Behavior Of Propellants Research Articles

Investigation of catalytic efficiency of nanoparticles of alloys on thermal behavior of AP and AP-based solid propellants

In this article, we present the catalytic proficiency of three different nano metal alloys Cu–Co, Cu–Fe, and Cu–Zn) on thermal behavior of powder ammonium perchlorate (AP) and composite solid propellants (CSPs) samples. A hydrazine reduction method was used for synthesized Cu–Co, Cu–Fe, Cu–Zn alloys nanoparticles and they were characterized by XRD, FTIR, and SEM. The catalytic impact of nano alloys on thermal behavior AP and CSPs is established by implementing through TG-DSC technique. The Kissinger Akahira Sunose (KAS), Flynn wall Ozawa (FWO), and Starink methods were used to determine activation energies of all AP and CSPs samples. The Cu–Zn Nanoalloys acted as good catalyst for thermal decomposition of AP and CSPs and it reduced the decomposition temperature and activation energy of AP and CSPs. It increased the burning rate of CSPs.

Combustion Behaviour of ADN-Based Green Solid Propellant with Metal Additives: A Comprehensive Review and Discussion

Solid propellants play a crucial role in various civil, scientific, and defence-related aerospace propulsion applications due to their efficient energy release, high energy density, low fabrication cost, and ease of operation. Ammonium dinitramide (ADN) has gained considerable attention as a potential oxidizer for green solid propellants due to its high oxygen content, significant energy density, non-toxicity, and non-polluting combustion products, leading to lower environmental impact. As ADN is a new desirable oxidizer in the field of solid propellants, understanding the practicality and viability of the use of ADN in composite solid propellants necessitates a thorough understanding of its chemical and thermal decomposition pathways in addition to its combustion characteristics in the presence of other ingredients. ADN is being explored as an alternative to the traditionally used ammonium perchlorate (AP), a toxic oxidizer containing chlorine (Cl). Additionally, AP monopropellants often suffer from moderate burning rates and poor mechanical strength. To address these limitations, researchers have explored the incorporation of metal additives, such as aluminium (Al), magnesium (Mg), and metalloid boron (B), to enhance the combustion performance and burn rate of AP. These metals not only act as energy-rich additives but also influence the combustion process through various mechanisms. The incorporation of metal additives into ADN has shown promising enhancements in the overall energetic performance of green solid propellants. This review aims to provide an in-depth analysis of the thermal decomposition of ADN and its combustion behaviour, along with the combustion of ADN-based solid propellants with metal additives. Finally, based on an extensive review of the existing literature, various research pathways for focused future collaborative efforts are identified to further advance ADN-based “green” solid propellants.

Research on equation of state parameters for high-energy solid propellants based on improved cylinder test and particle swarm optimization

With the development of high energy solid propellants, it is critical to evaluate the safety and power performance of solid propellants in the face of threats such as unmanned aerial vehicles (UAVs) when transporting and using them in contemporary warfare. An electric probe-type cylinder test measured the displacement-time behavior of NEPE high-energy solid propellant, and the parameters of the Jones-Wilkins-Lee (JWL) equation of state (EOS) were derived using particle swarm optimization (PSO) with the Gurney energy model. Further, the parameters of JWL-Miller EOS, determined through AUTODYN simulations, were validated by comparing airburst process simulations with experimental overpressure data. The study established a method for determining EOS parameters of high-energy propellants, achieving a high degree of accuracy. The derived parameters ensure precise modeling of propellant behavior, offering a reliable foundation for future applications in solid rocket motor performance optimization and safety assessment.

Study on the Micromechanical Interface Response Behavior of Propellants Based on Nano-Impact Testing

Abstract This study utilizes a nano-impact experimental platform to investigate the stress-strain response of propellant interfaces with two different binders, HTPE and GAP. The mechanical behavior of HTPB-AP and GAP-AP interfaces was examined at the nano-scale under varying strain rates, with experiments conducted at rates up to 100 s−1. These experiments successfully captured the strain rate-dependent mechanical properties of both propellant components and their interfaces. The experimental results align well with the rate-dependent power-law viscoplastic constitutive models developed for HTPE, HTPE/AP, GAP, and GAP/AP interfaces, validating the model’s effectiveness in describing the viscoplastic behavior of these materials and their interfaces. The study demonstrates that interfaces generally exhibit lower stress responses compared to bulk materials. HTPE shows higher initial stress responses and more pronounced strain hardening than GAP.

Damage characteristics and failure mechanism analysis of NEPE propellant at high strain rates

The study of mechanical properties and failure mechanism of propellants under impact loads is crucial for analyzing structural integrity of propellant charges. An experimental investigation was conducted on NEPE propellant using a separated Hopkinson pressure bar to conduct high strain rate uniaxial impact tests. Deformation and failure processes of the propellant under impact conditions were recorded with a high-speed camera. The microscopic failure forms of the propellants were observed using a scanning electron microscope and an optical microscope. Stress-strain curves and high-speed images revealed that the damage behavior and failure mechanism of NEPE propellants are significantly influenced by strain rate. As the strain rate increases, there is a notable increase in the deformation degree of the propellant specimens, with a more pronounced shear effect. This leads to an earlier occurrence of failure and a more severe degree of failure. The predominant failure forms observed in NEPE propellants include transgranular failure, matrix tearing, and cavity merging. A nonlinear visco-hyperelastic constitutive model with damage at high strain rates was established to provide a precise account of the mechanical response of NEPE propellant under high strain rates.

Experimental study on droplet dynamics behavior and combustion characteristics of high performance green propellant in electrical ignition mode

High performance green propellant represented by ammonium dinitramide-based liquid propellant and its new ignition method are the research hotspots of space propulsion in the 21st century. Exploring the complex multi-scale physical properties of multi-component ammonium dinitramide-based liquid propellant droplets in the electrical ignition mode has wide application significance for spray, propulsion system design and combustion control. The droplet dynamics behavior and combustion characteristics of propellant droplets at different ignition voltages were studied experimentally. The droplet dynamics behavior during the evaporation process, including violent volume oscillation, approximate steady-state expansion, contraction, secondary expansion, puffing and micro-explosion, have been determined by the generation, growth, and discharge of vapor bubbles. In the initial evaporation process, the heterogeneous nucleation is dominant. As the droplet is continuously heated, homogenization nucleation gradually dominates. The main physical and chemical mechanisms of bubble evolution driven by temperature involve methanol boiling, water overheating, ammonium dinitramide decomposition and combustion reaction between vapor molecules. Increasing the ignition voltage increases the droplet dynamics behavior and the combustion, but promotes the combustion instability. Increasing the ignition voltage increases the ignition delay time, puffing delay time, droplet lifetime, maximum temperature of droplet, and reduces the ignition critical diameter. It is proposed that the method of suppressing the droplet breakup dynamics at decomposition area and enhancing the droplet breakup dynamics at the combustion area are conducive to the combustion control of the thruster in electrical ignition mode. This research provides novel insight into the study of the electrical ignition mechanism of liquid fuels.

Modeling method of random collision of ellipsoidal particles in mechanical simulation for high energy solid propellant

Abstract It is based on the molecular dynamics algorithm of elliptical optimization to establish a mesostructure model of oval particles of high-energy solid propellant considering gradation and controllable filling rate according to the mesostructure characteristics of high-energy solid propellant. The bilinear cohesion model was applied to describe the interface damage behavior and carry out the high-energy propellant tensile test at three rates. The rationality of the elliptical particle model has been verified between the comparison of the calculated results with the experimental results established to describe the micromechanical behavior of high-energy propellants, which is to reveal the mesoscopic damage law of high-energy solid propellant under different tensile rates in this paper.

Effect of AP and AN on the combustion and injection performance of Al-H2O gelled propellant

Aluminum-water propellants (Al-H2O propellants), representing a novel class of solid propellants, demonstrate the merits of cost efficiency and reduced feature signal characteristics. However, the conventional formulations of Al-H2O propellants are hampered by the generation of substantial condensed residues. In our investigation, we explored the incorporation of oxidizers into the Al-H2O propellant grain, aiming to enhance combustion and injection performance. Employing a multifaceted experimental approach, we conducted thermal gravimetric analysis, laser ignition experiments, and ignition tests within a lab-scale solid rocket motor (SRM) firing to systematically examine the effects of varying content of ammonium perchlorate (AP) and ammonium nitrate (AN) on the combustion and injection performance of Al-H2O propellants. Our findings indicated that integrating AP and AN at a mass fraction of 3 % each notably curtailed ignition delay time by approximately 67 % and 90 %, respectively, and concurrently decreased burning rates by approximately 50 % and 58 %. Significantly, it has been observed that a composition incorporating a 5 % mass fraction of AP enhances the combustion efficiency of the Al-H2O propellant system by approximately 2 %. Conversely, the integration of a 5 % mass fraction of AN into the same propellant matrix results in an augmentation of the injection efficiency by an estimated 47 %. Empirical evidence validating the augmentative impacts of AP and AN on the performance of Al-H2O propellants has been substantiated through a series of motor hot firing experiments. Furthermore, the combustion behavior of Al-H2O propellants has been elucidated through an analysis of the combustion physical mechanism of Al particles. The thermal decomposition of AP yields a substantial volume of oxidizing gases, which effectively accelerates the combustion rate of the Al particles, subsequently leading to an enhancement in the overall combustion efficiency of the propellant. Conversely, the decomposition of AN results in an increased production of nitrogen gas, thereby augmenting the velocity of gas flow and, consequently, elevating the injection efficiency of the propellant. This finding holds promise for guiding the developmental trajectory of Al-H2O propellants and refining the design parameters of propulsion systems.

Multi-scale modeling of damage evolution for particle-filled polymer composites

In this study, a multi-scale modeling framework that spans from molecular chains to macroscopic structure was proposed for a typical particle-filled polymer composite (HTPB propellants). The cohesive zone model (CZM) is utilized in the RVE model of HTPB propellants to capture the debonding phenomena at the AP/HTPB interface. For the HTPB matrix, a free energy function based on the Gaussian chain network is employed. To depict the chain scission behavior, the phase fracture (PF) method along with gradient-damage theory is introduced. Subsequently, microscale fracture behavior under uniaxial tensile load was investigated based on the constructed RVE model, and a phenomenological macroscopic damage model was developed correspondingly. In this developed model, two damage factors related to the debonding of AP/HTPB interface and the growth of voids in matrix are introduced respectively. Thus, it can not only predict the macroscopic stress–strain response, but also can give the microscopic damage evolution information. Overall, this multi-scale modeling framework can offer us a deeper insight into the microstructural changes and the resulting macroscopic mechanical behavior of HTPB propellants.

Investigation on mixed mode I/II crack propagation in nitrate ester plasticized polyether propellant: Experimental and numerical study

The fracture of solid propellant is predominantly attributed to the existence of mixed mode cracks, so it is essential to investigate the the fracture behavior of solid propellant with mixed mode I/II crack. This paper presents fracture characteristics of nitrate ester plasticized polyether (NEPE) propellant under different crack inclination angles (β = 30°–90°). Based on the combination of a drawing machine and a high-speed camera, the mechanical response, crack propagation velocity and crack-path morphology were investigated. The critical equivalent stress intensity factor Keqc was calculated to assess the fracture toughness of the NEPE propellant, and a potential simplified criterion related to the stress intensity factor was proposed. The experimental results demonstrated that the NEPE propellant with mixed mode I/II crack exhibited blunting fracture phenomena during crack propagation, resulting in fluctuating crack propagation velocity. As the crack inclination angle decreases, the fracture toughness of the NEPE propellant increases and then decreases, and the value of Keqc reaches its maximum at β = 45°. Furthermore, numerical studies based on bond-based peridynamic (BBPD) were performed by modeling the crack propagation process of the NEPE propellant, including the crack phase field diagram and the load–displacement curve of the NEPE propellant. The simulation results were then compared with the experiments.

Control of burning rate pressure sensitivity for solid propellants by changing the interfacial contact of Al/HMX/AP with precisely located graphene-based energetic catalysts

The control of burning rate pressure sensitivity is essential for stable and reliable combustion of solid propellants. It has been proved that the combustion behavior of propellants can be effectively tuned by interfacial control of Al/oxidizers. In this work, core-shell Al-based composites, using oxidizers such as ammonium perchlorate (AP) and cyclotetramethylene tetranitramine (HMX) as the shell layer, have been prepared with a well-controlled location of graphene-based carbohydrazide complexes (GO-CHZ-M, M = Co2+ or Ni2+) as the catalysts. The catalysts can be located inside HMX or embedded on the surface of AP particles. The decomposition of AP and HMX could be greatly promoted with a trace amount of catalyst. Under the synergistic effects of Al/oxidizer interfacial control and GO-CHZ-M, the ignition delay time is shortened by >48 % with increased in flame radiation. More importantly, the burning rate (r) and pressure exponent (n) of the solid propellants are effectively regulated in a wide range. In particular, the use of Al@HMX/Co results in a lowered n of 0.29 within 1∼20 MPa compared to 0.79 for the blank reference sample. The agglomeration of Al particles during combustion was also inhibited due to the micro-explosion effect of Al@HMX composites. Novelty and Significance statementThe innovative approaches of integrating Al/HMX/AP composites and precise catalysis of graphene-based energetic catalysts in solid propellants have successfully achieved, regarding the modulation of the burning rates and pressure sensitivity. Moreover, the effect of catalyst location on the ignition delay and burning rates has also been studied thoroughly and clarified. This paper provides new insight into the regulation of combustion performance of solid propellants, with improved reaction efficiency and maintained energy density.

3D‐DIC for mechanical characterization of composite solid propellant under uniaxial compression

AbstractA novel experimental setup, utilizing 3D Digital Image Correlation (3D‐DIC), is employed to characterize the mechanical behaviour of composite solid propellant (CSP) under uniaxial compression at three displacement rates (1, 7, and 50 mm/min). At larger deformation, 3D‐DIC consistently shows smaller strains than nominal strain values, and this difference increases with deformation across all the displacement rates. Displacement rates significantly affect the non‐linear stress‐strain response of the CSPs. After the completion of the compression test, the specimen is unloaded, and the lengths of the unloaded specimens measured after 24 hour indicate a recovery of 90–94 % of the original length of the specimens. The recovered length increases with an increase in the displacement rate. Initially, Poisson's ratio is close to 0.5, and dilatation is zero, indicating an incompressible behaviour. However, both Poisson's ratio and dilatation increase with an increase in longitudinal strain, indicating a transition to compressible behaviour. Comparing the scanning electron microscope (SEM) micrographs of the virgin and compressive‐loaded samples, noticeable debonding is observed at the matrix‐particle interfaces.

Study on the thermal behavior, kinetics, thermodynamics and chemical reactions of double-base propellant under multiple heating rates

Study on the thermal behavior, kinetics, thermodynamics and chemical reactions of double-base propellant under multiple heating rates

Thermal decomposition kinetics and spectral analysis of mixed ester propellants

Mixed ester propellants are extensively used in artillery weapons due to their superior mechanical properties. This study investigates the decomposition kinetics and mechanism of mixed ester propellants using Differential Scanning Calorimetry (DSC) and Thermogravimetry-Fourier Transform Infrared Spectroscopy-Mass Spectrometry (TG-FTIR-MS). Kinetic parameters were determined via a model-free approach, while laser diagnostic technology captured radicals and molecular fragments during the decomposition-combustion process. Results indicate a single exothermic peak during decomposition, with apparent activation energy (Ea) increasing initially (0.01 ≤ α ≤ 0.4) and stabilizing around 278.43 kJ/mol later. The thermal decomposition behavior of mixed ester propellants follows the Sestak-Berggren equation, consistent with an autocatalytic reaction. NO2 generated during decomposition acts as a catalyst, accelerating the decomposition process. CN* radicals were detected throughout the combustion stages, indicating the resilience of the CN bond against breaking. This study can provide a theoretical basis for predicting fire development and for the selection or design of fire sensors.

Unraveling and in-situ observation on the interfacial mechanical behavior of the NEPE propellant reinforced by NPBA via molecular dynamics simulation

Excellent mechanical properties are the lifeline for the application of solid propellants. Understanding the strengthening mechanism of bonding agent is of great significance for design and application of high-performance bonding agents. In this study, the strengthening mechanism of neutral polymer bonding agent (NPBA) for the NEPE propellant and dynamic mechanical response were explored through MD simulation. Significant difference in bonding role for RDX and HMX surface is first revealed with a more effective improvement in HMX surface. NPBA requires higher peak pulling force to achieve conformational transformation compared with binder throughout the peeling process. The chain orientation and movement undergo significant changes in nitroglycerin environment and an interface peeling model is proposed to reveal the potential mechanism. Finally, the effect of NPBA insertion on interfacial micro-peeling process indicates that no significant detachment of NPBA until the binder was severely deformed, resulting in a higher pulling force required.

Dynamic mechanical response and failure behavior of solid propellant under shock wave impact

Solid rocket motor propellants are typically subjected to shock wave loads during ignition. To analyze the dynamic mechanical response and failure behavior of hydroxyl-terminated polybutadiene (HTPB) propellant under varying shock intensities, this study innovatively employed a shock tube apparatus in conjunction with schlieren imaging and 3D-DIC techniques. Shock loading experiments were conducted on propellant samples of three different thicknesses under pressures ranging from 0.3 to 0.7 MPa, capturing the dynamic deformation processes. Results revealed that deformation initiated at the clamped region, extending towards the center and forming a parabolic shape. The maximum deformation of the samples shows an approximately linear relationship with the launch pressure and decreases with increasing sample thickness. The 5 mm sample failed under a 0.6 MPa shock pressure, with electron microscopy images identifying matrix damage, particle debonding, and particle fracture as the principal failure mechanisms. Finite element simulations based on the generalized Maxwell linear viscoelastic constitutive model were conducted, demonstrating good agreement with experimental data. The critical stress for fracture was determined to be 4.12 MPa, and the ultimate shock wave pressures for 3, 6, 9, and 12 mm thicknesses were approximately 0.3 MPa, 0.65 MPa, 1.1 MPa, and 1.4 MPa, respectively. These findings provide valuable insights for assessing the structural integrity of solid rocket motors under ignition shock conditions.

Research on the low-frequency fatigue behavior of NEPE solid composite propellant based on fractional derivative constitutive model

The long-term fatigue loading history from offshore vibration environment will cause microdamage and affect the mechanical properties of NEPE solid propellant grains. The paper investigates the evolution law of microdamage through constant-strain-amplitude fatigue tests, and proposes an improved fractional derivative constitutive model for effectively predicting the low-frequency fatigue behavior of NEPE solid propellant based on the experimental phenomena. The evolution law of microdamage is negative power functional with the loading time and exponential with the maximum loading strain during the fatigue loading process. The stress-softening behavior, the Mullins effect, and the accumulation of residual strain are observed, as characteristics of low-frequency fatigue behavior. The theoretical modeling of the stress-softening behavior and the Mullins effect is proven to be significant for effectively predicting the low-frequency fatigue behavior by the improved fractional derivative constitutive model, while strain-modfication is also necessary for eliminating the influence of residual strain. The fatigue damage in solid propellant grains cannot be neglected when assessing the structural integrity of a solid propellant grain which has experienced long-term transportation or offshore storage.

Exploring the characteristics and thermal behavior of double base propellants based on nitrocellulose and diethylene glycol dinitrate in the presence of ternary-nanothermites containing various oxidizers

Exploring the characteristics and thermal behavior of double base propellants based on nitrocellulose and diethylene glycol dinitrate in the presence of ternary-nanothermites containing various oxidizers

A numerical determination of complex solid gun propellant burn rates through closed bomb simulation

AbstractClosed bomb testing is a prominent means of characterizing the combustion behavior of solid gun propellants. This sub‐scale test allows the propellant to burn in a constant volume environment, where the resulting pressure‐time trace can be collected via a pressure transducer. Historically, numerical procedures have been developed to determine the burn rates of the gun propellants from these pressure‐time traces; however, no standardized procedure exists to determine the burn rates of grains with variable surface thermochemistry and ignition criteria. To address this capability gap, a non‐linearly constrained, multivariate optimization algorithm has been developed to decouple propellant grain surfaces and determine surface‐specific burn rates [1]. In this work, the optimization algorithm as well as the legacy Excel‐based Closed Bomb (XLCB) program [2] were used to determine the burn rates of homogeneous, deterred, and layered propellants from experimental data. Closed bomb simulations using these burn rates were then conducted with the two‐phase, multidimensional, interior ballistics solver, iBallistix [3]. The maximum mean error between the simulated and experimental pressure‐time curves was 6.8 % for the optimization algorithm and 23.8 % for XLCB, showing a marked improvement with our new approach. Furthermore, the approach discussed herein improves burn rate predictions of complex solid gun propellants when compared with legacy closed bomb data reduction analysis programs.

Probing the Propeller Regime with Symbiotic X-ray Binaries

At the moment, there are two neutron star X-ray binaries with massive red supergiants as donors. Recently, De et al. (2023) proposed that the system SWIFT J0850.8-4219 contains a neutron star at the propeller stage. We study this possibility by applying various models of propeller spin-down. We demonstrate that the duration of the propeller stage is very sensitive to the regime of rotational losses. Only in the case of a relatively slow propeller model proposed by Davies and Pringle in 1981, the duration of the propeller is long enough to provide a significant probability to observe the system at this stage. Future determination of the system parameters (orbital and spin periods, magnetic field of the compact object, etc.) will allow putting strong constraints on the propeller behavior.