Detonation propagation in a circular arc: reactive burn modelling

2017 ◽  
Vol 835 ◽  
pp. 970-998 ◽  
Author(s):  
Mark Short ◽  
James J. Quirk ◽  
Carlos Chiquete ◽  
Chad D. Meyer
Keyword(s):  
Supersonic Flow ◽  
Outer Surface ◽  
Detonation Front ◽  
Angular Speed ◽  
Mach Stem ◽  
Circular Arc ◽  
Detonation Propagation ◽  
High Impedance ◽  
Steady Detonation ◽  
Stem Structure

The dynamics of steady detonation propagation in a two-dimensional, high explosive circular arc geometry are examined computationally using a reactive flow model approach. The arc is surrounded by a low impedance material confiner on its inner surface, while its outer surface is surrounded either by the low impedance confiner or by a high impedance confiner. The angular speed of the detonation and properties of the steady detonation driving zone structure, i.e. the region between the detonation shock and sonic flow locus, are examined as a function of increasing arc thickness for a fixed inner arc radius. For low impedance material confinement on the inner and outer arc surfaces, the angular speed increases monotonically with increasing arc thickness, before limiting to a constant. The limiting behaviour is found to occur when the detonation driving zone detaches from the outer arc surface, leaving a region of supersonic flow on the outer surface. Consequently, the angular speed of the detonation becomes insensitive to further increases in the arc thickness. For high impedance material confinement on the outer arc surface, the observed flow structures are significantly more complex. As the arc thickness increases, we sequentially observe regions of negative shock curvature on the detonation front, reflected shock formation downstream of the reaction zone, and eventually Mach stem formation on the detonation front. Subsequently, a region of supersonic flow develops between the detonation driving zone and the Mach stem structure. For sufficiently wide arcs, the Mach stem structure disappears. For the high impedance material confinement, the angular speed of the detonation first increases with increasing arc thickness, reaches a maximum, decreases, and then limits to a constant for sufficiently large arc thickness. The limiting angular speed is the same as that found for the low impedance confiner on the outer arc surface.

Steady detonation propagation in a circular arc: a Detonation Shock Dynamics model

2016 ◽  
Vol 807 ◽  
pp. 87-134 ◽  
Author(s):  
Mark Short ◽  
James J. Quirk ◽  
Chad D. Meyer ◽  
Carlos Chiquete
Keyword(s):  
Surface Wave ◽  
Angular Speed ◽  
Order Correction ◽  
Two Dimensional ◽  
Normal Surface ◽  
Circular Arc ◽  
First Order ◽  
Shock Dynamics ◽  
First Order Correction ◽  
Steady Detonation

We study the physics of steady detonation wave propagation in a two-dimensional circular arc via a Detonation Shock Dynamics (DSD) surface evolution model. The dependence of the surface angular speed and surface spatial structure on the inner arc radius ($R_{i}$), the arc thickness ($R_{e}-R_{i}$, where $R_{e}$ is the outer arc radius) and the degree of confinement on the inner and outer arc is examined. We first analyse the results for a linear $D_{n}$–$\unicode[STIX]{x1D705}$ model, in which the normal surface velocity $D_{n}=D_{CJ}(1-B\unicode[STIX]{x1D705})$, where $D_{CJ}$ is the planar Chapman–Jouguet velocity, $\unicode[STIX]{x1D705}$ is the total surface curvature and $B$ is a length scale representative of a reaction zone thickness. An asymptotic analysis assuming the ratio $B/R_{i}\ll 1$ is conducted for this model and reveals a complex surface structure as a function of the radial variation from the inner to the outer arc. For sufficiently thin arcs, where $(R_{e}-R_{i})/R_{i}=O(B/R_{i})$, the angular speed of the surface depends on the inner arc radius, the arc thickness and the inner and outer arc confinement. For thicker arcs, where $(R_{e}-R_{i})/R_{i}=O(1)$, the angular speed does not depend on the outer arc radius or the outer arc confinement to the order calculated. It is found that the leading-order angular speed depends only on $D_{CJ}$ and $R_{i}$, and corresponds to a Huygens limit (zero curvature) propagation model where $D_{n}=D_{CJ}$, assuming a constant angular speed and perfect confinement on the inner arc surface. Having the normal surface speed depend on curvature requires the insertion of a boundary layer structure near the inner arc surface. This is driven by an increase in the magnitude of the surface wave curvature as the inner arc surface is approached that is needed to meet the confinement condition on the inner arc surface. For weak inner arc confinement, the surface wave spatial variation with the radial coordinate is described by a triple-deck structure. The first-order correction to the angular speed brings in a dependence on the surface curvature through the parameter $B$, while the influence of the inner arc confinement on the angular velocity only appears in the second-order correction. For stronger inner arc confinement, the surface wave structure is described by a two-layer solution, where the effect of the confinement on the angular speed is promoted to the first-order correction. We also compare the steady-state arc solution for a PBX 9502 DSD model to an experimental two-dimensional arc geometry validation test.

Numerical Study of Detonation Propagation in an Insensitive High Explosive Arc with Confinement Materials

2020 ◽  
pp. 2050117
Author(s):  
Yupei Qin ◽  
Kuibang Huang ◽  
Huan Zheng ◽  
Yousheng Zhang ◽  
Xin Yu
Keyword(s):  
Stainless Steel ◽  
Steady State ◽  
Detonation Wave ◽  
High Explosive ◽  
Numerical Study ◽  
Detonation Front ◽  
Outer Boundary ◽  
Outer Part ◽  
Transition Phase ◽  
Detonation Propagation

Detonation propagation in a confined circular arc configuration of an insensitive high explosive PBX9502 is investigated via numerical simulation in this paper. We introduce a steady detonation wave entering the explosive arc with confinements of stainless steel, and then it undergoes a transition phase and reaches a new steady state with a constant angular speed eventually. The influences of the inner and the outer confinements on the propagating detonation wave as well as the characteristics of the detonation driving zone (DDZ) in the steady state are discussed, respectively. Ignition and Growth (I&G) reaction rate and Jones–Wilkins–Lee (JWL) equations of state for the reactants and the products of PBX9502 are employed in the numerical simulations on the basis of a two-dimensional Eulerian code. The equation of state for stainless steel is in the Grüneisen form with a linear shock speed–particle speed Hugoniot relationship. Our results show that the inner confinement dominates the evolution of the detonation wave and the outer confinement only takes effect in a local region near the outer boundary within a limited initial stage during the transition phase. As for the steady state, the existence of the inner confinement makes the DDZ possess a certain width on the inner boundary. While as to the outer part of the detonation wave, the width of the DDZ decreases until the sonic locus intersects with the detonation front shock, which results in the detachment of the DDZ from the outer boundary and makes the detonation propagation fully independent of the outer confinement.

ON THE CHARACTERISTICS OF THE MACH STEM

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1511-1514 ◽  
Author(s):  
YU-XIN REN ◽  
LIAN-HUA TAN ◽  
BO GAO ◽  
ZI-NIU WU
Keyword(s):  
Current Status ◽  
Vehicle Design ◽  
Mach Stem ◽  
Circular Arc ◽  
Shape Characteristics

The characteristics of Mach stem in steady and unsteady Mach reflections are important in supersonic vehicle design. In this paper we give an overview of the current status of the study on the height and shape characteristics of Mach stem. Notably, we will show that in many cases the shape of the Mach stem seems to be well approximated by a circular arc.

scholarly journals Steady detonation propagation in thin channels with strong confinement

2020 ◽  
Vol 889 ◽  
Author(s):  
Mark Short ◽  
Stephen J. Voelkel ◽  
Carlos Chiquete
Keyword(s):  
Detonation Propagation ◽  
Image Position ◽  
Strong Confinement ◽  
Steady Detonation

Numerical Investigation of Viscous Laminar Supersonic Flow Past an Asymmetric Biconvex Circular-Arc Aerofoil

2013 ◽  
Vol 390 ◽  
pp. 147-151
Author(s):  
Saif Akram ◽  
Nadeem Hasan ◽  
Aqib Khan
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Supersonic Flow ◽  
Numerical Investigation ◽  
Lower Surface ◽  
Two Dimensional ◽  
Circular Arc ◽  
Flow Past ◽  
Supersonic Regime ◽  
Force Characteristics

A numerical investigation of two-dimensional unsteady, viscous and laminar compressible flow past an asymmetric biconvex circular-arc aerofoil in supersonic regime is carried out. The focus of the present work is to investigate the effects of variation of Mach number, at two different angles of attack, on the flow and force characteristics on NACA 2S-(50)(04)-(50)(20) aerofoil. The value of Reynolds number is taken as 5x105. The computations are carried out at Mach numbers of 1.25, 1.5 and 2.0 at an angle of attack of α=0° and α=10°. It is found that the aerofoil works well in the supersonic flow and, unlike the conventional symmetric biconvex aerofoil, generates finite lift at α=0° due to stronger shock waves at the lower surface. Moreover, the L/D ratio at α=10° is always found to be more than 2.5.

Application of the Continuous Rotating Detonation to Gas Turbine

2015 ◽  
Vol 782 ◽  
pp. 3-12 ◽  
Author(s):  
Piotr Wolański
Keyword(s):  
Experimental Study ◽  
Numerical Simulations ◽  
Gas Turbine ◽  
Thermodynamic Parameters ◽  
Experimental Research ◽  
Detonation Front ◽  
Complex Flow ◽  
Detonation Propagation ◽  
Rotating Detonation

In this paper experimental research on rotating detonation carried out at the Institute of Aviation (IA) in Warsaw are presented. Research was focused on 3-D numerical simulations of detonation propagation in cylindrical chambers and on evaluation of conditions at which rotating detonation is propagating in cylindrical channels for kerosene-hydrogen-air mixtures. Conducted simulations are used for analysis of complex flow – detonation front interaction and for estimating the thermodynamic parameters of the outflow gases. Extensive research on continuously propagating rotating detonation in many different chambers and in different fuel-air mixtures were tested. On bases of conducted calculations, as well as results of experimental study, a few chamber were selected for tests with GTD-350 engine. It was shown that application of the continuously rotating detonation to GTD-350 engine can results with increased efficiency of the engine.

Mach stem structure in exothermic systems

1973 ◽  
Vol 20 (1) ◽  
pp. 19-31 ◽  
Author(s):  
Rimantas Liaugminas ◽  
Harold O. Barthel ◽  
Roger A. Strehlow
Keyword(s):  
Mach Stem ◽  
Stem Structure

scholarly journals Elastic-plastic transition stresses in a thin rotating disc with rigid inclusion by infinitesimal deformation under steady-state temperature

2010 ◽  
Vol 14 (1) ◽  
pp. 209-219 ◽  
Author(s):  
Thakur Pankaj
Keyword(s):  
Outer Surface ◽  
Room Temperature ◽  
Circumferential Stress ◽  
Internal Surface ◽  
Angular Speed ◽  
Incompressible Material ◽  
Plastic State ◽  
Rotating Disc ◽  
Elastic Plastic ◽  
Different Temperatures

Stresses for the elastic-plastic transition and fully plastic state have been derived for a thin rotating disc with rigid shaft at different temperatures and results have been discussed and depicted graphically. It has been observed that at room temperature rotating disc made of compressible material and of smaller radii ratio yields at the internal surface at a higher angular speed as compared to rotating disc made of incompressible material. With the introduction of thermal effect rotating disc yields at the outer surface at a lesser angular speed as compared to rotating disc at room temperature. The circumferential stress is maximum at the outer surface of the rotating disc with further increases with the increase in temperature. It means that angular speed of the rotating disc is less than that of the temperature-loaded disc in the fully plastic case.

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