Combustion Performance Of Propellant Research Articles

The effects of Al (111) and Al2O3/Al (111) surfaces on the decomposition of ammonium perchlorate: A DFT-D study

Ammonium perchlorate (AP) is a crucial oxidizing agent in composite solid propellants, where aluminum (Al) is used as an additive to increase the energy density of composite solid propellants. The interaction between AP and Al significantly improves the ignition and combustion performance of propellants, but the mechanism of their interactions still lacks essential understanding, especially the interaction between AP and Al, as well as the Al surface containing aluminum oxide (Al2O3). To solve this problem, the adsorption and decomposition processes of AP and its decomposition products such as perchloric acid (HClO4) and ammonia (NH3) on the pure-Al (111) and Al2O3/Al (111) surfaces were studied by using the density functional theory (DFT). The effects of temperature and pressure on the adsorption and reactions were discussed. AP tends to adsorb on the pure-Al (111) surface with O-termination, while under the influence of Al2O3, AP is more inclined to adsorb on the surface of Al2O3/Al (111). At the low-temperature stage, the Al2O3 molecules on the surface of Al (111) promote the disengagement H of AP decomposition and the adsorption and decomposition of NH3, while at the high-temperature stage, the pure Al surface is more conducive to the AP disengagement H and NH3 decomposition. The increase in the pressure is in favor of NH3 adsorption, but the effect gradually decreases. HClO4 cannot adsorb on the pure-Al (111) and AP (001) surfaces, but it can adsorb on the surface of Al2O3/Al (111). In the gas phase, the decomposition of HClO4 priors to NH3. At the high temperature and pressure, the pure-Al (111) surface can contribute significantly to the adsorption and activation of NH3. The findings are very valuable for regulating the combustion of solid propellants.

Influence of different energetic plasticizers on the performance of NC-RDX nitramine gun propellants

Energetic plasticizers are an essential component of propellants and have a significant impact on their performance, such as energy, combustion, and mechanics. Therefore, there is significant practical value in understanding how plasticizers affect the performance of propellants. In this work, the glass transition temperatures of several energetic plasticizers were compared. By adding energetic plasticizers with good compatibility with the propellant and a low glass transition temperature to the propellant, nitramine gun propellants containing different energetic plasticizers were prepared through a semi-solvent method. The compatibility, thermal behavior, phase structure, composition, mechanical properties, energy, and combustion performance of the nitramine gun propellants were characterized. The influence of plasticizers on the phase structure of the propellant and its mechanism on the combustion performance of the propellant were discussed. Energetic plasticizers GAPE, DNPH, and BuNENA have good compatibility and chemical stability with NC-RDX and display good plasticization. GAPE–NC–RDX, DNPH–NC–RDX, and BuNENA–NC–RDX propellants exhibit stable combustion performance at −40 °C, 20 °C, and 50 °C. Compared with the nitramine gun propellant plasticized with NG, the impact strength of the propellant plasticized with DNPH and BuNENA increased by 108.1 % and 17.2 % at −40 °C, respectively. This work offers a solution to improve the phase structure, mechanical properties, and combustion stability of heterogeneous gun propellants and provides a way to suppress the excessive burning rate and flame temperature of propellants.

Electrochemical Synthesis of the Energetic Combustion Catalyst Co(BODN)·9H2O and Its Catalytic Effect on Ammonium Perchlorate Thermal Decomposition.

Safe, efficient, and green synthetic energetic combustion catalysts are of great importance for the application of ammonium perchlorate (AP) in solid propellants. In this study, a novel, simple, efficient, and green electrochemical method for synthesizing energetic combustion catalysts was designed and implemented to successfully synthesize Co(BODN)·9H2O (BODN = [2,2'-bi{1,3,4-oxadiazole}]-5,5'-dinitramide), a novel energetic combustion catalyst. The target products were characterized via single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, optical microscopy, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. Results reveal that Co(BODN)·9H2O crystallizes in the triclinic P1̅ space group and has a density of 1.836 g cm-3. The size of the Co(BODN)·9H2O crystal increases gradually with the increase in the reaction current and the prolongation of the reaction time, respectively. However, the change in reaction current and time does not affect the crystal form. In addition, with the increase in Co(BODN)·9H2O content, the peak temperature of high-temperature decomposition (HTD) and apparent activation energy of AP/Co(BODN)·9H2O gradually decrease, and the heat release during thermal decomposition gradually increases. The HTD peak temperature and apparent activation energy of AP/Co(BODN) 9H2O (10%) decrease by 97.9 °C and 94.2 kJ·mol-1, respectively, compared with those of pure AP, and the heat release during thermal decomposition increases by 1613 J·g-1. Furthermore, compared with those of the propellant containing pure AP, the burning rate and flame temperature of the propellant containing AP/Co(BODN)·9H2O (10%) increase by 8.15 mm s-1 and 458.44 °C, respectively. Real-time Fourier transform infrared spectroscopy reveals that CoO catalyzes the thermal decomposition of AP mainly by promoting electron transfer to accelerate the oxidation of NH3 and the conversion of N2O to NO. In brief, this work provides new insights into synthesizing energetic combustion catalysts. Moreover, Co(BODN)·9H2O synthesized through the electrochemical method exhibits considerable application prospects for improving the thermal and energy performance of AP and the combustion performance of propellants.

Combustion process of a promising catalyst [Cu(Salen)] for HMX-CMDB propellants.

Metal organic complexes are regarded as a series of promising combustion catalysts for solid rocket propellants. Their effects on the combustion performance of propellants are closely related to the reaction mechanism. Here, the metal-organic complex Cu(Salen) was investigated as a candidate material for the combustion catalyst of the HMX-added composite modified double-base propellant (HMX-CMDB). The combustion performance of the propellant was found to be evidently enhanced in the presence of Cu(Salen) compared with the propellant samples containing Benzoic-Cu or without catalyst. The addition of Cu(Salen) can improve the burning rate and combustion efficiency of the propellant - and greatly reduce the burning rate pressure index. Analysis shows that the addition of Cu(Salen) can increase the combustion area, flame brightness and combustion surface uniformity of the propellant to a higher degree. The sample can spray more beams of bright filaments on the flat combustion section, and the amount of gas generated by decomposition also greatly increases. In addition, Cu(Salen) shows amazing advantages in improving the surface of the propellant and the temperature gradient of the combustion flame.

Effect of Block Structure of Copolyether Binder on Slow Cook‐Off Response of Composite Propellant

AbstractAs the typical insensitive propellants, hydroxyl‐terminal block copolyether (HTPE) and hydroxyl‐terminal block copolyether (PET) propellant all belong to copolyether propellants. The two binders of propellants have different arrangements of copolyether structure. But, the effect of copolyether structure arrangement on the slow cook‐off behavior of propellants and its possible mechanism has been unknown. So, in this paper, the slow cook‐off behaviors of HTPE and PET propellants were tested. The result showed PET propellant responded more violently than HTPE propellant. Then, the changes of mass loss, explosion heat, and combustion performance of propellants during the cook‐off test were studied. Combined with the slow cook‐off behavior of AP and binders, the mechanism of block structure effect on slow cook‐off response of propellant was proposed. It expressed that, the binders of HTPE and PET propellant all degraded into liquid products due to the copolyether structure; but the block structure has a significant effect on the chain scission process of copolyether binder, which makes slight degradation and the mild response to slow cook‐off for HTPE propellant. While the binder of PET propellant with the random structure degraded seriously, making more mass loss, bigger explosion heat, and worse combustion performance, the PET propellant responds violently to slow cook‐off.

Experimental Study on Microwave-Assisted Ignition and Combustion Characteristics of ADN-Based Liquid Propellant.

Microwave-assisted ignition is a new ignition method, which has the advantages of reliable ignition and high ignition energy and requires no preheating. In this study, experimental methods were used to study the microwave-assisted ignition and combustion characteristics of ADN-based liquid propellant, and the effects of microwave power and propellant flow rate on combustion flame structure, spectral emission characteristics, and flame temperature were investigated. In the experiment, a microwave-assisted ignition experimental device was established first. The ADN-based liquid propellant was injected into the microwave high-energy region from the bottom of the resonator through a hollow straight tube with an inner diameter of 1 mm, and the gas was introduced in a coaxial manner. The research results demonstrated that when the microwave power increased from 1000 to 2000 W, the flame height increased from 11.12 to 17.32 mm; the free radical intensity of C2*, NH2, and HNO* increased significantly; the flame temperature increased by about 28.9%. The increase in microwave power is helpful to the generation of intermediate products and the combustion performance of propellant is better. When the propellant flow rate was increased from 25 to 45 mL/min, it was found that the spray combustion effect was the best when the propellant flow rate was 30 mL/min, the flame height increased by 25.2%, and the flame temperature increased by about 11.3%.

THE INFLUENCE OF SPHERICAL GRANULAR PROPELLANTS ON THE COMBUSTION PROPERTIES OF HIGH-BURNING-RATE PROPELLANT

Novel spherical grain-binding, high-burning-rate propellant is a kind of compound structure propellant (called a consolidated propellant) that is prepared using a spherical granular propellant (spherical propellant grains) as the dispersed phase and a colloidal binder as the continuous phase. The effects of composition, particle-size, and morphology of spherical propellant grains on the combustion performance of propellants were each investigated. The results show that the burning rate of the propellant decreases with the increase of the burning rate of spherical propellant grains. The greater the difference in burning rate between the spherical propellant grains and the binder, the higher the burning rate of the propellant will be. The burning rate of the consolidated propellant increases with a decrease in particle size. When compared with that of propellants prepared with smooth-faced spherical propellant grains, the burning rate of propellants prepared with shaggy spherical propellant grains is much higher; however, combustion can become less stable.

VLW equation of state of detonation products

Based on the virial theory, we proposed VLW equation of state of detonation products (VLW EOS). Its basic theory and applications were described. The distinct features of the VLW EOS were First, the detonation performance of the new high energy density materials could be predicted more reliably. Second, it had extensive application. The detonation parameters of both the condensed high energy density materials and the gaseous fuel air explosives could be calculated. Moreover, combustion performance of propellants could also be precisely calculated. The calculation results were satisfactory.

Area 6: Ignition and Combustion Performance of Propellants for Rocket Propulsion

Area 6: Ignition and Combustion Performance of Propellants for Rocket Propulsion

Area 6: Ignition and Combustion Performance of Propellants for Rocket Propulsion

Area 6: Ignition and Combustion Performance of Propellants for Rocket Propulsion