风洞T型冲击三通管道流场特性数值模拟

在24 m跨声速风洞进气管路T型冲击三通连接处和隔板位置,每隔一定时间会出现裂纹,影响了风洞的安全稳定运行。为了解裂纹出现的原因,同时为改进设计提供依据,采用CFD(computational fluid dynamics)对风洞现有三通和优化方案进行了对比。控制方程为三维黏性不可压缩Navier-Stokes方程。结果表明：无隔板时,三通内的流动为最常见的类型,支管内存在3个分离区,在转向过程中形成第1分离区,即马蹄涡;随后是第2分离区,一对反向旋转的旋涡,即Dean涡,及三通顶部壁面形成第3分离区。流场沿y=0 mm和z=0 mm平面基本呈对称分布。有隔板时,流场的左右和上下结构均不对称;在隔板和外侧壁面间的角点形成范围较小的驻涡,在支管内形成不稳定的螺旋状分离涡,致使气流振荡,从而使得三通连接和隔板处管壁出现裂纹。根据上述流态设计了管路优化方案和整流装置,优化后能有效减小或消除分离;其中去掉隔板最简单易行,可以解决裂纹的问题。     

民用航空发动机型号审定概念设计阶段风险模型

为了在审定项目概念设计阶段识别潜在风险并规划处理措施以提高审定效率,通过综合条款分类统计、符合性方法及实施风险、技术要点解析等方法建立了典型民用航空发动机概念设计阶段工作模型,并开发了条款工作状态信息表。模型在某型民用航空发动机型号审定的实施识别了278项潜在风险,并针对典型结构完整性条款从要求确定到设计实现各个过程的潜在风险进行了详细分析,验证了模型的有效性。     

Water takeoff performance calculation method for amphibious aircraft based on digital virtual flight

Owing to the strong coupling among the hydrodynamic forces, aerodynamic forces and motion of amphibious aircraft during the water takeoff process, the water takeoff performance is difficult to calculate accurately and quickly. Based on an analysis of the dynamics and kinematics characteristics of amphibious aircraft and the hydrodynamic theory of high-speed planing hulls, a suitable mathematical model is established for calculating the hydrodynamics of aircraft during water takeoff. A pilot model is designed to illustrate how pilots are affected by the lack of visual reference and the necessity to simultaneously control the pitch angle, flight velocity and other parameters during water takeoff. Combined with the aerodynamic model, engine thrust model and aircraft motion model, a digital virtual flight simulation model is developed for amphibious aircraft during water takeoff, and a calculation method for the water takeoff performance of amphibious aircraft is proposed based on digital virtual flight. Typical performance indicators, such as the liftoff time and liftoff distance, can be obtained via digital virtual flight calculations. A comparison of the measured flight test data and the calculation results shows that the calculation error is less than 10%, which verifies the correctness and accuracy of the proposed method. This method can be used for the preliminary evaluation of airworthiness compliance of amphibious aircraft design schemes, and the relevant calculation results can also provide a theoretical reference for the formulation of flight test plans for airworthiness certification.     

Coactive design of explainable agent-based task planning and deep reinforcement learning for human-UAVs teamwork

Unmanned Aerial Vehicles (UAVs) are useful in dangerous and dynamic tasks such as search-and-rescue, forest surveillance, and anti-terrorist operations. These tasks can be solved better through the collaboration of multiple UAVs under human supervision. However, it is still difficult for human to monitor, understand, predict and control the behaviors of the UAVs due to the task complexity as well as the black-box machine learning and planning algorithms being used. In this paper, the coactive design method is adopted to analyze the cognitive capabilities required for the tasks and design the interdependencies among the heterogeneous teammates of UAVs or human for coherent collaboration. Then, an agent-based task planner is proposed to automatically decompose a complex task into a sequence of explainable subtasks under constrains of resources, execution time, social rules and costs. Besides, a deep reinforcement learning approach is designed for the UAVs to learn optimal policies of a flocking behavior and a path planner that are easy for the human operator to understand and control. Finally, a mixed-initiative action selection mechanism is used to evaluate the learned policies as well as the human’s decisions. Experimental results demonstrate the effectiveness of the proposed methods.     

转子系统挤压油膜阻尼器设计与动力特性

鉴于挤压油膜阻尼器(SFD)设计必须要同时考虑转子系统的动力学特性,提出了一种转子系统与挤压油膜阻尼器耦合设计方法,给出了详细的设计流程。对所设计的阻尼器进行了CFD数值模拟、油膜压力测量以及减振效果实验,结果证明所提出的设计方法是有效的。相比未采用阻尼器,采用阻尼器后转子系统两个转盘的振幅分别下降了46%和39%。通过实验还研究了不平衡量、支承刚度、供油压力和滑油温度对挤压油膜阻尼器减振效果的影响。结果表明,相比于不平衡量和支承刚度对减振效果的影响,供油压力和滑油温度的影响并不显著。进行挤压油膜阻尼器设计时,重点应该关注转子上的不平衡量大小和支承刚度。     

基于VALOR NPI的航空电子模块DFM分析实现

为有效解决设计缺陷造成的航空电子模块可制造性问题,结合航空电子模块产品特点和工艺技术水平,提出建设基于VALOR的航空电子模块可制造性设计自动化设计平台,实现DFM自动化分析与设计,阐述了DFM设计的必要性、技术原理和实现过程,提出了“三库”构建方法和基于物料清单的印制电路板数据分析方法,应用结果表明,提出的方法能够覆盖PCB可制造性问题,提高分析效率。     

基于任务场景分析的机载导航页面人机界面设计过程研究

顶层飞行任务场景是民机机载显示系统需求捕获的重要来源,显示系统的人机界面设计通过自顶向 下的飞行任务场景分析,识别显示信息内容,开展信息内容设计,继而开展样式设计、交互行为设计与接口设 计等工作。本文以导航页面为例,综合运用层次任务分析和场景用例分析法,阐述了机载显示系统人机界面的 设计约束和过程,可为民机机载显示系统人机界面的正向设计过程提供借鉴。 [ 关键词] 机载显示系统;导航页面;任务场景;人机界面设计     

航空发动机高原起动性能改善措施

为了解决航空发动机高原起动超温和转速悬挂等问题,以某型航空发动机起动过程为研究对象,根据高原环境对发动机起动过程的影响进行理论分析,提出了优化高原起动措施,并进行了高原试验验证,摸索出各措施对起动过程的影响程度。结果表明:在发动机起动过程中采用飞机卸载的方式可使排气温度降低3%,起动机脱开转速提高3%;起动机功率提高约1%,点火转速及脱开转速提高约2%,起动时间缩短约8%。     

大涵道比涡扇发动机风扇/ 增压级试验件结构 设计及验证

某大涵道比风扇/增压级试验件为1级风扇加3级增压级结构,为实现风扇/增压级部件特性录取,结构设计在满足气动设计要求的基础上,重点考虑了合理性和可靠性问题,采用理论结合工程经验的方法完成了转子支撑、静子连接和轴承润滑及密封等难点设计,兼顾大涵道比风扇/增压级结构及气动特点,采用宽弦风扇叶片设计、榫头/榫槽圆弧榫连及装配式风扇转子流路板结构。顺利完成试验件研制工作,经试验验证,压比、效率等性能参数达到或超过设计指标。     

面向军用飞机任务能力的健康评估方法

军用飞机健康评估在工程实际中存在应用困难的问题。以军用飞机为研究对象,开展包括面向任务 的能力分析、基于故障劣化的功能分析以及参数化的健康评估等研究,得到基于任务分析的“飞机-任务功 能-影响参数暠两级映射作为健康评估的对象;综合利用劣化度、严酷度及极大熵改进区间层次分析法等多种 方法,得到飞机健康状态评估结果。结合具体实例及参数分析结果,表明该评估方法可信度高,具有较高的工 程实用价值。