Mach 6–8+ Hydrocarbon-Fueled Scramjet Flight Experiment: The HIFiRE Flight 2 Project

Abstract

The Hypersonic International Flight Research Experimentation (HIFiRE) program is a collaborative international effort designed to study basic hypersonic phenomena through flight experimentation. On 1 May 2012, the HIFiRE Flight 2 project successfully flew a hydrocarbon-fueled, Mach 8 scramjet experiment and demonstrated the ability to fly an accelerating, constant dynamic pressure trajectory consistent with a scramjet-powered flight vehicle using unguided sounding rocket techniques. The project goals of capturing high-quality flight data from a research scramjet operating through dual-to-scram mode transition up to and beyond Mach 8 were achieved. HIFiRE Flight 2 is unique in its contribution to scramjet research, providing a reference dataset to the hydrocarbon scramjet community while maturing a novel and reduced-cost strategy for performing similar future experiments. This paper describes the programmatic approach, the overall scramjet flight test experiment mission objectives, and the flight test strategy. It also includes an overview of launch system and payload hardware, and brief discussions of flight activities, flight data, and experimental results. Preliminary results from flight indicate a fully successful mission and experiment. Based on evaluations of data collected during the project, including ground test, flight test, and multiple analysis activities, all project-level scientific objectives have been successfully achieved.

Physical Insight into Fuel-Air Mixing for Upstream-Fuel-Injected Scramjets via Multi-Objective Design Optimization

“…The present paper focuses particularly on the former concept, that is, upstream fuel injection in the intake surface rather than conventional injection in the combustor, due to the advantages offered by early promotion of fuel/air mixing in a decrease in the vehicle length and skin friction, and consequently a reduction in the structural weight [6,9,10]. A similar fueling strategy was used in the Mach 6 − 8 HIFiRE Flight 2, where the primary injectors were positioned in the constant area isolator upstream of the combustor in conjunction with the secondary injectors positioned downstream [5].…”

“…Supersonic combustion ramjet (scramjet) propulsion is a promising technology that can enable efficient and flexible transport systems by removing the need to carry oxidizers and other limitations of conventional rocket engines. The last decade has seen remarkable milestones achieved by various flight experiments including the HyShot II of The University of Queensland in July 2002 [1,2], the NASA X-43 vehicles in the Hyper-X program in March and November 2004 [3], the Boeing X51AWaveRider in May 2010 [4], and the hydrocarbon HIFiRE Flight 2 in May 2012 [5].…”

Experimental investigation of open cavity as flame holder of supersonic combustor

“…Together with this, the development and testing of the propulsion system is a key problem in the implementation of hypersonic flights. The relevance of such studies is confirmed by national and international programs [1,2]. A key element of the scramjet is the combustion chamber with supersonic flow speed at the entrance.…”

Cavity-based flameholding for chemically-reacting supersonic flows

“…The scramjet combustor flowpath consisted of parallel cavity flameholders. Fuel -a gaseous mixture of ethylene (64% by volume) and methane (36% by volume), used to kinetically simulate partially cracked JP-7 -was injected both upstream and downstream of the cavities [40]. prediction of the corresponding amplitudes has proven more difficult.…”

“…Although their non-intrusive nature translates into reduced drag, total pressure losses, and aerodynamic heating when compared with other flameholder designs, it also leads to a limited influence of the piloting zone on the core flow and large local wall heat fluxes. Nonetheless, their effectiveness in enabling sustained combustion and improving supersonic combustor performance has been demonstrated in both ground and flight test experiments [51,61,49,28,32,40].…”