scholarly journals Analysis of the Detonation Wave Structure in a Linearized Rotating Detonation Engine

AIAA Journal ◽  
2020 ◽  
Vol 58 (12) ◽  
pp. 5063-5077 ◽  
Author(s):  
Supraj Prakash ◽  
Romain Fiévet ◽  
Venkat Raman ◽  
Jason Burr ◽  
Kenneth H. Yu
Keyword(s):  
Detonation Wave ◽  
Wave Structure ◽  
Rotating Detonation Engine ◽  
Detonation Engine ◽  
Rotating Detonation

scholarly journals Numerical Analysis of Detonability Assessment in a Natural Gas-Air Fueled Rotating Detonation Engine

2019 ◽  
Author(s):  
Pankaj Saha ◽  
Peter Strakey ◽  
Donald Ferguson ◽  
Arnab Roy
Keyword(s):  
Natural Gas ◽  
Detonation Wave ◽  
Hydrogen Fuel ◽  
Air Breathing ◽  
Wave Characteristics ◽  
Fuel Blends ◽  
Rotating Detonation Engine ◽  
Continuous Detonation ◽  
Detonation Engine ◽  
Rotating Detonation

Abstract Rotating Detonation Engines (RDE) offer an alternative combustion strategy to replace conventional constant pressure combustion with a process that could produce a pressure gain without the use of a mechanical compressor. Recent numerical and experimental publications that consider air as the oxidizer have primarily focused on the ability of these annular combustors to sustain a stable continuous detonation wave when fueled by hydrogen. However, for this to be a viable consideration for the land-based power generation it is necessary to explore the ability to detonate natural gas and air within the confines of the annular geometry of an RDE. Previous studies on confined detonations have expressed the importance of permitting detonation cells to fully form within the combustor in order to achieve stability. This poses a challenge for natural gas–air fueled processes as their detonation cell size can be quite large even at moderate pressures. Despite the practical importance, only a few studies are available on natural gas detonations for air-breathing RDE applications. Moreover, the extreme thermodynamic condition (high temperature inside the combustor) allows limited accessibility inside the combustor for detailed experimental instrumentations, providing mostly single-point data. Recent experimental studies at the National Energy Technology Laboratory (NETL) have reported detonation failure at higher methane concentration in an air-breathing RDE fueled by natural gas-hydrogen fuel blends. This encourages to perform a detailed numerical investigation on the wave characteristics of detonation in a natural gas-air fueled RDE to understand the various aspects of instability associated with the natural gas-air detonation. This study is a numerical consideration of a methane-air fueled RDE with varying operating conditions to ascertain the ability to achieve a stable, continuous detonation wave. The simulations have been performed in a 2D unwrapped RDE geometry using the open-source CFD library “OpenFOAM” employing an unsteady pressure-based compressible reactive flow solver with a k–ε turbulence model in a structured rectangular grid system. Both reduced and detailed chemical kinetic models have been used to assess the effect of the chemistry on the detonation wave characteristics and the underlying flow features. A systematic grid sensitivity study has been conducted with various grid sizes to quantify the weakly stable overdriven detonation on a coarse mesh and oscillating features at fine mesh resolutions. The main focus of the current study is to investigate the effects of operating injection pressure on detonation wave characteristics of an air-breathing Rotating Detonation Engine (RDE) fueled with natural gas-hydrogen fuel blends. Wave speeds, peak pressures and temperatures, and dominant frequencies have been computed from the time histories. The flow structures were then visualized using 2D contours of temperature and species concentration.

Multidimensional Numerical Simulations of Reacting Flow in a Non-Premixed Rotating Detonation Engine

2019 ◽  
Author(s):  
Pinaki Pal ◽  
Gaurav Kumar ◽  
Scott A. Drennan ◽  
Brent A. Rankin ◽  
Sibendu Som
Keyword(s):  
Detonation Wave ◽  
Performance Optimization ◽  
Design Space Exploration ◽  
Operating Conditions ◽  
Air Injection ◽  
Design Parameters ◽  
Cfd Model ◽  
Rotating Detonation Engine ◽  
Detonation Engine ◽  
Rotating Detonation

Abstract Over the last two decades, detonation based propulsion has received a great deal of attention as a potential means to achieve significant improvement in the performance of air-breathing and rocket engines. Detonative combustion mode is particularly interesting due to the resulting pressure gain from reactants to products, faster heat release, decreased entropy generation, more available work and higher thrust compared to conventional deflagrative combustion. Rotating detonation engine (RDE) is one such novel combustor concept. Realistic RDE configurations utilize separate fuel and air injection schemes, hence are not perfectly premixed. Moreover, RDE performance is governed by a large number of design parameters and operating conditions. In this context, computational fluid dynamics (CFD) has the potential to enhance the understanding of RDE combustion and aid future development/optimization of this technology. In the present work, a CFD model was developed to simulate a representative non-premixed RDE combustor. Unsteady Reynolds-Averaged Navier-Stokes (RANS) simulations were performed for the full combustor geometry (including the separate fuel and air injection ports), with hydrogen as fuel and air as the oxidizer. Adaptive mesh refinement (AMR) was incorporated to achieve a trade-off between model accuracy and computational expense. A finite-rate chemistry model along with a 10-species detailed kinetic mechanism was employed to describe the H2-Air combustion chemistry. Two operating conditions were simulated, corresponding to the same global equivalence ratio of unity but different fuel and air mass flow rates. For both conditions, the capability of the model to capture the essential detonation wave dynamics was assessed. A validation study was performed against experimental data available on detonation wave frequency/height, reactant fill height, oblique shock angle, axial pressure distribution in the channel, and fuel/air plenum pressure. The CFD model predicted the sensitivity of these wave characteristics to the operating conditions with good accuracy, both qualitatively and quantitatively. The present CFD model offers a potential capability to perform rapid design space exploration and/or performance optimization studies for realistic full-scale RDE configurations.

Multiphase Rotating Detonation Engine

2020 ◽  
Author(s):  
Ian Dunn ◽  
Kareem Ahmed
Keyword(s):  
Detonation Wave ◽  
High Speed ◽  
Fourier Transforms ◽  
Operational Parameters ◽  
Discrete Fourier Transforms ◽  
Rotating Detonation Engine ◽  
Coal Particles ◽  
Detonation Engine ◽  
Rotating Detonation ◽  
Carbon Concentrations

Abstract The first experimental evidence of a solid-gas multiphase rotating detonation engine. Coal particles, carbon black with a volatility of 1% and a carbon concentration of 99%, were detonated successfully over many operational parameters. These operational parameters surrounding the various points of investigation are shown in multiple 2-D slices as well as plotted in one 3-D graph to show the effects of varying carbon concentrations. These parameters include: variation in total mass flux injected into the annulus ranging from (≅120–270 kg/(s*m2), variation in hydrogen-air equivalence ratio (0.65–1.0), and finally variation in total concentrations of carbon (0–42.5%). High-speed backend imaging allowed for the analysis of the detonation wave dynamics, where detonation velocities were deduced using Discrete Fourier Transforms. By varying the parameters mentioned above, detonation velocities experienced in the detonation channel allowed for an introduction of an optimal operational point. When carbon was injected into very lean hydrogen-air conditions, the detonation was over-driven, causing fluctuations in the detonation velocities upwards of ∼100 m/s. As carbon concentrations increased further, detonation wave velocities relative to Chapman-Jouguet detonation velocities decreased.

Tip to End Analysis of Air Breathing Rotating Detonation Engine System

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
P. Amrutha Preethi ◽  
V. Ramanujachari
Keyword(s):  
Detonation Wave ◽  
Air Breathing ◽  
System A ◽  
Rotating Detonation Engine ◽  
Continuous Detonation ◽  
Simulation Based ◽  
Detonation Engine ◽  
Air Intake ◽  
Expansion System ◽  
Rotating Detonation

A discovery was made recently that the heat release would be very efficient if it is associated with detonation phenomenon. A detonation wave imparts high pressure to the products of combustion which in turn produces large propulsive power as a result of expansion through the propulsive element. This kind of pressure gain combustor is a new idea which is going to be incorporated in the futuristic propulsive devices. A representative air breathing propulsive system configuration powered by the continuous detonation wave engine is chosen for the present investigation. This includes understanding of various processes occurring in the air intake, isolator, rotating detonation wave engine and flow expansion system. A detailed numerical modelling and simulation based on steady 1-D flow have been carried out. This analysis gave insight into the overall propulsion system performance taking into consideration of the interaction between various sub systems.

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