主 办：爆炸科学与技术国家重点实验室
             安全与防护协同创新中心
报告题目1：Meso-resolved simulations of shock-to-detonation transition(SDT) in liquid nitromethane with air-filled cavities

报告题目2：Statistical analysis of the wave and reaction characteristics of unstable gaseous detonations
报告人：Prof. XiaoCheng Mi 
               University of Cambridge,UK
时间：2019年8月6日下午14:30
地点：北京理工大学3号教学楼146会议室

报告摘要1:

Two-dimensional, meso-resolved numerical simulations are performed to investigate the complete shock-to-detonation transition (SDT) process in a mixture of liquid nitromethane (NM) and air-filled, circular cavities. The shock-induced initiation behaviors resulting from the cases with neat NM and NM with a statistically significant number of filled-cavities are examined. The cavities are explicitly resolved in the simulations using a diffuse-interface approach to treat two immiscible fluids and graphic processing unit-enabled (GPU-enabled) parallel computing. Different SDT behaviors resulting from the cases with neat and heterogeneous NM mixtures are captured by the simulations. The effect of different spatial distributions of cavities on the SDT process is examined. Further, the use of this simulation system to study the mechanism of preshcok desensitization is also explored. Statistical analysis on the meso-resolved simulation data provides more insights into the mechanism of energy release underlying the SDT process. Possible directions toward a quantitatively better agreement between the experimental and meso-resolved simulation results are discussed.

报告摘要2:

A framework of statistical analysis is proposed and performed to describe the wave and reaction characteristics of unstable gaseous detonations. Numerical simulations are based on the two-dimensional, inviscid Euler equations coupled with single-step Arrhenius chemical kinetics. Once the unstable structure of a detonation is fully developed, probability density functions (PDFs) of thermodynamic and flow variables and reaction rate are calculated for each instantaneous flow field; time-averaged PDFs can thus be obtained via collecting a large number of PDFs of instantaneous flow field. This analysis demonstrates that a “sonic surface” only exists in a statistical sense in multi-dimensional, unstable detonations. The critical parameters captured by a computational model of gaseous detonations (e.g., critical reactive layer thickness under a compressible confinement) are seemingly scaled by the mean sonic length at the same numerical resolution.