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Novel nitro, tetrazole, and halo‐substituted 1,3‐bishomocubanes have been successfully synthesized and characterized by various spectroscopic and analytical techniques, including single‐crystal X‐ray analysis. According to Density Functional Theory (DFT) calculations, performed at B3LYP/6‐311++G(d, p) level of theory, the densities and heats of formation of the newly synthesized compounds are in the range of 1.52–2.26 g cm−3 and −70.8–111.4 kcal mol−1, respectively. These compounds are predicted to exhibit enhanced propulsive properties in terms of density‐specific impulse (ρIsp), compared to that of conventional liquid propellant RP1 and solid propellant binder hydroxy‐terminated polybutadiene (HTPB), which makes them potential candidates for volume‐limited propulsion systems. However, two derivatives have exceptional calculated figures of merit for volume‐limited propulsion systems, a dibromoester (ρIsp 415.8 s), and a dibromonitroalcohol (ρIsp 421.3 s). Though its detonation properties indicate low explosive potential, the dibromonitroalcohol possesses the highest detonation pressure (20.1 GPa) and velocity (6.3 Km s−1), which are closer to the detonation performance of trinitrotoluene (TNT). Stability parameters, including Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energy gaps, thermogravimetric analysis, and differential thermal analysis, confirm the robust kinetic and thermal stability of our compounds. Highly strained bishomocubane‐based molecules bearing energetic functionalities have been synthesized from readily available dicyclopentadiene and cyclopentanone in a minimum number of steps. Due to their high density, thermal stability, and superior propulsive characteristics and burn rate, these compounds are potential replacements for conventional binders in solid propellants and additives to liquid propellants, especially for applications in volume‐limited environments.

Rockets have revolutionized space technology and human space exploration. Most rockets and missiles are both propelled by rocket motors that use composite solid propellants. The ICT code and the NSAS CEA code are two programs that can be used to forecast theoretical propulsion parameters for composite solid rocket propellant. Rocket propellant performance is governed by a specific impulse factor, which is calculated theoretical and experiment. In this paper, the theoretical specific impulse for different composite solid propellant formulations at 70 bar combustion pressure and an adapted nozzle (optimum expansion) were calculated by the NASA-CEA code and the ICT code. Meanwhile, a static firing test was performed on a small scale test motor to experimentally determine the actual specific impulse. The objective is to verify theoretical calculations from two codes with experimental data, via the determination of the specific impulse deviation co-efficient.

The homotopy method has been used as a useful tool in solving fuel-optimal trajectories with constant-specific-impulse low thrust. However, the specific impulse is often variable for many practical solar electric power-limited thrusters. This paper investigates the application of the homotopy method for optimization of variable-specific-impulse low-thrust trajectories. Difficulties arise when the two commonly-used homotopy functions are employed for trajectory optimization. The optimal power throttle level and the optimal specific impulse are coupled with the commonly-used quadratic and logarithmic homotopy functions. To overcome these difficulties, a modified logarithmic homotopy function is proposed to serve as a gateway for trajectory optimization, leading to decoupled expressions of both the optimal power throttle level and the optimal specific impulse. The homotopy method based on this homotopy function is proposed. Numerical simulations validate the feasibility and high efficiency of the proposed method.

The energy potential of hypothetical zwitterionic nitrohydrazine H 3 N N NO 2  as a component of solid composite propellants is estimated. Two-component formulations with a hydrocarbon or an active binder and three-component formulations with aluminum or aluminum hydride additives are considered. The highest calculated ballistic efficiency was obtained for formulations with an active binder and aluminum hydride. Their specific impulse exceeds 280 s, and with allowance for two-phase losses, the maximum effective impulse of the third stage rocket motor reaches 265.4 s, whereas for the optimized similar formulation based on ammonium dinitramide, this value is much lower (262.5 s).

In this article, Bi2O3/Al high-density energetic composites with a core-shell structure were prepared by a two-step ball milling method using a common planetary ball milling instrument, and their morphology, structure, and properties were characterized in detail. Through a reasonable ratio design and optimization of the ball milling conditions, the density of the Bi2O3/Al core-shell energetic composite is increased by about 11.3% compared to that of the physical mixed sample under the same conditions. The DSC (Differential Scanning Calorimetry) test also showed that the exothermic quantity of the thermite reaction of the energetic composite reached 2112.21 J/g, which is very close to the theoretical exothermic quantity. The effect of Bi2O3/Al core-shell energetic composite on the energy performance of insensitive HTPE propellant was further studied. The theoretical calculation results showed that replacing the partial Al with Bi2O3/Al core-shell energetic composite can make the density of propellant reach 2.056 g/cm3, and the density specific impulse reach 502.3 s·g/cm3, which is significantly higher than the density and density specific impulse of the conventional composite solid propellant. The thermal test showed that the explosive heat of the HTPE (Hydroxyl terminated polyether) propellant also increased with the increase of the content of Bi2O3/Al core-shell energetic composite.

Small-scale and supersonic convergent-divergent type micro-nozzles with characteristic sizes of around a few centimeters and exit and throat radii of tenths of millimeters were the subjects of this study. Using the schlieren Z-type optical technique, the supersonic airflows established at the exit of seven nozzles were visualized. The dependence of the shock cell characteristics on the nozzle pressure ratio (NPR), defined as the ratio of stagnation pressure to atmospheric pressure, was analyzed. The dependence of the nozzle thrust and the specific impulse on the NPR ratio and the mass flow rate was also studied using a simple device based on concepts of fluid mechanics. The results obtained are in agreement with similar results obtained in recently published research on double-bell nozzles. The thrust of all nozzles depends linearly on the shock-cell spacing, which is one of the most relevant findings of this research. In other words, the output airflow structure determines the performance of the nozzles, such as the thrust or the specific impulse they produce. These small nozzles offer significant advantages over conventional nozzles in low energy consumption and lower manufacturing cost, making them suitable for scientific research in space micro-propulsion and cooling microelectronic systems, among other applications.

Combined with the image explosion source method and LAMBR (LAMB revisied) model, a fast calculation method of wall load of implosion in cylindrical vessels with single explosion source was proposed. The verification results show that the maximum relative errors of the predicted and simulated values of overpressure peak and specific impulse on the structural wall are −13.66% and −17.84% respectively. The predicted overpressure and specific impulse time curves are in good agreement with that obtained by simulation, which can reflect the multimodality of the load at the measuring point under the action of implosion and verify the effectiveness of the method.

The specific impulse is one of the important parameters of the shock wave. The shock wave specific impulse test method based on the momentum block is an important method to measure the shock wave specific impulse. In this paper, by carrying out the simulation research on the impact response of the momentum ball and the spring-mass system, the maximum compression displacement of the spring under different loading speeds is linear, and it is feasible to use the spring-mass system as the carrier to measure the shock wave specific impulse.

In order to study the propagation characteristics of explosion shock waves in air under different temperature and pressure conditions, stress wave theory and detonation wave theory were first used to analyze the propagation characteristics of shock waves. Combined with numerical simulation results, the propagation characteristics of explosion shock waves were comprehensively analyzed and verified. The following conclusion was drawn: the higher the pressure, the larger the peak value of shock waves at the same spatial position, and the greater the specific impulse of shock waves, Shortening of shock wave propagation distance; The higher the temperature, the less the peak pressure changes at the same spatial position, the smaller the specific impulse of the shock wave, and the longer the propagation distance of the shock wave.

To discuss the influence of the gas layer on underwater explosion load, the influence of gas layer thickness on bubble pulsation period maximum radius, pressure peak value, and specific impulse during underwater explosion was first discussed. A simulation model of underwater explosion with gas layer charge is established by numerical simulation method, and the influence law of gas layer on the pulsation of underwater explosion bubble is calculated and analyzed. The results show that the pulsation period and maximum radius of the underwater explosion bubble increase with the increase of gas layer thickness. The peak value of bubble pulsation pressure decreases, while the specific impulse increases first and then decreases. The research conclusion shows that in a certain gas layer, the damage risk of protective structure may be increased due to the increase of pulsating pressure ratio impulse or the resonance between pulsating frequency and structure.