Numerical Simulation of Coupled CFD-flight Mechanics and Taguchi's Approach for Reliability and Safety Assessments in the Hot Stage Separation of a Launch Vehicle

Abstract

This research presents a numerical simulation of a two-stage launch vehicle's hot stage separation process. Important parameters, such as the separation altitude, flight Mach number, and the angle of attack during separation, were investigated. The effects of these factors and the motor thrust parameter on the distance between the two stages post-separation were evaluated using the Taguchi method. Numerical analysis was performed using ANSYS Fluent, solving the three-dimensional flow field under the six degrees of freedom (6DOF) assumption. The SST k-ω turbulence model was employed for turbulence modeling, with a tetrahedral unstructured mesh used for the computational domain. The simulation results showed that increasing the separation altitude from 10 km to 20 km increased the distance between the two stages by 5.75%, primarily due to reduced air density and drag forces. Raising the flight Mach number from 2 to 3.2 increased the separation distance of two stages by 2.2%. Additionally, a higher angle of attack increased the deviation of the stages from their original trajectory, necessitating stage control after separation. Among the parameters studied, the motor thrust has the most significant effect on increasing the distance between the stages and preventing collisions. In contrast, the angle of attack has the most minor influence. © (2025), (Isfahan University of Technology). All rights reserved.