箔片型红外面源诱饵扩散规律

目前红外面源诱饵已成为对抗红外成像制导导弹的重要方法。鉴于此,以箔片型红外面源诱饵为研究对象,利用计算流体力学（CFD）方法得到单个箔片和两平行箔片在不同迎角下的气动力系数。通过对箔片空中运动分析,特别是考虑到燃烧力作用的特殊性,将箔片的运动分为两个阶段：起燃阶段和完全燃烧阶段,并建立了两个阶段的运动模型。在单个箔片运动模型的基础上,设置上千个箔片初始姿态和旋转角速度的概率分布情况,同时对上千个箔片求解运动方程,即可得到整个红外面源诱饵的空间运动扩散规律。仿真结果表明：在高速运动平台上垂直向上发射红外面源诱饵,其扩散形状近似为前部稀疏后部密集的锥形云团;仿真得到的面源诱饵扩散尺寸和运动位置与实测数据吻合度较高,特别是面源诱饵在x轴方向扩散尺寸误差小于5%。     

对当前跨音风扇气动设计体系中损失系数和堵塞系数的关联分析

现有设计体系中对于损失系数主要是由实验和经验来确定。通流气动设计需计入叶片槽道内的附面层堵塞,反映附面层堵塞影响的堵塞系数也是依经验给定。本文对多台风扇设计进行分析后,发现现有的设计体系中损失系数和附面层堵塞系数之间彼此孤立,且不够协调,而事实上,两者是紧密相关的,体现在物理上就是损失和开式分离流之间的关系。本文在分析现有设计体系模型的基础上,提出了一个新的工程模型,把两者关联了起来,并给出了算例分析,且从算例结果中可以看到现有设计体系中单转子效率远大于级效率的原因之一。      

典型阶梯篦齿高转速密封性能试验

在高转速密封试验设备上,进行了实际尺寸阶梯篦齿压比(1.05～28)、相对密封间隙(齿尖密封间隙和齿宽比)(24～40)、泄漏流雷诺数(1900～28000)及旋转速度(0～12000r/min)等对密封性能影响的试验。结果显示:篦齿流量系数随压比变大而上升,随相对密封间隙变大而降低;转速低于5000r/min时,旋转对篦齿流量系数影响不明显,高转速、小压比时,篦齿流量系数随转速的升高而降低,降幅超过301%;较小雷诺数下,篦齿流量系数随雷诺数的减小快速降低,雷诺数超过6000以后,篦齿流量系数受雷诺数的影响不明显;气流通过阶梯篦齿第一道齿的压力损失最小,通过最后一道齿的压力损失最大,通过中间各齿的压力损失相当。基于试验测试数据,修正了典型阶梯篦齿流量系数的求解关系式,修正后的关系式计算值与实测值吻合良好。      

Developing an engineering-statistical model for estimating aerodynamic coeffcients of helicopter fuselage

The design of the geometric shape of a helicopter fuselage poses a serious challenge for designers. The most important parameter in determining the shape of the helicopter fuselage is its aerodynamic coefficients. These coefficients are determined using two methods:wind tunnel test and computational fluid dynamics (CFD) simulation. The first method is expensive, time-consuming and limited. In addition, estimates in regions away from data can be poor. The second method, due to the limitations of numerical solution, the number of nodes and the used solution, is often inaccurate. In this paper, with the aim of accelerating the design process and achieving results with reasonable engineering accuracy, an engineering-statistical model which is useful for estimating the aerodynamic coefficients was developed, which mitigated the drawbacks of these two methods. First, by combining CFD simulation and regression techniques, an engineering model was pre-sented for the estimation of aerodynamic coefficients. Then, by using the data from a wind tunnel test and implementation of statistical adjustment, the engineering model was modified and an engineering-statistical model was obtained. By spending less time and cost, the final model provided the aerodynamic coefficients of a helicopter fuselage at the desired angles of attack with reasonable accuracy. Finally, three numerical examples were provided to illustrate the application of the pro-posed model. Comparative results demonstrate the effectiveness of the engineering-statistical model in estimating the aerodynamic coefficients of a helicopter fuselage.     

行星齿轮系动力学特性分析及试验研究

采用集中质量法,考虑时变刚度、齿侧间隙、太阳轮的横向与纵向位移、太阳轮和行星轮的偏心误差激励,建立了行星齿轮传动系统的非线性动力学模型。采用龙塔库特法求解了系统的响应、相图、频谱图和动力学均载系数;通过测量系统齿根应力的动载荷应变图,获得齿根应变变形的相图、频谱图和系统的均载系数。研究结果表明:理论分析结果与试验测试结果比较吻合,说明采用的理论研究方法是合理的,测试方案是可行的。     

含缺陷三维编织复合材料热膨胀系数计算

通过将细观力学的Ｅｓｈｅｌｂｙ和Ｍｏｒｉ－Ｔａｎａｋａ理论与刚度平均化方法相结合，对含定向基体微裂纹的三维编织复合材料热膨胀系数进行了理论计算，分析了纤维体积含量，微裂纹密度和编织参数变化对热膨胀系数的影响，为材料设计和应用提供了理论基础。     

A hybrid original approach for prediction of the aerodynamic coe?cients of an ATR-42 scaled wing model

A new approach for the prediction of lift, drag, and moment coefficients is presented. This approach is based on the support vector machines (SVMs) methodology and an optimization meta-heuristic algorithm called extended great deluge (EGD). The novelty of this approach is the hybridization between the SVM and the EGD algorithm. The EGD is used to optimize the SVM parameters. The training and validation of this new identification approach is realized using the aerodynamic coefficients of an ATR-42 wing model. The aerodynamic coefficients data are obtained with the XFoil software and experimental tests using the Price–Pa?doussis wind tunnel. The predicted results with our approach are compared with those from the XFoil software and experimental results for different flight cases of angles of attack and Mach numbers. The main pur-pose of this methodology is to rapidly predict aircraft aerodynamic coefficients.     

复合材料飞机结构验证试验载荷放大系数法

载荷放大系数法的基本原理是将给定载荷（谱）下的结构Ｂ基准寿命验证试验转化为给定Ｂ基准寿命下的结构剩余强度验证试验，载荷放大系数可由理论推导方法和试验方法确定，讨论了复合材料飞机结构全尺寸验证试验采用载荷放大系数法的原因，前提条件、１．１５载荷放大系数的确定和应用的局限性等问题。     

分形粗糙表面掠入射时的全极化指数计算

为分析经典解析法不能有效求解掠入射时粗糙表面的散射特性,用高阶微扰法计算了二维分形导体表面的后向散射系数。计算值与测量值的比较证明了高阶微扰法的有效性。对不同粗糙度下掠入射时全极化指数的研究,获得了不同入射条件下极化指数与掠入射角余切函数曲线的拟合和有效表达式,修正了前人的结论,并发现用高阶解析法可区分粗糙表面的类型。     

调和微分求积法权系数矩阵的一种显式计算式

简要介绍了调和微分求积法，导出了求一阶导数权系数矩阵的显式计算公式。利用该公式和其中反心对称的性能，可进一步提高计算效率。由于均匀网点有时不能给出可靠的解，本文导出了几种能出可靠结果的不等距网点公式，其中一种公式虽然用不同的方法导出，但结果与Ｇａｕｓｓ－Ｌｏｂａｔｔｏ方法等价，本文还证明了调和微分求积法权系数矩阵具有中心对称或中心反对称的性质（取决于导数的阶数），利用这些性质可以进一步减少计算工程