MSC.Marc-ATAS Advanced Thermal Analysis Software for Modeling of Rocket Motors and Other Thermal Protection Systems

1
MSC.Marc-ATAS Advanced Thermal Analysis Software
for Modeling of Rocket Motors and Other Thermal
Protection Systems

• Fabrice Laturelle, Snecma Moteurs
• Sophie Fiorot, CS-SI
• Ted B. Wertheimer, MSC.

2
Project Overview

• The objectives of this work is to develop new
  software and procedures for the analysis of
  thermo-structures and thermal protection systems.
• This is a three year project focused on
• Thermal Degradation of Materials
• Complex Thermal Boundary Conditions
• Ablation / Erosion of Materials
• Radiation
• Numerical Efficiency
• Easy of Use, Reduced Time for Data Preparation

3
Background

• Snecma Moteurs, Solid Rocket Motors Division
• 40 years developing, testing, and manufacturing
• Solid propellant rocket motors
• Thermal protection systems for reentry vehicles

4
Design Objectives

• Replace the need for destructive full scale motor
  tests with precise numerical models
• Reduce time / costs for design / analysis
• Implement several complexity levels of advanced
  poro-thermal models
• Replace multiple 1-D and 2-D in-house developed
  special purpose programs with a single, easy to
  use, maintainable, comprehensive 3-D program
• Open the way for future coupling with CFD and
  radiative heat transfer codes, and fully coupled
  thermo-poro-mechanical analysis

5
Physical Problem

• Materials are subjected to
• Very High Thermal Fluxes 1-100 MW/m2
• Thermochemical oxidation
• (Thermo-)Mechanical and Dynamical Loads
• Mechanical and Chemical Reactions with Impacting
  Liquid and Solid Particles

6
Composite Materials

• Carbon/Carbon
• Carbon/Phenolic
• Silica/Phenolic
• Ceramic Matrix composites
• Rubber and Reinforced Rubber
• Low Mass Thermal Insulators

7
Physics overview

8
Thermo-Degradation process

9
Modeling Levels

• Level 1
• Simplified Homogeneous Material Model
• Effective Specific Heat which is Dependent on the
  Thermal Loading Path
• Level 2
• Mass Loss due to Pyrolysis
• One Dimensional Fluid Flow
• Advanced Material Behavior
• Level 3
• Three Dimensional Fluid Flow (Darcy Law)

10
Advanced Material Model

• Pyrolysis of Material
• Mass Density Controlled by Arrhenius Law
• Thermal Properties Change based upon a Kachanov
  Model between Virgin and Charred State
• Energy absorption and internal convection
• Water Vapor Creation
• Coking
• Carbon comes out of the Pyrolysis Gases and
  Deposits onto the Solid

11
Arrhenius Law
Heating Rate Dependent
12
Arrhenius Law for jj

• Dimensionless variable jj that goes from 1 to 0
  during pyrolysis calculated by a law of
  Arrhenius

13
Surface Energy Balance

14
Ablation

• Thermochemical Ablation (Gases, Particles)
• Mechanical Erosion
• Due to impacts of particles
• Due to other actions such as the shear stress of
  the flow and vibration of the part

15
Mass Balance Equation

• The mass equation of standard level 2 model is
  the mass equation of the gas, written in the
  stationary state, with a source term of
  decomposition.

16
Energy equation
17
Energy Equation Material Enthalpy During
Decomposition
18
(No Transcript)
19
Ablation Analysis Verification
20
Temperature Verification
21
Density Distribution
22
Mass Flow Rate of Gas
23
Rezoning Issues

• Shaver Mesher
• Rezone outer element during recession when
  necessary
• Update values associated with exterior SIP based
  upon recession
• Shift SIP when outer element removed
• Remove number of SIP points
• Relax Mesher
• Rezone complete mesh
• Update all SIP value
• Number of SIP points remain the same

24
Ablation
25

26
(No Transcript)
27
Thermal Contact

• Expansion of MSC.Marc Capabilities for Thermal
  Contact
• No Contact
• Thermal Convection to the Environment
• Close Contact
• Convection, Radiation Between Surfaces
• True Contact
• Conduction

28
Thermal Contact

• If dist lt d1 then thermal conduction
• If d1lt dist lt d2 then near contact
• If d2 lt dist then no contact

• Q hcv(T2-T1)hnt(T2-T1)ent
• sigmaeps(T24-T14)
• (hct (hct-hbl)gap/dqnear)(T2-T1)

29
Conclusions

• Advanced Thermal Analysis Capabilities Suitable
  to High Temperature Applications are Being Added
  to MSC.Marc
• Excellent Correlation has been Observed
• Increase Capability , with Less Costs
• Implementation of level 3 poro-thermal model,
  advanced radiation capabilities, and testing, are
  still in progress