应用流固耦合数值方法研究机翼的射流减振技术

采用流固耦合的数值计算方法研究了NACA 0 0 15翼型在大迎角 ( 15°～ 6 0°)范围的颤振 ,以及在翼型背部部分引入射流的减振技术。在流体区域用高精度、高分辨率算法求解Farve平均的Navier Stokes方程 ,在固体区域用四阶Runge Kutta法求解振动方程 ,并且每一个时间步后都在两个区域之间传递边界条件。计算结果表明在翼型背部引入适当射流会降低翼型的振动 ,并提高升力。但如果引入射流的速度过高 ,会在叶背处形成新的分离流 ,升力反而会下降     

某型飞机同时存在两种惯性耦合问题的探讨

根据稳定性理论，对某型高速飞机的惯性耦合进行初步研究，首先，对飞机的滚转－偏航耦合－俯仰耦合的机理进行分析，然后，在不影响问题本质的前提下提出了一些假设条件，将研究惯性耦合的六自由度全量方程进行简化，求出急滚稳定性判据，以某型机为例，计算出其惯性耦合特性，用急滚稳定性判据进行了分析，并进行了验证 。     

舰载飞机自动着舰系统的研究

介绍了舰载飞机的自动着舰系统（包括了飞机的飞行控制系统，推力控制系统及航空母舰的导引系统），并指出只有精确地控制飞机的不滑轨迹，才能使飞机在航空母舰上安全降落，本文着得讨论俯仰指令型的纵向自动着舰系统的原理、结构及设计，并指出导引指令中对舰体运动的补偿。     

Hybrid integration method for highly maneuvering radar target detection based on a Markov motion model

To detect highly maneuvering radar targets in low signal-to-noise ratio conditions, a hybrid long-time integration method is proposed, which combines Radon-Fourier Transform (RFT), Dynamic Programming (DP), and Binary Integration (BI), named RFT-DP-BI. A Markov model with unified range-velocity quantification is formulated to describe the maneuvering target’s motion. Based on this model, long-time hybrid integration is performed. Firstly, the whole integration time is divided into multiple time segments and coherent integration is performed in each segment via RFT. Secondly, non-coherent integration is performed in all segments via DP. Thirdly, 2/4 binary integration is performed to further improve the detection performance. Finally, the detection results are exported together with target range and velocity trajectories. The proposed method can perform the long-time integration of highly maneuvering targets with arbitrary forms of motion. Additionally, it has a low computational cost that is linear to the integration time. Both simulated and real radar data demonstrate that it offers good detection and estimation performances.     

A coupling VWM/CFD/CSD method for rotor airload prediction

A coupling fluid-structure method with a combination of viscous wake model(VWM),computational fluid dynamics(CFD) and comprehensive structural dynamics(CSD) modules is developed in this paper for rotor unsteady airload prediction. The hybrid VWM/CFD solver is employed to model the nonlinear aerodynamic phenomena and complicated rotor wake dynamics;the moderate deflection beam theory is implemented to predict the blade structural deformation; the loose coupling strategy based on the ‘delt method' is used to couple the fluid and structure solvers.Several cases of Helishape 7A rotor are performed first to investigate the effect of elastic deformation on airloads. Then, two challenging forward flight conditions of UH-60 A helicopter rotor are investigated, and the simulated results of wake geometry, chordwise pressure distribution and sectional normal force show excellent agreement with available test data; a comparison with traditional CFD/CSD method is also presented to illustrate the efficiency of the developed method.     

Effects of process parameters on mechanical properties of abrasive-assisted electroformed nickel

A cathode mandrel with translational and rotational motion, which was supposed to obtain uniform friction effect on surface, was employed in abrasive-assisted electroforming for revolving parts with complex profile. The effects of current density, translational speed and rotational speed on the deposit properties were studied by orthogonal test. The tensile strength, elongation and micro hardness value were measured to find out how the factors affected the properties. The optimized results show that changes of current density affect the tensile strength of nickel layer most, while translational speed has the most remarkable influences on both elonga-tion and micro hardness. The low rotational speed affects the properties least. In this experiment, a smooth nickel layer with tensile strength 581 MPa, elongation 17%and micro hardness 248HV is obtained by the orthogonal test.     

低速大转矩永磁游标电机在发酵罐中的应用

采用秸秆生产丁醇时,为了达到高效率发酵,需要使发酵液中菌体分布均匀,所加物料需要及时搅拌。工业化生产丁醇的发酵罐尺寸较大,搅拌过程对驱动电机的输出转矩要求较高,因此高效率、小体积、低速大转矩的秸秆发酵搅拌电机对工业化发酵生产丁醇意义重大。设计了一种定转子永磁游标电机用于发酵液搅拌,并对电机的槽极数、电磁性能进行了具体的研究。制造样机并采用滞环控制实现了对液态发酵对象的快速响应,且实现了低能耗、高效率的发酵过程。     

叶片反扭对跨声速大涵道比风扇性能的影响

使用基于流固耦合算法的叶片反扭程序,考虑了非定常气动力对叶片变形的非线性作用,研究了叶片反扭对跨声速大涵道比风扇性能的影响.以冷态叶型为起点,先计算离心力作用下的叶片变形,在此基础上使用流固耦合程序获得非定常气动力作用下的变形.考察了3个转速下叶片的动态变形对大涵道比风扇气动性能的影响.结果表明:在跨声速工况下,叶片表面激波位置的变化对叶片反扭角有很大作用,在考察的转速范围内,堵塞点使用设计叶型计算的流量大于动态叶型下的流量,数值达7%,将导致发动机起飞推力小于预测值.结果表明在大涵道比风扇设计阶段,预测气动性能使用准确叶型的重要性.      

整体弹性结构法及在叶片流固耦合分析中的应用

针对三维叶片时域流固耦合振动响应计算普遍耗时的问题,采用一种假设整体结构的模态位移,求解固体时域响应和实现高效网格变形,发展了一种3维时域流固耦合分析的整体弹性结构方法,并应用于压气机叶片0°和180°相位角的气动稳定性分析中。结果表明,所发展方法的计算结果与传统双向时域算法和文献的结果较为吻合,而计算效率相比于传统算法显著提升;在所分析的两个相位角下,叶片振动的气动阻尼均随流量减小先增大后降低,相比于0°相位角,180°下叶片的气动稳定性大幅提高,表明该方法能有效应用于叶片的工程流固耦合研究。