Abstract
In the current study, an analytical model to estimate the fuel surface regression rate of hybrid rocket engines with head-end swirling flow oxidizer injection is established. The model is based on a convective heat feedback approach and, in conjunction with the corresponding boundary layer (or zone) concept which accounts for transpiration, effective hydraulic diameters, and wall friction. The effective tangential (swirl) velocity of the gas provides a positive augmentation effect to the fuel regression rate, above that due to the axial mass flux component of the core gas flow. From the literature, a variety of propellant combinations, engine sizes, and flow swirl numbers are evaluated for engines having circular-port fuel grains, with sample results provided in this report for comparative purposes. The predicted fuel regression rates for the most part compare quite well with the corresponding experimental data. Additionally, the validity of the underlying assumption of a slowly decaying effective axial and tangential velocity of the gas as one moves downstream along the central fuel port is to some degree verified using a computational approach, based on a simplified engine flow model. As a final element of the overall study, the fuel regression rate model is evaluated for parameter sensitivity. The settings for some propellant and gas properties are found to have a significant influence on the quantitative predictive results.
Highlights
1 Introduction Hybrid rocket engines (HREs) have several performance characteristics that are potentially favorable to a variety of rocket operations
The improvement of HREs is of interest for a number of institutions and commercial firms around the world, where the goal is to minimize the problems caused by the issues listed above
One might assume that a swirl flow would behave close to a forced vortex, the flow profile observed from the brief Computational Fluid Dynamics (CFD) study discussed later in this study suggests that the flow may not necessarily behave exactly as a forced vortex due to various factors
Summary
Hybrid rocket engines (HREs) have several performance characteristics that are potentially favorable to a variety of rocket operations They have more nominal advantages than solid and liquid rocket engines in some flight applications, owing in part to the difference between the propellant phases, where the oxidizer is kept in a liquid/ gaseous phase and fuel is kept in a solid phase, allowing them to be safely separated and controlled . Hybrid rocket engines’ positive features, such as the aforementioned enhanced safety when they are being operated, include an ability to control thrust, and a nominal capability for shutting down and restarting, while in flight. They are commonly quite simple to be manufactured and are typically less expensive, relatively speaking. The improvement of HREs is of interest for a number of institutions and commercial firms around the world, where the goal is to minimize the problems caused by the issues listed above
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
