A Streamlined Approach to Spatial Mapping of Complex 3D Thermal Boundary Condition Data

Spatial mapping of 1D, 2D, and particularly 3D thermal boundary condition data is essential for accurate thermal simulation of spacecraft and launch vehicles. This information typically is available in simple ASCII file format but can be problematic to use for thermal simulations. Difficulties that can be encountered include the ability to directly use the available file format, transformation of the data into the desired reference coordinate system in 3D space, and accurate interpolation of the data onto the thermal calculation domain. This paper presents a streamlined approach to spatial mapping of complex unsymmetrical 3D cold wall heat flux data using the fields’ capability in Simcenter3D. A recent example of 3D thermal plume simulation at MSFC will be employed to illustrate the use of text, csv, and Excel files, specifying coordinate systems for transformation of data in 3D space, and use of the various interpolation schemes available for spatial mapping. Spatial boundary condition verification is also very important, and the spacecraft thermal analyst needs effective visualization tools to develop confidence in the boundary condition definitions. Visualization of the spacecraft plume raw field data, the calculated field data, and the interpolated field data onto the thermal calculation domain will be discussed, with a particular focus on real-time viewing of the interpolated data for available interpolation schemes.

The objective of this paper is to outline the modeling techniques used with the integrated
thermal analysis of a terrestrial lunar lander demonstrator. Specifically, the techniques
outlined herein focus on spatial mapping of convective and radiative exhaust plume results
from a computational fluid dynamics (CFD) analysis. Two cases were investigated, however, the
modeling techniques that were utilized translate to both cases seamlessly. Those two cases
were as follows:
• Lunar lander demonstrator firing on-pad (worst case).
• Lunar lander demonstrator hovering at an elevated position above the launch pad.
For the purposes of information control, this paper will focus on the modeling techniques only,
using altered or dimensionless data where necessary.
BACKGROUND
The thermal model examined in this paper is of the lunar lander demonstrator known as XL-1T
(terrestrial), born from a collaborative effort between Masten Space Systems (MSS) and NASA,
under NASA’s Lunar CATALYST (also known as Lunar Cargo Transportation and Landing by Soft
Touchdown) initiative. The lander is a reusable vertical takeoff/vertical landing (VTVL) test bed
which is controlled by four throttleable main engines utilizing green hypergolic propellants.