1. Al 2 O 3 Post Combustion Chamber Post Combustion Chamber ANSYS Thermal Model (Embedded Fuel Grain Concept) Outer radius: 1.25” (0.03175 m) Inner radius: 1” (0.0254 m) Height: 1.5” (0.0381 m) Outer radius: 1.75” + 0.5 mm (0.03225 m) Inner radius: 1.25” (0.03175 m) Height: 1.5” (0.0381 m) Al 7075-T6 Housing (0.5 mm) Model Geometry

2. Post Combustion Chamber ANSYS Thermal Model (Embedded Fuel Grain Concept) Material Properties Al 2 O 3 Density: 3970 kg/m 3 Specific Heat: 774.977 J/(kg-K) Thermal Conductivity: variable Al 7075-T6 Density: 2810 kg/m 3 Specific Heat: 960 J/(kg-K) Thermal Conductivity: 130 W/(m-K) Assumptions Constant Aluminum properties Chamber ends are adiabatic Constant film coefficients Constant bulk temperatures

3. Post Combustion Chamber ANSYS Thermal Model (Embedded Fuel Grain Concept) Meshed Model Nodes: 9,589 Elements: 5,602 Volumes meshed using ANSYS SmartSize 1 with tetrahedral elements

4. Post Combustion Chamber ANSYS Thermal Model (Embedded Fuel Grain Concept) Boundary Conditions Outer Surface Film coefficient, h = 5 W/(m-K) Bulk temperature, T ∞ = 298 K Simulates free convection of N 2 0 on Al housing Inner Surface Film coefficient, h = 300 W/(m-K) Bulk temperature, T ∞ = 3000 K Simulates convection of the propellant gas inside the combustion chamber All nodes initially set to 298 K

5. Post Combustion Chamber ANSYS Thermal Model (Embedded Fuel Grain Concept) Transient Results

6. Post Combustion Chamber ANSYS Thermal Model (Embedded Fuel Grain Concept) Discussion of Results This model demonstrates heat transfer across multiple ANSYS volumes, which will be necessary to derive a film coefficient from thermocouple data A transient analysis was also performed by hand using ANSYS input conditions with results matching ANSYS output to within 100 Kelvin. The transient model is considered validated for this test case.

7. Post Combustion Chamber ANSYS Thermal Model (Engine Core) Future Models A model of the post combustion chamber and nozzle is being developed to utilize data that will be collected by the test stand team. The model will be used to back out an average film coefficient and to determine if the engine structure will meet the Guidance burn time of 50 seconds.