Search

In this article, we present a front capturing method for compressible reactive flows, where a shock tracking technique is applied with level set method. In stiff reaction problems, the difficulty arises when the time scale of the source term is significantly shorter than the time scale of the homogeneous conservation law. The spurious numerical phenomenon may occur due to the smeared out shock profiles. In order to overcome the difficulty, the detonation front is captured sharply by level set technique, and a modified finite volume scheme is developed at the computational cells cut by detonation front. The mass, momentum, and energy transitions are occurred on shock front for chemical reactive flows. In our method, the interface exchanges are calculated by considering a Riemann problem. Unlike the standard level set/ghost fluid method, our method can maintain the conservation on the shock discontinuity. One‐ and two‐dimensional numerical examples including stable and unstable detonation problems are illustrated to verify the good reliability and robustness of our method. [ABSTRACT FROM AUTHOR]

A high‐pressure shock wave generated by a donor charge subjected to an underwater explosion can sympathetically detonate an acceptor. Experimental research is the most effective method of studying sympathetic detonation because information regarding pressure evolution, pressure peak, and bubble pulsing cycle can be obtained directly. In this study, a set of underwater sympathetic detonation tests were conducted to investigate the pressure characteristics and critical distance for the sympathetic detonation of a 1‐kg TNT donor and acceptor charges. Following the experiment, the energy, pressure, and bubble pulsing cycle were empirically analyzed. The results indicate that the best transmission and safety distances for sympathetic detonation were 99.55 and 128.92 mm, respectively. The acceptor charges were partially detonated by the donor when the gap distances were 109.90 and 119.98 mm. The degree of sympathetic detonation can be determined by analyzing the energy, bubble pulsing cycle, and pressure evolution. [ABSTRACT FROM AUTHOR]

Polymer nanofiber aerogels are highly flexible and elastic. However, their preparation in a simple, low‐cost, and environmentally friendly manner remains challenging. Herein, a green strategy for preparing an ultralight poly(vinyl alcohol) (PVA) nanofiber aerogel by electrospinning and freeze‐drying is reported. A simple thermal crosslinking method is used to make a mechanically robust material that can withstand up to 1000 times its own weight, i.e., no toxic crosslinking agents or organic solvents are used in any part of the fabrication process. The optimal aerogel has high porosity (99.1%), and consequently excellent thermal insulation performance and low thermal conductivity (0.033 W m−1 K−1). Furthermore, the flexibility and hierarchical micronano structure of the aerogel qualify it as a promising candidate for air filters and intelligent wearable sensors. [ABSTRACT FROM AUTHOR]

Cover Picture: Investigation of Underwater Sympathetic Detonation (Prop., Explos., Pyrotech. Keywords: Underwater explosion; Sympathetic detonation; Energy; Pressure characteristics EN Underwater explosion Sympathetic detonation Energy Pressure characteristics 1669 1669 1 11/07/20 20201101 NES 201101 B The cover picture b based on the Full Paper Investigation of Underwater I Sympathetic Detonation i by Zhifan Zhang et al., https://doi.org/10.1002/prep.202000099. Underwater explosion, Sympathetic detonation, Energy, Pressure characteristics. [Extracted from the article]