利用涡扇发动机喷管红外辐射特征模拟试验台,对二元塞式喷管的红外辐射特征进行试验研究,得到塞锥冷却对二元塞式喷管红外辐射特性的影响规律,并与轴对称收扩喷管(基准喷管)进行了对比.试验结果表明:在探测角0°方向上,相比基准喷管,二元塞式喷管在不采取冷却措施时红外特征降低了12.1%,冷气流量为1.0%总流量时红外辐射强度降低了40.8%,冷气流量为2.8%总流量时红外辐射强度降低了51.2%.

FAsT-Match(Fast Affine Template Matching)算法很好地实现了二维仿射变换情况下的模板在连续图像中的快速、精准定位.该算法对光照变化不敏感,具有较强的鲁棒性,但是对于有多个目标的图像,只能定位到一个近似全局最优解.因此,首先对FAsT-Match算法进行改进,将通过对得到的仿射变换矩阵进行模糊c均值聚类而得到的目标区域作为新的目标图像,然后采用原始的FAsT-Match算法进行定位,最后将新目标位置返回到原始目标图像中.该方法弥补了FAsT-Match算法只能定位单目标的不足,应用到无线激光模拟射击系统中能够降低硬件成本,快速、精确地定位靶位目标.实验结果表明,该方法是有效的,可以在满足定位多个目标的需求的基础上实现多靶位定位,具有一定的实用价值.

轴流压气机转子叶片排振荡疲劳失效是常见的气动弹性失稳问题.当转子叶栅处于非同步振荡状态下时,压气机管道内部将伴随着异常噪声的产生,这类噪声的频率既不是分布在叶片通过频率及其谐波上,也不是分布在转子轴频率及其谐波上,同时也不满足简单多普勒效应.为了解释这种异常噪声现象,以三维升力面理论为基础,讨论叶片对其附近流体施加非定常载荷的发声问题,给出了转子叶栅振荡异常发声问题的物理解释,建立了声场频率及模态特性与转子声源特性的直接关系式,并给出了频率特性不同于叶片通过频率且不符合简单多普勒效应的完整解释.在此基础上,通过机理性实验研究证实了该模型的正确性.实验结果表明,理论预测声场的频率和周向模态特性与实验结果完全一致.

To solve the problem of early NC programs lack of corner processing,an algorithm about corner recognition and automatical generation of processing program for planar profiles around NC code is proposed.This method can meet the product upgrades and high processing requirements of NC machining,and further ensure the security and the surface quality of parts.Firstly the common NC code structure is summed up.Secondly the NC Code geometry representation is expressed as edge chains.Then the direction of those chains and the edge tangent in chains are computed.And the corners are classed as point and arc corners.At the same time,the recognition rules of corner,considering these factors such as discrete structure of arc corner and closure of chains,are presented.To reduce the instantaneous cutting amount of processing at the corner position from the tool axis,Corner machining is layered.Each layer of corner processing tool path consists of feeding,cutting in,corner processing,cutting out and retracting sections.Layers of path are connected with feeding-retracting lines.Finally,an experimental result is showed to prove this algorithm.

The coating with low infrared emissivity was employed to suppress the infrared radiation(IR) of axisymmetric convergent nozzle for a turbofan engine,and experimental research was conducted on the simulation test bench of turbofan engines.The infrared radiation intensity in 3～5 mm of axisymmtric convergent nozzle on the orientation of 0°,5°,10°,15°,20°,30°,45°,60°,75° and 90° on horizontal plane was measured with and without the nozzle low infrared emissivity coating.The results show that low infrared emissivity coating can reduce the IR intensity of the nozzle by about 15%.The coating can distinctly suppress the IR radiation intensity from nozzle wall but it has little effect on IR radiation intensity of gas plum.

本文基于复合材料结构宏观力学理论模型,首先建立了典型复合材料层合板结构在四边简支边界条件下的动力学理论模型,并计算得到其前六阶固有频率,同时在MSC.Nastran/Patran有限元软件中完成了该层合板固有频率的仿真计算,理论计算和数值仿真结果非常接近;其次,以层合板各单层连续变化的铺层角度为设计变量,在有限元软件中对层合板结构的基频进行优化分析,在四边简支和固支条件下,结构的基频分别提高了4.9%和16.2%,并对优化前后结构的静力失效强度做了分析比较。

设计了一种用于测量智能蒙皮力学性能的多通道测试系统。根据该系统集成化的要求,设计了直流供电电源,静态应变测试模块、振动测试模块和过载指示模块。采用极低偏置电流芯片AD549和极低失调电压芯片TLC2652作为核心芯片,并通过相应的调理电路配置,组成完整的两用测量系统,使用接地技术和屏蔽技术设计电路板和电源模块,提高了该测控系统电源的稳定性和抗干扰能力。经实验验证,该测量系统比市场上同类产品性能更优,最后通过设计外壳封装和接口,完成了系统的产品化设计。

To reduce the infrared radiation of an axisymmetric exhaust system of turbofan engine,the infrared suppression laws by reducing exhaust system surface temperature and emissivity were investigated.Firstly,the infrared suppression effects of cooling and low emissivity coating on the cone surface were investigated by simulative experiment.Secondly,the computer code adopted in current research was validated with the experimental results.Lastly,the effect laws of reducing temperature and emissivity distribution on the infrared radiation（IR） characteristics of turbofan engine exhaust system with typical size were computed by the validated code.The results show that the IR intensity within the region of α15° could be clearly suppressed by reducing temperature and emissivity of cone and other components.If the temperature of cone decreases by 100K,and the surface emissivity of cone,blade and radial flame holder reduce to 0.2.The IR intensity can decrease by more than 40%,and the detection range can be reduced by about 20%.

The leakage patterns and floating-lift of lifting-pads of finger seals are simulated in this essay,seal groups is treated as a porous region,the gap between seals and rotor is fixed in constant,and fluid-solid interaction is not considered.The research work indicates:seal gap is the primary factor affecting leakage;increasing layers of high pressure seals has influence on leakage;the rotor speeds hardly influences leakage;the floating-lift of lifting-pads increases when pressure differentials increases,while seal gap is invariable;the floating-lift of lifting-pads increases when seal gap decreases,while pressure differentials is unchanged;the higher the rotor speeds is,the smaller the floating-lift becomes.

The method for evolving analog circuits based on FPTA is presented,the architecture of FPTA is an-alysed and the evolutionary algorithm is introduced．In extrinsic evolution,circuits are converted into a modelsimulated by PSpice．The process of evolving analog circuits is controlled by VB and algorithm is realized alsoby it．The experiment of 4-bit DAC shows that the function can be achieved using four FPTA cells．

The globalization of manufacture brings in economic globalization, requires urgently the networked product design and manufacture. The booming Internet technology makes it possible to carry out Web-based CAD/CAM system. This paper analyzes the relevant current technological situation and the situation of implementation both at home and abroad, expounds several key technologies in developing this system, including technology of graphics interactivity. It puts forward a kind of development tactics.