Rotating detonation engines (RDEs), also known as continuous detonation engines, have gained much worldwide interest lately. Such engines have huge potential benefits arising from their simplicity of design and manufacture, lack of moving parts, high thermodynamic efficiency and high rate of energy conversion that may be even more superior than pulse detonation engines, themselves the subject of great interest. However, due to the novelty of the concept, substantial work remains to demonstrate feasibility and bring the RDE to reality. An assessment of the challenges, ranging from understanding basic physics through utilizing rotating detonations in aerospace platforms, is provided.

https://arc.uta.edu/publications/cp_files/AIAA%202011-6043%20Rotating%20detonation%20wave%20propulsion%20experimental%20challenges,%20modeling,%20and%20engine%20concepts%20(invited).pdf

Rotating detonation wave propulsion: Experimental challenges, modeling, and engine concepts

Chemiluminescence imaging of an optically accessible non-premixed rotating detonation engine

Rotating detonation combustors and their similarities to rocket instabilities

Large-scale hydrogen–air continuous detonation combustor

Three-dimensional numerical investigations of the rotating detonation engine with a hollow combustor

An experimental study on rotating detonation is presented in this paper. The study was focused on the possibility of using rotating detonation in a rocket engine. The research was divided into two parts: the first part was devoted to obtaining the initiation of rotating detonation in fuel–oxygen mixture; the second was aimed at determination of the range of propagation stability as a function of chamber pressure, composition, and geometry. Additionally, thrust and specific impulse were determined in the latter stage. In the paper, only rich mixture is described, because using such a composition in rocket combustion chambers maximizes the specific impulse and thrust. In the experiments, two kinds of geometry were examined: cylindrical and cylindrical-conic, the latter can be simulated by a simple aerospike nozzle. Methane, ethane, and propane were used as fuel. The pressure–time courses in the manifolds and in the chamber are presented. The thrust–time profile and detonation velocity calculated from measured pressure peaks are shown. To confirm the performance of a rocket engine with rotating detonation as a high energy gas generator, a model of a simple engine was designed, built, and tested. In the tests, the model of the engine was connected to the dump tank. This solution enables different environmental conditions from a range of flight from 16 km altitude to sea level to be simulated. The obtained specific impulse for pressure in the chamber of max. 1.2 bar and a small nozzle expansion ratio of about 3.5 was close to 1,500 m/s.

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Experimental research on the rotating detonation in gaseous fuels–oxygen mixtures

Experimental research on rotating detonation in liquid fuel–gaseous air mixtures

The paper outlines an experimental study of influence of the ignition position and obstacles on explosion development in premixed methane–air mixtures in an elongated explosion vessel. As the explosion vessel, 1325 mm length tube with 128.5 mm diameter was used. Location of the ignition was changeable, i.e., fitted in the centre or at one of ends of the tube, when the tube was in a horizontal position. When it was in a vertical position, three locations of the ignition (bottom, centre and top) were used. In the performed study, the influence of obstacles on the course of pressure was investigated. Two identical steel grids were used as the obstacles. They were placed 405 mm from either end of the tube. Their blockage ratio (grid area to tube cross-section area) was determined as 0.33 for most of experiments. A few additional experiments (with smaller blockage ratio—0.16) were also conducted in order to compare the influence of the blockage ratio on the explosion development. Also some experiments were conducted in a semi-cylindrical vessel with volume close to 40 l. All the experiments were performed under stabilized conditions, with the temperature and pressure inside the vessel settled to room values and controlled by means of electronic devices. The pressure–time profiles from two transducers placed in the centreline of the inner wall of the explosion vessel were obtained for stoichiometric (9.5%), lean (7%) and rich (12%) methane–air mixture. The results obtained in the study, including maximum pressures and pressure–time profiles, illustrate a quite distinct influence of the above listed factors upon the explosion characteristics. The effect of ignition position, obstacles location and their BR parameters is discussed. The additional aim of the performed experiments was to find the data necessary to validate a new computer code, developed to calculate an explosion hazard in industrial installations.

Influence of ignition position and obstacles on explosion development in methane–air mixture in closed vessels

Experimental and numerical study of rotating detonation is presented. The experimental study is focused on the evaluation of the geometry of the detonation chamber and the conditions at which the rotating detona- tion can propagate in cylindrical channels. Lean hydrogen air mixtures were tested in the experiments. The pressure measured at dierent loca- tions was used to check the detonative nature of combustion. Also, the relationship between detonation velocity and operation conditions is ana- lyzed in the paper. The experimental study is accompanied with numer- ical analysis. The paper brie§y presents the results of two-dimensional (2D) numerical simulation of detonative combustion. The detonating mixture is created by mixting hydrogen with air. The air is injected axially to the chamber and hydrogen is injected through the inner wall of the chamber in radial direction. Application of proper injection con- ditions (pressure and nozzle area) allows establishing a stable rotating detonation like in the experiments. The detonation can be sustained for some range of conditions which are studied herein. The analysis of mean parameters of the process is provided as well. The numerical simulation results agree well with the experiments.

/pdf/experimental-and-numerical-study-of-the-rotating-detonation-3ln5nqzsp5.pdf

Experimental and numerical study of the rotating detonation engine in hydrogen-air mixtures

Detonation waves successively rotating in an annular chamber are numerically investigated to understand an overall ∞owfleld structure in the combustion chamber of an engine and its basic operation with a continuous fuel injection. This study leads to further investigation into continuously rotating detonation wave, which is the backbone in developing a rotating detonation-based propulsion system. A computational code developed is based on multi-dimensional Euler equations with source terms due to chemical reactions. Spatial terms in governing equations are discretized with a flnite volume method and a MUSCLbased Roe scheme, while temporal terms are discretized with a second-order, three-step Runge-Kutta method. Source terms are treated with a time-operator splitting method in order to isolate stifiness. The detonation is modeled with the one-step chemical reaction of a hydrogen and air mixture. A detailed ∞owfleld structure including detonation properties is presented in two- and three-dimensional annular chamber. The propulsive parameters of a rotational detonation engine are evaluated and its comparison of one- and two-waved detonation engine is performed in a three-dimensional chamber.

Jan Kindracki

Papers

Experimental research on the rotating detonation in gaseous fuels–oxygen mixtures

Experimental research on rotating detonation in liquid fuel–gaseous air mixtures

Influence of ignition position and obstacles on explosion development in methane–air mixture in closed vessels

Experimental and numerical study of the rotating detonation engine in hydrogen-air mixtures

A Three-Dimensional Numerical Study of Rotational Detonation in an Annular Chamber