【作者】 陈亮中；

【导师】 邓小刚；

【作者基本信息】 中国空气动力研究与发展中心 ， 流体力学， 2009， 博士

【摘要】 先进战斗机要求在大攻角时具有过失速机动飞行性能,其中向上快速拉升和俯仰运动是实现战术机动的两个典型动作。为了协调不同速度范围对机翼平面形状的需求,现代战斗机设计通常采用三角翼/双三角翼或者类似外形的机翼布局。因此,开展对三角翼/双三角翼静止时的大攻角分离流场和俯仰运动时的动态流场中非线性特性的研究、深入认识分离流场及其动态特性、全面掌握大攻角下的各种非定常流动现象及其产生机理是实现超机动飞行所必须的。本文的研究目的是发展适用于双三角翼大攻角非定常分离流场模拟的数值方法,围绕某一战斗机的两个简化外形,开展双三角翼静态时的流场特性随攻角的变化规律、快速拉升及俯仰振荡时的动态流场特性以及不同运动参数对动态流场结构及气动特性的影响规律等内容研究;围绕低速流动,开展了数值模拟方法的研究,发展了微可压缩模型,扩大了该模型的应用范围。全文共八章,各章主要内容概述如下:第一章简述了开展本文研究工作的意义;综述了对三角翼/双三角翼大攻角非定常分离流场和俯仰动态流场研究的现状和进展情况;简要地介绍了本文完成的主要工作。第二章系统地介绍本文中采用的数值方法,包括:控制方程、边界条件、空间离散格式、方程组求解、湍流模型、动网格生成技术、多重网格算法、并行计算和非定常气动力系数积分等几个内容。第三章通过对几个拥有丰富实验数据或理论结果的流场进行数值模拟研究,考核了基于第二章中的数值方法而开发的计算程序的空间计算精度和时间计算精度,重点考察了计算程序对三角翼和椭球等外形在大攻角下的非定常湍流分离流动的模拟精度。第四章数值研究了静态双三角翼在不同攻角下的流场特性,分析了背风区流场中分离涡系的空间分布特点和不同涡系之间的相互作用;给出了流场特性和气动力特性随攻角的变化规律;确定了不同流态存在的攻角区间;比较和分析了两个不同前翼平面形状的双三角翼流场结构和气动力性能的差异。第五章数值研究了双三角翼向上快速拉升时的动态流场特性,给出了动态流场结构和气动力性能随攻角的变化规律;重点研究了减缩频率、起始攻角和转轴位置等运动参数对动态流场特性的影响,并初步分析了这些运动参数对动态流场施加影响的物理机制;比较和分析了两个不同前翼平面形状的双三角翼动态气动力性能的差异。第六章数值研究了双三角翼俯仰振荡时的动态流场特性,给出了动态流场结构和气动力性能随攻角的变化规律;重点研究了减缩频率、转轴位置、平均攻角和振幅等参数对动态流场迟滞效应和气动力曲线迟滞环的影响;比较和分析了两个不同前翼平面形状的双三角翼动态气动力性能的差异。第七章开展了对微可压缩模型的研究,深入分析了几种方程处理形式的优缺点;在原始SCM模型的基础上将求解压力变量本身改为求解压力改变量,降低了计算机截断误差的影响;并引入多重网格算法和并行计算技术,实现了计算过程的加速;初步地将SCM模型应用于大攻角分离流场的数值模拟研究。第八章是结束语,总结了全文的工作,并对今后的研究方向提出了一些想法。最后是本文的致谢和参考文献。更多还原

【Abstract】 Advanced combat aircrafts are in increasing requirement to have higher maneuvering performance at high angles of attack beyond post-stall conditions. In the process of maneuverability, rapidly pitch-up and pitching motions are typical. In order to meet the requirements in the wide range of flight speeds, delta /double-delta or similar wing layouts are commonly adopted in the design of the modern aircrafts. In order to achieving super-maneuverability, it is necessary to study the nonlinear phenomena in the separation flow field when the wings are in either static or pitch-motion state to find out the characteristics of the separation flow, and to observe the unsteady phenomena and their correlative mechanism comprehensively.The first objective in this thesis is to develop some numerical methods that are suitable for simulating the unsteady separation flows around two double-delta wings at high angles of attack and to study the evolution laws of the flow characteristics when the wings are in static or pitch-motion states and the influence of different motion parameters on the characteristics of the unsteady flows. The second is to study the numerical methods used to simulate the low-speed flows and to develop the Slightly Compressible Model (SCM) aiming at widening the application areas.This thesis is divided into eight chapters as follows:In the first chapter, the significance of the present research work is briefly introduced. The status in quo and the progress of the researches in the flow fields around delta wing/double-delta wing are reviewed. The innovation works in this thesis are then described in brief.In the second chapter, the numerical methods applied in this thesis are presented in detail. The main contents include: governing equations, boundary conditions, numerical flux schemes, time-marching methods, turbulence models, moving grid generation techniques, multi-grid methods, parallel computing techniques and unsteady aerodynamic force integration formulas.In the third chapter, several flows with abundant experimental data or academic results are numerically simulated. In these research works, the spatial and the temporal precisions are examined to validate the reliability of the program based on the numerical methods introduced in Chap.2. The emphases are placed on the numerical results of the calculated flows around a delta wing and a spheroid at high angles of attack.In the fourth chapter, the flow characteristics around a static double-delta wing at different angles of attack are investigated thoroughly. The characteristics of the spatial distribution of the vortex system in the leeward side of the wing and the correlations among these different vertical flows are analyzed. The evolvement laws of the characteristics of the flows and their aerodynamics are revealed. The ranges of the angles of attack existing different flow types are confirmed. The differences in the flow structure and the aerodynamics performance between two types of double-delta wings are compared and analyzed.In the fifth chapter, the dynamic characteristics of the flow fields around a double-delta wing during pitch-up motion are researched by numerical methods. The evolvement laws of the dynamic flow fields and its aerodynamics performances following the change of the angles of attack are presented. The studies are concentrated on the investigations of the influences of some motion parameters (such as reduced frequency, the initiative angle of attack and the position of rotation axis) on the dynamic flow performance and the investigations of the physical mechanism producing these influences. In this chapter the aerodynamics performances between two double-delta wings with different wing plane shapes are compared.In the sixth chapter, the dynamic characteristics of the flow fields around a double-delta wing during pitching motion are researched. The evolvement laws of the dynamic flow fields and the aerodynamic performances following the change of the angles of attack are presented. The studies are concentrated on the investigation of the influences of some motion parameters (such as reduced frequency, the averaged angle of attack, position of rotation axis and the pitching amplitude) on the time-lag effects of the dynamic flow field and the hysteresis-loops of the aerodynamic coefficients. In this chapter the difference of the aerodynamics performances between two double-delta wings with different wing plane shapes are given.In the seventh chapter, the Slightly Compressible Model is developed and used. First, some former equation types of the SCM model are reviewed. The merits and the drawbacks of the equations are analyzed theoretically. Then, the calculation of pressure in the original SCM equations is replaced by the calculation of the dispersion of the pressure in this thesis. So the truncation error of the computer is reduced. The multi-grid methods and parallel computing techniques are also applied in this SCM model to accelerate the computing speed. In the last section of this chapter, some unsteady separation flows around a delta wing at high angle of attack are simulated by the SCM model.In the eighth chapter, all the works in this thesis are reviewed, and the innovation and the shortages are also described. Moreover, some considerations on the further research work in this area are listed.Finally, the acknowledgements and references are presented.更多还原