Detonation Stability Research Articles

Experiments on critical behavior of oblique detonation wave in stratified mixtures

Two-stage gas-gun ballistic experiments are performed to investigate the feasibility of stratified mixtures with variable global equivalence ratios Φglobal for the formation of sphere-induced oblique detonation wave (ODW) and quantify their critical behaviors, which include local quenching and transitional structure to ODW, by testing conventional detonation criteria for uniform mixtures. 2 Φglobal H2 + O2 + 3Ar mixtures are tested with different concentration gradients for each fuel-lean/fuel-rich global composition. Opposite responses are observed depending on the global equivalence ratio: the lean mixture of Φglobal = 0.7, which forms ODW in the uniform mixture, fails partly in the strongest stratification, whereas the richest mixture of Φglobal = 2.0 turns to ODW in the strongly stratified conditions. As elucidated in the authors' previous work, Chapman–Jouguet (C–J) theory, including the curvature effects, reproduces the wave angles of the stable ODWs, as well as provides a good prediction on the local quenching of ODW occurring in the area with less reactive composition. Comparison of different wave regimes observed in the explored conditions reveals that wave curvature governs the critical behaviors of ODW far away from the projectile, whereas the initiation structure around the projectile is also influenced by the non-dimensional diameter. Surface energy theory is proven to quantify well the initiation structure on the projectile using a local equivalence ratio. These results indicate a new possibility of controlling the methodology of ignition and stabilization of detonation in aerospace engines, in which perfect mixing is difficult and non-stoichiometric and non-uniform mixtures are expected.

Symmetric Refunctionalization of Diaminodinitropyrazine with Hydrazine and Aminotetrazole: Strategy for Enhancing Detonation Performance and Safety in Energetic Materials.

Two novel nitrogen-rich green energetic compounds were synthesized for the first time from readily available and cost-effective pyrazine starting materials. All newly synthesized molecules were comprehensively characterized, including infrared spectroscopy, nuclear magnetic resonance, elemental analysis, mass spectrometry, and thermogravimetric analysis-differential scanning calorimetry. All compounds have additionally been validated by single-crystal X-ray diffraction analysis. The physicochemical properties of compounds 2, 4, and 5 were thoroughly investigated. Notably, all compounds exhibit remarkable performance, such as a high density (>1.84 g cm-3), excellent detonation properties (VOD > 8582 m s-1, and DP > 31.3 GPa), outstanding thermostability (>205 °C), and high insensitivity (IS > 35 J, and FS = 360 N). These attributes are quite comparable to those of secondary benchmark explosives such as TATB, RDX, LLM-105, and FOX-7. This tuned performance evidences that the incorporation of hydrazine, nitro, and aminotetrazole into the pyrazine framework fosters robust nonbonded interactions, ultimately enhancing thermal stability and reducing sensitivity. The findings of this study not only signify that compounds 2 and 5 have excellent detonation properties and stability but also prove that the strategy of replacing amino groups with hydrazine and aminotetrazole is a practical means of developing new insensitive energetic materials.

Numerical Investigation of Hydrogen Role on Detonation of CH4/H2/air Mixtures

ABSTRACT Steady one-dimensional Zeldovich-von Neumann-Dӧring (ZND) calculation and thermo-chemical analysis are performed to investigate the hydrogen role on ZND detonation of CH4/H2/air mixtures. Different hydrogen blend ratios (i.e. Hbr) ranging from 0% to 100% are selected in this paper. The results show that hydrogen blend ratio has a significant impact on the ZND detonation reaction pathway of stoichiometric CH4-air mixtures. When Hbr ≤ 20%, CH4 is converted to CO2 by route 1: CH4 => CH3 => C2H6 => … => CO2 and route 2: CH4 => CH3 => CH3O => CH2O => HCO => CO => CO2. When Hbr ≥ 50%, CH3 in route 2 is directly converted to CH2O through R97 (CH3 + O <=> CH2O + H). This causes different ZND detonation structures. The induction length decreases with hydrogen addition. This is because R0 (H + O2 <=> O + OH) governs the heat release during the induction stage, enhancing the energy absorption in induction stage and the molecular thermal decomposition after leading shock wave. Finally, the effect of hydrogen blend ratio on the detonation cell size is explored, and a prediction model of detonation cell size incorporated with detonation stability parameter and induction length is developed for CH4/H2/air mixtures.

Air-breathing rotating detonation engine supplied with liquid kerosene: propulsive performance and combustion stability

Experimental results are presented for a rotating detonation engine supplied with liquid kerosene and preheated air without liquid or gaseous additions to the propellant mixture. Various combustion modes for the generic combustor geometry design were observed—from deflagration, through pulsed combustion and high-frequency instabilities, to stable detonation propagation. Attention was paid to detonation stability (if present), its characteristics, and the propulsive performance of the combustor with a focus on specific thrust and pressure gain through thrust and outlet total pressure measurement. These parameters measured for the observed modes were compared. The stability of the detonation combustion proved not to be critical to achieve high performance of the combustion chamber. For example, high performance was achieved for combustion modes with high-frequency instabilities.

Experimental study on the influence of the wall cavity on stability of kerosene two-phase rotating detonation combustion

The combustion characteristics in annular rotating detonation combustors are experimentally investigated using 40% oxygen-enriched air and liquid aviation kerosene (RP-3) as reactants. Two types of wall cavity structures, embedded in the outer and the inner wall of the annular combustors, respectively, are employed to study their effects on detonation stability. The characteristics of typical combustion modes observed in the annular combustors are firstly analyzed. The regime of typical combustion modes is then examined in the phase diagram of mass flow rate and equivalence ratio. Results show that the single-wave mode regime can be affected by wall cavities. In comparison to the combustor without a wall cavity, the regime is expanded for the cavity in the inner wall but significantly reduced for the cavity in the outer wall. When the single-wave mode forms, the cavities embedded in the inner wall result in a significant increase of the apparent detonation wave velocity but a decrease in the velocity fluctuation rate, and the effects are changed with the axial location of the cavities. The axial location of the cavity can also influence the stable propagation location of the detonation wave. Additionally, the analysis of the high-frequency pressure signals indicates that the cavities do not affect the initiation process of the formation of the combustion modes. However, the variation of oxidizer mass flow rate and equivalence ratio can evidently influence the evolution time of different combustion modes after ignition. The study indicates that the wall cavity structure has a significant influence on the propagation behavior of rotating detonation waves in the combustors, and it can be utilized to enhance the stability of kerosene two-phase rotating detonation combustion.

Curvature effect on stabilization of cellular detonations in channel, circular arc and spherical shell geometries

The stability and propagation characteristics of gaseous detonations are numerically investigated, specifically in configurations where global front surface curvature plays a significant role. The simulations use idealized constitutive models representing a weakly unstable mixture and the simulated geometries include both two-dimensional arc and spherical shell sections with rigid walls and a straight channel geometry with compliant confinement. Depending on the inner and outer arc radius, differing levels of curvature can be imparted on the propagating wave in the two curved geometries. For thinner explosive regions, cellular type instabilities develop as the wave propagates around the arc and shell. However, as the thickness of the explosive increases and progressively greater surface curvature is imposed, laminar flow regions develop which can coexist with regions dominated by unstable cellular propagation. Here, the appearance and persistence of this laminar zone is shown to coincide with a critical level of surface curvature for both the arc and shell geometries. This critical curvature concept is also tested in the corresponding straight channel configuration with a compliant confiner, which similarly produces global surface curvature on the propagating detonation front but now as function of imposed wall divergence. Similarly, the propagation in the channel is found to stabilize when the maximum surface curvature exceeds a certain critical value that is close to the analog from the curved geometries. These results support the likely existence of a critical surface curvature mechanism or criterion that ensures the stabilization of a nominally unstable cellular detonation.

Microstructure and mechanical properties of T2 copper /316L stainless steel explosive welding composite with small size wavy interface

Copper/stainless steel composite is often used for preparation of superconducting busbar “double box” lap joints. However, it is a challenge for the large thickness T2 copper/316L stainless steel composite is fabricated by explosive welding, because of the bonding interface is always present many problems such as large ripple size, many microscopic defects, low bonding strength and poor sealing etc. In this paper, the big-thickness T2 copper/316L stainless steel composite with small size wavy interface was successfully fabricated by explosive welding. Microstructure of bonding interface indicated that the welding process could be divided into three stages: detonation growth stage, detonation stabilization stage, detonation descent stage. The morphology of bonding interface presented a regular wavy interface and no defects such as cracks, voids and intermetallic compound were formed in the stable stage, which was consistent with the results of ultrasonic and permeability quality inspection. The hardness of copper side and stainless steel side close to the bonding interface reached 131HV and 432HV, respectively. Dynamic recrystallization and fine grain generated in the bonding interface. The mechanical properties of tensile strength, pull-off strength and shear strength in the stable detonation stage is greater than 110 MPa, which is meeting the requirements of preparation of superconducting busbar “double box” lap joints. The deformation failure mainly occurred in the copper side near the bonding interface, which presented a higher bonding strength than copper. Some dimples and tearing edges with different sizes on the fracture surfaces, indicating that the fracture was a typical ductile fracture.

Transition from Fast-Flame to Detonation

Flame acceleration within a channel is facilitated by repeating obstacles that generate turbulence. As the flame accelerates to supersonic velocities, it generates compression waves that coalesce to form a strong leading shock. This shock-flame complex continues to accelerate until it reaches a maximum velocity equal to the speed of sound in the combustion products; the complex is referred to as a fast-flame. Shock reflection driven onset of detonation may occur, characterized by an instantaneous jump in velocity to the theoretical ‘Chapman-Jouguet’ velocity. A more fundamental problem is the transition from a fast-flame to detonation without the presence of obstacles. &#x0D; In the current study, a 7.6 cm square ‘optical section’ housing a perforated plate was used to study the transition from fast-flame to detonation. A spark- and glow- plug served as ignition sources. The optical section had windows installed on its side and end walls so that Schlieren- and direct- photography could be captured. Soot foils were also utilized to record detonation cell structure. The fast-flame was generated by the passage of a detonation wave through the perforated plate, after which the transition to detonation could be studied. &#x0D; Gaseous fuel-oxygen mixtures of varying degrees of detonation stability over a wide range of pressures were tested. In low-pressure tests, delayed onset of detonation was observed, and detonation initiation sites were located at the channel walls indicating that flame-generated turbulence alone is not sufficient for the transition process. As pressure was increased, onset occurred immediately after the perforated plate at various locations across the channel cross-section, not strictly at the walls. For this abrupt ignition mode, transverse shock collisions played an important role in the transition to detonation. &#x0D;

Detonation stabilization in supersonic expanding channel with velocity gradients

The present work aims at exploring the stabilization mechanism of detonation propagating in a supersonic expanding channel with inflow velocity gradients. To achieve this, two-dimensional numerical simulations of a stoichiometric hydrogen–oxygen mixture are performed by solving the Navier–Stokes equations with a one-step two-species reaction model. A hybrid sixth-order weighted essentially non-oscillatory centered difference scheme is utilized to solve the governing equations. The results show that the detonation wave reaches a dynamic stabilization in a supersonic expanding channel affected by the inflow velocity gradients. By contrast, the detonation wave fails to self-sustain propagation in the channel with uniform inlet velocity for the same average velocity, highlighting the significant role of inlet velocity gradients in controlling the propagation and attenuation of detonation waves in confined channels. The mechanism of the dynamic detonation stabilization with the inflow velocity gradients is related to the compression of the flow field by large-scale unburned jets and the interactions of transverse waves and shear layers, which are conducive to improving the pressure and combustion rate of the unburned gases behind the detonation wave. Additionally, to a certain extent, the larger the inflow velocity gradient, the easier it is for the detonation wave to achieve dynamic stabilization at a certain position in the expanding channel.

DDT run-up distance in an obstructed tube

Self-luminous high-speed photography was used to study flame acceleration and deflagration-to-detonation transition (DDT) in a clear polycarbonate round tube equipped with orifice plates. The 288 cm long, 7.6 cm inner-diameter tube was equipped with equally spaced 50% and 75% area-blockage orifice plates. The primary test mixture was stoichiometric ethylene–oxygen diluted with varying amounts of nitrogen, and the initial pressure was varied between 5 and 90 kPa. Tests were also performed with stoichiometric hydrogen–oxygen with large argon dilution to study the effect of detonation cell structure regularity. High-speed video showed that the initial DDT always occurred following shock reflection off an obstacle, allowing an accurate determination of the DDT run-up distance. Soot foils were used to measure cell size at the end of the obstacle-free tube. A correlation for flame acceleration to one-half the Chapman–Jouguet detonation velocity (VCJ) predicted the measured DDT run-up distance successfully for the most reactive mixture conditions. However, the measured DDT run-up distance increasingly deviated from the correlation with decreasing initial pressure, significantly under predicting the run-up distance at the DDT limit. A correlation for the DDT run-up distance was proposed based on the concept of flame acceleration to one-half VCJ followed by an induction phase that ends with the transition to detonation. For a given tube and obstacle configuration, the flame acceleration distance depends on the flame properties, and the DDT induction distance depends on the properties that quantify the detonation length-scale and stability.

Numerical Investigation of the Oblique Detonation Waves and Stability in a Super-Detonative Ram Accelerator

This study numerically investigates the effects of diluent gas proportion, the overdrive factor, and throat width on the wave structure and thrust performance of a ram accelerator operating in super-detonative mode. For premixed gas of a high energy density, a typical unstart oblique detonation wave system is observed due to the ignition on the front wedge of the projectile, and the detonation waves move downstream to the shoulder as the energy density decreases. In the start range of the overdrive factor, the wave position also shows a tendency to move downstream as the projectile velocity increases, accompanied by oscillations of the wave surface and thrust. As the throat width increases, the wave standing position changes non-monotonously, with an interval of upstream movement and Mach reflection. The typical wave structure of a ram accelerator in super-detonative mode is identified, as well as the unstart stable wave features and the unstable process for choking, which can provide theoretical guidance for avoiding unstart issues in ram accelerators and optimizing their performance.

Crowding-out strategy to enhance energetics of 3-nitro-1,2,4-triazol-5-one based E-MOFs at the molecular level through adjusting pH

Based on the combination of coordination chemistry and the noncovalent interactions, the crowding-out concept is put forward to fundamentally solve the problem that the structural H2O in E-MOFs results in a decreased stability, density and heats of detonation. In this paper, “filling” the 4,4′-azobis(1,2,4-triazole) (ATRZ) molecules into the structure of NTO (3-nitro-1,2,4-triazol-5-one) E-MOFs, the coordination and crystal water molecules were successfully extruded to gain anhydrous [Cu(NTO)2(ATRZ)] (a) / [Zn(NTO)2(ATRZ)] (c) and hypohydrous [Co(NTO)2(ATRZ)(H2O)2]·ATRZ (b) by adjusting pH at room temperature and pressure, which is friendly for energetic materials. With the addition of ATRZ (high HOF) and the departure of water, the ΔfHmθ of them are becoming higher. The heat of detonation is increased by 1.33, 2.39 and 0.74 times respectively and the calculated detonation velocity of three compounds is enhanced by about 1000 m s−1 contrasted to the corresponding hydrates. The removal of water molecules did not result in a high sensitivity. More importantly, as potential catalysts for AP-based solid propellants, a and c still showed excellent catalysis for the thermal decomposition of AP (ammonium perchlorate) after modification. In this study, it took a whole new idea to radically solve the difficulties in the area of E-MOFs by a simple and original way, and this is a significant innovation for the safety of energetic material.

Effects of detonation instability and boundary layer on flame propagation behavior in millimeter-scale smooth tubes

Small pre-detonators have potential applications in practical pulse detonation engines or rotating detonation engines. The effects of detonation stability parameter and area divergence on flame propagation in capillary tubes are experimentally analyzed using high-speed cinematography. The four mixtures (namely, stoichiometric methane/oxygen, ethylene/oxygen, propane/oxygen and stoichiometric acetylene/oxygen/50% Ar mixtures) used have different values of stability parameter. The inner diameters of the tubes (namely, 0.5, 1.0, 2.0, and 4.0 mm) investigated provide a variation in area divergence at initial pressures p0 ranging from 5 to 100 kPa. The results show that stability parameter and area divergence play positive and inhibitory roles, respectively, in the process of flame propagation. Five propagation modes are observed (namely, steady detonation, stuttering detonation, galloping detonation, deflagration, and no flame), among which the stuttering detonations have three different forms, depending on the product of stability parameter and area divergence. For the most-unstable mixture (stoichiometric methane/oxygen, with the largest values of stability parameter), the range of the product of stability parameter and area divergence in which steady detonation can occur is the narrowest. The results also indicate that the stoichiometric ethylene/oxygen and stoichiometric propane/oxygen, with similar values of the product of stability parameter and area divergence, have the same propagation modes. Further analysis suggests that the Chapman–Jouguet deflagration-to-detonation transition (DDT) distance L decreases with increasing of stability parameter and area divergence for all four mixtures. Compared with the other three mixtures, stoichiometric methane/oxygen, which has the smallest values of L because it is the most unstable mixture with the greatest propensity for hotspot formation, is most likely to undergo DDT under the same initial and boundary conditions. These conclusions agree well with the various characteristics of L obtained for larger tubes.

Numerical study of the effect of a sudden change in inflow velocity on the stability of an oblique detonation reflected wave system

<p indent="0mm">The oblique detonation engine (ODE) is expected to be used in future hypersonic power systems, bringing many technical advantages to the engine by regulating the combustion mode. However, few studies concern the wave structure of an oblique detonation wave (ODW) in confined spaces, particularly for the stability of reflected wave systems under complex inflow conditions. On the basis of a simplified ODE combustor model, the effects of a changing inflow velocity on the steadiness of the oblique detonation reflected wave system are studied in this paper. The numerical results show that the evolution of the reflected wave system undergoes two processes, including long-term accumulation and sudden acceleration, which is unfavorable for an ODE application and can be efficaciously harnessed by increasing the inflow Mach number. The inflow disturbance aroused by this increase may restabilize the originally unstable reflected wave system, and the effects depend on the time and amplitude of the increase of the inflow Mach number. The earlier the disturbance occurs and the greater the increase in Mach number, the more easily a stable reflected wave system will develop. Furthermore, by analyzing the flow field characteristics of ODWs disturbed by inflow, the re-stabilization mechanism of a reflected wave system is revealed; that is, the flow choking induced by the subsonic zone behind the Mach stem is suppressed by the inflow disturbance.

A study of pulsating behavior and stability parameter for one-dimensional non-ideal detonations

One-dimensional numerical simulations of non-ideal detonations were performed by using inviscid reactive Euler equations. Chemical reactions in the equations were described by two-step consecutive irreversible reactions A → B → C, which include an exothermic step (A → B) followed by an endothermic step (B → C). Non-ideal detonations are achieved when endothermicity exists in the system. The periodic oscillation behavior of peak pressure during the propagation of a one-dimensional detonation wave was studied with the different exothermicity/endothermicity and different degrees of overdrive. The results show that the increase in exothermicity, the reduction in endothermicity, and the enhanced degrees of overdrive can stabilize the propagation of detonation waves. The influence of the exothermic reaction plays a dominant role for the stability of the one-dimensional non-ideal detonations, which is further confirmed by a theoretical analysis. In addition, the stability parameter χ, proposed originally by Radulescu “The propagation and failure mechanism of gaseous detonations: experiments in porous-walled tubes,” Ph.D. thesis (McGill University, Montreal, Canada, (2003), was extended to predict the stability of non-ideal detonations, based on the Zel'dovich–Neumann–Döring structure of the non-ideal detonations. The results show that the extended stability parameter can well match the stability boundary for all of cases in the present study.

Experimental Proof of Concept of a Noncircular Rotating Detonation Engine (RDE) for Propulsion Applications

A noncircular engine cross-section could provide great flexibility in the integration of propulsion into the airframe. In this work, a tri-arc RDE was constructed and tested as an example of noncircular cross-sectioned RDE. The operational characteristics of detonation wave propagation and thrust performance were investigated and compared with an equivalent circular RDE under the same operating conditions. High-speed camera images, short-time Fourier transform (STFT), and fast Fourier transform (FFT) were used for the investigation. The tri-arc RDE showed very similar characteristics to the circular RDE but exhibited slightly better stability and propulsion performance than the circular RDE. We consider that repeated curvature changes positively affect the stability of detonation wave propagation. The experimental data show contradicting results from the numerical analysis with a homogeneous mixture assumption in which the detonation pressures at the convex corner were greater than those at the concave corner. It is reasoned that the tri-arc injector design provides a non-uniform mixture composition, resulting in a strong detonation at the convex corner. Overall, the noncircular RDE of a tri-arc shaped cross-section is demonstrated, one which performs slightly better than an ordinary circular-shaped RDE both in detonation stability and performance.

Statistical analysis of detonation wave structure

Hydrocarbon fueled detonations are imaged in a narrow channel with simultaneous schlieren and broadband chemiluminescence at 5 MHz. Mixtures of stoichiometric methane and oxygen are diluted with various levels of nitrogen and argon to alter the detonation stability. Ethane is added in controlled amounts to methane, oxygen, nitrogen mixtures to simulate the effects of high-order hydrocarbons present in natural gas. Sixteen unique mixtures are characterized by performing statistical analysis on data extracted from the images. The leading shock front of the schlieren images is detected and the normal velocity is calculated at all points along the front. Probability distribution functions of the lead shock speed are generated for all cases and the moments of distribution are computed. A strong correlation is found between mixture instability parameters and the variance and skewness of the probability distribution; mixtures with greater instability have larger skewness and variance. This suggests a quantitative alternative to soot foil analysis for experimentally characterizing the extent of detonation instability. The schlieren and chemiluminescence images are used to define an effective chemical length scale as the distance between the shock front and maximum intensity location along the chemiluminescence front. Joint probability distribution functions of shock speed and chemical length scale enable statistical characterization of coupling between the leading shock and following reaction zone. For more stable, argon dilute mixtures, it is found that the joint distributions follow the trend of the quasi-steady reaction zone. For unstable, nitrogen diluted mixtures, the distribution only follows the quasi-steady solution during high-speed portions of the front. The addition of ethane is shown to have a stabilizing effect on the detonation, consistent with computed instability parameters.

Theoretical calculation of nitro‐1‐(2,4,6‐trinitrophenyl)‐1H‐azoles energetic compounds

AbstractIn order to study the properties of new energetic compounds formed by introducing nitroazoles into 2,4,6‐trinitrobezene, the density, heat of formation and detonation properties of 36 nitro‐1‐(2,4,6‐trinitrobenzene)‐1H‐azoles energetic compounds are studied by density functional theory, and their stability and melting point are predicted. The results show that most of target compounds have good detonation properties and stability. And it is found that nitro‐1‐(2,4,6‐Trinitrophenyl)‐1H‐pyrrole compounds and nitro‐1‐(2,4,6‐trinitrop‐enyl)‐1H‐Imidazole compounds have good thermal stability, and their weakest bond is CNO2 bond, the bond dissociation energy of the weakest bond is 222–238 kJ mol−1 and close to 2,4,6‐trinitrotoluene (235 kJ mol−1). The weakest bond of the other compounds may be the CNO2 bond or the NN bond, and the strength of the NN bond is related to the nitro group on azole ring.

Comparative testing of various composition granulites

Blasting of rocks both in open pit and underground mining commonly uses cheap explosives. Their competitiveness ensues from the minimum cost, simple composition, application safety, fabricability and ease of charging. The basis of composition of cheap explosives are economic materials&mdash;solid oxidizer (ammonium nitrate) and liquid fuel (diesel fuel). Explosive manufacture machinery includes mixing and charging equipment of many types and modifications, ensuring blasting with regard to specific technology of shooting. This article presents the studies into the detonation parameters of cheap explosives including ammonium nitrate with different technical properties and pricing characteristics (cost, porosity, absorbent and retention capacity) and of a mixed fuel composed of liquid phase (waste oil products, fuel mixtures, diesel fuel) and solid phase (crumb rubber, coal powder, coke breeze). The solid phase components have different natures and particle parameters, which governs adhesion and retention of liquid fuel at the surface of ammonium nitrate granules having insufficient adsorbability and retention ability. It is shown that explosion spread (the rate and completeness of detonation) depends stronger on the properties of an oxidizer than fuel. The mixed fuel (liquid+solid phases) maintain the balance and physical stability of cheap explosives and reduce the production cost. On the basis of the experimental indicators of detonation stability, the choice of the composition is substantiated so that to provide high detonation ability of cheap explosive and to ensure economic efficiency of blasting.

Unfolding the chemistry of FOX-7: Unique energetic material and precursor with numerous possibilities

From the discovery of FOX-7 in 1998, this compound has witnessed great attention from the synthetic, theoretical, and application perspective compared to any other energetic material reported in the literature. FOX-7 is an exceptional precursor because of its surprising chemical reactivity, and extensive research has been performed on its structure modifications to achieve better performance while retaining stability. The energetic materials comprising FOX-7′s structural fragments in their backbone promise to develop potential compounds. • Compilation of the published work on FOX-7 from year 2016 to 2021. • Summary of several synthetic strategies used for structural modification of FOX-7. • Comparison of energetic properties of newly developed FOX-7 derivatives with TNT, RDX, HMX, and FOX-7. • Emphasizing the importance of FOX-7′s structural fragments in reported molecules for combining performance and stability. • This review may stimulate further work to expand the chemistry of FOX-7. FOX-7 demonstrates a fascinating explosophoric motif with a unique combination of detonation performance and stability. Unlike classical explosives, such as TNT, TATB, and RDX, FOX-7 exhibits superior energetic performance originating from its high density, oxygen balance, and dinitro groups. Indeed, owing to its unique energetic properties and versatile molecular structure, a variety of neutral compounds and salts have been synthesized during the past two decades and continuing. These materials comprise NH 2 and NO 2 groups on the C = C bond as an integral structural unit that provides an opportunity for a diverse blend of physical and detonation properties. This critical review summarizes several synthetic strategies used for structural modification of FOX-7 and highlighted their energetic properties. Due to the chemically tailorable framework, synthetic accessibilities, and superior energetic characteristics, FOX-7 is subjected to intense and expansive research and is undoubtedly considered a promising precursor for developing new explosives, propellants, and pyrotechnics.