Numerical Research on the Toroidal Shock Wave Focusing Detonation Initiation

Abstract Pressure gain combustion (PGC) is considered to be a potential technology to increase the cycle efficiency of gas turbine. As one viable candidate for PGC, rotating detonation engine (RDE) draws more attention due to its significant advances in continuous mode of operation. In practical, one of the basic challenges for RDE application is to reliably initiate detonation wave. For this purpose, both detonation initiation mechanism and enhancement approach are urgently needed to be understood. In this work, a toroidal shock wave focusing detonation initiator is presented. On this basis, the two-dimensional numerical simulations are carried out to investigate the detonation initiation characteristics by using the toroidal shock wave focusing. All of the flame acceleration, shock wave focusing, detonation wave forming, and propagation are analyzed in detail. The numerical results show that the toroidal shock wave focusing initiator developed in this study can rapidly realize the detonation initiation over a short distance and performs significantly better than the traditional smooth or obstructed tube based imitators under different operating conditions. Under the same operating condition, the novel developed initiator decreases time of 59.2% and distance of 84.7% for the smooth tube based initiator, and time of 52% and distance of 78.9% for the obstructed one. Besides, the multifield analysis indicates that both the local explosion induced by shock wave focusing in concave cavity and the entrainment vortex generated by shock wave and jet flame in front of diaphragm are important mechanisms to initiate detonation wave. This study is expected to enhance the understanding of the physical mechanism of shock wave focusing detonation initiation and contribute to the development of detonation propulsion technology.

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Numerical Research on the Toroidal Shock Wave Focusing Detonation Initiation

Volume 4A: Combustion, Fuels, and Emissions ◽

10.1115/gt2019-90082 ◽

2019 ◽

Author(s):

Xiang Chen ◽

Ningbo Zhao ◽

Hongtao Zheng ◽

Xiongbin Jia ◽

Shizheng Liu ◽

...

Keyword(s):

Shock Wave ◽

Detonation Wave ◽

Detonation Initiation ◽

Operating Conditions ◽

Initiation Mechanism ◽

Wave Focusing ◽

Jet Flame ◽

Rotating Detonation Engine ◽

Detonation Engine ◽

Shock Wave Focusing

Abstract Pressure gain combustion (PGC) is considered to be a potential technology to increase the cycle efficiency of gas turbine. As one viable candidate for PGC, rotating detonation engine (RDE) draws more attention due to its significant advances in continuous mode of operation. In practical, one of the basic challenges for RDE application is to reliably initiate detonation wave. For this purpose, both detonation initiation mechanism and enhancement approach are urgently needed to be understood. In this work, a toroidal shock wave focusing detonation initiator is presented. On this basis, the two-dimensional numerical simulations are carried out to investigate the detonation initiation characteristics by using the toroidal shock wave focusing. All of the flame acceleration, shock wave focusing, detonation wave forming and propagation are analyzed in detail. The numerical results show that the toroidal shock wave focusing initiator developed in this study can rapidly realize the detonation initiation over a short distance and performs significantly better than the traditional smooth or obstructed tube based imitators under different operating conditions. Under the same operating condition, the novel developed initiator decreases time of 59.2% and distance of 84.7% for the smooth tube based initiator, and time of 52% and distance of 78.9% for the obstructed one. Besides, the multi-fields analysis indicates that both the local explosion induced by shock wave focusing in concave cavity and the entrainment vortex generated by shock wave and jet flame in front of diaphragm are important mechanisms to initiate detonation wave. The present study is expected to enhance the understanding of the physical mechanism of shock wave focusing detonation initiation and contribute to the development of detonation propulsion technology.

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Numerical investigation on detonation initiation using toroidal shock wave focusing

Aerospace Science and Technology ◽

10.1016/j.ast.2019.06.016 ◽

2019 ◽

Vol 92 ◽

pp. 300-313 ◽

Cited By ~ 3

Author(s):

Xiang Chen ◽

Ningbo Zhao ◽

Xiongbin Jia ◽

Shizheng Liu ◽

Hongtao Zheng ◽

...

Keyword(s):

Shock Wave ◽

Numerical Investigation ◽

Detonation Initiation ◽

Wave Focusing ◽

Shock Wave Focusing

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

Volume 4B: Combustion, Fuels, and Emissions ◽

10.1115/gt2019-91931 ◽

2019 ◽

Cited By ~ 1

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.

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Effect of reflection type on detonation initiation at shock-wave focusing

Shock Waves ◽

10.1007/s001930050008 ◽

2000 ◽

Vol 10 (3) ◽

pp. 205-215 ◽

Cited By ~ 17

Author(s):

A.M. Bartenev ◽

S.V. Khomik ◽

B.E. Gelfand ◽

H. Grönig ◽

H. Olivier

Keyword(s):

Shock Wave ◽

Detonation Initiation ◽

Wave Focusing ◽

Shock Wave Focusing

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Effect of ignition parameters on detonation initiation using toroidal shock wave focusing

Aerospace Science and Technology ◽

10.1016/j.ast.2020.106421 ◽

2021 ◽

Vol 109 ◽

pp. 106421

Author(s):

Xiang Chen ◽

Ningbo Zhao ◽

Hongtao Zheng ◽

Xiongbin Jia ◽

Mingzhang Pan ◽

...

Keyword(s):

Shock Wave ◽

Detonation Initiation ◽

Wave Focusing ◽

Shock Wave Focusing

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Adjoint-based optimisation of detonation initiation by a focusing shock wave

Shock Waves ◽

10.1007/s00193-020-00973-w ◽

2021 ◽

Author(s):

S. Bengoechea ◽

J. Reiss ◽

M. Lemke ◽

J. Sesterhenn

Keyword(s):

Shock Wave ◽

Incident Shock ◽

Incident Shock Wave ◽

Detonation Initiation ◽

Axisymmetric Nozzle ◽

Exponential Factor ◽

Pulsed Detonation Engine ◽

Pulsed Detonation ◽

Detonation Engine ◽

Adjoint Approach

AbstractAn optimisation study of a shock-wave-focusing geometry is presented in this work. The configuration serves as a reliable and deterministic detonation initiator in a pulsed detonation engine. The combustion chamber consists of a circular pipe with one convergent–divergent axisymmetric nozzle, acting as a focusing device for an incoming shock wave. Geometrical changes are proposed to reduce the minimum shock wave strength necessary for a successful detonation initiation. For that purpose, the adjoint approach is applied. The sensitivity of the initiation to flow variations delivered by this method is used to reshape the obstacle’s form. The thermodynamics is described by a higher-order temperature-dependent polynomial, avoiding the large errors of the constant adiabatic exponent assumption. The chemical reaction of stoichiometric premixed hydrogen-air is modelled by means of a one-step kinetics with a variable pre-exponential factor. This factor is adapted to reproduce the induction time of a complex kinetics model. The optimisation results in a 5% decrease of the incident shock wave threshold for the successful detonation initiation.

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