一种适用于复杂加载状态下微喷射物质面密度测量的Asay膜方法

An improved Asay foil method for measuring areal density of ejecta under complex loading conditions

为了解决传统Asay膜方法不适用于复杂加卸载条件下微喷射物质面密度测量的问题,采用光子多普勒速度计(photonic Doppler velocimetry,PDV)测量微喷射物质速度结合传统Asay膜方法的膜速曲线发展了测试复杂加载条件下微喷射面密度的新方法。采用数值实验和轻气炮实验对新方法进行了分析和评估。针对3种典型微喷射物质速度分布情况,利用数值实验分析评估了实际应用场景下因PDV给出的微喷物速度偏离理论值对面密度测量的影响,通过对PDV给出的微喷物速度线性插值处理,可确保新方法与理论值测量偏差小于20%。通过轻气炮加载预置粉末样品实验对比评估了新方法和传统方法的测量效果,采用2种方法分别处理同一发实验数据,结果显示,新方法相较于传统Asay膜方法的测量偏差小于20%。

The Asay foil has been a widely applied diagnostic in ejecta measurement since its design was first reported in 1976.An Asay foil is a foil of a known mass(or areal density),whose velocity changed when it is impacted by ejecta.The Foil velocity is measured using velocimetry and the ejecta velocity is inferred from the initial gap between foil and free surface and the ejecta fly time.The mass of the impacting ejecta can then be inferred from the change in momentum of the foil.In some cases,the ejecta spray out from complex loading conditions such as double shock loading condition,the initial gap and fly time are unable to measure accurately,thus the Asay foil method doesn’t work.Therefore,it is necessary to develop an Asay foil method that does not depend on the initial gap and fly time.An improved Asay foil method is then developed based on the traditional Asay foil method.This method uses photonic Doppler velocimetry(PDV)to obtain the ejecta velocity in the testing area of the Asay foil probe,and the Asay foil probe obtains the foil velocity curve after the ejecta collides with the foil.Based on spatial position constraints and precise temporal correlation,the combination of the two velocity curve results can provide the total amount and distribution of ejecta under complex loading conditions.A numerical experimental method was used to generate ejecta particle groups with different distribution states,as well as the PDV velocity curve and Asay foil velocity curve to analyze the applicability of the method.In addition,the numerical experimental analysis results were verified using light gas gun experiments.The numerical experimental analysis results show that this method has good applicability in three typical ejecta distribution cases,with a deviation of less than 20%between the measured value and the theoretical value.The results of the light gas gun tests indicate that the deviation between the improved method and the traditional Asay foil method is less than 20%.