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Study on Aerodynamic Characteristics of Supersonic Airfoil 预览
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作者 Wentao Yong 《现代机械工程(英文)》 2019年第1期13-19,共7页
With the invention of the aircraft, it has become much faster and larger than the original Wright Brothers aircraft. When the speed is high enough to cross the speed of sound, air conditions will be different than tha... With the invention of the aircraft, it has become much faster and larger than the original Wright Brothers aircraft. When the speed is high enough to cross the speed of sound, air conditions will be different than that in low speed due to the existence of shock wave. In this work, we introduce several numerical ways to analyze the performance of the airfoil when the speed is higher than the speed of sound. With these numerical methods, we analyzed the performance of diamond-shaped airfoil under different angles of attack and speed. With this data, engineers can choose a better airfoil to attain a lower drag coefficient as well as lift coefficient when designing a high-speed aircraft. 展开更多
关键词 Aerodynamic SUPERSONIC SPEED Diamond-Shape AIRFOIL Drag COEFFICIENT LIFT COEFFICIENT
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A generalized model for estimation of aerodynamic forces and moments for irregularly shaped bodies 预览
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作者 Elvedin Kljuno Alan Catovic 《Defence Technology(防务技术)》 CAS CSCD 2019年第3期369-389,共21页
A novel method for estimation of an aerodynamic force and moment acting on an irregularly shaped body (such as HE projectile fragments) during its flight through the atmosphere is presented. The model assumes that fra... A novel method for estimation of an aerodynamic force and moment acting on an irregularly shaped body (such as HE projectile fragments) during its flight through the atmosphere is presented. The model assumes that fragments can be approximated with a tri-axial ellipsoid that has continuous surface given as a mathematical function. The model was validated with CFD data for a tri-axial ellipsoid and verified using CFD data on aerodynamic forces and moments acting on an irregularly shaped fragment. The contribution of this method is that it represents a significant step toward a modeling that does not require a cumbersome CFD simulation results for estimation of fragment dynamic and kinematic parameters. Due to this advantage, the model can predict the fragment motion consuming a negligible time when compared to the corresponding time consumed by CFD simulations. Parametric representation (generalization) of the fragment geometrical data and the conditions provides the way to analyze various correlations and how parameters influence the dynamics of the fragment flight. 展开更多
关键词 Aerodynamic FORCE Aerodynamic MOMENT FRAGMENTS
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Effect of Bowed/Leaned Vane on the Unsteady Aerodynamic Excitation in Transonic Turbine
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作者 LIU Jian QIAO Weiyang DUAN Wenhua 《热科学学报:英文版》 SCIE EI CAS CSCD 2019年第1期133-144,共12页
To investigate the effect of bowed/leaned vane configurations on the aerodynamic performance and aerodynamic excitation in transonic high-pressure turbine, the full three-dimensional viscous unsteady numerical simulat... To investigate the effect of bowed/leaned vane configurations on the aerodynamic performance and aerodynamic excitation in transonic high-pressure turbine, the full three-dimensional viscous unsteady numerical simulation was performed by solving N-S equations based on SAS SST method.The influence of bowed/leaned vanes on turbine efficiency and efficiency fluctuation was investigated. The action of vane modelling to the overall aerodynamic fluctuation level and the amplitude of each vane passing frequency were analyzed. By comparing instantaneous pressure fluctuation contours in the blade passage with space-time maps, the link of the pressure fluctuation on blade surface with flow distortions was achieved, which can reveal the mechanism of the impact of the vane modelling. As the results suggest, the turbine efficiency is promoted with positively leaned and bowed vane modelling, and the fluctuation of stage turbine efficiency is repressed, which contributes to the smooth running of the turbine stage. The blade aerodynamic excitation on the rotor blade is characterized by the motion of vane trailing edge shock system, and the vane configurations can reduce the fluctuation level on the rotor blade surface effectively. For the positively leaned vane configuration, the aerodynamic excitations at the root and tip region are affected by the impact of the amplitude of the first harmonic, whereas they are reduced with the decrease of the amplitude of the second and higher harmonics at midspan. For the positively bowed vane, aerodynamic excitation is repressed by reducing the amplitude of the third harmonic at the root region, and the first harmonic at the tip region, and the amplitude of each harmonic is reduced at the middle region. 展开更多
关键词 TRANSONIC TURBINE leaned bowed aerodynamic performance aerodynamic EXCITATION NUMERICAL simulation
Aerodynamic characteristics of unsymmetrical aerofoil at various turbulence intensities
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作者 S.ARUNVINTHAN S.NADARAJA PILLAI 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第11期2395-2407,共13页
A series of wind tunnel tests were performed to investigate the effect of turbulent inflows on the aerodynamic characteristics of the unsymmetrical airfoil at various turbulence intensities and Reynolds number. To ass... A series of wind tunnel tests were performed to investigate the effect of turbulent inflows on the aerodynamic characteristics of the unsymmetrical airfoil at various turbulence intensities and Reynolds number. To assess the aerodynamic characteristics, surface pressure measurements were made over the unsymmetrical airfoil surface by using a simultaneous pressure scanner MPS4264 of Scanivalve make. Self-generated passive grids made of parallel arrays of round bars were placed at four different locations to generate various Turbulence Intensities(TI) in the wind tunnel. The location of the passive grid has been normalized in terms of considering the distance between the entry of the test section and the leading edge of the model. Based on the wind tunnel results, by comparing the baseline without grid low turbulence case TI = 0.51% with other turbulence generated cases like TI = 4.68%, 4.73%, 6.04% and 8.46% at different Reynolds number, it is found that the coefficient of lift increases with the increase in the turbulence intensity. Results also reveal that the flow featuring turbulence can effectively delay the stall characteristics of an airfoil by attaching the flow over the airfoil for an extended region. Additionally, attempts were made to understand the influence of turbulence on the aerodynamic hysteresis. 展开更多
关键词 Aerodynamic efficiency Aerodynamic hysteresis Passive grid Simultaneous pressure distribution Turbulence intensity
基于气动外形优化和主动流动控制的减阻技术 预览
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作者 李立 刘峰博 梁益华 《航空科学技术》 2019年第9期1-8,共8页
增升和减阻是民用飞机设计的永恒目标。本文对民用飞机减阻技术最新进展及未来发展进行综述,在此基础上,报道了计算所团队通过数值优化设计及主动流动控制实现减阻的研究进展。为此,发展了基于壁面模化大涡模拟(WMLES)准确模拟湍流边界... 增升和减阻是民用飞机设计的永恒目标。本文对民用飞机减阻技术最新进展及未来发展进行综述,在此基础上,报道了计算所团队通过数值优化设计及主动流动控制实现减阻的研究进展。为此,发展了基于壁面模化大涡模拟(WMLES)准确模拟湍流边界层的先进数值方法,以及利用伴随方程方法实现气动外形快速数值优化的技术。在具体实践中,通过组合基于自由变形(FFD)的几何参数化模块、基于线弹性体法的网格变形模块,以及基于伴随方程方法和序列二次规划(SQP)的优化算法模块,搭建了面向工程、适于超大规模变量优化设计的整机气动优化设计平台,在NASACRM模型上实现了设计变量超过600的大变量、跨声速气动数值优化设计,在合理的工程约束条件下,有效削弱了机翼表面激波,总体减阻率达到2%以上;通过对湍流平板边界层外层结构进行射流非定常控制,在中等雷诺数Reτ=4700条件下,实现了5%~6%的当地减阻率。研究证实,数值优化设计和基于外层射流控制的主动流动控制技术将是大型民用飞机减阻中非常有前景和值得重视的两种方法。 展开更多
关键词 湍流减阻 主动流动控制 外形优化 空气动力学 CFD
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Efficient multi-response adaptive sampling algorithm for construction of variable-fidelity aerodynamic tables
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作者 Maxim TYAN Jae-Woo LEE 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第3期547-558,共12页
Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-res... Adaptive sampling is an iterative process for the construction of a global approximation model. Most of engineering analysis tools computes multiple parameters in a single run. This research proposes a novel multi-response adaptive sampling algorithm for simultaneous construction of multiple surrogate models in a time-efficient and accurate manner. The new algorithm uses the Jackknife cross-validation variance and a minimum distance metric to construct a sampling criterion function. A weighted sum of the function is used to consider the characteristics of multiple surrogate models. The proposed algorithm demonstrates good performance on total 22 numerical problems in comparison with three existing adaptive sampling algorithms. The numerical problems include several two-dimensional and six-dimensional functions which are combined into singleresponse and multi-response systems. Application of the proposed algorithm for construction of aerodynamic tables for 2 D airfoil is demonstrated. Scaling-based variable-fidelity modeling is implemented to enhance the accuracy of surrogate modeling. The algorithm succeeds in constructing a system of three highly nonlinear aerodynamic response surfaces within a reasonable amount of time while preserving high accuracy of approximation. 展开更多
关键词 Adaptive sampling Aerodynamic DATABASE Multi-response system Surrogate MODELING VARIABLE FIDELITY MODELING
Aerodynamic characteristics of rigid coaxial rotor by wind tunnel test and numerical calculation
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作者 Jinghui DENG Feng FAN +2 位作者 Ping'an LIU Shuilin HUANG Yongfeng LIN 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第3期568-576,共9页
Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m×6 m low-speed straightflow wind tunnel of China Ae... Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m×6 m low-speed straightflow wind tunnel of China Aerodynamics Research and Development Center. In the experiment,a 4 m diameter composite model rigid coaxial rotor is designed and manufactured, and firstorder flapping frequency ratio of the blade is 1.796 to ensure sufficient stiffness at the blade root.Rotor aerodynamic performance is measured under hovering and high advance ratio conditions.Also, the numerical method is used to calculate aerodynamic characteristics in typical states of the rigid coaxial rotor for analysis purpose. The rotor lift-drag ratio and lateral lift offset in the experiment are emphatically analyzed for the rigid coaxial rotor. The results indicate that in forward flight condition, the rotor lift-drag ratio first increases and then decreases with the increment of advance ratio and lift offset. When advance ratio remains constant, with the increment of lift offset, the lift-drag ratio of rigid coaxial rotor first increases and then decreases. 展开更多
关键词 Aerodynamic characteristics High-speed HELICOPTER Lateral LIFT OFFSET RIGID COAXIAL ROTOR Wind tunnel test
Aerodynamic actuation characteristics of radio-frequency discharge plasma and control of supersonic flow
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作者 杨臻 宋慧敏 +3 位作者 王宏宇 郭善广 贾敏 王康 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第2期321-330,共10页
In this paper, aerodynamic actuation characteristics of radio-frequency(RF) discharge plasma are studied and a method is proposed for shock wave control based on RF discharge. Under the static condition, a RF diffuse ... In this paper, aerodynamic actuation characteristics of radio-frequency(RF) discharge plasma are studied and a method is proposed for shock wave control based on RF discharge. Under the static condition, a RF diffuse glow discharge can be observed;under the supersonic inflow, the plasma is blown downstream but remains continuous and stable.Time-resolved schlieren is used for flow field visualization. It is found that RF discharge not only leads to continuous energy deposition on the electrode surface but also induces a compression wave. Under the supersonic inflow condition, a weak oblique shock wave is induced by discharge. Experimental results of the shock wave control indicate that the applied actuation can disperse the bottom structure of the ramp-induced oblique shock wave, which is also observed in the extracted shock wave structure after image processing. More importantly, this control effect can be maintained steadily due to the continuous high-frequency(MHz) discharge. Finally, correlations for schlieren images and numerical simulations are employed to further explore the flow control mechanism. It is observed that the vortex in the boundary layer increases after the application of actuation, meaning that the boundary layer in the downstream of the actuation position is thickened. This is equivalent to covering a layer of low-density smooth wall around the compression corner and on the ramp surface, thereby weakening the compressibility at the compression corner. Our results demonstrate the ability of RF plasma aerodynamic actuation to control the supersonic airflow. 展开更多
关键词 radio-frequency(RF) DISCHARGE PLASMA surface DISCHARGE FLOW control aerodynamic ACTUATION
旋翼螺旋桨的快速气动优化设计 预览
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作者 黄胤强 陈海昕 《风机技术》 2019年第5期19-27,共9页
Aerodynamic design of convertible prop-rotor is a challenging and complex task.Instead of focus on a design condition,prop-rotor are requested to attain good performance in wide range of operating conditions.In presen... Aerodynamic design of convertible prop-rotor is a challenging and complex task.Instead of focus on a design condition,prop-rotor are requested to attain good performance in wide range of operating conditions.In present work,to further improve performance of prop-rotor under each operating condition,the concept of variable-pitch proprotor has been proposed.However,a compromising aerodynamic design of prop-rotor is inevitable,due to discrepancy of operating condition.Consequently,a multi-objective optimization is implemented with genetic algorithm.Factors which has significantly influenced on aerodynamic characteristics of prop-rotor are employed as design variable.To avoid expensively computational cost,two theories has been implemented and validated while it able to provide a promising result without high consuming of time.Eventually,several designed individuals within different performance has been analyzed and discussed.Subsequently a calculation of aerodynamic characteristic with highfidelity solver has been conducted as validation for designed individual. 展开更多
关键词 Aerodynamic DESIGN Optimization Prop-Rotor PRELIMINARY DESIGN BEMT VORTEX Theory
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A note on the Galilean invariance of aerodynamic force theories in unsteady incompressible flows 预览
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作者 An-Kang Gao Jiezhi Wu 《力学学报:英文版》 SCIE EI CAS CSCD 2019年第6期1150-1154,共5页
As a basic principle in classical mechanics,the Galilean invariance states that the force is the same in all inertial frames of reference.But this principle has not been properly addressed by most unsteady aerodynamic... As a basic principle in classical mechanics,the Galilean invariance states that the force is the same in all inertial frames of reference.But this principle has not been properly addressed by most unsteady aerodynamic force theories,if the partial force contributed by a local flow structure is to be evaluated.In this note,we discuss the Galilean-invariance conditions of the partial force for several typical theories and numerically test what would happen if these conditions do not hold. 展开更多
关键词 Galilean invariance Aerodynamic force theory Unsteady flow Flow diagnoses
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Effects of yaw-roll coupling ratio on lateraldirectional aerodynamic characteristics
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作者 Lin SHEN Da HUANG Genxing WU 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第2期272-280,共9页
Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide di... Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide different coupled motions from low to high angles of attack.A parameter ‘‘coupling ratio' was introduced to indicate the extent of yaw-roll coupling. At each pitch angle, seven coupling ratios were designed to study the yaw-roll coupling effects on the lateraldirectional aerodynamic characteristics systematically. At high angles of attack, the damping characteristics of yawing and rolling moments drastically varied with coupling ratios. In the coupled motions with the rotation taking place about the wind axis, the lateral-directional aerodynamic moments exhibited unsteady characteristics and were different from the ‘‘quasi-steady' results of the rotary balance tests. The calculated results of the traditional aerodynamic derivative method were also compared with the experimental data. At low and very high angles of attack, the aerodynamic derivative method was applicative. However, within a wide range of angles of attack, the calculated results of aerodynamic derivative method were inconsistent with the experimental data, due to the drastic changes of damping characteristics of lateral-directional aerodynamic moments with yaw-roll coupling ratios. 展开更多
关键词 High ANGLES of ATTACK HYSTERESIS Lateral-directional aerodynamic characteristics UNSTEADY Yaw-roll coupling
Aerodynamic optimization design of general parameters for cycloidal propeller in hover based on surrogate model
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作者 ZENG Jianan ZHU Qinghua +2 位作者 WANG Kun ZHU Zhenhua SHEN Suiyuan 《航空动力学报》 EI CAS CSCD 北大核心 2019年第8期1741-1750,共10页
A surrogate-model-based aerodynamic optimization design method for cycloidal propeller in hover was proposed,in order to improve its aerodynamic efficiency,and analyze the basic criteria for its aerodynamic optimizati... A surrogate-model-based aerodynamic optimization design method for cycloidal propeller in hover was proposed,in order to improve its aerodynamic efficiency,and analyze the basic criteria for its aerodynamic optimization design.The reliability and applicability of overset mesh method were verified.An optimization method based on Kriging surrogate model was proposed to optimize the geometric parameters for cycloidal propeller in hover with the use of genetic algorithm.The optimization results showed that the thrust coefficient was increased by 3.56%,the torque coefficient reduced by 12.05%,and the figure of merit(FM)increased by 19.93%.The optimization results verified the feasibility of this design idea.Although the optimization was only carried out at a single rotation speed,the aerodynamic efficiency was also significantly improved over a wide range of rotation speeds.The optimal configuration characteristics for micro and small-sized cycloidal propeller were:solidity of 0.2-0.22,maximum pitch angle of 25°-35°,pitch axis locating at 35%-45% of the blade chord length. 展开更多
关键词 cycloidal PROPELLER aerodynamic shape OPTIMIZATION KEY design PARAMETERS surrogate-based OPTIMIZATION dynamic overset MESH
高速铁路堤堑防风过渡段气动分析与工程优化 预览
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作者 李鲲 《铁道工程学报》 EI 北大核心 2019年第10期23-26,87,共5页
研究目的:兰新高铁在联调联试及大风专项试验期间,高速列车通过不同防风工程过渡段时,工程边界的变化引发列车气动性能产生急剧变化,进而导致车体晃动。本文对兰新高铁路堤到路堑的防风工程过渡段的气动特性进行研究,探明突变边界引发... 研究目的:兰新高铁在联调联试及大风专项试验期间,高速列车通过不同防风工程过渡段时,工程边界的变化引发列车气动性能产生急剧变化,进而导致车体晃动。本文对兰新高铁路堤到路堑的防风工程过渡段的气动特性进行研究,探明突变边界引发的风切变机制及演化规律,针对过渡段风流场的突变环节提出完善的、可实施的工程优化方案,并对工程效果进行对比分析,为优化工程的实施提供依据。研究结论:(1)列车通过不同防风工程过渡段时,头车、中车、尾车侧向力与倾覆力矩增幅明显,遮蔽区内流场结构及风速、风向的变化导致列车气动性能发生较大变化,进而影响列车的稳定舒适性;(2)以过渡段风场变化规律研究为基础,对于典型的路堤到路堑的防风工程过渡段,提出了加高过渡段挡风墙的工程优化措施,列车通过时侧向力与倾覆力矩幅值明显降低且变化缓和,优化效果明显;(3)对于其他更为复杂的防风工程过渡段,需重视不同结构过渡边界引发的风切变机制及演化规律的研究,重点从改善突变流场结构入手,结合地形地貌及工程条件因地制宜地采取工程优化措施;(4)本研究结论可为高速铁路防风工程过渡段的计算、设计及工程优化提供参考。 展开更多
关键词 高速铁路 防风工程 过渡段 气动性能 工程优化
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Effect of surface blowing on aerodynamic characteristics of tubercled straight wing
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作者 N.GANESH S.ARUNVINTHAN S.NADARAJA PILLAI 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第5期1111-1120,共10页
Recent research proves that wings with leading-edge tubercles have the ability to perform efficiently in post-stall region over the conventional straight wing. Moreover, the conventional straight wing outperforms the ... Recent research proves that wings with leading-edge tubercles have the ability to perform efficiently in post-stall region over the conventional straight wing. Moreover, the conventional straight wing outperforms the tubercled wing at a pre-stall region which is quintessential. Even though tubercled wing offers great performance enhancement, because of the complexity of the flow, the trough region of the tubercled wing is more prone to flow separation. Henceforth, the present paper aims at surface blowing-an active flow control technique over the tubercled wing to enhance the aerodynamic efficiency by positively influencing its lift characteristics without causing any additional drag penalty. Flow parameters like blowing velocity ratios and the location of blowing were chosen to find the optimised configuration keeping the amplitude and frequency of the leading-edge tubercles constant as 0.12 c and 0.25 c respectively. Numerical investigations were carried out over the baseline tubercled wing and tubercled wing with surface blowing at various blowing jet velocity ratios 0.5, 1 and 2 over four different chordwise locations ranging from 0.3 c to 0.8 c.The results confirm that blowing at various x/c with different blowing velocity ratios performs better than the conventional tubercled wing. Comparatively, blowing velocity ratio 2 at 0.3 c shows peak performance of about 28% enhancement in the lift characteristics relative to the baseline model. Particularly, in the pre-stall region, 25-50% increase in aerodynamic efficiency is evident over the tubercled wing with surface blowing compared with the baseline case. Additionally,attempts were made to delineate the physical significance of the flow separation mechanism due to blowing by visualizing the streamline pattern. 展开更多
关键词 ACTIVE FLOW CONTROL Aerodynamic EFFICIENCY Biomimetics BLOWING Tubercles
Conceptual design and optimization of a tilt-rotor micro air vehicle
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作者 M.HASSANALIAN R.SALAZAR A.ABDELKEFI 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第2期369-381,共13页
The conceptual design and optimization of a tilt-rotor Micro Air Vehicle(MAV) for a well-defined mission are performed. The objective of this design cycle is to decrease the design time in order to efficiently create ... The conceptual design and optimization of a tilt-rotor Micro Air Vehicle(MAV) for a well-defined mission are performed. The objective of this design cycle is to decrease the design time in order to efficiently create a functional tilt-rotor drone. A flight mission is firstly defined for a tiltrotor MAV performing hovering and cruise flight scenarios. Secondly, a complex wing shape is chosen and modeled in order to determine the final shape. The initial shape is scaled in order to acquire an arbitrary wingspan of one meter. For the specific area and wingspan, the aspect ratio of the designed wing shape is found to be equal to 2.32. Thirdly, a constraint analysis of the MAV is performed by using an energy balance analysis for six different flight scenarios. This analysis yields the required power loading and wing loading. Fourthly, the weight of the vehicle is estimated using both statistical and computational methods. After estimating the total weight and the wing loading of the MAV, the surface of the wing is determined, yielding a final wingspan of 0.76 m. Subsequently, considering the total weight of the designed MAV, the needed lift coefficient is determined.Fifthly, using the lift coefficient in conjunction with XLFR5, a batch of airfoils is selected and analyzed to evaluate the aerodynamic coefficients of the wing with each airfoil. This analysis ultimately leads to the optimum airfoil being selected. Finally, design of the fuselage and tail, internal components selection, and servo-mechanisms design are carried out prior to a stability analysis. All these proposed steps are needed to design efficient and functional tilt-rotor MAVs. 展开更多
关键词 Aerodynamic analysis SIZING Tilt-rotor MAV VTOL STABILITY
柔性空间扑翼机构的刚柔耦合动力特性分析 预览
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作者 屠凯 侯宇 +1 位作者 华兆敏 李诗雷 《机械设计与制造》 北大核心 2019年第7期215-219,共5页
针对目前扑翼驱动机构无法以简单结构实现复杂仿生运动问题,由空间四杆机构出发,引入柔性杆件设计思路,设计了一种柔性空间扑翼驱动机构。在单驱动条件下,实现了翅翼的扑动-扭转-挥摆耦合运动。建立了机构的运动学和气动力计算模型,求... 针对目前扑翼驱动机构无法以简单结构实现复杂仿生运动问题,由空间四杆机构出发,引入柔性杆件设计思路,设计了一种柔性空间扑翼驱动机构。在单驱动条件下,实现了翅翼的扑动-扭转-挥摆耦合运动。建立了机构的运动学和气动力计算模型,求解了机构在运动过程中扑动角、扭转角、挥摆角以及翅翼所受的气动力变化。根据机构特性,在Adams中建立了考虑动力学特性与机构强度的刚柔耦合模型,分析了机构的运动轨迹、运动特性及柔性杆件的应力变化情况。结果表明,该驱动机构具有运动对称性与稳定性,翅翼实现了扑动-扭转-挥摆的耦合仿生运动,同时又满足了柔性机构的强度设计要求。 展开更多
关键词 刚柔耦合 扑翼机构 气动力 动力特性 结构强度
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Evaluation of Aerodynamic Force and Stress Properties of Propeller of Model Airplane Using by Finite Element Analysis 预览
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作者 Satoshi Fukui Masayuki Nishida 《土木工程与建筑:英文版》 2019年第4期259-264,共6页
The purpose of this study is to evaluate propeller safety using three-dimensional finite element method analysis software.We concluded that the propeller is safe for flying.Propeller is indispensable for generating th... The purpose of this study is to evaluate propeller safety using three-dimensional finite element method analysis software.We concluded that the propeller is safe for flying.Propeller is indispensable for generating the impellent force.Therefore,safety evaluation of propeller is necessary.The object of the analysis is a propeller for model airplane.The propeller material is carbon fiber reinforced plastics and there is a carbon cross in the one side surface of the propeller.Other parts are formed with resin.The forces acting on a propeller include centrifugal force,air resistance,and vibration by mass imbalance.We analyzed centrifugal force and air resistance in this study.We made analysis model of propeller by ANSYS.Results show,that the maximum principal stress due to centrifugal force was 23.0 MPa.In addition,the maximum principal stress due to aerodynamic force was 2.3 MPa,and the maximum principal stress due to both forces was 24.0 MPa. 展开更多
关键词 method CENTRIFUGAL FORCE aerodynamic FORCES
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Performance improvement of optimization solutions by POD-based data mining
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作者 Yanhui DUAN Wenhua WU +4 位作者 Peihong ZHANG Fulin TONG Zhaolin FAN Guiyu ZHOU Jiaqi LUO 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第4期826-838,共13页
The performance of an optimized aerodynamic shape is further improved by a second-step optimization using the design knowledge discovered by a data mining technique based on Proper Orthogonal Decomposition(POD) in the... The performance of an optimized aerodynamic shape is further improved by a second-step optimization using the design knowledge discovered by a data mining technique based on Proper Orthogonal Decomposition(POD) in the present study. Data generated in the first-step optimization by using evolution algorithms is saved as the source data, among which the superior data with improved objectives and maintained constraints is chosen. Only the geometry components of the superior data are picked out and used for constructing the snapshots of POD. Geometry characteristics of the superior data illustrated by POD bases are the design knowledge, by which the second-step optimization can be rapidly achieved. The optimization methods are demonstrated by redesigning a transonic compressor rotor blade, NASA Rotor 37, in the study to maximize the peak adiabatic efficiency, while maintaining the total pressure ratio and mass flow rate.Firstly, the blade is redesigned by using a particle swarm optimization method, and the adiabatic efficiency is increased by 1.29%. Then, the second-step optimization is performed by using the design knowledge, and a 0.25% gain on the adiabatic efficiency is obtained. The results are presented and addressed in detail, demonstrating that geometry variations significantly change the pattern and strength of the shock wave in the blade passage. The former reduces the separation loss,while the latter reduces the shock loss, and both favor an increase of the adiabatic efficiency. 展开更多
关键词 Aerodynamic shape OPTIMIZATION Computational ?uid dynamics Data mining Particle SWARM OPTIMIZATION PROPER Orthogonal Decomposition TRANSONIC ?ow TURBOMACHINERY
A comparison of piecewise cubic Hermite interpolating polynomials, cubic splines and piecewise linear functions for the approximation of projectile aerodynamics 预览
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作者 C.A.Rabbath D.Corriveau 《Defence Technology(防务技术)》 CAS CSCD 2019年第5期741-757,共17页
Modelling and simulation of projectile flight is at the core of ballistic computer software and is essential to the study of performance of rifles and projectiles in various engagement conditions.An effective and repr... Modelling and simulation of projectile flight is at the core of ballistic computer software and is essential to the study of performance of rifles and projectiles in various engagement conditions.An effective and representative numerical model of projectile flight requires a relatively good approximation of the aerodynamics.The aerodynamic coefficients of the projectile model should be described as a series of piecewise polynomial functions of the Mach number that ideally meet the following conditions:they are continuous,differentiable at least once,and have a relatively low degree.The paper provides the steps needed to generate such piecewise polynomial functions using readily available tools,and then compares Piecewise Cubic Hermite Interpolating Polynomial(PCHIP),cubic splines,and piecewise linear functions,and their variant,as potential curve fitting methods to approximate the aerodynamics of a generic small arms projectile.A key contribution of the paper is the application of PCHIP to the approximation of projectile aerodynamics,and its evaluation against a set of criteria.Finally,the paper provides a baseline assessment of the impact of the polynomial functions on flight trajectory predictions obtained with 6-degree-of-freedom simulations of a generic projectile. 展开更多
关键词 Aerodynamic coefficients PIECEWISE POLYNOMIAL FUNCTIONS CUBIC splines Curve fitting PIECEWISE linear FUNCTIONS PIECEWISE CUBIC HERMITE interpolating POLYNOMIAL PROJECTILE modelling and simulation Fire control inputs Precision Ballistic computer software
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Aerodynamic and trajectory characteristics of a typical mortar projectile with a deflectable nose 预览
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作者 Yu-ming Ren Shu-shan Wang +2 位作者 Jing-wei Li Xun-cheng Guo Yue-song Mei 《Defence Technology(防务技术)》 CAS CSCD 2019年第5期758-767,共10页
Deflectable nose control is a new trajectory correction method.In this paper,the aerodynamic and trajectory characteristics of a typical mortar projectile with a deflectable nose are investigated with respect to its f... Deflectable nose control is a new trajectory correction method.In this paper,the aerodynamic and trajectory characteristics of a typical mortar projectile with a deflectable nose are investigated with respect to its flight conditions.Using the method of wind tunnel testing,the aerodynamic coefficients of four kinds of mortar models were measured under the conditions of different angles of attack from-10°to 10°and Mach numbers from 0.3 to 0.9.Based on the aerodynamic coefficients,the trajectory ranges at different nose deflection angles and times were calculated.Furthermore,a trajectory optimization was performed by reducing the static margin.The results and discussions show that the nose deflection provided limited lift,while the pitching moment varied significantly.The mortar obtained the extended flight range and trajectory correction ability with nose deflection. 展开更多
关键词 NOSE DEFLECTION Aerodynamic characteristics WIND TUNNEL test TRAJECTORY simulation
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