复杂来流下内埋武器舱流动特性和武器安全分离研究

Modern fighter aircraft designs often employ internal weapon bays in order to reduce the radar cross-section and for the additional advantage of drag reduction. However, when the weapon is released and the cavity is exposed to the complex inflow, strong pressure fluctuations and acoustic resonance generating from a feedback loop within the cavity threatens the safety of aircraft and the weapon release process. In this study wind tunnel test combined with numerical simulation are employed, several advanced techniques such as particle image velocimetry, neon-tracer planar laser scattering and improved delayed detached eddy simulation method are used. The cavity flow mechanism is analyzed in detail based on boundary layer theory, shear layer stability analysis and vortex flow theory. Aeroacoustic time- frequency characteristics and shear layer properties including instability location, shedding vortex frequency and collision point on the rear wall are obtained through joint time frequency analysis, POD method and numerical schlieren technique. The mechanism of the effect of unsteady, uneven inflow on cavity aeroacoustic characteristics is clarified and the influences of complex inflow on weapon separation characteristics are also studied. The result of this research can provide technique support for buried weapon bay optimal design and weapon safety separation criteria design.

新一代战机为了降低飞行阻力、提高隐身能力，在气动布局中广泛采用内埋式武器舱。在复杂来流条件下内埋武器舱在打开舱门进行武器投放时，由自持振荡效应引起的气动噪声问题严重威胁着机载设备及武器分离的安全。本课题采用风洞试验（PIV、NPLS等先进测量技术）和高精度数值模拟（IDDES湍流模拟方法）相结合的方法，以空气动力学的边界层理论、剪切层稳定性分析、旋涡流动理论等为基础，以POD方法、数值纹影技术及联合时频分析等数据处理方法为手段，研究复杂来流（前缘几何形状及气动干扰引起的非均匀来流、内埋武器舱攻角及速度连续改变引起的非定常来流）对剪切层稳定性、失稳点位置、涡脱落频率、脱落涡撞击点位置等的影响，明确非定常、非均匀来流对内埋武器舱气动声学特性的影响规律及其内在机理，并在此基础上分析复杂来流对弹体分离特性的影响。本课题的研究成果能够为内埋武器舱的优化设计以及武器安全分离准则的制定提供技术支撑。

新一代战机为降低雷达反射面积、减小气动阻力，布局中广泛采用了内埋式武器舱，当舱门开启后，弹舱内会形成大幅度的压力脉动，造成剧烈震荡并产生刺耳的噪声，对控制武器的电子系统及相关结构造成疲劳破坏。在发射导弹时，受到内埋武器舱内强非定常流场的影响，弹体下落轨迹及姿态发生改变，降低武器命中率，甚至会造成武器与载机相互碰撞，威胁载机安全。 .本项目围绕非均匀来流及非定常来流对舱内气动声学特性和武器分离安全性的影响，采用风洞实验和大规模并行数值模拟相结合的方法开展相关研究，得到了准定常来流空间非均匀性对内埋武器舱流动特性的影响、非定常来流对内埋武器舱流动特性的影响，明确了内埋武器舱流动结构及气动噪声对非定常来流的响应特性。针对来流空间非均匀性对于武器安全分离的影响和来流非定常特性对于武器安全分离的影响开展分析，明确了复杂来流对弹体分离轨迹的影响规律，并得到其对弹体下落姿态产生影响的机理，得到了复杂来流条件下，影响弹体分离安全性的关键因素。.本文研究的前缘几何形状及气动干扰引起的非均匀来流、内埋武器舱攻角及速度连续改变引起的非定常来流对舱内气动声学特性和武器分离安全性影响的结论可以为战斗机内埋武器舱设计提供参考。