飞机减速板模拟气动力加载控制系统的设计与实现

介绍了气动力加载系统的特点,然后给出了跟踪微分器和加载控制算法的设计与实现,并给出系统软、硬件结构。最后针对某机减速板系统,给出了其仿真与试验的结果,表明该算法具有结构简单、易于实现、可靠性高等特点。     

Improved fixed point iterative method for blade element momentum computations

The blade element momentum (BEM) theory is widely used in aerodynamic performance calculations and optimization applications for wind turbines. The fixed point iterative method is the most commonly utilized technique to solve the BEM equations. However, this method sometimes does not converge to the physical solution, especially for the locations near the blade tip and root where the failure rate of the iterative method is high. The stability and accuracy of aerodynamic calculations and optimizations are greatly reduced due to this problem. The intrinsic mechanisms leading to convergence problems are addressed through both theoretical analysis and numerical tests. A term from the BEM equations equals to zero at a critical inflow angle is the source of the convergence problems. When the initial inflow angle is set larger than the critical inflow angle and the relaxation methodology is adopted, the convergence ability of the iterative method will be greatly enhanced. Numerical tests have been performed under different combinations of local tip speed ratio, local solidity, local twist and airfoil aerodynamic data. Results show that the simple iterative methods have a good convergence ability which will improve the aerodynamic or structural design of wind turbines. Copyright © 2017 John Wiley & Sons, Ltd.     

An inverse method for transonic wing design

A fast, efficient and reliable code for wing design has been developed at INTA coupling a residual‐correction method by Bauer, McFadden and Garabedian to an inviscid solver for wing analysis in transonic flow. Smoothing procedures, including Bèzier cubic splines, are used to avoid irregularities of the wing surface, as well as the twist distribution. A modified version of FLO22 code is used as the flow solver. The original code has been adapted to improve its accuracy. Some results are presented, showing the reliability of the code. The redesign of a wing in transonic flow—which was used as test case in LARA project of BRITE‐EURAM II during 1993–94—is presented with promising results. Copyright © 1999 John Wiley & Sons, Ltd.     

Downstroke and upstroke conflict during banked turns in butterflies

For all flyers, aeroplanes or animals, making banked turns involve a rolling motion which, due to higher induced drag on the outer than the inner wing, results in a yawing torque opposite to the turn. This adverse yaw torque can be counteracted using a tail, but how animals that lack tail, e.g. all insects, handle this problem is not fully understood. Here, we quantify the performance of turning take-off flights in butterflies and find that they use force vectoring during banked turns without fully compensating for adverse yaw. This lowers their turning performance, increasing turn radius, since thrust becomes misaligned with the flight path. The separation of function between downstroke (lift production) and upstroke (thrust production) in our butterflies, in combination with a more pronounced adverse yaw during the upstroke increases the misalignment of the thrust. This may be a cost the butterflies pay for the efficient thrust-generating upstroke clap, but also other insects fail to rectify adverse yaw during escape manoeuvres, suggesting a general feature in functionally two-winged insect flight. When lacking tail and left with costly approaches to counteract adverse yaw, costs of flying with adverse yaw may be outweighed by the benefits of maintaining thrust and flight speed.     

基于空气动力学的浮游菌采样器采集物理效率检测方法的研究

基于空气动力学原理,提出了一种针对浮游菌采样器采集物理效率的新型检测方法,并搭建了检测装置,可以得到连续的采样效率曲线,直观获取不同动力学粒径对应的采集物理效率。分别评价了2款国产及1款进口的浮游菌采样器采集物理效率,结果发现国产采样器采样效率不及进口品牌,质量还有待提升。研究了多分散的亚利桑那超细试验粉尘与单分散颗粒物标物检测结果的差异,发现国产采样器的差异大于进口采样器。所提检测方法有助于提高浮游菌采样器采集物理效率检测的准确性、科学性及检测效率。     

扑翼飞行的气动建模与仿真分析

用计算流体力学的数值仿真方法对微扑翼飞行的非定常空气动力学问题进行了建模与仿真研究。在对昆虫扑翼飞行运动的仿生模拟基础上,建立了简化的扑翼运动二维翼型的运动学与空气动力学模型。利用任意拉格朗日欧拉（ALE）有限元方法求解出N-S方程的数值解,将流场仿真结果与实验进行了对比,并分析了扑翼运动产生的前缘漩涡对升力的作用。文中的建模、分析方法和结论对微扑翼飞行器的分析设计和应用提供了一定的理论依据。     

系留多旋翼无人机模拟训练系统设计与实现

为满足操作手对系留多旋翼无人机及其搭载任务载荷操作的模拟训练需求,对系留多旋翼无人机模拟训练系统进行设计与实现。该系统由飞行模拟计算机系统、便携式操控终端模拟器和教官导控台构成,提出基于系留线缆的系留多旋翼无人机及其空气动力学、飞行场景、想定战场环境及场景目标等模拟仿真模型。从系统架构优化、通信链路协议、实装设备原位替代等方面进行设计实现。结果表明：该系统结构完整、安全性好,配置精简、灵活、方便,成本低,适用于野战训练。     

轴流式压气机_逆流_的气动力学机理探讨

本文叙述了“逆流”的概念。对轴流压气机逆流工况下通流部分内部的气体动力学机理作了初步的探讨,并试图解释在“逆流”时造成压气机严重破坏的原因。     

高精度迎风格式的射弹粘性绕流场数值模拟

应用四阶的NUSCL TVD格式,求解雷诺平均的N－S方程,对超音速射流与弹体绕流流场和弧形翼的空气动力特性进行了数值模拟研究,计算结果与实验对比表明,该方法可以获得高分辨率的流场结构。     

级间分离气动力特性数值研究

对超声速飞行弹体级间分离过程中的流场开展了数值模拟研究,得到了两级弹体在不同分离状态下的气动特性.计算中采用分区多块网格技术,并对计算所得的气动力结果进行摩擦阻力修正.根据计算结果,分析了主级通气和非通气两种状态下的流场结构和气动力变化特性;研究了弹体气动力随马赫数的变化规律.