scholarly journals Descending Modal Transition Dynamics in a Large Eddy Simulation of a Rotating Detonation Rocket Engine

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3387
Author(s):  
Armani Batista ◽  
Mathias C. Ross ◽  
Christopher Lietz ◽  
William A. Hargus
Keyword(s):  
Detonation Wave ◽  
Failure Time ◽  
Rocket Engine ◽  
Detonation Waves ◽  
Rocket Engines ◽  
Operation Performance ◽  
Eddy Simulation ◽  
Upstream Pressure ◽  
Detonation Failure ◽  
Rotating Detonation

Rotating detonation rocket engines (RDREs) exhibit various unsteady phenomena, including modal transitions, that significantly affect their operation, performance and stability. The dynamics of the detonation waves are studied during a descending modal transition (DMT) where four co-rotating detonations waves decrease to three in a gaseous methane-oxygen RDRE. Detonation wave tracking is applied to capture, visualize and analyze unsteady, 3D detonation wave dynamics data within the combustion chamber of the RDRE. The mechanism of a descending modal transition is the failure of a detonation wave in the RDRE, and in this study, the failing wave is identified along with its failure time. The regions upstream of each relative detonation show the mixture and flow-field parameters that drive detonation failure. Additionally, it is shown that descending modal transitions encompass multiple phases of detonation decay and recovery with respect to RDREs. The results show high upstream pressure, heat release and temperature, coupled with insufficient propellants, lead to detonation wave failure and non-recovery of the trailing detonation wave during a descending modal transition. Finally, the Wolanski wave stability criterion regarding detonation critical reactant mixing height provides insight into detonation failure or sustainment.

Application of a Convolutional Neural Network for Wave Mode Identification in a Rotating Detonation Combustor Using High-Speed Imaging

2020 ◽  
Author(s):  
Kristyn B. Johnson ◽  
Donald H. Ferguson ◽  
Robert S. Tempke ◽  
Andrew C. Nix
Keyword(s):  
Neural Network ◽  
Detonation Wave ◽  
High Speed ◽  
Wave Mode ◽  
Classification Performance ◽  
Detonation Waves ◽  
Single Image ◽  
High Speed Imaging ◽  
Mode Identification ◽  
Rotating Detonation

Abstract Utilizing a neural network, individual down-axis images of combustion waves in a Rotating Detonation Engine (RDE) can be classified according to the number of detonation waves present and their directional behavior. While the ability to identify the number of waves present within individual images might be intuitive, the further classification of wave rotational direction is a result of the detonation wave’s profile, which suggests its angular direction of movement. The application of deep learning is highly adaptive and therefore can be trained for a variety of image collection methods across RDE study platforms. In this study, a supervised approach is employed where a series of manually classified images is provided to a neural network for the purpose of optimizing the classification performance of the network. These images, referred to as the training set, are individually labeled as one of ten modes present in an experimental RDE. Possible classifications include deflagration, clockwise and counterclockwise variants of co-rotational detonation waves with quantities ranging from one to three waves, as well as single, double and triple counter-rotating detonation waves. After training the network, a second set of manually classified images, referred to as the validation set, is used to evaluate the performance of the model. The ability to predict the detonation wave mode in a single image using a trained neural network substantially reduces computational complexity by circumnavigating the need to evaluate the temporal behavior of individual pixels throughout time. Results suggest that while image quality is critical, it is possible to accurately identify the modal behavior of the detonation wave based on only a single image rather than a sequence of images or signal processing. Successful identification of wave behavior using image classification serves as a stepping stone for further machine learning integration in RDE research and comprehensive real-time diagnostics.

Detonation Wave Interaction Classifications in a Rotating Detonation Rocket Engine

2020 ◽  
Author(s):  
Armani Batista ◽  
Mathias Ross ◽  
Christopher Lietz ◽  
William A. Hargus
Keyword(s):  
Detonation Wave ◽  
Rocket Engine ◽  
Wave Interaction ◽  
Rotating Detonation

scholarly journals Investigating Instabilities in a Rotating Detonation Combustor Operating With Natural Gas–Hydrogen Fuel Blend—Effect of Air Preheat and Annulus Width

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Arnab Roy ◽  
Clinton R. Bedick ◽  
Donald H. Ferguson ◽  
Todd Sidwell ◽  
Peter A. Strakey
Keyword(s):  
Natural Gas ◽  
Detonation Wave ◽  
Air Temperature ◽  
Detonation Waves ◽  
Operating Pressure ◽  
Hydrogen Fuel ◽  
Fuel Blend ◽  
Operational Envelope ◽  
Rotating Detonation ◽  
Gap Width

Abstract Propagation characteristics of a detonation wave in an air-breathing rotating detonation combustor (RDC) using natural gas (NG)–hydrogen fuel blends is presented in this paper. Short-duration (∼up to 6 s) experiments were performed on a 152.4 mm OD uncooled RDC with two different annulus gap widths (5.08 mm and 7.62 mm) over a range of equivalence ratios (0.6–1.0) at varying inlet air temperatures (∼65–204 °C) and NG content (up to 15%) with precombustion operating pressure slightly above ambient. It was observed that the RDC, with an annulus gap width of 5.08 mm, was inherently unstable when NG was added to the hydrogen fuel while operating at precombustion pressures near ambient and at an inlet air temperature of 65 °C. Increasing the annulus gap width to 7.62 mm improved the stability of the detonation wave at similar temperatures and pressure permitting operation with as much as 5% NG by volume. While observed speeds of the detonation waves were still below theoretical values, an increase in inlet air temperature reduced the variability in wave speed. The frequency analysis thus explored in this study is an effort to quantify detonation instability in an RDC under varying operational envelope. The data presented are relevant toward developing strategies to sustain a stable detonation wave in an RDC using NG for land-based power generation.

scholarly journals Combustion Characteristics in Rotating Detonation Engines

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yuhui Wang ◽  
Wenyou Qiao ◽  
JialingLe
Keyword(s):  
Detonation Wave ◽  
Flow Rate ◽  
Detonation Waves ◽  
Outer Diameter ◽  
Combustion Mode ◽  
Hydrogen Flow ◽  
Pulsed Detonation ◽  
Rotating Detonation Engine ◽  
Rotating Detonation Engines ◽  
Rotating Detonation

A lot of studies on rotating detonation engines have been carried out due to the higher thermal efficiency. However, the number, rotating directions, and intensities of rotating detonation waves are changeful when the flow rate, equivalence ratio, inflow conditions, and engine schemes vary. The present experimental results showed that the combustion mode of a rotating detonation engine was influenced by the combustor scheme. The annular detonation channel had an outer diameter of 100 mm and an inner diameter of 80 mm. Air and hydrogen were injected into the combustor from 60 cylindrical orifices in a diameter of 2 mm and a circular channel with a width of 2 mm, respectively. When the air mass flow rate was increased by keeping hydrogen flow rate constant, the combustion mode varied. Deflagration and diffusive combustion, multiple counterrotating detonation waves, longitudinal pulsed detonation, and a single rotating detonation wave occurred. Both longitudinal pulsed detonation and a single rotating detonation wave occurred at different times in the same operation. They could change between each other, and the evolution direction depended on the air flow rate. The operations with a single rotating detonation wave occurred at equivalence ratios lower than 0.60, which was helpful for the engine cooling and infrared stealth. The generation mechanism of longitudinal pulsed detonation is developed.

Application of a Convolutional Neural Network for Wave Mode Identification in a Rotating Detonation Combustor Using High-Speed Imaging

2021 ◽  
pp. 1-22
Author(s):  
Kristyn B. Johnson ◽  
Donald H. Ferguson ◽  
Robert S. Tempke ◽  
Andrew C. Nix
Keyword(s):  
Neural Network ◽  
Detonation Wave ◽  
High Speed ◽  
Wave Mode ◽  
Classification Performance ◽  
Detonation Waves ◽  
Single Image ◽  
High Speed Imaging ◽  
Mode Identification ◽  
Rotating Detonation

Abstract Utilizing a neural network, individual down-axis images of combustion waves in a Rotating Detonation Engine (RDE) can be classified according to the number of detonation waves present and their directional behavior. While the ability to identify the number of waves present within individual images might be intuitive, the further classification of wave rotational direction is a result of the detonation wave's profile, which suggests its angular direction of movement. The application of deep learning is highly adaptive and therefore can be trained for a variety of image collection methods across RDE study platforms. In this study, a supervised approach is employed where a series of manually classified images is provided to a neural network for the purpose of optimizing the classification performance of the network. These images, referred to as the training set, are individually labeled as one of ten modes present in an experimental RDE. Possible classifications include deflagration, clockwise and counterclockwise variants of corotational detonation waves with quantities ranging from one to three waves, as well as single, double and triple counter-rotating detonation waves. The ability to predict the detonation wave mode in a single image using a trained neural network substantially reduces computational complexity by circumnavigating the need to evaluate the temporal behavior of individual pixels throughout time. Results suggest that while image quality is critical, it is possible to accurately identify the modal behavior of the detonation wave based on only a single image rather than a sequence of images or signal processing.

scholarly journals Investigating Instabilities in a Rotating Detonation Combustor Operating With Natural Gas-Hydrogen Fuel Blend: Effect of Air Preheat and Annulus Width

2019 ◽  
Author(s):  
Arnab Roy ◽  
Clinton Bedick ◽  
Donald Ferguson ◽  
Todd Sidwell ◽  
Peter Strakey
Keyword(s):  
Natural Gas ◽  
Detonation Wave ◽  
Air Temperature ◽  
Gas Content ◽  
Detonation Waves ◽  
Operating Pressure ◽  
Hydrogen Fuel ◽  
Fuel Blend ◽  
Rotating Detonation ◽  
Gap Width

Abstract Propagation characteristics of a detonation wave in an air-breathing Rotating Detonation Combustor (RDC) using natural gas-hydrogen fuel blends is presented in this paper. Short duration (∼up to 6s) experiments were performed on a 152.4mm OD uncooled RDC with two different annulus gap widths (5.08mm and 7.62mm) over a range of equivalence ratios (0.6–1.0) at varying inlet air temperatures (∼65°C-204°C) and natural gas content (up to 15%) with pre-combustion operating pressure slightly above ambient. It was observed that the RDC, with an annulus gap width of 5.08mm, was inherently unstable when natural gas (NG) was added to the hydrogen fuel while operating at pre-combustion pressures near ambient and at an inlet air temperature of 65°C. Increasing the annulus gap width to 7.62mm improved the stability of the detonation wave at similar temperatures and pressure permitting operation with as much as 5% NG by volume. While observed speeds of the detonation waves were still below theoretical values, an increase in inlet air temperature reduced the variability in wave speed. The frequency analysis thus explored in this study is an effort to quantify detonation instability in an RDC under varying operational envelope. The data presented is relevant towards developing strategies to sustain a stable detonation wave in an RDC using natural gas for land based power generation.

Visualization of detonation waves inside a rotating-detonation rocket engine by using point-diffraction interferometry

2022 ◽  
Author(s):  
Toshiharu Mizukaki ◽  
Faming Wang ◽  
Makoto Kojima ◽  
Hideto Kawashima ◽  
Shingo Matsuyama ◽  
...  
Keyword(s):  
Rocket Engine ◽  
Detonation Waves ◽  
Rotating Detonation

scholarly journals Driving and damping mechanisms for transverse combustion instabilities in liquid rocket engines

2017 ◽  
Vol 820 ◽  
Author(s):  
A. Urbano ◽  
L. Selle
Keyword(s):  
Rocket Engine ◽  
Three Dimensional ◽  
Rocket Engines ◽  
Combustion Instabilities ◽  
Time Resolved ◽  
Physical Mechanisms ◽  
Eddy Simulation ◽  
Liquid Rocket Engines ◽  
Large Eddy ◽  
Liquid Rocket

This work presents the analysis of a transverse combustion instability in a reduced-scale rocket engine. The study is conducted on a time-resolved database of three-dimensional fields obtained via large-eddy simulation. The physical mechanisms involved in the response of the coaxial hydrogen/oxygen flames are discussed through the analysis of the Rayleigh term in the disturbance-energy equation. The interaction between acoustics and vorticity, also explicit in the disturbance-energy balance, is shown to be the main damping mechanism for this instability. The relative contributions of Rayleigh and damping terms, depending on the position of the flame with respect to the acoustic field, are discussed. The results give new insight into the phenomenology of transverse combustion instabilities. Finally, the applicability of spectral analysis on the nonlinear Rayleigh and dissipation terms is discussed.

Sign in / Sign up

Export Citation Format

Share Document