Importing orbits and space environments

You can use Thermal Model Exchanger to import Orbit modeling objects and Orbital Heating simulation objects from Simcenter 3D Space Systems Thermal into Thermal Desktop as External Heating Environment boundary conditions.

Thermal Model Exchanger (TMX) allows you to import the following Simcenter 3D Space Systems Thermal boundary conditions, which define orbits and space environments:

  • Orbit modeling object
  • Orbital Heating simulation object

TMX does not support importing Solar Heating Space and Free Molecular Heating simulation objects.

The Simcenter 3D Orbit modeling object specifies the planet, orbit type and parameters, and the spacecraft attitude that are used by the Orbital Heating simulation object to compute the heat transfer between the spacecraft and the space environment. This simulation object specifies the parts of the model that are affected by the orbit, and the calculation method used to compute the radiation with the environment.

TMX supports importing both the Illuminate All Elements and Illuminate Selected Elements types of Orbital Heating simulation object. During the import process, the application creates a Thermal Desktop analysis group based on the selected type:

  • For the Illuminate All Elements type, the analysis group includes all elements from the Simcenter 3D model.
  • For the Illuminate Selected Elements type, the analysis group includes only the selected elements.

TMX converts the imported Orbit modeling object and Orbital Heating simulation object in Thermal Desktop as External Heating Environment boundary condition for defining orbits and space environment for your spacecraft.

Supported orbit characteristics

In Thermal Desktop, all the orbit characteristics and parameters are defined within the External Heating Environment of the Orbit type dialog box with several tabs. The first tab changes with the type of orbit you select.

Each orbit characteristic and parameter from Simcenter 3D is imported into Thermal Desktop as follows:

Planets and orbit types

TMX supports all the planets available in the Simcenter 3D Orbit modeling object. For the orbit types, Simcenter 3D offers a larger list of orbits than Thermal Desktop. For each Simcenter 3D orbit type that TMX converts, the following table lists the corresponding Thermal Desktop External Heating Environment type.

Simcenter 3D Orbits Thermal Desktop External Heating Environments
Beta-Angle Basic Orbit
Geostationary Keplerian Orbit
Classical Keplerian Orbit
Sun-synchronous Keplerian Orbit
Shuttle Keplerian Orbit
Molniya Keplerian Orbit
Sun Planet Vectors Orbital Sun/Planet/Radius Vector List
Spacecraft Attitude

When you define the spacecraft attitude or orientation in Thermal Desktop, you can only select a predefined axis while in Simcenter 3D you can specify any vector. TMX reproduces the spacecraft attitude specified in Simcenter 3D calculating additional rotations needed to align the +Z axis in Thermal Desktop with the Aim at vector specified in Simcenter 3D.

TMX supports all the Simcenter 3D alignment options except the Orbit Normal, South and North options for the Aim at and Align with vectors, which you specify on the Spacecraft Attitude page in the Simcenter 3D Orbit dialog box. These alignment options are not supported in Thermal Desktop. If you import a Simcenter 3D orbit that uses one of these alignment options, TMX keeps the default values of the Orientation tab and displays a warning in the import summary.

Sun Planet Characteristics

TMX uses the information specified on the Sun Planet Characteristics page in the Simcenter 3D Orbit modeling object to fill the options on the Planetary Data, Solar, Albedo and IR Planetshine tabs in the Thermal Desktop Orbit dialog box.

Orbit Parameters

Because the Simcenter 3D Beta-Angle orbit and the Thermal Desktop Basic Orbit are equivalent, TMX does not apply specific operations during the import process.

Because the Simcenter 3D Geostationary, Classical, Sun-synchronous, Shuttle and Molniya orbit types are all special cases of the Keplerian Thermal Desktop orbit type, the application converts the parameters specified in Simcenter 3D into the equivalent parameters specified in Thermal Desktop.

For the Simcenter 3D Sun Planet Vectors orbit type, Thermal Model Exchanger imports the table field used to specify time, coordinates of the sun and planet vectors and the spacecraft altitude to the Vector Input tab in the Thermal Desktop Orbital Sun/Planet/Radius Vector List orbit type. The application converts the spacecraft altitude into the ratio of distance from Earth's center to Earth's radius required by Thermal Desktop.

Calculation Positions

TMX supports full and partial Simcenter 3D orbits.

For orbits that use the Number of Intervals angular interval method, TMX enables the Use Equal Increments option on the Positions tab in the Thermal Desktop Orbit dialog box.

For orbits that use the Angular Positions angular interval method, TMX enables the Use Positions option on the Positions tab in the Thermal Desktop Orbit dialog box.

Supported element types

You can import Orbital Heating simulation objects applied on 2D, 1D and 0D elements.

Orbital Heating simulation objects of the Illuminate All Elements type applied on 0D elements are imported as analysis groups applied on solid sphere primitives.

The Orbital Heating simulation objects of the Illuminate Selected Elements type applied on 0D elements are:
  • Imported as analysis groups applied on a solid sphere primitive when the 0D elements have a diameter.
  • Ignored and not imported when the 0D elements have no diameter.

TMX imports the Orbital Heating simulation object applied to a 1D mesh, as a solid cylinder primitive, with the RMAX face included in the Radiation Analysis Group of the External Heating Environment boundary condition.

TMX does not support importing Orbital Heating simulation objects applied on 3D elements.