Andrew T Norris | Search NASA

NASA NTRS2022

VULCAN-CFD Theory Manual: Ver. 7.2.0

VULCAN-CFD offers a comprehensive set of capabilities to enable the simulation of continuum flowfields from subsonic to hypersonic conditions. The governing equations that are employed include allowances for both chemical and thermal nonequilibrium processes, coupled with a wide variety of turbulence models for both Reynolds-averaged and large eddy simulations. A description of the physical and numerical models available in the software are presented in this document. However, it is emphasized that the descriptions provided are not intended to fully document every aspect of the models employed. Instead, the governing equations, and the models required to simulate them numerically, are presented with the goal of providing a sufficient level of detail to understand their strengths and limitations. The reader is encouraged to access the references provided throughout this document for a more complete explanation of the formulations presented.

VULCAN-CFD Theory Manual↗

NASA NTRS2022

VULCAN-CFD User Manual: Ver. 7.2.0

VULCAN-CFD offers a comprehensive set of capabilities to enable the simulation of continuum flowfields from subsonic to hypersonic conditions. The governing equations that are employed include allowances for both chemical and thermal nonequilibrium processes, coupled with a wide variety of turbulence models for both Reynolds-averaged and large eddy simulations. The software package can simulate two-dimensional, axisymmetric, or three-dimensional problems on structured multiblock meshes or fully unstructured meshes. A parabolic (i.e., space-marching) treatment can also be used for any subset of a structured mesh that can accommodate this solution strategy. The flow solver provides a significant level of geometric flexibility for structured grid simulations by allowing for arbitrary face-to-face C(0) continuous and non-C(0) continuous block interface connectivities. The unstructured grid paradigm allows for mixed element unstructured meshes that contain any combination of tetrahedral, prismatic, pyramidal, and hexahedral cell elements. The flow solver is also fully parallelized using MPI (Message Passing Interface) libraries in a data-parallel fashion, allowing for efficient simulations on modern High Performance Computing (HPC) systems. This document provides information related to the installation and execution of the VULCAN-CFD software package. A detailed description of the physical and numerical models available in the software are provided in the VULCAN-CFD Theory Manual.

VULCAN-CFD User Manual↗

NASA NTRSDate not supplied

TPSAS-NF1676L-32577-DND

The ground testing of hypersonic vehicles requires the replication of the flow conditions at high speed and altitude. To produce these flow conditions, stored compressed air is expanded through a convergent-divergent nozzle to produce the required pressures and speed. However, the expansion process also cools the air, and so to match the flight temperatures, some form of heating needs to be employed. Vitiated heating is a common method, where the air is heated by burning fuel in the low speed side of the nozzle, and then oxygen is added to bring the level of O2 up to match that of standard air. The resulting flow no longer has the same composition as standard air, (except for the oxygen level), but rather contains combustion products, often referred to as vitiates as part of the mixture. The presence of these vitiates in the flow effects the wind tunnel test conditions. For example, the specific heat and molecular density are changed, the kinetics of combustion are altered and the flow features in the test article are altered. In this talk, the effects of the vitiates on the testing conditions and on the performance of test articles is described. Specific examples include the effects of molecular density on the flow, how combustion processes are altered by the presence of vitiates and how condensation of vitiates can alter the test conditions. In addition, the effect of the less common vitiates produced by arc-heated tunnels are mentioned, such as NO, non-thermal equilibrium and the presence of copper solids in the flow. Finally some thoughts on how large an effect these vitiates have on the test results are presented.

Andrew T Norris↗