隔板型式对旋转冲压压缩转子性能的影响

为了改善旋转冲压压缩转子的总体性能,通过改变隔板前、后段的型式获得不同的隔板改型方案,并利用FLUENT流体计算软件对采用不同隔板改型方案的旋转冲压压缩转子进行了数值研究。结果表明,改变隔板前段型式可以改变隔板前缘激波和进气流量,进而影响旋转冲压压缩转子的总体性能;改变隔板后段型式,可以改变旋转冲压压缩转子的流场结构,并影响其增压能力;融合隔板前、后段最佳型式的隔板组合改型方案对旋转冲压压缩转子性能的提升最大,其总压比和效率相较于原型分别提升了12.0%和7.1%。     

浅谈几种典型镁合金激光表面改性技术

镁合金具有密度小,比强度高和生物相容性好等优点,然而,表面性能不佳限制了其进一步应用。通过表面改性技术提高镁合金的耐腐蚀性和耐磨性可扩展镁合金的应用范围。激光技术在镁合金的表面改性中效果显著,得到广泛应用。主要介绍激光熔凝、纹理化和熔覆等几种典型镁合金表面改性技术,从激光–合金相互作用、微观组织结构的演变规律出发,分析表面性能增强机理。     

中英颜色隐喻“白/white”的对比

对中英两种语言及其文化进行深入地对比研究,发现两种语言中颜色隐喻的异同,为英语学习者在学习颜色同时提供一定的借鉴。     

单排突片激励热射流作用下楔形凹腔表面对流换热研究

为了改善发动机整流支板凹腔防冰结构热气射流冲击换热效果,在常规圆形射流孔上采取了突片激励,通过三维内外流耦合数值模拟的方法研究了突片数量、突片穿透比(l/d)以及射流冲击间距(H/d)对楔形凹腔表面换热的影响。研究结果表明:突片能够提高射流核心区的速度和湍流动能,使得冲击换热效果增强;相对于圆形射流孔,4-tabs,6-tabs和8-tabs所对应的的楔形凹腔表面温度和Nu数分别提高了1.2K,2.3K,2.8K和17%,28%,33%;凹腔表面温度随着突片穿透比的增大而有所提高;射流冲击间距(H/d)对凹腔内部对流换热有很大的影响,无突片激励作用时,H/d=6的凹腔表面最高温度和Nu数比H/d=12提高了7.2K和67%;在突片激励作用下,H/d=6时的凹腔表面最高温度和Nu数分别比H/d=12时提高了8.5K和90%。突片数量和突片穿透比的增大都会引起次流总压损失的增加。     

最小二乘法在复杂曲面拟合中的应用

针对复杂曲面,讨论了怎样利用最小二乘法求解非线性曲线的数据拟合问题,基于VB与Matlab进行了数据处理系统软件的设计,实验结果表明,此算法具有良好的拟合效果,并在实际工程项目中通过了检验.     

数字化车间异构设备数据源集成关键技术研究与应用

通过对异构设备工业网络环境下的统一数据接口技术、制造现场异构数据统一存储访问技术以及制造数据源可视化应用进行研究,结合金属件热加工车间异构设备的特点和具体需求,开展了C/S和B/S模式相结合的网络架构设计、数据源通道架构设计以及数据源实时性及有效性设计.对超塑成形设备、TAV气体扩散炉、热成形设备、热扭转设备、热校形设...     

二维展开太阳翼地面展开试验装置设计与验证

针对二维展开太阳翼地面展开过程中重力卸载较困难的情况,设计了适用于二维展开太阳翼的地面展开重力卸载装置,建立了某二维太阳翼在此地面展开试验装置上的动力学模型并进行了动力学仿真分析,分析结果表明太阳翼能够正常展开并锁定,除了太阳翼一次和二次锁定前后瞬间,其余展开过程中吊挂绳索张力最大变化量仅为7％,展开后最大变化不超过2％;该试验装置在某太阳翼上的应用结果表明太阳翼展开前后吊挂绳索吊挂力变化不超过1 N.此试验装置可为其他空间二维展开机构的地面展开试验提供参考.     

A New Probabilistic Transformation in Generalized Power Space

The mapping from the belief to the probability domain is a controversial issue, whose original purpose is to make (hard) decision, but for contrariwise to erroneous widespread idea/claim, this is not the only interest for using such mappings nowadays. Actually the probabilistic transformations of belief mass assignments are very useful in modern multitarget multisensor tracking systems where one deals with soft decisions, especially when precise belief structures are not always available due to the existence of uncertainty in human being's subjective judgments. Therefore, a new probabilistic transformation of interval-valued belief structure is put forward in the generalized power space, in order to build a subjective probability measure from any basic belief assignment defined on any model of the frame of discernment. Several examples are given to show how the new transformation works and we compare it to the main existing transformations proposed in the literature so far. Results are provided to illustrate the rationality and efficiency of this new proposed method making the decision problem simpler.     

闭式脉动热管启动性能的实验研究

实验研究了以乙醇为工质的闭式脉动热管在不同工况下的启动性能,分析了充液率、倾斜角、热负荷对脉动热管启动性能的影响。研究发现脉动热管具有两类启动方式:温度飞升式启动和温度渐进式启动。脉动热管启动性能最优的最佳充液率范围在41%～52%之间。相同热负荷下,随着倾斜角在0°～90°范围内逐渐增大,热管启动性能将得到改善。随着热负荷的增大,启动时间缩短但最高启动温度随之升高。     

Physical Body Impact After High Altitude Bail-out

In most of the emergency circumstances,the aircrew leaves the aircraft under unsatisfied conditions,such as too high relative velocity to the ambient air or low partial oxygen pressure.The aircrew must pass through this area as quickly as possible before opening the parachute safely,viz.,free-fall.Numerical simulations are conducted in this paper to explore the major characteris-tics of the aircrew free-fall process by using a commercial computational fluid dynamic(CFD) software,FLUENT.Coupled with the classical pressure-altitude and temperature-altitude relations,Navier-Stokes(N-S) equations for compressible flow are solved by using finite volume method.The body velocity and the attitude are predicted with six-degree of freedom(6DOF) module.The evolution of velocities,including horizontal,vertical components and angular velocity,is obtained.It is also analyzed further according to the particle kinetic theories.It is validated that the theories can predict the process qualitatively well with a modi-fied drag effect,which mainly stems from the velocity pressure.An empirical modification factor is proposed according to the fitting results.