Study of the pitting effects during the pre-ignition plasma–propellant interaction process

Self Cite

In order to study the characteristics of electrothermal plasma interaction with energetic materials, especially the ignition ability, a novel model considering polyethylene and copper ablation is developed, and an ignition experiment system is set up. The parameters of the plasma and the surface conditions of the energetic materials are measured in the testing. The results show the measured first peak pressure to be ~2.2 MPa, the second peak pressure to be ~3.9 MPa, and the visible flame velocity to be ~2000 m s −1 . Circular pits of the order of microns and nanometers in size are observed on the surface of the energetic materials. Further, the parameters of the plasma, including static pressure, total pressure, density, temperature, velocity, copper concentration and PE concentration, are calculated and analyzed by the established model, under discharge currents of 9 kA. The simulation is similar to those of experimental results. A shock wave is observed in the experiment and is presented in the calculations; it plays an important role in the performance of the plasma in the nozzle region, where the parameters of the plasma variation trends are very complex. With the aim of obtaining the overall performance of the plasma, the coupling characteristics of multiple parameters must be taken into account, in accordance with the developed electrothermal plasma model.

“…Plasma with a higher temperature has a stronger radiative and ablative ability, which further enhances the ignition effect. This finding is in agreement with [26,27].…”

Section: The Distribution Of Plasma Temperaturesupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

An electrothermal plasma model considering polyethylene and copper ablation based on ignition experiment

Zhang¹,

Li²,

Yang³

2018

Self Cite

“…Obviously, under the transient conditions, the convective heat transfer and radiation heat transfer caused by the plasma jet could not be ignored. More than 80% of the plasma energy flow deposited on the propellant is the radiant energy flow [31,33]. At the same time, according to the experimental results, the jet pressure generated by the plasma ignition has no great advantage compared with the conventional ignition method.…”

Section: The Numerical Resultsmentioning

confidence: 98%

“…In our previous paper [31], the unique pitting effect during the PPI process is observed. It is found that the pitting of the propellant surface after ignition is mainly caused by plasma radiation.…”

Section: Introductionmentioning

confidence: 88%

Study of the enhanced burning rate during the plasma-propellant interaction process

Wang

Yang

Fan

et al. 2019

Self Cite

Plasma ignition technology has been widely used for decades due to its great improvement in enhanced burning rate. However, the interaction process between the plasma jet and the solid propellant is still far from being elucidated. In this paper, coupling the flow model of plasma jet and the chemical reaction model of propellants, a more comprehensive model for predicting the plasma enhanced burning rate is presented. Three types of energetic thermoplastic elastomers propellant are involved. In addition, the closed bomb vessel test is conducted to investigate the burning characteristics of propellant under the action of plasma for comparison. It demonstrates that the enhanced combustion phenomenon of propellants in the experiment can be well described by an enhanced burning rate coefficient epsilon calculated with the model, which could reflect the effect of plasma jet to some extent. The results show that the composition of the energetic material and its surface temperature are the key factors influencing the plasma-enhanced combustion. This model would bring some insight on the interaction mechanisms between plasma and different propellants.

“…For other applications aiming to utilize the pulsed optical radiation or thermal plasmas, like initiating energetic materials via exploding wires, figuring out the evolution of optical emission from explosion products would also be of great importance. Recent experiments on the interactions between plasma and explosive have shown the necessity of strong optical emission for the ignition process of explosives [32]. Therefore, the evolution of plasma radiation in electrical wire explosion needs to be further understood.…”

Section: Introductionmentioning

confidence: 99%

Spatial–temporal evolution of plasma radiation in electrical wire explosion: a morphological observation

Han¹,

Zhu²,

Wu³

et al. 2020

This paper deals with an experimental study regarding the spatial–temporal evolution of single wire explosions in air and water at atmospheric pressure. Experiments were carried out with a microsecond timescale pulsed current source under 500 J stored energy. The morphology of the exploding wire with different discharge type, wire material, insulating coat, and ambient medium was intensively observed via self-emission images. The results revealed that the plasma radiation of wire explosion in air mainly contained two stages: initial intense radiation from optically thick plasma, and later decaying radiation from expanded arc-like plasma. A hollow structure was observed in a Cu exploding wire in air, and the plasma channel tended to develop inside it. As for W case, there would always be a core-corona structure, resulting in lower expansion rate and shock wave strength. Moreover, the plasma radiation of the underwater wire explosion was mainly determined by two factors: expansion rate and chemical reaction. The expansion rate of the radiant region in water was only 10–1 mm μs–1 level (1 mm μs–1 level for air), leading to the lagging radiation. No noticeable difference in morphology was found between Cu and W wire explosions in water. Particularly, the Al wire explosion generated a bright light emission due to chemical reactions. Finally, radiative characteristics in an exploding wire were preliminarily concluded and existing problems proposed.