CFD在舰船甲板流场计算与特性研究中的应用

本文通过运用CFD技术数值模拟舰船的运动,来求解各种舰桥风速和风向下的甲板流场。建立了某型舰船的物理模型和外流场网格,给出了甲板流场的结果矢量图,并与试验结果进行对比分析,得出流场规律,为直升机在甲板上的安全起降提供技术支持。     

电弧加热射流O2激光诱导荧光技术温度测量

采用ArF准分子激光器作为激发光源来激励O2-Schumann-Runge带系(B3Σ-u←X3Σ-g)193.3nm附近的转动吸收谱线,用紫外光电倍增管探测该带系256nm附近的荧光信号,建立了ArF准分子激光器O2激光诱导荧光流场测试系统.在建立O2单带测温模型和软件的基础上,利用Schumann-Runge带系(10,2)带的荧光信号、测量了氧氩混合电弧加热射流的径向温度分布.结果表明我们建立的ArF准分子激光器O2-LIF测试系统是成功的.     

高超声速风洞变雷诺数试验技术研究

为满足高超声速飞行器气动力雷诺数效应研究需求,在CARDC的Φ1米高超声速风洞中开展了变雷诺数试验技术研究.该项试验技术是利用Φ1米高超声速风洞采用高压下吹-真空抽吸驱动运行方式、风洞运行参数范围宽的特点,通过宽范围内调节风洞运行总压而大幅改变模拟雷诺数.研究采用了单点变雷诺数试验技术和连续变雷诺数试验技术两种手段来开展高超声速飞行器气动力雷诺数效应模拟.单点变雷诺数试验是通过一系列不同雷诺数条件、不同试验车次的试验结果,获得气动特性随雷诺数的变化规律;连续变雷诺数试验时,控制风洞总压从高到低连续变化,测量获取模型处于某一姿态角条件时气动力随雷诺数的变化规律.本文介绍了变雷诺数试验的风洞开车方式、试验及数据处理方法等,并开展了某升力体飞行器和某弹头模型雷诺数效应试验研究.研究结果表明:采用单点和连续变雷诺数试验技术相结合的方式,能较为完整、准确地获得飞行器模型气动力随雷诺数的变化规律.     

Key Parameters and Conceptual Configuration of Unmanned Combat Aerial Vehicle Concept

The nature and characteristics of attack unmanned combat aerial vehicle (UCAV) are analyzed. The principles of selecting takeoff thrust-weight ratio and takeoff weight of attack UCAV are presented by analyzing the statistical data of weights for various main combat aircraft. The UCAV airborne weapons are analyzed, followed by the preliminary estimation of the payload weight. Various typical engines are analyzed and one of them is selected. Then the takeoff weight of the UCAV is determined. Based on some basic parameters and assumptions, the qualitative decomposition calculation for takeoff weight is completed. The key factors for obtaining longer endurance of aircraft with small aspect ratio configuration are found to be high lift-drag ratio and internal space. On the basis of the conclusions mentioned above, a highly blended flying-wing plus lifting body concept is proposed. According to this concept, the UCAV configuration is designed and optimized. Finally, the UCAV configuration with small aspect ratio, high lift-drag ratio, and high stealth characteristic is obtained.     

基于上游渐扩管安装条件的内锥流量计性能预测

针对内锥流量计使用灵活性要求，利用计算流体动力学数值仿真和实流实验相结合的方法，研究上游渐扩管安装条件对内锥流量计性能的影响，以获取所需的最短直管段长度。研究对象是100mm口径、β值分别为0．45，0．65，0．85三种结构类型的样机。开展了基线和渐扩管两种类型的实验，仿真和实验的介质均为常温水，雷诺数范围分别为0．2488×10^5～2．488×10^5和0．3843×10^5-2．479×10^5，仿真结果和实验结论一致。利用附加不确定度和流出系数相对误差作为主要的评价标准，给出了上游渐扩管安装条件内锥流量计所需的直管段长度。     

非定常N－S方程的线化及其差分求解

在微幅简谐振荡的假设下，对计算平面内非定常Ｎ－Ｓ方程进行了线比，并在ＭａｃＣｏｒｍａｒｋ于１９８０年提出的半隐格式的基础上，发展了一种适用于求解计算平面内线化Ｎ－Ｓ方程的差分格式．用该差分格式求解计算平面内的线化Ｎ－Ｓ方程时，可以避免求解五对角方程；且时间步长可以取得较大，计算效率高．     

A second-order numerical method for elliptic equations with singular sources using local flter

The presence of Dirac delta function in differential equation can lead to a discontinuity,which may degrade the accuracy of related numerical methods.To improve the accuracy,a secondorder numerical method for elliptic equations with singular sources is introduced by employing a local kernel flter.In this method,the discontinuous equation is convoluted with the kernel function to obtain a more regular one.Then the original equation is replaced by this fltered equation around the singular points,to obtain discrete numerical form.The unchanged equations at the other points are discretized by using a central difference scheme.1D and 2D examples are carried out to validate the correctness and accuracy of the present method.The results show that a second-order of accuracy can be obtained in the fltering framework with an appropriate integration rule.Furthermore,the present method does not need any jump condition,and also has extremely simple form that can be easily extended to high dimensional cases and complex geometry.     

绕振动旋成体的跨声速流数值分析

本文采用Ｅｕｌｅｒ方程和ＴＶＤ格式数值求解了小幅振动旋成体的非定常跨声速绕流问题，，假设在绕小幅振旋成体的非定常气流中，物理量的变化为平均定常扰动物理量的高阶小量，然后对Ｅｕｌｅｒ方程进行摄动展开，导出前两阶（零阶及一阶）摄动量的控制方程和相庆的边界条件，并进行数值求解。文中仅给出了振动旋成体的非定常压力分布。     

头部旋转对细长体大迎角不对称涡系影响机理的实验研究

本文介绍了头部旋转对大迎角不对称涡系影响的观测结果,说明了由此而抑制大迎角不对称涡系的机理。 实验结果表明,头部旋转对细长体无侧滑大迎角不对称涡系涡迹的影响是:随头部的逐渐转动,涡系的不对称发生了周期性变化;此时,由于涡不可能迅速改变状态,从而抑制、甚至接近消除了大迎角时出现的涡系不对称现象。     

非定常气动力对飞机飞行影响的拓扑分析

 根据飞机六自由度运动模型和微分非定常气动力模型, 计算了周期轨道及平衡运动的拓扑结构图,初步研究了非定常气动力对飞机飞行的全局影响, 并通过系统的导算子矩阵根轨迹、时域仿真及其灵敏度分析, 提炼出非定常气动力对飞机飞行影响的初步机理。结果表明, 非定常气动力对飞机平衡运动的振荡不稳影响明显, 可以改变其稳定特性, 延迟Ho pf 分叉的出现。对于稳定的周期运动, 由于增加了系统的阻尼耗散项从而减少了振荡幅度。