Calculation of the process of detonation initiation in liquid explosives by a shock wave with a decaying profile

1973 ◽  
Vol 7 (1) ◽  
pp. 98-101
Author(s):  
S. N. Buravova ◽  
A. N. Dremin
Keyword(s):  
Shock Wave ◽  
Detonation Initiation ◽  
Liquid Explosives

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

Shock Waves ◽  
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.

Numerical Research on the Toroidal Shock Wave Focusing Detonation Initiation

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.

scholarly journals Numerical investigation of detonation initiation by a focusing shock wave

Shock Waves ◽  
2020 ◽  
Author(s):  
S. Bengoechea ◽  
J. Reiss ◽  
M. Lemke ◽  
J. Sesterhenn
Keyword(s):  
Shock Wave ◽  
Numerical Study ◽  
Transition Process ◽  
Detonation Initiation ◽  
Axisymmetric Nozzle ◽  
Geometry Design ◽  
Pulsed Detonation ◽  
Detonation Combustion ◽  
One Step ◽  
Adjoint Approach

Abstract This work presents a numerical study of detonation initiation by means of a focusing shock wave. The investigated geometry is a part of a pulsed detonation combustion chamber, consisting of a circular pipe in which the flow is obstructed by a single convergent–divergent axisymmetric nozzle. This obstacle acts as a focusing device for an incoming shock wave, serving as a low-energy detonation initiator. The chamber is filled with stoichiometric premixed hydrogen-enriched air. The simulation uses a one-step chemical model with variable parameters optimized by the adjoint approach in terms of the induction time $$\tau _{\text {c}}$$ τ c . The model reproduces $$\tau _{\text {c}}$$ τ c of a complex kinetics model in the range of pressures and temperatures appearing at the focusing point. The results give a comprehensive description of the shock-induced detonation initiation, which is the mechanism for the deflagration-to-detonation transition in this type of configurations. Potential geometry design improvements for technical applications are discussed. The first attempt to parameterize the transition process is also undertaken.

Numerical Research on the Toroidal Shock Wave Focusing Detonation Initiation

2019 ◽  
Vol 141 (11) ◽  
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 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.

Numerical investigation on detonation initiation using toroidal shock wave focusing

2019 ◽  
Vol 92 ◽  
pp. 300-313 ◽  
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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