Public Domain Aeronautical Software (PDAS)  

A computer program has been developed to analyze the transient response of an ablating axisymmetric body, including the effect of shape change. The governing differential equation, the boundary conditions for the analysis on which the computer program is based, and the method of solution of the resulting finite-difference equations are based upon NASA TN D-6220. The original program by Lona Howser, known as NASA Langley program D2430, is described in NASA TM X-2375. The program has been converted to modern Fortran and the outdated plotting procedure has been replaced with Gnuplot output.

Some of the features of the analysis and the associated program are

  1. the ablation material is considered to be orthotropic with temperature-dependent thermal properties;
  2. the thermal response of the entire body is considered simultaneously;
  3. the heat transfer and pressure distribution over the body are adjusted to the new geometry as ablation occurs;
  4. the governing equations and several boundary-condition options are formulated in terms of generalized orthogonal coordinates for fixed points in a moving coordinate system;
  5. the finite-difference equations are solved implicitly; and
  6. the instantaneous body shapes can be displayed.

The physical problem to be modeled with the analysis is described by Fortran input variables. For example, the external body geometry is described in the W, Z coordinates; material density is given; and the stagnation cold-wall heating rate is given in a time-dependent array. Other input variables are required which control the solution, specify boundary conditions, and determine output from the program. The equations have been programmed so that either the International System of Units or the U. S. Customary Units may be used.

This program was released by NASA through COSMIC as LAR-11049. The italicized text above is from the official NASA release.

Public Domain Aeronautical Software (PDAS)