高速射弹超空泡流动的重力和压缩性效应

超空泡射弹是一种新型的水下高速动能武器。基于理想可压缩势流理论,考虑流体的重力效应,建立了水下细长锥形射弹超空泡流动的统一理论模型和数值计算方法,分别导出了亚、超声速条件下用于计算细长锥形射弹超空泡形态的积分-微分方程。采用二次多项式局部拟合空泡,提出了超空泡形态的数值离散和递推求解方法。通过超空泡长细比的渐近解与数值解计算结果比较,验证了所建立的理论模型和计算方法的有效性。通过分析细长锥形射弹在不同运动方式、深度、速度条件下的超空泡形态和流体动力系数计算结果,明确了流体重力和压缩性效应对超空泡尺度、射弹表面压力分布和压差阻力系数的影响。     

近空间飞行器的气动复合控制原理及研究进展

简单回顾与讨论了在飞行器穿越大气层时,使用气动复合控制方案的必要性与可能性.其中最复杂情况为发动机喷流推力与舵面空气动力共同使用所形成的复合控制.喷流与外流相撞引起的强干扰形成了十分复杂的干扰流场,文中介绍了复杂流动形成的原因、流场结构的特点以及干扰引起的流场改变影响了飞行器性能的预估.基于3种研究途径:理论建模与数值模拟技术、地面试验模拟技术、飞行试验技术的研究,以及它们的发展及互相验证, 用来预估飞行器的性能.为了保证地面模拟与真实飞行之间存在相似关系, 研究相似准则的作用,及分析目前的模拟能力, 涉及到许多空气动力学界至今尚未解决的难题,为了解决这些困难对今后的研究及应用提出了多方面的需求.      

Controlling the level of the sonic boom generated by a flying vehicle by means of cryogenic forcing. 2. Distributed injection of a supercooled gas from the vehicle surface

The possibility of improving the efficiency of cryogenic forcing on the parameters of the hanging shock determining the length of the region of minimization of the sonic boom (middle zone) generated by a modified power-law body is studied. The effect of distributed injection of the coolant from the body surface on the formation of a perturbed flow near the body and at large distances from the body is considered. The scheme of distributed injection and the regime of coolant exhaustion are demonstrated to exert a significant effect on the length of the middle zone of the sonic boom. A scheme of cryogenic forcing is determined, which ensures reduction of bow shock wave intensity by more than 40% at distances corresponding to 7000 body diameters. The mechanism of cryogenic forcing on the flow structure near the body is discussed. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 2, pp. 136–144, March–April, 2009.     

超声速红外长波光学整流罩设计技术研究

红外光学整流罩的性能直接影响超声速飞行器的成像质量和探测性能.本文提出了一种基于硫化锌材料的整流罩设计方法,详细讨论了材料选择、外形尺寸、厚度、镀膜、与壳体连接方式等问题,分析了试验验证对整流罩设计的重要性.     

超声波电氧化合成纳米MnO_2及其在制备甘油醛中的应用

于阳离子隔膜的电解槽中,以MnO2/Mn2+电对作催化氧化的媒介,在超声波高频振荡下,电生成的MnO2颗粒以几十nm至几μm尺寸分散在溶液中.随后将甘油电化学氧化为甘油醛,该MnO2/Mn2+电对催化活性的选择性高,电流效率可达97.4%.     

Stability analysis and transition prediction of hypersonic boundary layer over a blunt cone with small nose bluntness at zero angle of attack

Stability and transition prediction of hypersonic boundary layer on a blunt cone with small nose bluntness at zero angle of attack was investigated. The nose radius of the cone is 0.5 mm; the cone half-angle is 5°, and the Mach number of the oncoming flow is 6. The base flow of the blunt cone was obtained by direct numerical simulation. The linear stability theory was applied for the analysis of the first mode and the second mode unstable waves under both isothermal and adiabatic wall condition, and eN method was used for the prediction of transition location. The N factor was tentatively taken as 10, as no experimentally confirmed value was available. It is found that the wall temperature condition has a great effect on the transition location. For adiabatic wall, transition would take place more rearward than those for isothermal wall. And despite that for high Mach number flows, the maximum amplification rate of the second mode wave is far bigger than the maximum amplification rate of the first mode wave, the transition location of the boundary layer with adiabatic wall is controlled by the growth of first mode unstable waves. The methods employed in this paper are expected to be also applicable to the transition prediction for the three dimensional boundary layers on cones with angle of attack.     

光在超声速湍流边界层中的传输

采用数值方法分析超声速边界层流场对光传输的影响,并根据光波的变化对流场特征进行分析.用法福尔质量加权平均N-S方程及两方程湍流模型求解三维超声速平板湍流边界层流动;光在流场中的传输采用傍轴近似光波传输方程描述,用相屏法和快速傅里叶变换(FFT)技术求解.利用穿越流场的光波光强和相位的改变,直观分析光波畸变和流场的部分特征信息.     

微波波谱法研究分子间相互作用

微波波谱是一种微波频段的波谱学方法,近年来在研究分子系统结构及分子间弱相互作用上发展迅速,是一种高分辨率和高灵敏度的分析工具. 本文介绍了它的原理及应用,尤其是对脉冲喷射傅里叶变换微波谱仪研究范德华力配合物、氢键配合物、弱氢键配合物、卤键配合物等弱相互作用体系的微波转动谱也作了简要的综述.      

Stability of a supersonic flat-plate wake (Comparison of numerical and experimental results)

The stability of the wake downstream of a plat plate with a blunt trailing edge is numerically investigated at a supersonic freestream velocity. The calculated stability characteristics are compared with the experimental data.     

Shock wave structure in a diatomic gas based on a kinetic model

The structure of a normal (direct) shock in a gas for the parameters corresponding to nitrogen is investigated with allowance for the rotational degrees of freedom on the basis of a model kinetic equation. For various Mach numbers the structure is compared with both the known experimental results and the solutions of the Navier-Stokes approximation within the framework of two-temperature hydrodynamics. The possibility of assuming the constancy of the fraction of excited rotational degrees of freedom is studied.