共查询到20条相似文献，搜索用时 164 毫秒
1.
基于Fluent的多翼型低速气动特性比较 总被引：1，自引：0，他引：1
利用计算流体力学软件Fluent对较适用于小型无人机的NACA0009、NACA6409、NACA64A010三种翼型进行了二维外部流场的数值模拟,采用Spalart-Allmaras计算模型求解几种翼型在不同攻角、不同雷诺数下的速度、压力分布,进而对不同翼型在不同攻角下的气动特性进行研究,为小型无人机的设计提供一定的理论依据. 相似文献
2.
3.
基于多重网格方法的思想,在二维非结构网格上建立了一种求解Euler方程的快速稳健间断Galerkin方法。采用Roe迎风型数值通量,时间步采用显式Runge-Kutta多步法推进。数值模拟了绕NACA0012翼型流场,并比较了单重网格算法和多重网格算法计算结果,表明该方法具有优良的加速收敛效果。 相似文献
4.
利用数值计算的方法对涡轮流量计内的三维湍流流动进行建模和基于N—S方程的仿真分析。数值计算采用k-ε模型来模拟湍流流动,得到涡轮流量计的内部流场三维流动形态,并分析其内部的流动规律、流速和压力分布;以三维湍流仿真的仿真结果为依据,对前导流器进行了优化。结果表明：流线型前导流器能降低整个流量计的压损。 相似文献
5.
《实验室研究与探索》2017,(8):129-132
覆冰对风力发电机叶片会造成一定的伤害,为了研究覆冰对风力发电机叶片气动性能的影响,使用κ-ε紊流模型对NACA 23012翼型进行了仿真分析,着重分析了在40°攻角情况下翼型覆冰前后的气动性能,发现该翼型在仿真条件下升力明显减小、阻力增大,升阻比由覆冰前的1.594下降到了覆冰后的0.7,机翼附近的压强云图显示翼型上表面已形成了涡流区域,说明空气动力性能发生恶化,翼型产生了失速现象。同时对比了覆冰前后翼型附近的压强、空气速度,仿真结果表明覆冰的存在是翼型周围的空气压强、速度场畸变得更严重。 相似文献
6.
曹利刚 《杨凌职业技术学院学报》2023,(3):12-15
NACA63-215在小角度攻角时的气动模拟结果与实验数据基本相同,通过对襟翼DOE的多组数值模拟实验数据和翼型下方的压力分布模拟图形分析得知,数值模拟的方法为翼型的气动性能优化提供了理论支持。 相似文献
7.
二维HM方程解的衰减 总被引：1，自引：0，他引：1
陈静 《楚雄师范学院学报》2012,27(3):44-50
Hasegawa-Mima(简记为HM)方程是研究漂移波和湍流漂移波的模型。本文运用"Fourier-Splitting"技术得到了二维HM方程初始问题解的L2衰减估计和L∞衰减估计。 相似文献
8.
翼型是机翼等气动部件的二维截面,对于机翼乃至飞行器全机的气动性能都有着重要影响,所以翼型研究是先进飞行器设计的基础和重点。翼型风洞是进行翼型实验的最适用风洞,在翼型研究中发挥着不可替代的作用,但由于其专用性,目前关于翼型风洞设计的公开成果并不多见。基于翼型实验的参数要求,综合运用空气动力学知识,确定了一种吸气式二元翼型风洞的气动设计方案。设计的翼型风洞包括动力段、扩压段、实验段、收缩段和稳定段等洞体,并配有阻尼网、蜂窝器等内部整流装置。经过计算和分析,结果表明此风洞具有结构紧凑、湍流度低、能量利用率高的优势,可以较好完成翼型实验,推动飞行器技术发展。 相似文献
9.
为分析水翼绕流速度对非稳态空化现象的影响规律以及水翼空化过程演变机理，对NACA6408水翼空化过程进行了三维数值模拟计算，研究了不同绕流速度工况下水翼不同位置的压力、湍动能、速度等参数的变化规律，分析空化现象的周期性发展过程。结果表明：随着进口速度的不断提高，各截面上的平均湍动能以及速度的幅值增大，空化发生区域的压力、湍动能以及流场速度变化明显，空化形态具有周期性特征；在4°攻角下水流流经翼型压力面时流场相对稳定，水流流经翼型吸力面时流场相对紊乱；当绕流速度超过15 m/s时，在翼型中后段开始发生空化，其压力以及平均湍动能变化较为明显，同时在非流动方向上产生回射流现象，导致空化流动失稳。该研究对进一步认识水翼空化特性和发展水翼抗空化技术具有指导意义。 相似文献
10.
用有限差分法建立有关阳极焙烧炉传热过程的离散方程,采用Ｋ—ε双方程湍流模 型和ＳＩＭＰＬＥ算法讨论气体绕流的扩展Ｋ－ε模型,从而分别得到焙烧炉内主要点的温度场和气 流分布等流场信息． 相似文献
11.
Particle image velocimetry （PIV） experimental results of wake flow structure of a NACA0012 airfoil with small attack angle mounted above water surface are introduced.The experiment was carried out in a small-scale wind-wave tunnel.The diameter of wind-wave tunnel test section is 1.7 m （long） × 0.4 m （width） × 0.4 m （height）.The flow fields around the airfoil were measured under four diffierent conditions by varying the distance between the airfoil and the water surface.The attack angle of the airfoil was kept 10- during the experiment.For each experimental condition,the time series of particle images was captured to calculate continuous evolution of the velocity fields.The velocity fields were ensemble averaged to get the statistic parameters such as mean velocity and vorticity.Typical instantaneous velocity fields for each case are introduced to show the basic flow structure of wind surface flow separation.The aerodynamic loads acting on the airfoil are analyzed qualitatively according to the mean vorticity distribution in the flow field based on the theory of vorticity aerodynamics.The results indicate that the flow structures and drag/lift force of the airfoil alter remarkably with the changing distance between the airfoil and water surface. 相似文献
12.
整体风轮中的叶片形状设计是否合理,将影响风轮装置传动的速度和平稳性。文中以NACA2406风轮翼型为参考,对影响整体风轮传动的相关参数进行设计分析,使叶片的设计更合理。 相似文献
13.
An excellent airfoil with a high lift-to-drag ratio may decrease oil consumption and enhance the voyage. Based on NACA 0012, an improved airfoil is explored in this paper. The class/shape function transformation has been proved to be a good method for airfoil parameterization, and in this paper it is modified to improve imitation accuracy. The computational fluid dynamics method is applied to obtain numerically the aerodynamic parameters of the parameterized airfoil, and the result is proved credible by comparison with available experimental data in the open literature. A polynomial-based response surface model and the uniform Latin hypercube sampling method are employed to decrease computational cost. Finally, the nonlinear programming by quadratic Lagrangian method is utilized to modify the multi-island genetic algorithm, which has an improved optimization effect than the method used on its own. The obtained result shows that the modified class/shape function transformation method produces a better imitation of an airfoil in the nose and tail regions than the original method, and that it will satisfy the tolerance zone of the model in a wind tunnel. The response surface model based on the uniform Latin hypercube sampling method gives an accurate prediction of the lift-to-drag ratio with changes in the design variables. The numerical result of the flow around the airfoil shows reasonable agreement with the experimental data graphically and quantitatively. Ultimately, an airfoil with better capacity than the original one is acquired using the multi-island genetic algorithm based nonlinear programming by quadratic Lagrangian optimization method. The pressure contours and lift-to-drag ratio along with the attack angle have been compared with those of the original airfoil, and the results demonstrate the strength of the optimized airfoil. The process for exploring an improved airfoil through parameterization to optimization is worth referencing in future work. 相似文献
14.
针对变化风场尤其是大气紊流严重影响无人机飞行安全的问题,通过构建大气紊流数学模型并分析其对飞行的影响,为非线性无人机建立了六自由度模型,设计了一种模糊自整定PID控制器并进行了Matlab仿真。仿真结果表明,该控制器可提高无人机在变化风场中的稳定性和稳态精度。 相似文献
15.
综合利用润扬结构健康监测系统(SHMS)风环境子系统实时记录的各种参数时程数据以及强风期间上桥实测强风样本,分析得到了桥址区实测强风的风速和风向、紊流强度、紊流积分尺度、紊流功率谱密度函数等特性,重点对比研究了台风与强北风特性之间的差异性.结果表明,与台风相比,强北风的平均风速略小、平均风向更加稳定;台风与强北风的实测紊流强度值均比规范建议值大;台风与强北风的紊流积分尺度之间无明显的规律性;就顺风向紊流功率谱而言,强北风与Kaimal谱更加吻合.研究结果为建立桥址区台风特性数据库,确定当地强风特性参数的合理取值提供了实测依据. 相似文献
16.
基于采用对称翼型的小展弦比三角形机翼模型,对其在亚音速状态和超音速状态时的升力特性、阻力特性、升阻比特性、稳定性特性进行了理论计算分析。并针对该模型进行数值模拟,分析其超音速流场特性,与理论分析结果进行对比,发现相差不大。得出结论:该翼型机翼在飞机巡航速度为Ma=2时气动性能较好。 相似文献
17.
In this paper, a stabilized finite element technique, actualized by streamline upwind Petrov-Galerkin (SUPG) stabilized method
and three-step finite element method (FEM), for large eddy simulation (LES) is developed to predict the wind flow with high
Reynolds numbers. Weak form of LES motion equation is combined with the SUPG stabilized term for the spatial finite element
discretization. An explicit three-step scheme is implemented for the temporal discretization. For the numerical example of
2D wind flow over a square rib at Re=4.2×105, the Smagorinsky’s subgrid-scale (SSGS) model, the DSGS model, and the DSGS model with Cabot near-wall model are applied,
and their results are analyzed and compared with experimental results. Furthermore, numerical examples of 3D wind flow around
a surface-mounted cube with different Reynolds numbers are performed using DSGS model with Cabot near-wall model based on
the present stabilized method to study the wind field and compared with experimental and numerical results. Finally, vortex
structures for wind flow around a surface-mounted cube are studied by present numerical method. Stable and satisfactory results
are obtained, which are consistent with most of the measurements even under coarse mesh. 相似文献
18.
Mahmoud Mekadem Taha Chettibi Samir Hanchi Laurent Keirsbulck Larbi Labraga 《浙江大学学报(A卷英文版)》2012,13(2):105-120
The propulsive efficiency of a plunging NACA0012 airfoil is maximized by means of a simple numerical optimization method based
on the response surface methodology (RSM). The control parameters are the amplitude and the reduced frequency of the harmonic
sinusoidal motion. The 2D unsteady laminar flow around the plunging airfoil is computed by solving the Navier-Stokes equations
for three Reynolds number values (Re = 3.3×103, 1.1×104, and 2.2×104). The Nelder-Mead algorithm is used to find the best control parameters leading to the optimal propulsive efficiency over
the constructed response surfaces. It is found that, for a given efficiency level and regardless of the considered Re value, it is possible either to obtain high thrust by selecting a high oscillation frequency or to reduce the input power
by adopting a low plunging amplitude. 相似文献
19.
In order to investigate the wind characteristics of coastal areas of China, a long-term field measurement of natural wind
was carried out. Based on the field measurement results, this paper presents the natural wind characteristics of typhoons
and strong monsoons at the site of Xi-hou-men Bridge, including mean wind speed, mean wind direction, mean wind elevation
angle, turbulent intensity, gust factor, turbulence integral length scales, power spectrum of wind speed and spatial correlation
of gusty wind, the profiles of mean wind speed and turbulent intensity, etc. The correlation among wind characteristics is
analyzed in detail, and the similarities and differences of wind characteristics between typhoons and monsoons are analyzed.
These results can provide detailed wind characteristics of coastal areas of China. 相似文献
20.
Characteristics of strong winds at the Runyang Suspension Bridge based on field tests from 2005 to 2008 总被引：1，自引：0，他引：1
Field measurement of strong wind characteristics is of great significance for the development of bridge wind engineering. Located in east China, the Runyang Suspension Bridge （RSB） with a main span of 1490 m is the longest bridge in China and the third longest in the world. During the last four years, the RSB has suffered from typhoons and strong northern winds on more than ten occasions. To determine the strong wind characteristics of the RSB, wind measurement data obtained from field tests during strong winds and data from the wind environment monitoring subsystem of the structural health monitoring system （SHMS） of the RSB were combined to analyze the wind speed and direction, variation in wind speed with height, turbulence intensity, turbulence integral length, wind friction speed and the power spectrum. Comparative studies on the characteristics of these different strong winds were carried out based on the current wind-resistant design specification for highway bridges. Results showed that some regularity in wind characteristics can be found in these different typhoons passing through the RSB. The difference between a strong northern wind and a typhoon is relatively clear, and in summer the typhoon is the dominant wind load acting on the RSB. In addition, there were some differences between the measured strong wind characteristics and the values suggested by the specification, especially in respect to turbulence intensity and turbulence integral length. Results provide measurement data for establishing a strong wind characteristic database for the RSB and for determining the strong wind characteristic parameter values of this coastal area in east China. 相似文献