Nonidealities in Rotating Detonation Engines

Abstract

A rotating detonation engine (RDE) is a realization of pressure-gain combustion, wherein a traveling detonation wave confined in a chamber provides shock-based compression along with chemical heat release. Due to the high wave speeds, such devices can process high mass flow rates in small volumes, leading to compact and unconventional designs. RDEs involve unsteady and multiscale physics, and their operational characteristics are determined by an equilibrium between large- and small-scale processes. While RDEs can provide a significant theoretical gain in efficiency, achieving this improvement requires an understanding of the multiscale coupling. Specifically, unavoidable nonidealities, such as unsteady mixing, secondary combustion, and multiple competing waves associated with practical designs, need to be understood and managed. The secondary combustion processes arise from fuel/air injection and unsteady and incomplete mixing, and can create spurious losses. In addition, a combination of multiple detonation and secondary waves compete and define the dynamical behavior of mixing, heat release distribution, and the overall mode of operation of the device. This review discusses the current understanding of such nonidealities and describes the tools and techniques used to gain insight into the extreme unsteady environment in such combustors. Expected final online publication date for the Annual Review of Fluid Mechanics, Volume 55 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Experimental Study on the Propagation Characteristics of Rotating Detonation Wave with Liquid Hydrocarbon/High-Enthalpy Air Mixture

“…In the non-premixed chamber, a dual-wave system can emerge. This occurs when unburned reactants survive the leading detonation wave in the injector near field and are subsequently consumed within a trailing azimuthal reflected-shock combustion zone [39]. Furthermore, the trailing oblique shock wave reflects off the outer wall of the detonation chamber further downstream from the detonation wave.…”

“…The presence of deflagration within the rotating detonation chamber has a substantial effect on the behavior of the rotating detonation wave. The deflagration process contributes to the weakening of the detonation front and, from a thermodynamic perspective, reduces the cycle efficiency [39]. As more propellant is consumed by deflagration, less propellant remains to support the detonation wave.…”

Analysis of the flow field of kerosene-fueled rotating detonation engine with film cooling

“…Detonation engines, as a new type of propulsion device, possess advantages such as simple structure, higher thermal cycle efficiency, and rapid heat release [1,2]. The rotating detonation engine (RDE) is a However, the practical applications of the RDE are faced with another challenge -the need of thermal protection for long-term operation [15].…”

Numerical and boundary condition effects on the prediction of detonation engine behavior using detailed numerical simulations

“…Pressure gain combustion is increasingly being seen as a viable pathway to increasing efficiency of gas turbine engines (Raman et al, 2023;Lu and Braun 2014;Zhou et al, 2016). Unlike constant pressure thermodynamic cycles used in the current generation of gas turbines, pressure gain combustors use a modified cycle where the heat release is accompanied by an increase in pressure.…”

“…The design augments turbulence-induced mixing in order to have a large region of near-homogeneous mixture that is processed by the azimuthal wave. However, as in other turbulence-driven combustion systems, there is invariably some level of inefficiency leading to losses (Raman et al, 2023). The focus of this work is in understanding the structure of the flow field and the detonation wave in such non-premixed combustors, with the goal of gaining insight into the mixing and reaction processes.…”