多斜孔壁与机加环气膜冷却燃烧室面换热特性数值研究

数值研究了在燃烧室实际工作条件下,多斜孔壁冷却燃烧室和机加环气膜冷却燃烧室的流动、换热特性,比较分析了内、外壁温度场以及冷却流量的变化.研究发现,采用多斜孔壁后,壁面冷却效果得到强化,相比机加环气膜冷却燃烧室,燃烧室前段壁温略有升高,而后段受到气膜冷却效果增强的影响,壁面温度有所降低,壁面温度梯度明显减小.流量系数明显减小,冷却空气量降低23%,用于组织燃烧用气量增加.多斜孔壁冷却技术可以为高温升燃烧室的发展提供有效的冷却技术.      

Evaluation Model of Design for Operation and Architecture of Hierarchical Virtual Simulation for Flight Vehicle Design

In order to take requirements for commercial operations or military missions into better consideration in new flight vehicle design, a tri-hierarchical task classification model of "design for operation" is proposed, which takes basic man-object interaction task, complex collaborative operation and large-scale joint operation into account. The corresponding general architecture of evaluation criteria is also depicted. Then a virtual simulation-based approach to implement the evaluations at three hierarchy levels is mainly analyzed with a detailed example, which validates the feasibility and effectiveness of evaluation architecture. Finally, extending the virtual simulation architecture from design to operation training is discussed.     

Nonlinear Adaptive Robust Force Control of Hydraulic Load Simulator

This paper deals with the high performance force control of hydraulic load simulator. Many previous works for hydraulic force control are based on their linearization equations, but hydraulic inherent nonlinear properties and uncertainties make the conventional feedback proportional-integral-derivative control not yield to high-performance requirements. In this paper, a nonlinear system model is derived and linear parameterization is made for adaptive control. Then a discontinuous projection-based nonlinear adaptive robust force controller is developed for hydraulic load simulator. The proposed controller constructs an asymptotically stable adaptive controller and adaptation laws, which can compensate for the system nonlinearities and uncertain parameters. Meanwhile a well-designed robust controller is also developed to cope with the hydraulic system uncertain nonlinearities. The controller achieves a guaranteed transient performance and final tracking accuracy in the presence of both parametric uncertainties and uncertain nonlinearities; in the absence of uncertain nonlinearities, the scheme also achieves asymptotic tracking performance. Simulation and experiment comparative results are obtained to verify the high-performance nature of the proposed control strategy and the tracking accuracy is greatly improved.     

Visualization Experiments of a Specific Fuel Flow Through Quartz-glass Tubes Under both Sub- and Supercritical Conditions

The present work is a visualization study of a typical kerosene (RP-3) flowing through vertical and horizontal quartz-glass tubes under both suband supercritical conditions by a high speed camera. The experiments are accomplished at temperatures of 300-730 K under pressures from 0.107-5 MPa. Six distinctive two-phase flow patterns are observed in upward flow and the critical point of RP-3 is identified as critical pressure pc=2.33 MPa and critical temperature Tc=645.04 K and it is found that when the fluid pressure exceeds 2.33 MPa the flow can be considered as a single phase flow. The critical opalescence phenomenon of RP-3 is observed when the temperature is between 643.16 K and 648.61 K and the pressure is between 2.308 MPa and 2.366 MPa. The region filled by the critical opalescence in the upward flow is clearly larger than that in the downward flow due to the interaction between the buoyancy force and fluid inertia. Morecover, obvious layered flow phenomenon is observed in horizontal flow under supercritical pressures due to the differences of gravity and density.     

中国民航运输系统性测度研究

对民航运输系统发展程度的有效测度是实现民航运输系统协同发展的前提和基础,从民航运输系统性内涵出发,构建了民航运输系统性测度模型。借助数据包络分析评价方法,建立了民航运输系统总体评价方法,基于协同理论建立了民航运输子系统协调度测度模型和方法。并应用所建立的模型和方法,对中国民航运输系统性状况进行了实证研究。研究结果表明,中国民航系统的有效性有待提高,航空公司系统、机场系统与空管系统两两之间均处于中度协调状态,动态协调度呈现出上升趋势。     

大型柔性结构自由频响地面试验方法

因诸如大型可展开天线等大型柔性空间结构的基频很低,很难通过现在广泛应用的低频悬吊方法来模拟其自由状态。为得到这类结构的自由频响,研究了一种方法:对待测结构施加弹性支撑,在分别获得整体与支撑结构频响后,通过后续处理去除支撑结构对待测结构的影响,进而得到待测结构自由状态的频响。数值与试验结果表明,这一方法是可行的,可以考虑进一步应用于实际工程结构。     

电子产品传导干扰的抑制

讨论了电子产品传导干扰的基本特性及其抑制措施,详细探讨了电源滤波器在抑制传导干扰中的应用,并以KGY-XXX型开关电源产品为例,介绍了传导干扰的抑制方法。     

求解Hamilton-Jacobi方程的一类无波动的耗散差分格式

利用Hamilton-Jacobi方程与双曲型守恒律的紧密联系,借助于求解双曲型守恒律的一类无波动无自由参数的耗散差分(NND)格式构造了一类求解Hamilton-Jacobi方程的差分格式.数值实验结果表明:该格式具有计算量小且高分辨率等优点.