Numerical Investigations of Fuel-Oxidizer Mixing on the Propagation of a Detonation Wave

The rapid and violent combustion of a detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock wave. Such mode of combustion has been theoretically shown to provide a higher combustion efficiency than the commonly employed subsonic, isobaric methods. Recently, the scientific community is migrating toward exploring the use of a detonation wave for engineering purposes to innovate combustor technologies and increase efficiency. Many detonation-based devices concepts have been proposed, but the Rotating Detonation Engine (RDE) has shown tremendous advantages over the other concepts due to its low complexity and continuous self-sustained propagation of a detonation within the combustion chamber. In an RDE one or multiple detonations propagate azimuthally around an annular chamber where high speed discrete injection systems are employed. Improved understanding of the flow physics is required to aid with future designs. Many experiments have shown that the injector configuration can lead to poor mixing between propellants that ultimately leads to substantial decrease in performance and stability of the wave. Numerical advances have made it possible to perform calculations in order to predict the main characteristics of the flow-field inside such devices. This thesis focuses to improve the understanding of detonation waves propagating in non-premixed mixtures. Using high-fidelity numerical simulations, this work will assess the effects of fuel distribution and mixture preparation on the formation and propagation of a detonation wave. First, a full-scale H2-air three-dimensional non-premixed RDE with radial injection is simulated. Extensive analysis is performed when the fuel and air mass flow rate are varied to hold a unity global equivalence ratio. To explore a wider range of conditions and reduce the computational cost, a new canonical setup is then developed and investigated. The main differences with the previous configuration are absence of curvature effects and the reduction of fuel injector number. Here, the role of mixture preparation is investigated through a statistical description to suggest and develop a novel regime map based solely on mixture state ahead of the wave. Thus, the influence of the current studies can potentially aid in the development of new injection strategies to promote the steady operation of novel detonation-based combustors.

Date

2022-04-05

Resource Type

Text

Resource Subtype

Dissertation

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