Abstract
This report assesses the performance characteristics of a ramjet compression system in the application of a hypersonic vehicle. The vehicle is required to be self-powered and perform a complete flight profile using a combination of turbojet, ramjet and scramjet propulsion systems. The ramjet has been designed to operate between Mach 2.5 to Mach 5 conditions, allowing for start-up of the scramjet engine. Multiple designs, including varying ramp configurations and turbo-ramjet combinations, were investigated to evaluate their merits and limitations. Challenges arose with attempting to maintain sufficient pressure recoveries and favourable flow characteristics into the ramjet combustor. The results provide an engine inlet design capable of propelling the vehicle between the turbojet and scramjet phase of flight, allowing for the completion of its mission profile. Compromises in the design, however, had to be made in order to allow for optimisation of other propulsion systems including the scramjet nozzle and aerodynamics of the vehicle; it was concluded that these compromises were justified as the vehicle uses the ramjet engine for a minority of the flight profile as it transitions between low supersonic to hypersonic conditions.
Highlights
Following the discovery of flight in 1903, the Wright brothers sparked a challenge that would keep engineers busy for decades to come
To achieve hypersonic velocity, combined-cycled engines of varying configurations have been proposed over the years and this paper proposes once such cycle focussing on the intermediate stage to propel the concept aircraft proposed up to Mach 5 before the hypersonic stage kicks-in
The ramjet must create sufficient thrust at its given operating conditions while minimising the drag of the vehicle when at hypersonic conditions; this resulted in a compromise in performance characteristics to maintain an aerodynamic shape
Summary
Following the discovery of flight in 1903, the Wright brothers sparked a challenge that would keep engineers busy for decades to come. The challenges included methods of propulsion, aircraft aerodynamic design, aircraft structural design and control methods Many of these issues have been solved for both subsonic and supersonic flight, the hypersonic flight profile is still a relatively new concept, bringing a variety of challenging issues along with it. Thermal loading is a major issue for aircraft flying at high Mach numbers caused by the skin friction between the air and vehicle body. Another issue that requires careful attention is the aerodynamic design of the aircraft and its wings; the aircraft must take into consideration the shock waves formed, while the wing design must be able to achieve sufficient lift at low speed and low altitude conditions, as well as at high speed and high altitude conditions. To achieve hypersonic velocity, combined-cycled engines of varying configurations have been proposed over the years and this paper proposes once such cycle focussing on the intermediate (ramjet) stage to propel the concept aircraft proposed up to Mach 5 before the hypersonic (scramjet) stage kicks-in
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