Recoil Impulse Research Articles

Mechanisms of fluid–structure interaction in an underwater muzzle brake

A fluid–structure interaction (FSI) mechanism of a shock-type underwater muzzle brake is examined. A bidirectional coupling interior ballistic approach is employed to achieve accurate projectile velocity. A velocity–pressure separation solution algorithm, semi-implicit method for pressure-linked equations and the Schnerr–Sauer cavitation model are used to address the volume of fluid multiphase Navier–Stokes equations with compressible cavitation. The full ballistic muzzle flow field distribution is comprehensively modeled. Analyzing the force and flow parameters of the T-shaped underwater muzzle brake based on the numerical solution reveals detailed insights. The underwater muzzle brake provides significant braking force in the interior ballistic period due to the presence of the water medium, which is quite different from air launch. Moreover, while both the internal and intermediate ballistic periods utilize the kinetic energy of the fluid against the wall, the muzzle brake principle in the interior ballistic period is a positive kinetic impact of water, mainly dependent on the flow velocity inside the barrel, and provides 17% recoil impulse. The side holes are significantly affected by cavitation phenomena. In contrast, during the intermediate ballistic period, the kinetic impact of gas, primarily dependent on the high-pressure gas expansion, decreases exponentially with time and provides 36% recoil impulse.

Numerical Simulation of the Two-phase Flow of a Constant-pressure Rear-spray Low Recoil Weapon with Two Chambers

To study the effect of a constant-pressure rear-spray low recoil weapon with two chambers on weapon launch performance, based on two-phase flow theory, the valve-spring type constant-pressure rear-spray low recoil weapon firing process with two chambers was studied numerically. Considering the movement of the valve-spring system, a mathematical model of the weapon launch process combining the two-phase flow of gas and solid in the front and back chambers, the movement of the projectile and the transient flow of gas in the lateral rear nozzle is established. Using a 30 mm chain gun as an example, numerical simulation was carried out, and the distribution law of the flow field in the two chambers and the lateral rear nozzle during the firing of the weapon was obtained and compared with the internal flow field of the traditional weapon chamber. The results show that by reasonably matching parameters to control the flow of gunpowder gas in the two chambers, the recoil impulse can be reduced by 81.58% under the premise that the initial velocity of the projectile does not decrease, and the purpose of making full use of gunpowder gas energy to greatly reduce arms recoil is realized.

Parameter Analysis and Experiment Validation of Deployment Characteristics of a Rectangular Tether-Net

Tether-nets in space applications are flexible capture systems for removing space debris. A new, low-mass, rectangular tether-net deployed by ten towing blocks is proposed in this paper for the purpose of capturing the main body of satellites. The dynamic model of a rectangular tether-net during the deployment process was established. The accuracy of the simulation model was validated by comparing it with on-ground experiments. In addition, the influence of towing block mass and launch speed on the maximum deployment area and the deployment lengths of the long side and short side of the rectangular tether-net were systematically analyzed. The results show that the tether-net configuration and launch distance of the simulations were consistent with those of the experiments, demonstrating the good accuracy of the simulation model. Moreover, with the increase in towing block mass, the maximum deployment area and deployment lengths of both sides of the rectangular tether-net showed a gradually increasing tendence, while the recoil impulse and structural weight increased. When the launch speed of the towing blocks increased, the maximum deployment area and deployment lengths increased significantly and further caused the extension of the shape-preserving distance.

Study of the Recoil Impulse of Gaseous Products of IR Laser Ablation of Polystyrene and Polystyrene/Carbon Nanotubes Composite Obtained by Radiation Polymerization of Styrene

Study of the Recoil Impulse of Gaseous Products of IR Laser Ablation of Polystyrene and Polystyrene/Carbon Nanotubes Composite Obtained by Radiation Polymerization of Styrene

An Analysis and Calculation Method for One‐Dimensional Balanced Interior Ballistics of a Recoilless Gun

AbstractThe balancing force of the interior ballistics is an important issue in the design of the recoilless gun. It has been found in practice that the balancing force design method for recoilless guns based on the traditional classical interior ballistic theory cannot guide the balance from the physical mechanism and process. In order to study the unbalanced force experienced by the recoilless gun during the firing of the projectile and the variation law of its various parameters with time, the analysis and calculation method of the balanced interior ballistics is proposed in this article. This method separately models the aerodynamic and propellant combustion processes of the recoilless gun, using the characteristic line method to solve the model numerically. This method can be used to predict the change of the unbalanced force acting on the recoilless gun during the projectile firing of the recoilless gun. The reliability of the algorithm is verified by the interior ballistic performance when China 78 type 82 mm recoilless smoothbore gun launches the projectile. The study found that the unbalance impulse generated by the gas inside the barrel fired by the recoilless gun accounts for only 1.5 % of the total recoil impulse, but it has a great influence on the amount of impulse a shooter has can take. This approach provides a better understanding of this complex internal ballistic process, which has important implications for the design and improvements of recoilless guns.

Study of the Recoil Impulse of Gaseous Products of IR Laser Ablation of Polytetrafluoroethylene

Study of the Recoil Impulse of Gaseous Products of IR Laser Ablation of Polytetrafluoroethylene

Study on Micro Recoil Mechanism of the Weapon with a Nozzle and Two Chambers Separated by a Partition

In order to improve the recoil reduction ability of the weapon without reducing the projectile velocity, the weapon with a nozzle and two chambers separated by a partition is proposed. Taking the 35 mm caliber grenade launcher as the research object, the physical model of its launching process is proposed, and the one-dimensional two-phase flow interior ballistic model is established. MacCormack difference scheme is used to calculate the coupling of multiple physical fields formed by front and rear chambers and nozzles. Compared with the calculation results obtained by using the classical interior ballistic model, the correctness of the two-phase flow interior ballistic model is verified. The effects of the charge amount in the rear chamber and the size of the air guide hole in the barrel on the internal ballistic performance of the weapon with a nozzle and two chambers separated by a partition. The calculation results show that compared with conventional weapons, the recoil impulse can be reduced with maintaining muzzle velocity, and the recoil reduction efficiency can reach 72.27%, which is of great significance for improving weapon performance.

Measurement of Momentum and Recoil Impulse of Plasma Jet of Vacuum Arc Thruster

To measure the mechanical momentum of a plasma jet, the deflection of a collector suspended on long threads in front of the jet was analyzed (ballistic pendulum method). Alternatively, the recoil impulse in frequency mode of arc operation was measured with a specially designed thrust balance. The dependence of the vacuum arc plasma jet momentum and recoil impulse on the arc current amplitude was studied in the current range from 10 to 800 A. The experiment shows that at a relatively low arc current ( $150~\mu \text{N}$ /A, which is consistent with the known data; with a further increase in the arc current (>100–150 A), the specific reaction force increases and can significantly exceed the above mentioned value. In addition, the specific reaction force strongly increases when the axial magnetic field is applied to the discharge cell. The experiments performed with two cathode materials are also compared. The material presented in the article is of interest for fundamental and methodological issues as well as for applications primarily to the creation and testing of vacuum arc based micro-thrusters ( $\mu $ VAT) for small/ultra-small satellites.

Recoil reduction method of gun with lateral nozzle controlled by electromagnetic valve

A new recoil reduction method of gun was proposed in this work to reduce the recoil without reducing the muzzle velocity and changing the continuous firing mode. Its recoil reduction mechanism was studied based on the two-phase flow theory. First, combining the gas-solid two-phase flow in the barrel, the electromagnetic control in the electromagnetic valve, the fluid-solid coupling in the piston cavity, and the transient gas flow in the exhaust pipe, an eight-stage mathematical model of the gun propulsion process was established. Next, the propagation law of the rarefaction wave in the barrel was discussed. Then, the propulsion difference between the gun proposed here and the traditional gun was presented. The results showed that the proposed method could reduce the recoil impulse by 38.20% without reducing the muzzle velocity under reasonable matching of the structural parameters.

Experimental research on impulse coupling effect of a multi-pulse laser on an aluminum target

Impact and torsion pendulums are applied in impulse coupling experiments of high-energy laser irradiation of space debris. It is difficult to achieve a multi-pulse experiment and thus hard to analyze the multi-pulse impulse coupling effect. Here, we designed a new recoil impulse experimental measurement system of non-contact, multi-degrees of freedom, and multi-pulse irradiation. The system used a low-pressure and low-temperature vacuum chamber to simulate the space environment, the pinning effect of magnetic levitation to achieve aluminum target suspension, and high-speed cameras to record the displacement over time to calculate the impulse of the target. Then the impulse coupling experiment of multi-pulse laser irradiation on the aluminum target was performed. The result shows that the multi-pulse impulse coupling effect is not the linear accumulation of coupling results by every single-pulse and multi-pulse coefficient that decreases with the increase of the number of pulses, and eventually stabilizes as the decrease gets smaller.

Near-Surface Plasma Formation in Air with Exposure to Dual Laser Pulses at Two Wavelengths

We have experimentally studied the spectra and structure of a near-surface plasma and measured the recoil impulses when brass and graphite targets are exposed in air to dual laser pulses at the wavelengths 0.532 μm and 1.065 μm, as a function of the time interval between the laser pulses and the pulse sequence. We have established the dependences of the temperature of the laser plasma and the concentration of charged particles and also the recoil impulse on the parameters of the dual laser pulses for laser power density 4·109 W/cm2. We show that the optimal conditions for recording the spectra of the ablation plasma occur when the second-harmonic radiation arrives first with time interval between laser pulses of 1.5–6 μs, and the optimal conditions for generating the recoil impulse involve an interval of 1.5–2 μs, which is important for improving the performance of emission laser spectral analysis and laser plasma micromotors for aerospace applications.

Impulse calculation and characteristic analysis of space debris by pulsed laser ablation

Ablation by high-energy pulsed laser provides recoil impulse that results in the de-orbiting and atmospheric re-entry of space debris, which may be the best method of clearing space debris in the size range of 1–10cm. Both the magnitude and direction of the recoil impulse depend on the shape and orientation of the target and serve as the foundation for studying orbital evolution and evaluating removal effects. However, how to calculate the recoil impulse and analyze the features of recoil impulse have not received sufficient attention in the literature. Based on certain assumed conditions, a general numerical method is proposed to calculate the recoil impulse of free motion debris under a set of laser pulses. Selecting cylindrical debris as the research target, we derive an analytical method to calculate the ablation-driven impulse. Moreover, the characteristics of single impulses changing over time and the total impulse are examined using analytical expressions. Finally, simulation experiments are conducted to validate both the numerical and analytical methods.

Measuring the mechanical recoil impulse of a polymeric target upon impact of a high power electron beam

A method for measuring the mechanical recoil impulse of a target produced by the relativistic electron beam of the Calamary accelerator is described. A detector based on a piezoelectric sensor is used in measurements. Results of measurements are presented for the mechanical recoil impulse produced by the relativistic electron beam with an energy as high as 300 keV, a current of up to 30 kA, and a duration of ~100 ns that is incident on an epoxy target. The energy flux density on the target surface is varied in the range of 1–10 GW/cm2. The maximum measured impulse value is 0.32 N · s at an energy flux density of 10 GW/cm2 (an energy fluence of 810 J/cm2).

Research of metallic materials irradiation with high energy pulsed laser impact

In the process of metallic materials treatment by pulsed laser beams with nanosecond duration occurs extremely rapid and intensive heating of their surface. In this case a thin surface layer of material is heated to the boiling point and rapidly evaporates. This leads to arising substantial forces of reactive nature which significantly influence on the shape of the solidified melt and in some cases may cause deformation of the underlying layers. The considered question is relevant in the research of precision treatment of miniature products by laser beams. A metallic powder with microfine material structure was selected as the object of research and was exposed to laser irradiation with nanosecond duration. At the core of reactive forces calculation used the approach similar for laser rocket engines. The paper also presents the model and the results of the forces and the reactive recoil impulse calculation occurring during laser impact to the microfine metallic powder.

Numerical Simulation on Laser Propulsion Capability of Polymer Target

A computational model of laser ablated polymer was established. Set the ablation criterion based on threshold energy. Put forward the polymer ablation criterion in the numerical model. It established the energy distribution equation to describe the laser ablation process. When the ablation products ejected, the target gained recoil impulse from ejection process. Get the ejection energy and the recoil momentum of target based on momentum conservation law. The numerical analysis model can reflect the propulsion capability of different polymer propellant, revealed the law of propulsion parameters in laser ablation process.

Dynamic response of metals under high-intensity pulsed ion beam irradiation for surface modification

A piezoelectric transducer based on lead–zirconte–titanate (PZT) piezoelectric ceramic thin plate was applied to characterize the stress waves in titanium targets under high-intensity pulsed ion beam (HIPIB) irradiation at a peak accelerating voltage of 350 kV and an ion current density up to 400 A/cm 2 with pulse duration of about 150 ns. The magnitude of recorded stress wave signals was increased along with the irradiation intensity, presenting a slow growth with a value below 100 V in the range of 200–300 A/cm 2, and then a rapid increase of about four times up to 400 A/cm 2. The measured stress waves were explained by space–time diagram analysis. The generation and propagation of the stress wave can be attributed to the coupled thermal–dynamic effects during HIPIB irradiation onto metallic targets, where the thermal shock due to ultra-fast heating/cooling process and the recoil impulse due to ablation process have a combined contribution to the induced stress waves, dependent on the irradiation intensity. It is indicated that a fast attenuation of stress wave proceeded during its propagation from the irradiated surface to the target/PZT interface. The large amount of energy delivered by the stress wave effectively converted and dissipated into plastic deformation and/or defects formation in target materials. The dynamic response of metallic materials under HIPIB irradiation accounts for the effective surface modification of metals and alloys into a depth well beyond the ion range.

Design Considerations for Electromagnetic Railguns

Electromagnetic (EM) railguns are similar to powder guns in that both provide an accelerative force to the projectile, while accepting the resulting recoil impulse. They are designed to contain lateral and axial pressure. They must be capable of surviving the thermal environment to which they are exposed. Although there are similarities, there are also striking differences. Both are explored in the present paper with emphasis placed on EM railgun design.

The 212.8-nm photodissociation of formic acid: Degenerate four-wave mixing spectroscopy of the nascent OH(X 2Πi) radicals

The 212.8-nm photodissociation dynamics of formic acid was investigated utilizing degenerate four-wave mixing spectroscopy. The background-free rotational spectrum of the nascent OH radicals was obtained, and a cold rotational energy distribution peaking at N″=3 was extracted from the DFWM spectrum. The distribution was well approximated by a Boltzmann distribution with a rotational temperature of Trot∼716 K, which corresponds to an average rotational energy of ∼498 cm−1. The observation of a nonstatistical spin–orbit state distribution, with a preference for the low-energy F1 manifold, implies the absence of any interactions with nearby triplet states during dissociation. Preferential population of the Λ-doublet was observed, indicating that the ν7 H–O–C bending vibration in HCOOH(Ã) and the recoil impulse are the principal sources of the OH rotation.

Detection of “ended” NO recoil in the 355 nm NO2 photodissociation mechanism

Circularly polarized 1+1′ REMPI with ion imaging detection was used to probe μ–v–j angular correlations of the NO (X 2Π1/2,3/2, v=0) photoproduct from linearly polarized 355 nm photodissociation of NO2 in a molecular beam. Rotational angular momentum orientation was measured for the NO product, with the sense and magnitude of the orientation depending upon the direction of the NO recoil velocity with respect to the polarization vector of the photolysis light. The rotational orientation is shown to originate from the directionality of the torque responsible for NO rotational motion. The experimentally observed sense of rotation in the plane of the NO2 parent molecule is consistent with an effective recoil impulse force applied to the N end of the NO product. A preliminary measure of the bipolar moment associated with this orientation for the j=21.5 and j=36.5 rotational levels gives a value of approximately β02(21)=0.2.

On Extreme Dynamic Parameters of a Powerful Ion Beam–Metallic Target System

AbstractA model for the interaction of a power ion–beam a metallic target is briefly discussed. It is taken as a base for simulating numerically the interaction of a 1.5 MeV proton beam with an aluminium target at current densities up to 1.5 MA/cm2. The magnitudes of pressure applied to the target and recoil impulse of plasma scattered from the irradiated surface are found to tend to saturation. It is found that a heavy fraction present in the light ion beam diminishes the efficiency of providing the beam energy for a target.