激波边界层的相互作用对扰动波传播的影响

利用线性稳定性理论和直接数值模拟研究了带有入射斜激波的、来流马赫数Ma=4．5条件下的平板边界层的失稳特性。重点考察了在由于激波边界层相互干扰,平板边界层上形成分离区,又进而产生激波、膨胀波和旋涡等复杂流动现象的流场上游,引入小扰动的TS波后,扰动波传播通过带有这些复杂流动现象的流场时,扰动波的发展变化特点。通过对流场中扰动波（包括基本波和衍生波）演化特征的分析,研究分离和激波等复杂流动现象对平板边界层稳定性的影响特点。数值模拟发现,激波的出现不同于一般的压缩波,在亚声速区与超声速区对扰动波演化的影响是不同的,此外,分离对扰动有稳定作用。     

进气温度畸变对某发动机稳定性影响的研究

本文采用有效的畸变传递模型,就进气温度畸变对某发动机稳定性和性能的影响进行了较深入的数值研究．详细地分析了温度畸变对发动机稳定性和性能的影响,探讨了温度畸变在发动机系统中的传递和分布情况。结果表明：对于发动机进口空间温度畸变,发动机稳定裕度损失更多地取决于畸变强度而非周向范围：向对于与时间相关的温度畸变,发动机进口温升率比周向范围的影响更为显著。     

碘化钾类稳定剂在化学镀Ni-P工艺中的应用

在合理选择化学Ni-P合金配方和工艺条件的前提下，采用对比试验比较了几种稳定剂对化学镀Ni-P合金镀液及镀层性能的影响，选取合适的工艺参数，采取正交试验方案，研究了KI与其他稳定剂复配时的性能变化规律，探讨了KI的稳定机理。结果表明，备稳定剂之间有的相互兼容、相互促进，有的则相互抵触、相互削弱对方的作用。复合稳定剂综合性能的提高程度明显优于单稳定剂，获得了复合稳定剂KI与Pb（Ac）2质量浓度分别为8g／m^3和1．2g／m^3匹配的最佳工艺参数。     

Modeling and control for cooperative transport of a slung fluid container using quadrotors

In this paper, dynamic modeling and control problem for transfer of a sloshing liquid container suspended through rigid massless links from a team of quadrotors are investigated. By the proposed solution, pose of the slung container and fluid sloshing modes are stabilized appropriately. Dynamics of the container-liquid-quadrotors system is modeled by Euler-Lagrange method. Fluid slosh dynamics is included using multi-mass-spring model. According to derived model, a proper control law is designed for a system with three or more quadrotors. Implementing the proposed control law, quadrotors can control pose of the container, directions of the links and liquid sloshing modes simultaneously. Stability of closed loop system of tracking errors and sloshing modes are demonstrated using a theory of singularly perturbed systems and Lyapunov stability theorem. Also, the capability of the proposed feedback control laws in solving a formerly organized transport problem of a liquid filled container has been demonstrated in simulations. Moreover, priority of the proposed control scheme to an existing slung load controller in the literature is demonstrated.     

New design simulation for a high-altitude dual-balloon system to extend lifetime and improve floating performance

This paper presents a comprehensive simulation for a high-altitude dual-balloon system which consists of zero- and super-pressure balloons. Preliminary calculations were established to describe the basic concept of the new integrated system. A mathematical model was investigated to simulate the ascending and floating processes which considered the atmospheric conditions and thermodynamic variations. Based on the simulation, results showed that the floating altitude stability between daytime and nighttime was improved. This integrated system supports higher floating altitude levels than those of ordinary balloons and extends the lifetime of floating balloon systems. Moreover, results demonstrated that the integrated system was lighter than ordinary balloons, saving useful weight for effective payload. Furthermore, exploiting the advantages of both kinds of balloons while avoiding the difficulties was a significant goal in the current design to promote the floating performance of high-altitude balloons technology.     

Experimental study of a controlled variable double-baffle distortion generator engine test rig

In order to explore the total-pressure distortion test assessment method for a turbofan engine, a Controlled Variable Double-Baffle Distortion Generator(CVDBDG) with a horizontal symmetry moving form was developed, which can adjust the steady-state and time–variant distortion separately in real time. The inlet total-pressure distortion test was conducted on an afterburner turbofan engine. The distortion parameters of CVDBDG and the instability characteristics of the engine were measured. The experimental data were modeled and analyzed by using back propagation artificial neural networks, and the work envelope of CVDBDG was obtained. Based on the analysis of the data on the engine's instability, the properties of CVDBDG used for the stability assessment were preliminarily evaluated. The results show that CVDBDG can simulate both steady-state and time–variant distortions simultaneously in a range determined by three envelopes.Under the condition of symmetric double baffles, a critical depth of insertion exists, beyond which the symmetric baffles will generate an asymmetric flow field. In the case of double baffles, compared to a single baffle, the engine exhibited different instability characteristics. Based on CVDBDG, it is expected that more efficient engine stability and durability assessment methods can be developed.     

基于试车试验的涡轴发动机整机喘振裕度研究

某涡轴发动机在外场使用过程中,由于进气环境的影响和多发不同的装机位置等因素,致使发动机出现偶发喘振或前喘征兆等现象。为此,对原型机转子进行改进设计。同时,采用试车试验的方法,测算并验证改型机的整机喘振裕度。结果表明:在整个工作范围内,改型机的整机喘振裕度得到了全面提升,设计点喘振裕度由10.65%提高至16.21%。试验可为该系列发动机设计制造和改进使用提供数据参考。     

涡轮转子叶尖泄漏涡涡核稳定性及控制

以GE-E3第一级涡轮转子为研究对象,对转子叶尖泄漏涡涡核破碎特征和稳定性机理进行了分析和归纳。研究表明:叶尖泄漏涡涡核破碎的动力是离心不稳定性;发生失稳后,涡核区域迅速膨胀,形成低速的回流区;涡核的稳定性取决于螺旋因子和逆压梯度两个因素。然后,从涡核稳定性的角度开展了叶尖泄漏损失控制的研究,计算表明:叶尖叶型的负荷前移能够减少叶片尾缘附近间隙内的横向压力梯度;吸力面喉部位置以后型线拉直能够减少喉道后的扩压系数;通过这两个措施生成的新叶片能够有效地减弱叶尖泄漏涡,抑制涡核的不稳定性,减少叶尖泄漏流损失。      

硼笼化合物对含铝液固高能燃料点火及燃烧性能的影响

为了探究硼笼化合物对液固凝胶型高能燃料的点火及燃烧性能的影响,采用高密度碳氢燃料MCRI-1、辅助分散剂胶凝剂和纳米铝粉为原料,制备了系列含铝液固凝胶型高能燃料(简称含铝高能燃料),并考察了含铝高能燃料的组成对其分散稳定性(即凝胶成型效果)的影响。在此基础上,考察了三种硼笼化合物对含铝高能燃料的密度、热值、点火及燃烧性能的影响。结果表明,提高胶凝剂含量或固液质量比(Al/MCRI-1)均可提高含铝高能燃料的分散稳定性。含铝高能燃料的密度和体积热值随着硼笼化合物的添加略有降低,但其质量热值在添加硼笼T和硼笼A后分别增加了11.6%和12.4%。硼笼化合物可将含铝高能燃料的燃温峰值提高21.1%～52.9%,点火延迟缩短44.5%～65.2%。硼笼化合物明显改善了含铝高能燃料的点火及燃烧性能。整体上,硼笼A添加效果最佳,且热解及燃烧可产生较多的气体,一定程度上增强了含铝高能燃料的膨胀做工能力。     

耦合热、动载荷的超超临界汽轮机迷宫密封动力特性

密封汽流激振严重影响超超临界汽轮机的安全运行,采用DEFINE_CG_MOTION和DEFINE_PROFILE控制宏建立转子的涡动方程,通过Workbench流固耦合方法计算热、动载荷下密封齿形变,根据快速傅里叶变化得到机组运行时的密封动力特性,并对转子稳定性进行分析。结果表明:蒸汽可导致密封齿膨胀变形,温度对密封齿长度变化影响可达1%~1.5%,压力和离心作用对其影响较小。热、动载荷使迷宫密封直接刚度减小,直接阻尼先增加后减小,交叉刚度先减小后增加,动力系数的最大变化为原来的2倍。35~55 Hz内转子稳定裕度急剧下降,转子对密封汽流激振更敏感。热、动载荷引起的压力波动集中在低频范围,密封周向压力波动可增高18.5 kPa。密封高压区的压力波幅剧增是汽流激振显著的主要原因。