Impinging Injector Design for a Paraffin-Nitrous Oxide Hybrid Rocket Engine used in Sounding Rockets Part I: CFD Simulation of Candidate Designs
- Paper number
IAC-16,C4,IP,36,x32159
- Author
Mr. Jeremy Chan-Hao Wang, University of Toronto Aerospace Team (UTAT), Canada
- Coauthor
Mr. Thomas Siu-Hong Leung, University of Toronto Aerospace Team, Canada
- Coauthor
Mr. Carl Pigeon, Space Flight Laboratory, University of Toronto, Canada
- Year
2016
- Abstract
This paper presents the candidate designs, CFD simulations, and critical performance metrics used in the design selection for a hybrid rocket engine impinging injector plate. The University of Toronto Aerospace Team (UTAT) Rocketry Division’s fourth-generation sounding rocket “Deliverance” is powered by a 4kN-thrust paraffin-nitrous oxide hybrid engine, with a target altitude of 25 000ft above ground level. Varying jet separation distances and hole diameters were compared for arrangements of impinging doublets. The key performance objectives of the injector were: (1) provide an average mass flow rate of 1.7kg/s at a steady-state pressure difference of 350psia; and (2) atomize the stored liquid oxidizer and promote mixing to support combustion. Furthermore, the injector had to meet {\it a priori} blow-out and quenching constraints. ANSYS Fluent was used to generate steady-state, 3D simulation results. Tetrahedral elements were used throughout the computational domain, which terminated 20cm upstream and downstream the injector assembly. The realizable k-$\omega$ω turbulence model was selected based on recent work by Najafi. A comparison of Reynolds, Ohnesorge, and Weber numbers in the pre-combustion region helped characterize the extent of atomization and turbulence. A total of six candidate designs were compared. Simulations predicted that the target mass flow rate can be achieved with 7 pairs of 2mm-hole doublets, impinging at a 60-degree angle, with a discharge coefficient of approximately 0.70. Higher hole length-to-diameter ratios tended to increase the size of the dispersion cloud. Shorter jet separation distances yielded larger dispersion clouds as a result of greater kinetic energy concentrated at the impingement point. The maximum diameter of the dispersion cloud was typically attained 1-2 inches downstream the injector plate. In a separate paper, these simulations are compared to experimental cold-flow results to validate these predictions.- Abstract document
- Manuscript document
(absent)