Vortex combustion in a hybrid rocket motor

The work is focused on a vortex flow pancake hybrid rocket motor (VFP). This hybrid rocket configuration is characterized by two flat solid fuel disks and a tangential injection between them. The gap between the two flat disks serves as combustion chamber. After the ignition, a vortex drain type flow-field is induced within the combustion chamber, causing the regression of both fuel surfaces. The fuel disks have two ports. One lodges the motor igniter, while the second yield to the gasdynamic nozzle. The length to diameter ratio for this rocket is lower than 1. Two stages are involved in the work: the first one involves the internal flow-field experimental and numerical characterization and the second the firing tests. The OpenFOAM® software is used to implement a 3D code for initial assessment of the vortex flow-field behavior. The finite volume code solves the Navier-Stokes equations with a RANS approach. Cold flow simulations are performed to characterize the fuel and oxidizer mixing. The second stage focuses on test firings. The fuel is a blend of paraffin (60 wt.%), and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene grafted with maleic anhydride (SEBS, 40 wt.%). The oxidizer is gaseous oxygen (GOX). The test firings allow to evaluate the combustion efficiency, which is low due to the properties of the investigated fuel, and the regression rate, which is measured by using TOT-based data reduction and wire-cut sensors. The experimental and numerical obtained results show the opportunity to further investigate this unusual rocket configuration.