Wave Expansion Research Articles

Experimental investigation of the shock wave/boundary layer interaction at a compression corner and an incident shock wave generator

The separation of the boundary layer is one of the main failures in scramjets due to its influence on the amount of oxygen used in combustion, reducing thrust and specific impulse. The main objective of this paper was to perfom experimental investigations to study the shock wave/boundary layer interaction and boundary layer separation. The experimental investigation was done in the T2 shock tunnel using the throats/nozzles for theoretical Mach numbers of 6.5 and 8.3. Compression ramp (30° and 20°) models made of aluminum and printed on plastic filament in the 3D printer were designed and produced, as well as two shock generators models with 30°. The flow analysis was performed using pressure sensors and the schlieren image technique. In the cases of shock generators, the incident shock wave caused an increase in pressure and reached a plateau inside the separation bubble (from 81.84 kPa to 360.01 kPa). The highest pressure values were related to the reattachment line. Then, the expansion waves cause a reduction in pressure and adjacent phenomena cause increase in pressure. The ramps caused an increase in pressure and an effect close to a plateau. Then, the boundary layer is replaced and the pressure continues to increase until the end of the ramp, obtaining values from 15.9 kPa to 93.8 kPa. The highest pressure values were observed in the region of interaction of the incident shock wave with the reattachment shock. The pressure values between the aluminum and plastic filament models measured different values along the ramp (45.6 kPa and 28.8 kPa) in the last sensor. The images in schlieren were of excellent quality and the technique was highly efficient to visualize the phenomena. As results of these campaigns, it was possible to visualize the adverse pressure gradient, the flow separation structure, including the separation bubble and reattachment of the boundary layer.

Numerical investigation of the effects of dry gas model and wet steam model in solar-driven refrigeration ejector system

Abstract Nowadays, the use of equipment with little pollution is essential due to the increase in the planet’s temperature. Ejectors are considered one of the equipment with no pollution, and their failure rate is low due to the lack of moving parts. Also, scholars have recently focused on improving the efficiency of industrial equipment. The use of accurate modeling is required to improve steam ejector performance. In a steam ejector, non-equilibrium condensation creates a two-phase flow situation. The wet steam model, used in this study, characterizes this two-phase flow. The study’s objective was to compare this wet steam model with the dry gas model. In the wet steam model, the liquid mass fraction is 0.25, and its calculated entrainment ratio is lower than the dry gas model, closely matching experimental observations. The dry gas model reaches a maximum Mach number of about 5, while the wet steam model approximates 4. A significant temperature difference exists between the two models, with the dry gas model indicating lower temperatures compared to the wet steam model. Diagonal shocks and expansion waves are evident in the mixing chamber, fixed cross-section, and diffuser. These phenomena occur with greater intensity and a slight delay in the wet steam model compared to the dry gas model.

The differences in quenching characteristics of H2/Air deflagration and detonation propagation in the T-shape pipeline

Bifurcated pipeline is a typical structure in industrial and transportation; paying attention to the propagation of explosions in it and taking measures to prevent explosions are extra important. The deflagration and detonation propagation characteristics of stoichiometric H2/Air mixture were investigated under initial pressure ranging from 25 kPa to 45 kPa based on the T-shape pipeline experimental system; the effects of flame arrester locations and structure were further experimentally explored under different initial pressures. Differences in the velocity characteristics of deflagration and detonation in the T-shape pipeline and the quenching characteristics after passing through differently positioned flame arresters were found. The results show that enhanced turbulence caused by the change in cross-section at the T-junction promotes the deflagration propagation, and the diffraction generated by the corners at the T-junction suppresses the detonation. Moreover, the velocity changing magnitude (A) indicated that deflagration accelerates faster and detonation attenuation reduces as initial pressure rises in the branch. The experimental results of the flame arrester installed in the pipeline suggested that deflagration and detonation slow down, and installing locations influence quenching pressures and decelerating reduction magnitude (S). According to the pressure signals, there are four flame stages: none, weak, rises sharply to peak, and fluctuations decline. The quenching pressure of detonation is higher than deflagration when the flame arrester is in the same position. Deflagration has higher quenching pressure of 60 kPa and S of 84.5% when the flame arrester is installed in the branch; Detonation has higher quenching pressure of 80 kPa when the flame arrester is installed in the straight while a higher S of 83.3% in the upstream. The cavity experiments of the flame arrester confirmed that deflagration deceleration comes from the combined effects of turbulent acceleration due to cross-section changes and deceleration due to heat exchange in the flame arrester; Detonation deceleration is due to the obstruction of the expansion wave caused by the gradual-expansion entrance of the flame arrester.

Experimental reconstruction of sound fields over large spatial domains

This talk discusses sensing methods and reconstruction techniques for characterizing sound fields over large spatial domains. We focus specifically on reconstructing reverberant soundfields in rooms and enclosures. Two complementary approaches are presented in the talk: on the one hand, we present a method that leverages on modeling the spatio-temporal and statistical properties of enclosed sound fields via wave expansions, enabling to estimate the sound field over a large volume of space. On the other hand, we present a Physics Informed Neural Network, which learns the governing wave equation using a small set of measured data and enables to meaningfully interpolate and extrapolate the sound field to any position where no observations are available. Experiments in real rooms are presented, including an opera hall and an auditoria for oral communication. The experiments successfully demonstrate the volumetric acquisition and three-dimensional characterization of the sound fields. The presented techniques can be of relevance in applications pertaining to immersive and navigable audio, architectural acoustics and heritage preservation.

Characteristics of cellular structure of detonation waves propagating in annular channels

This study investigates the characteristics of stable and unstable cells and wavefronts of detonation waves propagating in annular channels with different inner radii and channel widths using two-dimensional Euler equations along with a two-step induction-exothermic reaction kinetics. The results reveal that the effect of annular channels on the detonation cell structure depends on both the inner radius and channel width. To quantify this effect, a parameter σ is introduced, representing the ratio of the inner and outer radii of the channel. We have discovered that for values of the parameter σ exceeding a critical value σs, the detonation wavefront demonstrates characteristics similar to those observed in a straight channel scenario. On the contrary, when σ is below σs, the wavefront becomes distorted, potentially leading to Mach reflection as σ decreases further to another critical value σm. Additionally, the interaction among expansion waves induced by the inner walls leads to an augmented induced length and the potential occurrence of localized decoupling of the detonation wave, particularly for unstable detonation waves. However, it is worth noting that the re-initiation of the detonation wave may be triggered by the formation of hotspots resulting from the interaction between transverse shock waves and the detonation wave. This study aims to characterize the propagation characteristics of detonation waves within annular channels, with the objective of providing valuable insights for the design and optimization of annular chamber configurations in systems involving detonation.

Study on the Aerothermoelastic Characteristics of a Body Flap Considering the Nozzle–Jet Interference

A body flap/RCS-integrated configuration is often used to achieve pitch trimming and controlled flight in near space for hypersonic vehicles. Under the high temperature and pressure load induced by the expansion wave at the nozzle exit, the body flap is prone to significant structural deformation, which leads to a change in the resulting moment, even comparable to the control ability, and bring additional challenges to the control system. Based on the CFD/CTD/CSD coupling method, the aerothermoelastic effect on the aerodynamic characteristics and structural deformation of the body flap under jet interaction is systematically studied. Numerical results indicate that the pitching moment coefficients show an increasing trend for all the models, rigid, elastic and thermoelastic, while the increment significantly decreases with the increase in trajectory altitudes. With the increase in deflection angle, the pitching moment coefficients of the three models decrease nonlinearly at high altitude, and the aerothermoelastic effect significantly decreases. At a middle-lower altitudes, the pitching moment coefficient is reversed at a lager deflection angle, and the trailing edge of the body flap presents the deformation characteristics of upward bending, which makes the aerothermoelastic phenomenon degenerate into an aeroelastic problem. From the station along the chord and spanwise direction, the change in displacement increment of the thermoelastic model reflects the competitive relationship between normal stress and thermal stress imposed by jet interaction.

Vorticity and magnetic dynamo from subsonic expansion waves

Context. The main driving forces supplying energy to the interstellar medium (ISM) are supernova explosions and stellar winds. Such localized sources are assimilable to curl-free velocity fields as a first approximation. They need to be combined with other physical processes to replicate real galactic environments, such as the presence of turbulence and a dynamo-sustained magnetic field in the ISM. Aims. This work is focused on the effect of an irrotational forcing on a magnetized flow in the presence of rotation, baroclinicity, shear, or a combination of any of the three. It follows an earlier analysis with a similar focus, namely, subsonic spherical expansion waves in hydrodynamic simulations. By including magnetic field in the model, we can evaluate the occurrence of dynamo on both small and large scales. We aim to identify the minimum ingredients needed to trigger a dynamo instability as well as the relation between dynamo and the growth of vorticity. Methods. We used the Pencil code to run resistive magnetohydrodynamic direct numerical simulations, exploring the ranges of values of several physical and numerical parameters of interest. We explored Reynolds numbers up to a few hundreds. We analyzed the temporal evolution of vorticity, kinetic, and magnetic energy, as well as their features in Fourier space. Results. We report the absence of a small-scale dynamo in all cases where only rotation is included, regardless of the given equation of state and rotation rate. Conversely, the inclusion of a background sinusoidal shearing profile leads to an hydrodynamic instability that produces an exponential growth of the vorticity at all scales, starting from small ones. This is know as vorticity dynamo. The onset of this instability occurs after a rather long temporal evolution of several thousand turbulent turnover times. The vorticity dynamo in turn drives an exponential growth of the magnetic field, first at small scales, followed by large ones. The instability is then saturated and the magnetic field approximately reaches equipartition with the turbulent kinetic energy. During the saturation phase, we can observe a winding of the magnetic field in the direction of the shearing flow. By varying the intensity of the shear, we see that the growth rates of this instability change. The inclusion of the baroclinic term has the main effect of delaying the onset of the vorticity dynamo, but then leads to a more rapid growth. Conclusions. Our work demonstrates how even purely irrotational forcing may lead to dynamo action in the presence of shear, thus amplifying the field to an equipartition level. At the same time, we confirm that purely irrotational forcing alone does not lead to any growth in terms of the vorticity, nor the magnetic field. This picture does not change in the presence of rotation or baroclinicity, at least up to a resolution of 2563 mesh points. To further generalize such a conclusion, we will need to explore how this setup works both at higher magnetic Reynolds numbers and with different prescriptions of the irrotational forcing.

Wall pressure fluctuations in wall heated and cooled shock wave and turbulent boundary layer interactions

Wall pressure fluctuations in shock wave and turbulent boundary layer interactions on heated and cooled walls are investigated by performing direct numerical simulations. The objectives of this study are to identify flow dynamics causing low- and high-frequency wall pressure fluctuations and evaluate wall heating and cooling effects on the wall pressure fluctuations. The wall pressure spectra highlight two characteristic low-frequency spectral peaks at the separation point and below the expansion waves. Conditional analysis reveals that the two spectral peaks originate from the oscillations of the reflected shock and expansion waves, coupled with the expansion and contraction motions of the separated turbulent shear layer. Regarding wall temperature effects, wall cooling enhances the magnitude of the wall pressure fluctuations regardless of the low- and high-frequency components. Furthermore, influences of the expansion waves are also enhanced by wall cooling, which increases the wall pressure fluctuations locally after the separation.

Similarity Analysis for Two-Dimensional Hypersonic Inlets Restart

The restart ability of inlets is significant to the robustness of hypersonic airbreathing vehicles. Classic starting theories based on the one-dimensional and inviscid flow assumption cannot predict the restart boundary accurately. To overcome the classic theories, the restart characteristics of two-dimensional contraction ducts in viscous flow are numerically studied. The restart boundaries for different configurations and flow conditions are determined, and the restart similarity laws are discovered. With the proposed dimensionless quantities (the dimensionless cowl length and the effective throat-entrance area ratio), the influences of multiple factors on restart are described simultaneously in a concise self-similar formulation. The restart characteristics can be described with any two variables in cowl angle, dimensionless cowl length, and effective area ratio. The restarts of two-dimensional inlets are classified into three types of the short-cowl, transitional, and long-cowl restarts according to the features of restart boundary lines and the flow structure. The three restart types are dominated by the competition between the cowl shock system and cowl tail expansion waves, the cowl shock system alone, and the complementation between the cowl shock system and throat choke, respectively. The wall pressure criteria for restart are correlated with the dimensionless cowl length and the characteristic separation scale at the restart critical state. It is observed that Kantrowitz limit is not generalizable for restart boundaries.

Numerical simulation of transpiration cooling for a high-speed boundary layer undergoing transition to turbulence

Cooling the surface of high-speed vehicles by injection of coolant into the flow stream aims to reduce the overall weight and cost of thermal protection systems. Here, the transpiration-based cooling method is studied for a Mach number M∞=5 with coolant injected through a porous layer composed of a staggered arrangement of spheres. Disturbances are introduced into the boundary layer upstream of the porous layer to study in detail the flow regime in which the boundary layer is transitional, including cases where transition is triggered either downstream or directly over the sample. The present work evaluates the effects of transition location, Reynolds number at injection location, and blowing ratio on the cooling performance downstream of the porous sample with heat fluxes that are comparable in magnitude to those seen in laboratory experiments. Flow within the porous layer is found to be unsteady, with a non-negligible streamwise pressure gradient introduced by shock and expansion waves at the leading and trailing edge of the porous sample. For cases where transition occurs just downstream of the sample, the lowest pressure/blowing ratio case results in more cooling immediately after the porous layer, but cooling performance worsens farther downstream. Higher blowing ratio cases show higher effectiveness for a longer distance downstream, despite the transition location moving upstream. For cases where transition occurs over the porous sample, the cooling effect is more consistent, with the heat flux decreasing monotonically with increasing pressure/blowing ratio. The results not only show a strong dependence on transition location, but also that opposite trends in cooling performance are possible when transition occurs just downstream of the injection.

Aerodynamic characteristics of fully enclosed sound barrier induced by the passing trains with 400 km/h

The fully enclosed sound barrier (FESB) has excellent sound reduction effect, but the relatively closed space will make train-induced wind effect more obvious. This study aims to quantify the aerodynamic characteristics on FESB during the trains passing through using a computational fluid dynamic (CFD) method, considering the effects of opening spacing ΔH, train length, and trains passing each other. An overset grid approach is applied to stimulate the relative motion between the train and the FESB, which is verified by correlated test data. The results demonstrate that compression and expansion waves induced by passing trains are the primary sources of pressure fluctuations within the FESB. Implementing a pressure relief scheme with a top opening, which modifies the propagation law of pressure fluctuations inside the FESB, can effectively mitigate the train-induced aerodynamic effects on the structure. Moreover, the head-wave effect on the FESB is less affected by the train length in such schemes. When the opening spacing ΔH value exceeds 1.5 m, the peak-to-peak pressure ΔPH induced by a train passing by gradually reaches a stable state, and there exists a perfectly negative exponential relationship between the aerodynamic force per unit length of FESB and the opening spacing ΔH. However, the train-induced aerodynamic effect on the FESB is amplified when two trains pass each other. In pressure relief scheme with ΔH of 1.5 m, compared to the ΔF observed on the near and far line sides during a single train passing by, those obtained during trains meeting operation are found to be 0.66 times and 2.64 times higher.

Equation of State for Tantalum at High Pressures in Waves of Shock Compression and Isentropic Expansion

Equation of State for Tantalum at High Pressures in Waves of Shock Compression and Isentropic Expansion

Distribution of Enthalpy in Rotating Detonation Engine

In Rotating Detonation Engine (RDE), the detonation wave rotates inside the annulus of thecombustor. After initiation by a pre-detonator, this detonation wave can be sustained by thecontinuous supply of fuel and oxidiser. The frequency of rotation is reported to be of the orderof 5-10 KHz indicating a near continuous operation which can be used in rocket andairbreathing propulsion systems. An experimental study on the RDE is being carried out atNational Centre for Combustion Research and Development (NCCRD), Indian Institute ofTechnology (IIT), Madras using hydrogen and air system. In addition,N2H4 - N2O4 hypergolicsystemreported in literature is considered for comparative study. In order to understand thevarious processes undergone by the flow through the RDE, a detailed thermodynamic analysisis performed. The procedure is explained in greater detail for the better understanding of thevarious state properties in the entire flow field. The flow field comprises of detonation wave,trailing oblique shock wave and Prandtl- Mayer expansion waves. There are two slip lines,one separating the fresh reactants and inert combustion products of the previous cycle ofdetonation wave propagation and another separating the products of detonation combustionand the shocked inert products. Though all the state properties will be evaluated, the enthalpydistribution is considered in the entire flow field of RDE and discussed. This provides theknowledge of the energy availability in various flow regimes and the extent of energyconversion due to detonative combustion, flow expansion, shock compression, and axial flowexciting through the combustor outlet. Propulsion parameters such as axial specific thrust andspecific impulse are computed to show the capability of this modelling approach.

Entropy and nitrogen oxides production in steady detonation wave propagating in hydrogen-air mixtures

Detonation engine, relying on the Fickett-Jacob cycle, may offer higher thermodynamic efficiency than engine relying on the Brayton (constant pressure) or Humphrey (constant volume) cycles. The present work quantitatively investigates the entropy production in steady detonation wave propagating in hydrogen-air mixtures. In particular, the contribution of each elementary chemical reaction to the total entropy production was investigated. The change of entropy during chemical processes was divided into the sensible and the reaction contributions. The study of the influence of several parameters including equivalence ratio, reactor model, initial pressure and temperature was embedded in a parametric study. It is shown that detonation conditions favor higher entropy production than constant volume and pressure combustion processes when considering the von Neumann state as the reference thermodynamic state. In general, the largest modifications in the entropy production pathways are induced by a change of equivalence ratio. In most cases, the largest contributions to total entropy production comes from the reactions H2 + OHH2O + H and H + OH + M = H2O + M, which are also the largest contributors to the energy release. The contributions of the sensible and reaction parts to the total entropy production demonstrate complex variations whose details depend on which specific reaction is considered. Besides, we studied the evolution of the main radicals and nitrogen oxides within the Taylor-Zeldovich expansion wave which brings the flow to rest. Significant change of the nitrogen oxides mole fraction occurs in this region, which indicates that this process should be accounted for when estimating pollutant formation in detonation.

Theoretical analyses on the one-dimensional charged particle transport in a decaying plasma under an electrostatic field

The spatiotemporal evolutions of a one-dimensional collisionless decaying plasma bounded by two electrodes with an externally applied electrostatic field are studied by theoretical analyses and particle-in-cell (PIC) simulations with the ion extraction process in a laser-induced plasma as the major research background. Based on the theoretical analyses, the transport process of the charged particles including electrons and ions can be divided into three stages: electron oscillation and ion matrix sheath extraction stage, sheath expansion and ion rarefaction wave propagation stage and the plasma collapse stage, and the corresponding criterion for each stage is also presented. Consequently, a complete analytical model is established for describing the ion extraction flux at each stage during the decaying of the laser-induced plasmas under an electrostatic field, which is also validated by the PIC modeling results. Based on this analytical model, influences of the key physical parameters, including the initial electron temperature and number density, plasma width and the externally applied electric voltage, on the ratio of the extracted ions are predicted. The calculated results show that a higher applied electric potential, smaller initial plasma number density and plasma width lead to a higher ratio of the extracted ions during the first stage; while in this stage, the initial electron temperature shows little effect on it. Meanwhile, more ions will be extracted before the plasma collapse once a higher electric potential is applied. The theoretical model presented in this paper is helpful not only for a deep understanding to the charged particle transport mechanisms for a bounded decaying plasma under an applied electrostatic field, but also for an optimization of the ion extraction process in practical applications.

Hypersonic Conical Shock-Wave/Turbulent-Boundary-Layer Interaction at High Reynolds Number

A parametric study of hypersonic impinging conical-shock-wave/turbulent-boundary-layer interaction (CSBLI) is carried out at hypersonic high-Reynolds-number conditions (Mach number 6.0, , based on the freestream momentum boundary-layer thickness and wall viscosity) by means of numerical simulation of the Reynolds-averaged Navier–Stokes (RANS) equations, with the eventual goal of establishing wall temperature effects. Comparison with available experimental data shows that RANS is capable of predicting the main features of hypersonic oblique shock-wave/turbulent-boundary-layer interaction, namely, typical size and distribution of the wall properties. A large number of flow cases, especially at high Reynolds number, were computed to examine the scaling of the heat transfer over a wide range of wall temperatures. As expected, the interaction zone of hypersonic CSBLI is reduced as the wall is cooled. A simple power of heat transfer originally introduced by Back and Cuffel (“Changes in Heat Transfer from Turbulent Boundary Layers Interacting with Shock Waves and Expansion Waves,” AIAA Journal, Vol. 8, No. 10, 1970, pp. 1871–1873) for planar shock-induced interactions is here considered to account for hypersonic CSBLIs, which is found to successfully collapse the data to the distributions obtained for supersonic/hypersonic, cold/hot interactions. The value range of the power exponent is within 0.75–0.95.

Aerodynamic load analyses of less-emission HTS maglev train in evacuated tube transport system

An evacuated tube transport (ETT) system is proposed by combining evacuated tube technology and high temperature superconducting (HTS) maglev technology in this paper. It can be predicted that this future transport mode can own the advantages of less emission, low noise, high efficiency, and suitable for high-speed or super-high-speed application. The train running at a high speed will inevitably cause complex aerodynamic load behaviors in an enclosed low-pressure tube. It further affects the real energy consumption and the fatigue life of the components. In order to explore how the aerodynamic load behaves in an ETT-HTS Maglev system, we established a three-dimension numerical calculation model based on ANSYS FLUENT software. The steady aerodynamic loads on the train’s surface and the tube’s inner surface are investigated under different pressures and different operation speeds. It is found that the aerodynamic load on the surface of the train and tube is significantly affected by the pressure inside the tube and the running speed of the train. The aerodynamic load fluctuations at the rear of the train are relatively more violent than those at the head. We also found that the impact of compression wave and expansion wave on aerodynamic loads at different positions of the tube is related to the size of the flow field space between the tube and the train. These results can provide some reference for the less-emission train body design and the whole ETT-HTS Maglev system structural strength in the near future.

Simulative Quantification of the Supersonic Discharge Process of Cold Gas Airbag Inflators

Abstract A simulative method for quantifying the discharge process of cold gas airbag inflators is presented. The pressure, mass flow and the influences of the flow field are relevant to a robust and predictive airbag deployment. Simulations in this regard are compared and validated with experimental data. It turns out that simulated mean pressures inside the inflator deviate by 5–10% from measured data. A complex and highly turbulent flow field with supersonic and subsonic flow emerges. An influential longitudinal vortex forms in the cold gas inflator, leading to a highly dynamic discharge process. This vortex would not be found with the current state-of-the-art methods, such as the simple tank test or analytical models. It is shown that a simple turbulence model such as the k−ω shear stress transport predicts the flow field with sufficient accuracy in comparison with the large eddy simulation. Real gas effects must be taken into account inside the high-pressure reservoir, leading to a faster discharge compared to the ideal gas, due to faster moving expansion waves in the reservoir. Real gas effects outside the high-pressure reservoir seem to be negligible. A simplified simulation model was developed that uses only part of the whole cold gas inflator model and serves as a good practical approach for airbag deployment simulations, with less computational effort. Thus, the method presented here can provide high-quality inflow data for airbag deployment simulations.

Timing control of impulse self balancing latch opening of expansion wave gun

Aiming at the problem of accurate latch opening control of expansion wave gun automatic gun, the mathematical model of accurate latch opening time is established, the travel curve of projectile and expansion wave, the velocity curve of projectile and expansion wave are studied, and the occurrence time of expansion wave and the time close to projectile are simulated and analyzed; The time-space evolution relationship between expansion wave velocity and local sound velocity, projectile velocity and gas velocity is simulated; The average pressure time curve and chamber resultant force curve of the two launch modes are compared and analyzed. After the projectile moves for 2.7ms, the chamber pressure and chamber resultant force of expansion wave launch are significantly reduced; The dynamic model of inertial latch opening is established; The changes of projectile initial velocity and recoil force under different latch opening times are studied. The test shows that the recoil force and recoil distance are greatly reduced when the projectile initial velocity decreases very weakly, which shows that the simulation calculation of latch opening time is accurate.

Post-detonation fireball modeling: Validation of freeze out approximations

A numerical simulation study was performed to examine the post-detonation reaction processes produced by the detonation of a 12 mm diameter hemispherical pentaerythritol tetranitrate (PETN) explosive charge. The simulations used a finite rate detailed chemical reaction model consisting of 59 species and 368 reactions to capture post-detonation reaction processes including air dissociation from Mach 19+ shock waves that initially break out of the PETN charge, reactions within the detonation products during expansion, and afterburning when the detonation products mix with the shock heated air. The multi-species and thermodynamically complete Becker–Kistiakowsky–Wilson real-gas equation of state is used for the gaseous phase to allow for the mixing of reactive species. A recent simplified reactive burn model is used to propagate the detonation through the charge and allow for detailed post-detonation reaction processes. The computed blast, shock structures, and mole fractions of species within the detonation products agree well with experimental measurements. A comparison of the simulation results to equilibrium calculations indicates that the assumption of a local equilibrium is fairly accurate until the detonation products rapidly cool to temperatures in the range of 1500–1900 K by expansion waves. Below this range, the computed results show mole fractions that are nearly chemically frozen within the detonation products for a significant portion of expansion. These results are consistent with the freeze out approximation used in the blast modeling community.