Ngetich, Gladys Chepkirui, Stober, K.J., Wood, D., "Numerical Simulation of Centrifugal Casting of Paraffin Wax: Influence of Rotational Speed and Fluid Viscosity," AIAA Propulsion and Energy Forum, August 2021.

Abstract

Paraffin wax as an alternative hybrid rocket propellant has received a lot of attention from researchers because of its attractive characteristics; high-performing, non-toxic, reusable, and easy to store. Paraffin wax fuel grains are normally manufactured through a centrifugal casting process. In the centrifugal casting process, fluid properties such as viscosity and casting tube geometrical parameters have a direct impact on the quality of the final cast product. In order to further understand and predict various heat and mass flow phenomena, and even optimise the centrifugal casting process, it is necessary to study fluid flow patterns in the centrifugal casting process. This research paper numerically investigates the influence of rotational speed and fluid viscosity in the centrifugal casting process of paraffin wax. Finite volume code in the Computational Fluid Dynamics (CFD) solver ANSYS Fluent was employed for the simulations. Liquid viscosity (water, SAE 5W-30 motor oil, and paraffin wax dotriacontane C32H66), and rotational speeds (1000 RPM, 2220 RPM, and 3000 RPM) were studied. From the transient twophase isothermal simulations, it was noted that viscosity played a major role in the centrifugal casting process; with high viscosity liquids like SAE 5W-30 motor oil forming a smooth, reliable annulus much faster, and even at relatively lower rotational speeds, unlike low viscosity liquids like water.