Dynamic fluidic nozzles for pulse detonation engine applications

Abstract

An efficient nozzle design is critical for enhancing the benefits of Pulse Detonation Engines (PDEs) and enabling their use as future propulsion or power generation systems. Due to the inherent variation in chamber pressure for Pulse Detonation Combustors, it has been difficult to design a nozzle, which has the capability to provide an appropriate exit-to-throat area ratio suited for both the detonation blow-down event and refresh pressures associated with the cyclic operation of a PDE. A two-dimensional PDE exit nozzle was designed, modeled, and constructed in an attempt to increase the overall efficiency of converting thermal energy to kinetic energy by providing a fluidic method to dynamically vary the effective nozzle area ratio. A fluidic nozzle configuration was evaluated, which had the ability to inject a small amount of air into the diverging section of the nozzle in order to dynamically create a more desirable exit-to-throat area ratio. Experimental testing was conducted on various injection flow rates, and a shadowgraph system was used to observe the fluid flow characteristics within the nozzle. Computer simulations were used to analyze the fluid flow properties within the nozzle. A comparison of the computer simulations and the experimental results was performed and demonstrated good agreement.