Blast overpressure modeling enhancements for application to risk-informed design of human space flight launch abort systems

This paper describes recent enhancements to the engineering-level analysis tools used by the simulation assisted risk assessment (SARA) project (Ref. 1) at NASA Ames Research Center in evaluating the blast overpressure risk to the crew. The primary enhancements to the model include incorporation of vapor cloud explosion (VCE) curve fits for propellant explosions, development of an improved model for the effects of vehicle velocity on blast propagation, improvement in the representation of blast/vehicle interaction effects, and incorporation of pressure vs. impulse (P-I) failure criteria to better represent structural failure modes. High-fidelity computational fluid dynamics (CFD) simulations, using the Overflow2 (Ref. 2) code, played a crucial role in the development of some of these enhancements. A subset of the high-fidelity results is presented.