Integrated batteries layout and structural topology optimization for a solar-powered drone

The purpose of this paper is to demonstrate an integrated optimization scheme for a solar-powered drone structure. Consider a primary beam in the wing of large aspect ratio, where 100 lithium batteries are assembled. In the proposed integrated optimization, the batteries are considered here as parts of the load-carrying structure. The corresponding mechanical behaviors are simulated in the structural design and described with super-elements. The batteries layout and the structural topology are then introduced as mixed design variables and optimized simultaneously to achieve an accordant load-carrying path. Geometrical nonlinearity is considered due to the large deformation. Different periodic structural configurations are tested in the optimization in order to meet the structural manufacturing and assembly convenience. The optimized designs are rebuilt and tested in different load cases. Maintaining the same structural weight, the global mechanical performances are improved greatly compared with the initial design.     

火箭子级垂直回收布局气动特性及发动机喷管影响

垂直回收可重复使用运载火箭是运载火箭发展的一个重要方向,大长细比的火箭子级垂直再入过程属于典型的非规则钝头体绕流,与传统低阻力流线体飞行器气动特性差异较大。采用风洞试验辅以数值仿真分析的方法,对基于栅格舵的火箭子级垂直回收构型基本气动特性和非规则钝头体绕流情况进行了研究,获得了发动机外露喷管和栅格舵对火箭子级垂直回收气动特性的影响规律,给出了火箭子级垂直回收布局设计建议。结果表明：火箭子级倒飞状态下肩部区域会在小迎角下产生大分离流动,外露发动机喷管左右两侧诱导出较强的分离涡结构,与火箭尾翼、肩部大分离流动相互作用;垂直回收构型在超声速下阻力会一直处于较高的水平,不同马赫数下压心移动量较大,倒飞时发动机外露喷管会产生较大的干扰静不稳定力矩,其量值与栅格舵提供的静稳定控制力矩基本相当,在火箭子级垂直回收方案设计时需要引起注意。     

中国商用飞机有限责任公司总经理助理 马恒儒先生访谈

2009年11月,中国商用飞机有限责任公司总经理助理马恒儒先生接受了本刊编辑部主任李华文的专访。在访谈中,马先生介绍了中国C919大型客机的研制和发展情况,分析了中国研制的客机用上中国研制的发动机的发展契机;阐述了中国商用飞机有限责任公司拟与中航商用发动机有限公司采取的合作方式,认为中国的航空发动机设计与制造机构其几十年不变的工作模式应当进行适当变革。     

一种轴对称平面反射阵天线的布阵方法

为了减少星载平面反射阵列天线设计所需的庞大计算量,提出了一种基于菲涅尔原理的新的天线布阵方法,该方法通过多种菲涅尔相位环带实现相位补偿,每一环带所用贴片单元一致。在此基础上设计了工作频率为94GHz,由4种菲涅尔相位环带组成的平面反射阵列天线。通过仿真计算,证明该方法合理有效,可应用于星载轴对称平面反射阵天线的设计。     

固体火箭发动机静止试验振动特性分析

以动力学、声学和信号系统分析等基础理论为依据,通过大量的实测数据,揭示了固体火箭发动机静止试验的全过程中在地面和高空模拟两种试验状态下,发动机壳体振动特性与发动机工作时产生的喷气噪声两者之间的内在关系。     

载人航天器初样试验总体规划

载人航天器初样研制阶段的系统级地面试验是为了充分验证系统总体设计的正确性以及技术要求和指标要求的满足情况,以此完善和修正系统总体方案。文章给出载人航天器初样的试验规划、试验方案、试验流程等,为后续载人航天器的研制提供参考。     

质量矩控制飞行器的压心不确定性问题研究

为了减小压心不确定性对质量矩控制的影响,提高活动质量块对系统的控制能力,本文推导了飞行器姿态配平角与压心偏差的关系,分析了压心系数偏差对飞行器控制性能的影响,给出了压心最大容许偏差范围的解析表达式,然后针对压心偏差对飞行器的影响进行了仿真计算,并在此基础上分析了压心测量偏差对质量矩控制飞行器总体参数的要求,提出了几种减小压心不确定性对飞行器控制性能影响的结构布局优化方法。结果表明:对于静稳定导弹,将径向滑块的滑道配置在飞行器的前鼻部,根据任务指标合理地设计各滑块的偏移量等措施都可以减小压心不确定性对质量矩控制的影响。     

发动机机匣弧面不规则管路的布局参数多目标优化设计

管路布局优化是降低发动机管路振动应力的重要手段,提出了一种发动机机匣弧面上不规则管路布局参数的多目标优化设计方法.从发动机机匣弧面的U形管路出发,建立了具有复杂布局走向的不规则单管路的参数化建模方法.分析了布局参数对管路的危险固有频率、多点激励响应的灵敏度.综合考虑错频和最大响应等多个目标,采用多目标遗传优化算法,对不...     

A model-scale test on noise from single-stream nozzle exhaust geometries in static conditions

A model-scale test with single-stream nozzle exhaust geometries was carried out at the anechoic chamber of Beihang University in Beijing, China. The spectral characteristics are investigated, and the effects of the following parametric variations are reported in this paper: impact of nozzle operating conditions on spectra; impact of the presence of a plug; and effectiveness of chevron configurations for noise mitigation. The measurement shows that the change of pressure values has more impact on spectra than the change of temperature values. The spectral change due to pressure is shown at all band numbers for unheated conditions whereas it is more pronounced at high-frequency ranges for heated conditions. An impact of the presence of a plug is also clearly observed. The reduction of noise is moderate up to band number of 35, and becomes more significant at higher band numbers. It is observed that chevron nozzles are more efficient at high pressure and temperature values. It is expected that the quantified analysis will be used to develop an empirical model of single jet noise, which will be the baseline for the development of prediction of noise from turbofan engines of high bypass ratios.