Numerical Simulations of the Internal Ballistics of Paraffin–Oxygen Hybrid Rockets at Different Scales

Abstract

Hybrid rockets are considered a promising future propulsion alternative for specific applications to solid or liquid rockets. In order to raise their technology readiness level, it is important to perform predictive numerical simulations of their internal ballistics. The objective of this work is to describe and validate a numerical approach based on Reynolds-averaged Navier–Stokes simulations with sub-models for fluid–surface interaction, radiation, chemistry, and turbulence. Particular attention is given to scale effects by considering two different paraffin–oxygen hybrid rocket engines and a simplified grain evolution approach from the initial to the final port diameter. Moreover, a mild sensitivity of the computed regression rate to paraffin’s melting temperature, surface radiation emissivity, and Schmidt numbers is observed. Results highlight the increasing importance of radiation effects at larger scales and pressures. A numerical rebuilding of regression rate and pressure is obtained with simulations at the time-space-averaged port diameter, producing a reasonable agreement with the available experimental data, but a noticeable improvement is obtained by considering the grain evolution in time.

Dynamic Numerical Simulation of Hybrid Rocket Motor with HTPB-Based Fuel with 58% Aluminum Additives

“…Typical hybrid rocket motors (HRMs) propellants consist of solid fuel and liquid oxidizers [1][2][3][4]. Since the propellants are stored in different phases, respectively, the hybrid rocket motor has obvious advantages compared with solid and liquid rocket motors in terms of simple structure, adjustable thrust, high safety, low cost, and multiple restart capabilities [5][6][7][8]. The advantages make it suitable for missile systems, attitude control motors, small launch vehicles, and space tourism.…”

Special Issue “Hybrid Rocket (Volume II)”

“…In the area of internal ballistics' simulations, Tindaro Migliorino et al [17] have discussed in this special issue the validity of Reynolds-averaged Navier-Stokes computations considering fluid-fuel surface interaction, radiation, and gas combustion. Palacz and Cieślik [18] have studied a model to evaluate possible two-phase flow effects when supplying a self-pressurized liquid oxidizer such as N 2 O. Viscor et al [19] have proposed the concept of equivalent burning time to account for the effect of engine start-up in determining the correlation between fuel regression rate and mass flux from combustion test results and have shown its effectiveness.…”