Experimental and numerical studies were conducted to investigate complex vortical flow structures that are established in cylindrical chambers when a fluid is injected tangentially. Usually this will result in the formation of a bi-directional co-axial vortex when the inlets are positioned at the base of the chamber which has been found to provide many benefits when employed in hybrid rocket engine combustion chambers. The aim of this study is to produce evidence that substantiates the findings of recent analytical solutions and experimental observations that suggest the possible existence of high order convoluted vortex structures. This entails obtaining the loci of zero axial velocity within the bi-polar flow which are also known as mantles. These regions of purely toroidal flow denote the transition between vortices of opposing axial velocities. Identification of the vortex fields which exhibit multiple flow reversals and the parameters that affect their structure will be an important step in establishing criteria for advanced hybrid rocket engine designs. Flow fields containing multiple flow reversals can then be applied to vortex injection hybrid rockets to further increase mixing and residence times of the combusting flow which results in enhanced performance. Planar PIV measurements were obtained in the axial and azimuthal planes of the flow for several chamber configurations. These results were then compared to CFD simulations of similar configurations to assess the effectiveness of each method in capturing salient features of the flow. The most significant conclusion presented in this paper is the first ever measurements of confined vortex flows which exhibit multiple flow reversals.
展开▼
