弹性体运载火箭建模及控制器设计

考虑运载火箭飞行过程中的弹性振动特性,对运载火箭进行全量动力学建模以及控制器设计。首先将运载火箭考虑为一维梁模型并建立全量动力学模型,分别引入自适应滤波姿态控制算法和H_2范数鲁棒增益调度控制算法设计控制器。仿真结果表明:在考虑舵机非线性情况下两种控制方法均能够满足精度要求,在具有较大外部扰动情况下,鲁棒增益调度控制算法相较于自适应滤波算法具有较强的鲁棒性。     

超微型高速空气轴承的动态特性

对微型转子（半径为1985mm）动态特性进行了数值模拟和实验研究。在数值模拟中,利用ANSYS对空气轴承 微转子系统进行了双向瞬态流固耦合研究;模拟了启动阶段转子在空气轴承调节下的运动过程。结果表明:转子的动态过程为一运动幅度逐渐减小的振荡过程,最后将稳定于某一平衡位置;在轴承供压越大时,转子运动幅度越大,且达到稳定所需时间更长。计算结果发现了轴承间隙宽度与轴承流量的正相关关系。在对应实验中,实验结果与模拟结果很好的相符。由数值模拟和实验研究,说明了在较大止推轴承供压下由于转子轴向运动幅度大,有更大发生碰撞的风险;而在70927Pa的供压下进行启动则更为合适。      

金属膜盘联轴器轴向振动特性研究

为研究金属膜盘联轴器的轴向振动特性,分别通过有限元计算和试验方法分析了金属膜盘联轴器的轴向拉伸刚度、轴向压缩刚度和轴向固有频率。根据分析结果,对某型膜盘联轴器开展了在运转条件下的轴向振动测试。结果表明:金属膜盘联轴器的轴向拉伸刚度和压缩刚度均呈现明显的非线性特性。在某型联轴器的工作转速范围内存在轴向振动固有频率,但仅在使用转速激励,且在联轴器的轴向固有频率下运转,联轴器才不会发生轴向共振。     

无筒空射运载火箭重力出舱机箭耦合动力学

研究了以运输机为平台的内装式空射运载火箭重力出舱载机-火箭两体动力学。根据火箭受力条件和相对运动自由度,将其出舱运动顺次分为5个阶段。给出了各阶段过渡的力学条件,基于牛顿-欧拉法分别建立了前4个阶段的机-箭两体动力学模型。定义了火箭出舱过程可能发生危险的多种异常情况,给出了发生异常的力学或几何条件。然后对火箭出舱全程作了数值仿真。若发射初始条件合理,仿真将顺次经历前4个或3个正常阶段,直至火箭离舱。如果异常情况的条件满足,火箭出舱将发生危险,仿真失去意义,故中止,需要调整发射初始条件后进一步仿真验证。本文给出的系统动力学模型和仿真数据可为工程部门设计空射型火箭的本体参数,以及设置空射初始条件提供参考。     

Decision-making of Aircraft Optimum Configuration Utilizing Multidimensional Game Theory

As multi-discipline coupling and components interference often affect the aircraft configuration decision-making and analysis during conceptual design process, this article presents an approach of multidimensional game theory based on aircraft components to deal with this problem. The idea is that the configuration decision-making process is regarded as the game for different disciplines and technologies, and the aircraft components are players. The payoff function with highest total gain means that according to the game protocols and multidimensional theory, the optimal aircraft configuration within the strategy set will be chosen. The decision-making model is applied to conceptual design process of the high altitude long endurance (HALE) unmanned aerial vehicle (UAV) based on the assessment of technological risk. The obtained optimum configuration is quite consistent with the current HALE UAV development trends. Thus, taking into account the coupling and interference factors, the multidimensional gaming model based on aircraft components will be an effective analysis method in the decision-making process of aircraft optimum configuration.     

西部地区高校国际交流与合作现状及思考

在经济全球化,教育国际化的大背景下,西部地区高校和西部大开发的强劲东风,积极拓展了教育国际间的交流与合作,有力地推动了西部地区高等教育国际化的进程。但又由于受地域偏远、交通不发达和经济发展缓慢的影响,西部地区高校国际交流与合作和我国东部发展地区相比,在广度和深度方面还有很大的差距,面临着很大的发展空间。     

热-机耦合分析的有限元法及其应用

基于有限元分析的基本原理,建立了热-机耦合问题分析的有限元基本方程,并对工件挤压过程及摩擦制动问题进行了分析。算例表明,热-机耦合分析方法能很好地模拟受热结构的温度场和应力应变场,为结构设计和工艺设计提供依据。     

Experimental investigation and correlation development of jet impingement heat transfer with two rows of aligned jet holes on an internal surface of a wing leading edge

Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° a 90°, and 13.2 r/d 42.03. The finding was that the heat transfer performance at the jet-impingement stagnation point with two rows of aligned jet holes was the same as that with a single row of jet holes or the middle row of three-row configurations when the circumferential angle of the two jet holes was larger than 30°. The attenuation coefficient distribution of the jet impingement heat transfer in the chordwise direction was so complicated that two zones were divided for a better analysis. It indicated that: the attenuation coefficient curve in the jet impingement zone exhibited an approximate upside-down bell shape with double peaks and a single valley; the attenuation coefficient curve in the non-jet impingement zone was like a half-bell shape, which was similar to that with three rows of aligned jet holes; the factors,including Rej, H/d and r/d, affected the attenuation coefficient value at the valley significantly.When r/d was increased from 30.75 to 42.03, the attenuation rates of attenuation coefficient increased only by 1.8%. Consequently, experimental data-based correlation equations of the Nusselt number for the heat transfer at the jet-impingement stagnation point and the distributionof the attenuation coefficient in the chordwise direction were acquired, which play an important role in designing the wing leading edge anti-icing system with two rows of aligned jet holes.     

Controlling factors of Region 2 field-aligned current and its relationship to the ring current: Model results

One essential component of magnetosphere and ionosphere coupling is the closure of the ring current through Region 2 field-aligned current (FAC). Using the Comprehensive Ring Current Model (CRCM), which includes magnetosphere and ionosphere coupling by solving the kinetic equation of ring current particles and the closure of the electric currents between the two regions, we have investigated the effects of high latitude potential, ionospheric conductivity, plasma sheet density and different magnetic field models on the development of Region 2 field-aligned currents, and the relationship between R2 FACs and the ring current. It is shown that an increase in high latitude potential, ionospheric conductivity or plasma sheet density generally results in an increase in Region 2 FACs’ intensity, but R2 FACs display different local time and latitudinal distributions for changes in each parameter due to the different mechanisms involved. Our simulation results show that the magnetic field configuration of the inner magnetosphere is also an important factor in the development of Region 2 field-aligned current. More numerical experiments and observational results are needed in further our understanding of the complex relationship of the two current systems.