The laser-guided bomb(LGB)is an air-to-ground pre-cision-guided weapon that offers high hit rates,great power,and ease of use.LGBs are guided by semi-active laser ground-seek-ing technology,which means that atmospheri...The laser-guided bomb(LGB)is an air-to-ground pre-cision-guided weapon that offers high hit rates,great power,and ease of use.LGBs are guided by semi-active laser ground-seek-ing technology,which means that atmospheric conditions can affect their accuracy.The spatial release region(SRR)of LGBs is difficult to calculate precisely,especially when there is a poor field of view.This can result in a lower real hit probability.To increase the hit probability of LGBs in tough atmospheric situa-tions,a novel method for calculating the SRR has been pro-posed.This method is based on the transmittance model of the 1.06μm laser in atmospheric species and the laser diffuse reflection model of the target surface to determine the capture target time of the laser seeker.Then,it calculates the boundary ballistic space starting position by ballistic model and gets the spatial scope of the spatial release region.This method can determine the release region of LGBs based on flight test data such as instantaneous velocity,altitude,off-axis angle,and atmospheric visibility.By more effectively employing aircraft release conditions,atmospheric visibility and other factors,the SRR calculation method can improve LGB hit probabi-lity by 9.2%.展开更多
静态电压稳定性是一种理想化的稳定性概念,其扰动无限小的假设不利于强非线性的电力系统在静态电压稳定域(steady-state voltage stability region,SVSR)内的安全运行。针对功率大扰动场景下由SVSR内的边界危机所引发的吸引域骤缩问题,...静态电压稳定性是一种理想化的稳定性概念,其扰动无限小的假设不利于强非线性的电力系统在静态电压稳定域(steady-state voltage stability region,SVSR)内的安全运行。针对功率大扰动场景下由SVSR内的边界危机所引发的吸引域骤缩问题,提出了一种考虑边界危机的电压稳定域(voltage stability region considering boundary crises,BCVSR)的划分方法。首先通过流形分析研究了边界危机的发生机理及其对电压稳定性的影响。其次通过相轨迹分析验证了理论研究的结果。然后通过分岔分析研究了参数变化对直驱风电并网系统的平衡集及动态特性的影响。最后划分了系统在注入功率空间中的单参数与双参数BCVSR,并将其与SVSR进行了对比。研究结果表明,在考虑功率大扰动的情形下,BCVSR的划分排除了SVSR内的边界危机对系统电压稳定性的威胁,有助于指导电力系统在实际运行中的功率调整。展开更多
[目的]翼身组合体是典型的高超声速飞行器构型之一,其独特外形对应的转捩现象及机理对于深入探究复杂外形的边界层转捩具有重要意义.[方法]采用隐式大涡模拟(implicit large eddy simulation,ILES)方法,对一种大翼展翼身组合体外形的边...[目的]翼身组合体是典型的高超声速飞行器构型之一,其独特外形对应的转捩现象及机理对于深入探究复杂外形的边界层转捩具有重要意义.[方法]采用隐式大涡模拟(implicit large eddy simulation,ILES)方法,对一种大翼展翼身组合体外形的边界层转捩现象及机理进行了深入分析.[结果]研究发现,在背/迎风面的机翼上,宽频扰动和角区流向涡展向相干,促使流动发生转捩;在背/迎风面的机身侧缘存在第二模态波,其下游流动同时还受横流效应和角区流动失稳转捩的影响;背风面双锥结构处的膨胀区会抑制不稳定波的振幅进而延迟该区域转捩;迎风面中心线上存在较强的流向涡不稳定性.[结论]在各局部几何结构上多种扰动的作用下,翼身组合体外形呈现由角区起始向下游扩展至机翼和机身,并最终呈三角形分布的转捩特征.这项研究不仅展示了翼身组合体特殊的边界层转捩现象,并揭示了其相关流动机理,也表明了ILES方法在预测高超声速复杂外形边界层转捩问题时的应用潜力,为复杂外形边界层转捩现象及机理的深入研究提供了参考.展开更多
基金This work was supported by the major research projects within the military-international class(JY2021B077).
文摘The laser-guided bomb(LGB)is an air-to-ground pre-cision-guided weapon that offers high hit rates,great power,and ease of use.LGBs are guided by semi-active laser ground-seek-ing technology,which means that atmospheric conditions can affect their accuracy.The spatial release region(SRR)of LGBs is difficult to calculate precisely,especially when there is a poor field of view.This can result in a lower real hit probability.To increase the hit probability of LGBs in tough atmospheric situa-tions,a novel method for calculating the SRR has been pro-posed.This method is based on the transmittance model of the 1.06μm laser in atmospheric species and the laser diffuse reflection model of the target surface to determine the capture target time of the laser seeker.Then,it calculates the boundary ballistic space starting position by ballistic model and gets the spatial scope of the spatial release region.This method can determine the release region of LGBs based on flight test data such as instantaneous velocity,altitude,off-axis angle,and atmospheric visibility.By more effectively employing aircraft release conditions,atmospheric visibility and other factors,the SRR calculation method can improve LGB hit probabi-lity by 9.2%.
文摘静态电压稳定性是一种理想化的稳定性概念,其扰动无限小的假设不利于强非线性的电力系统在静态电压稳定域(steady-state voltage stability region,SVSR)内的安全运行。针对功率大扰动场景下由SVSR内的边界危机所引发的吸引域骤缩问题,提出了一种考虑边界危机的电压稳定域(voltage stability region considering boundary crises,BCVSR)的划分方法。首先通过流形分析研究了边界危机的发生机理及其对电压稳定性的影响。其次通过相轨迹分析验证了理论研究的结果。然后通过分岔分析研究了参数变化对直驱风电并网系统的平衡集及动态特性的影响。最后划分了系统在注入功率空间中的单参数与双参数BCVSR,并将其与SVSR进行了对比。研究结果表明,在考虑功率大扰动的情形下,BCVSR的划分排除了SVSR内的边界危机对系统电压稳定性的威胁,有助于指导电力系统在实际运行中的功率调整。
文摘[目的]翼身组合体是典型的高超声速飞行器构型之一,其独特外形对应的转捩现象及机理对于深入探究复杂外形的边界层转捩具有重要意义.[方法]采用隐式大涡模拟(implicit large eddy simulation,ILES)方法,对一种大翼展翼身组合体外形的边界层转捩现象及机理进行了深入分析.[结果]研究发现,在背/迎风面的机翼上,宽频扰动和角区流向涡展向相干,促使流动发生转捩;在背/迎风面的机身侧缘存在第二模态波,其下游流动同时还受横流效应和角区流动失稳转捩的影响;背风面双锥结构处的膨胀区会抑制不稳定波的振幅进而延迟该区域转捩;迎风面中心线上存在较强的流向涡不稳定性.[结论]在各局部几何结构上多种扰动的作用下,翼身组合体外形呈现由角区起始向下游扩展至机翼和机身,并最终呈三角形分布的转捩特征.这项研究不仅展示了翼身组合体特殊的边界层转捩现象,并揭示了其相关流动机理,也表明了ILES方法在预测高超声速复杂外形边界层转捩问题时的应用潜力,为复杂外形边界层转捩现象及机理的深入研究提供了参考.
