Aeroacoustic and aerodynamic optimization of propeller blades

It is of great significance to develop a high-efficiency and low-noise propeller optimization method for new-generation propeller aircraft design. Coupled with free form deformation method, dynamic mesh interpolation technology, optimization algorithm, surrogate model, aerodynamic calculation and aeroacoustic prediction model module, the integrated aerodynamic and aeroacoustic design method of propeller is built. The optimization design for the six-blade propeller is carried out. The non-reduction in efficiency, thrust coefficient and the minimum of aerodynamic noise is treated as the optimization design objective. The spatial vorticity distribution of the propeller before and after the design is also analyzed by using unsteady computational fluid dynamics method. The results show that the optimized propeller can effectively reduce the aerodynamic noise level. The maximum total sound pressure level can be reduced by 5 dB without reducing its aerodynamic performance. The developed method has good application potential in low-noise optimization design of propeller and other rotating machinery.     

基于CPS的特殊阵列式元件配装

随着某些特殊阵列式器件精度要求的提高,其中单个元件的细小差异将对阵列整体性能带来极大的影响,使元件安装时不再具有互换性,因此需针对元件具体参数信息调整阵列分布.传统的生产方式,需通过手册查阅零件信息,不断的调试、组装,其过程过度依赖工人经验,错误率高,难以实现最优化配装.为此,提出了一种基于赛博物理系统(Cyber-Physical Systems,CPS)的阵列式器件配装辅助系统,将物理空间与信息空间相融合,使阵列式器件配装更加自动化和智能化,极大地提高了安装效率,降低了错误率.     

Optimization and design of an aircraft's morphing wing-tip demonstrator for drag reduction at low speeds,Part Ⅱ-Experimental validation using Infra-Red transition measurement from Wind Tunnel tests

In the present paper, an ‘in-house' genetic algorithm was numerically and experimentally validated. The genetic algorithm was applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The optimization was performed for 16 flight cases expressed in terms of various combinations of speeds, angles of attack and aileron deflections. The displacements resulted from the optimization were used during the wind tunnel tests of the wing tip demonstrator for the actuators control to change the upper surface shape of the wing. The results of the optimization of the flow behavior for the airfoil morphing upper-surface problem were validated with wind tunnel experimental transition results obtained with infra-red Thermography on the wing-tip demonstrator. The validation proved that the 2D numerical optimization using the ‘in-house' genetic algorithm was an appropriate tool in improving various aspects of a wing's aerodynamic performances.     

Two-phase framework for near-optimal multi-target Lambert rendezvous

This paper proposes a two-phase framework to obtain a near-optimal solution of multi-target Lambert rendezvous problem. The objective of the problem is to determine the minimum-cost rendezvous sequence and trajectories to visit a given set of targets within a maximum mission duration. The first phase solves a series of single-target rendezvous problems for all departure-arrival object pairs to generate the elementary solutions, which provides candidate rendezvous trajectories. The second phase formulates a variant of traveling salesman problem (TSP) using the elementary solutions prepared in the first phase and determines the final rendezvous sequence and trajectories of the multi-target rendezvous problem. The validity of the proposed optimization framework is demonstrated through an asteroid exploration case study.     

An optimal beam alignment method for large-scale distributed space surveillance radar system

Large-scale distributed space surveillance radar is a very important ground-based equipment to maintain a complete catalogue for Low Earth Orbit (LEO) space debris. However, due to the thousands of kilometers distance between each sites of the distributed radar system, how to optimally implement the Transmitting/Receiving (T/R) beams alignment in a great space using the narrow beam, which proposed a special and considerable technical challenge in the space surveillance area. According to the common coordinate transformation model and the radar beam space model, we presented a two dimensional projection algorithm for T/R beam using the direction angles, which could visually describe and assess the beam alignment performance. Subsequently, the optimal mathematical models for the orientation angle of the antenna array, the site location and the T/R beam coverage are constructed, and also the beam alignment parameters are precisely solved. At last, we conducted the optimal beam alignment experiments base on the site parameters of Air Force Space Surveillance System (AFSSS). The simulation results demonstrate the correctness and effectiveness of our novel method, which can significantly stimulate the construction for the LEO space debris surveillance equipment.     

基于粒子群算法的导弹PID控制参数选择

PID控制在导弹控制系统的设计中得到了较多的应用,但PID控制器的性能依赖于其参数的整定和优化。利用粒子群算法对控制器的参数进行优化,并对俯仰通道控制系统进行了仿真研究,结果表明,攻角和俯仰角速度都取得了较好的效果,当气动参数具有不确定性时,效果依然较好,验证了方法的有效性。     

A numerical optimization of high altitude testing facility for wind tunnel experiments

High altitude test facilities are required to test the high area ratio nozzles operating at the upper stages of rocket in the nozzle full flow conditions.It is typically achieved by creating the ambient pressure equal or less than the nozzle exit pressure.On average,air/GN2is used as active gas for ejector system that is stored in the high pressure cylinders.The wind tunnel facilities are used for conducting aerodynamic simulation experiments at/under various flow velocities and operating conditions.However,constructing both of these facilities require more laboratory space and expensive instruments.Because of this demerit,a novel scheme is implemented for conducting wind tunnel experiments by using the existing infrastructure available in the high altitude testing(HAT)facility.This article presents the details about the methods implemented for suitably modifying the sub-scale HAT facility to conduct wind tunnel experiments.Hence,the design of nozzle for required area ratio A/A*,realization of test section and the optimized configuration are focused in the present analysis.Specific insights into various rocket models including high thrust cryogenic engines and their holding mechanisms to conduct wind tunnel experiments in the HAT facility are analyzed.A detailed CFD analysis is done to propose this conversion without affecting the existing functional requirements of the HAT facility.     

一种兼顾卫星导航系统星间观测及通信的链路分配算法

卫星导航系统星间采用点波束建立星间链路时,由于星上波束数量小于可建立星间链路的卫星数量,因此便产生了如何有效分配有限波束来建立星间链路的问题。针对该问题首先利用星座运行的周期性提出了一种适用于星间观测及星间通信的拓扑处理方式,并以该拓扑处理方式为基础提出了一种链路分配算法。算法在保证星间观测数量最大化的前提下,以降低整网通信代价为优化目标,尽管为了保证星间观测数量会不可避免地导致通信性能的部分损失,但是仿真结果表明算法的性能整体上优于铱星系统所采用的网状链路分配方法的性能。     

排队论在高速公路收费系统中的应用

目的 排队论在高速公路收费系统中的应用；方法 建立比较合理的数学模型，最后对模型进行优化以达到更理想的效果；结果 通过对模型的优化设计，确定收费亭的数目，使得在成本一定的情况下，车辆排队等待的时间尽可能的短；结论 排队论在高速公路收费系统优化设计中具有实际用途。