Extension of analytical indicial aerodynamics to generic trapezoidal wings in subsonic flow

Analytical indicial aerodynamic functions are calculated for several trapezoidal wings in subsonic flow, with a Mach number 0.3 Ma 0.7. The formulation herein proposed extends wellknown aerodynamic theories, which are limited to thin aerofoils in incompressible flow, to generic trapezoidal wing planforms. Firstly, a thorough study is executed to assess the accuracy and limitation of analytical predictions, using unsteady results from two state-of-the-art computational fluid dynamics solvers as cross-validated benchmarks. Indicial functions are calculated for a step change in the angle of attack and for a sharp-edge gust, each for four wing configurations and three Mach numbers. Then, analytical and computational indicial responses are used to predict dynamic derivatives and the maximum lift coefficient following an encounter with a one-minus-cosine gust. It is found that the analytical results are in excellent agreement with the computational results for all test cases. In particular, the deviation of the analytical results from the computational results is within the scatter or uncertainty in the data arising from using two computational fluid dynamics solvers. This indicates the usefulness of the developed analytical theories.     

大型水陆两栖飞机特殊任务模式对总体设计的挑战

面向森林灭火和水上救援任务设计的大型水陆两栖飞机，由于其特殊的任务模式，给设计工作带来了许多全新的挑战。首先，分析了国内森林灭火和水上救援的需求，并介绍了对应的任务模式。然后，总结了在型号研制过程中不同于常规飞机的特殊设计和相应的解决方法，具体包括：以国内供应商为主体的构型管理体系的建立、气水动一体化设计、全新的起落架布局设计、任务系统集成和效能评估、驾驶舱集成设计、设备布置和腐蚀防护设计。最后，提出了在适航审定和集成应用方面仍需重点关注的4个研究方向。     

二进制乘法器的面—时平方复杂性研究

讨论了n位二进制整数乘法下界面－时平方复杂性问题，给出了一种树型布局的乘法器网络模型，并分析了它的AT~2复杂性     

纵向尾流间隔计算方法研究

综合考虑了飞机的速度、翼展、机翼面积、发动机推力等参数,应用空气动力学中的环量计算理论、尾流消散原理等,将动量定理和涡阻力的计算原理应用到尾流间隔的计算,分别建立了纵向尾流间隔计算模型。采用实际数据计算验证模型的正确性。     

飞行器空气动力特性的综合评估方法研究

空气动力评估是对飞行器进行全过程、全系统试验与鉴定的重要内容.依据层次分析原理,可分层、分类对飞行器的空气动力特性进行综合评估.采用专家调查法,获得专家个体对评估因素、评估因素的权重、以及评估结果等级与档次的意见;采用综合评估方法综合各专家个体的意见,获得对飞行器空气动力特性综合评估的定性结论和定量结果.     

Flight dynamics modeling of a small ducted fan aerial vehicle based on parameter identifcation

This paper presents a simple and useful modeling method to acquire a dynamics model of an aerial vehicle containing unknown parameters using mechanism modeling,and then to design different identifcation experiments to identify the parameters based on the sources and features of its unknown parameters.Based on the mathematical model of the aerial vehicle acquired by modeling and identifcation,a design for the structural parameters of the attitude control system is carried out,and the results of the attitude control flaps are verifed by simulation experiments and flight tests of the aerial vehicle.Results of the mathematical simulation and flight tests show that the mathematical model acquired using parameter identifcation is comparatively accurate and of clear mechanics,and can be used as the reference and basis for the structural design.     

过失速非定常空气动力实验技术

本文介绍了南航３米低速风洞中用于模拟过失速飞行的电控液压动态实验台、数据采集和处理等问题。该实验台可以较真实地模拟过失速飞行时迎角的变化规律，迎角可在０°～９０°内任意变化。数据处理时要注意到由于来流风速的滞后而产生的速度变化。     

Numerical investigation on jet interaction with a compression ramp

A numerical investigation on jet interaction in supersonic laminar flow with a compres- sion ramp is performed utilizing the AUSMDV scheme and a parallel solver. Several parameters dominating the interference flowfield are studied after defining the relative increment of normal force and the jet amplification factor as the evaluation criterion of jet control performance. The computational results show that most features of the interaction flowfield between the transverse jet and the ramp are similar to those between a jet and a flat plate, except that the flow structures are more complicated and the low-pressure region behind the jet is less extensive. The relative force increment and the jet amplification factor both increase with the distance between the jet and the ramp shortening till quintuple jet diameters. Inconspicuous difference is observed between the jet-before-ramp and jet-on-ramp cases. The variation of the injection angle changes the extent of the separation region, the plateau pressure, and the peak pressure near the jet. In the present computational conditions, 120 is indicated relatively optimal among all the injection angles studied. For cold gas simulations, although little influence of the jet temperature on the pressure distribution near the jet is observed under the computation model and the flow parameters studied, reducing jet temperature somehow benefits the improvement of the normal force and the jet efficiency. When the pressure ratio of jet to freestream is fixed, the relative force increment varies little when increasing the freestream Mach number, while the jet amplification factor increases.     

A 3D hybrid grid generation technique and a multigrid/parallel algorithm based on anisotropic agglomeration approach

A hybrid grid generation technique and a multigrid/parallel algorithm are presented in this paper for turbulence flow simulations over three-dimensional (3D) complex geometries. The hybrid grid generation technique is based on an agglomeration method of anisotropic tetrahedrons. Firstly, the complex computational domain is covered by pure tetrahedral grids, in which anisotropic tetrahedrons are adopted to discrete the boundary layer and isotropic tetrahedrons in the outer field. Then, the anisotropic tetrahedrons in the boundary layer are agglomerated to generate prismatic grids. The agglomeration method can improve the grid quality in boundary layer and reduce the grid quantity to enhance the numerical accuracy and efficiency. In order to accelerate the convergence history, a multigrid/parallel algorithm is developed also based on anisotropic agglomeration approach. The numerical results demonstrate the excellent accelerating capability of this multigrid method.