Modelling MLI

Multi-layer insulation to protect all satellite subsystems from external heat flows.

The multi-layer insulation (MLI) is used widely on the spacecraft or satellite subsystems to insulate the spacecraft or satellite subsystems from the external environment. The spacecraft or satellite subsystems such as instrument, antenna, etc. are subjected to the cold environment due to the space and hot environment due to the external heat fluxes (solar, albedo and planet) as well as the “aerothermal" effect caused by the high fluence of atomic oxygen in the case of VLEO applications or specific atmosphere such as Venus’s.

No standard method to model MLI

There are several thermal couplings which need to be considered when modelling MLI: the conduction through the layers of MLI, the radiation between the layers of MLI and themselves and the radiation between the external layer of MLI and its surroundings environment.

Although CAD softwares offer some capabilities to model MLI, to date there is no standard method to model MLI as well as a library of flown and qualified MLI properties available for the whole space thermal engineers' community.

Two common methods to model the multi-layer insulation

There are two common methods to model MLI: 

• You create one single geometry and set two thicknesses to it. One thickness (inner) will be created to model the structure of spacecraft or satellite subsystem and another one (outer) will be created to model the layers of MLI. You set the effective conductance and emittance values through the thickness of MLI. The thermo-optical properties of MLI will be assigned to the external surfaces of the geometry.  
  
• You create an additional geometry to the structure geometry to model the layers of MLI and translate it by 1 mm from the structure geometry outwards. One geometry (inner) will be created to model the structure of spacecraft or satellite subsystem and another one (outer) will be created to model the layers of MLI. You set the effective conductance and emittance values through the thickness of MLI. You assign the thermo-optical properties of MLI to the external surfaces of the MLI geometry.  

 Learn The 7 steps to build the geometry from CAD models for thermal analysis

Results

Benefits: Known approach.

Limitations: Modelling the MLI as well as searching for reliable MLI properties information is time-consuming. 

Why it matters. 

Standardising the modelling of MLI will reduce the space systems development time and risk of error. 

We’re thinking: 

We will standardise, validate with the flight data and fully automate this process, and  make it accessible to the entire space thermal engineers’ community via our Digital Engineer® Try it now

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