS 2011 – August 15-19, 2011

  3. Introduction The IXV (IntermediateeXperimentalVehicle) • An atmospheric re-entry demonstrator which will perform a suborbital flight and will re-enter in the atmosphere. • To be launched by the ESA/Vega from the Centre Spatial Guyanais (CSG) • It will experience the typical Low Earth Orbit re-entry thermal loads. TFAWS 2011 – August 15-19, 2011 3

  4. Introduction Main objective: To develop an analytical approach to be implemented for I/F design of IXV. Model characteristics changes operated by means of: • algorithms • configurations To properly simulate behaviour of items characterized by different: • thermal properties • thermo-mechanical properties • permeability Leading to different temperature requirement limits. TFAWS 2011 – August 15-19, 2011 4

  5. Introduction Interfaces (I/F) External critical regions in which environmental agents can find a preferential way to dangerously affect internal environment and items. Design requirements: • to limit sneak flow and act as thermal barriers (proper sealing); • to limit discontinuities (steps, gaps, and bowing) in the vehicle Outer Mould Line; • to allow depressurization and repressurization of IXV and TPS&H/S Assemblies. TFAWS 2011 – August 15-19, 2011 5

  6. Introduction Different types of I/Fs to be designed: • among different-type Thermal Protection Systems: • nose-to-windward • nose-to-leeward • leeward-to-windward • windward-to-hinge • hinge-to-rear • hinge-to-leeward • between TPSs and other subsystems: • floatation system ejectable panels insulation • venting hole • protection insulation over antennas • bridle channels insulation • protection insulation on umbilical mechanisms TFAWS 2011 – August 15-19, 2011 6

  7. Analysis Approach Modelingcriterion • ESATAN Thermal Lumped Parameter (TLP) solver • Technique resembles System Thermal Mathematical Model (TMM) one improving temperature mapping capabilities • highly customizable 2D mesh models and one 3D axisymmetric model • depending on the I/F type, a fluid leak (sneak flow) through sealing materials is simulated TFAWS 2011 – August 15-19, 2011 7

  8. I/F TMMs general description Thermal network basic concept • Thermal network organized in node blocks linked together to establish a geometrical hierarchy → propagation of changes by acting upon relevant parameters (e.g. modification of items sizing, material properties, etc.) • Node blocks wrapped into arithmetical nodes→ spreading effect of surface heat exchanges implicitly solved (reliable evaluation of I/F temperatures) TFAWS 2011 – August 15-19, 2011 8

  9. I/F TMMs general description Environment simulation • Internal environment: radiative and convective equivalent conductors (representative nodes defined on the basis of System TMM) • External environment: radiative conductors and heat fluxes (ATDB, max heat load trajectory) or input from dedicated thermo-ablative software • Sneak flow: modelled by means of a heat contribution calculated as: TFAWS 2011 – August 15-19, 2011 9

  10. I/F TMMs general description Air mass flow: calculated with Darcy law 1D formulation k permeability of the seal mair kinematic viscosity rair density thspatial term describing the flow path (seal thickness) ppressure Aflow area (gap× slot width) Sneak flow into non-passing through slots: air filling the gap is considered as stagnating (really thin and deep slots, highly conservative boundary layer temperature) TFAWS 2011 – August 15-19, 2011 10

  11. I/F TMMs general description • Air flow through venting hole: equivalent thermal conductor (h × A) linking duct with a inflow boundary node kairair conductivity rbushduct internal radius NuNusselt number From Petukhov-Gnielinski semi-empiric correlation: TFAWS 2011 – August 15-19, 2011 11

  12. I/F TMMs general description Analysis work logic TFAWS 2011 – August 15-19, 2011 12

  13. I/F TMMs general description Model example: typical TPS-to-TPS junction I/F TFAWS 2011 – August 15-19, 2011 13

  14. Analysis results and their application Local vs System TMMs DT are applied to overall vehicle temperature maps all along the I/Fs envelope at C/S and TPS level. Temperature maps are used as an input for System Thermo-elastic analyses→ overall steps and gaps requirements verification TFAWS 2011 – August 15-19, 2011 14

  15. New approach for TPS thermal analysis Current approach modeling (ESATAN) flaws: • ESATAN-TMS GUI is in early development phase→ code is usually written down by hand • Manual debugging and subroutine generation is the rule→ coding is more error-prone than a robust front-end approach • CAD interfacing tools are under development→ geometry is user discretized and modeled, usually in scripting form with graphic visualization • Data exchange is manually managed by means of properly written routines→ a coding endeavor is required TFAWS 2011 – August 15-19, 2011 15

  16. New approach for TPS thermal analysis Solution: switching to an hybrid approach tool. • Bi-directional from/to CAD geometry interfacing, with direct user intervention for simplification purposes • Finite element based model mesh generation • Possibility to chose between a Finite Element Method (FEM) or a TLP solution • Possibility to chose between FEM or TLP like postprocessing (temperatures interpolated over the node vs isothermal nodes) TFAWS 2011 – August 15-19, 2011 16

  17. New approach for TPS thermal analysis FEM-TLP hybrid workflow in NX environment An example of hybrid approach workflow applied to a preliminary TPS-to-TPS I/F analysis. TFAWS 2011 – August 15-19, 2011 17

  18. Summary & Conclusions The presented modelling approach has been developed in the frame of IXV programme resulting into a key feature of the I/F design assessment at System level. The adopted work logic resulted in an effective approach to: • Achieve the required detail level for I/Fs design justification • Reduce development times and iterations between the different disciplines involved • Minimize and enhance data exchange cycles among several analysis tools TFAWS 2011 – August 15-19, 2011 18

  19. Summary & Conclusions Improvements based on hybrid FEM/TLP analysis are being implemented to: • Boost up detail level for I/Fs design refinement • Further reduce development and coding endeavor (minimizing modeling mistakes) • Enhance data exchange among several CAD/analysis suites TFAWS 2011 – August 15-19, 2011 19

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