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1
Ološtiak, Martin. "To the relations between morphemic and word-formation structure of a word in Slovak". Journal of Linguistics/Jazykovedný casopis 70, nr 3 (1.12.2019): 545–72. http://dx.doi.org/10.2478/jazcas-2020-0004.
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AbstractThe paper focuses on relations between word-formation and morphemic structure of a Slovak word based on the material from Slovník koreňových morfém slovenčiny [Slovak Dictionary of Root Morphemes] (Sokolová et al., 2012). Particularly, manifestations of morphemic variation determined by word-formation poly-motivation are analysed. Poly-motivation arises from the re-grouping of the relations within a word-formation nest, where the mediated motivation can be understood as an alternative direct motivation, e.g. aerodynamika [noun, ‘aerodynamics’] → (aerodynamický [adjective, ‘related to aerodynamics’]) → aerodynamicky [adverb]. The adverb aerodynamicky is derived from the adjective (aerodynamický → aerodynamick-y ‘in an aerodynamic manner’) as well as from the noun (aerodynamika → aerodynamic-ky ‘with regard to aerodynamics’). Thus, the structure of affixes can be extended as a result of infixation conditioned by poly-motivation, cf. aerodynamick-y (suffix -y) / aerodynamic-ky (suffix -y with an infix: -k:y). As far as poly-motivation is concerned, a particular affix can have several morphemic and word-formation manifestations, e.g. Slovak adverb suffix -y can be manifested as -y, -ky, -icky, -isticky, -sky, -euticky, -aticky, -eticky, -ecky, -nícky.
2
Tian, Hong-qi. "Review of research on high-speed railway aerodynamics in China". Transportation Safety and Environment 1, nr 1 (1.07.2019): 1–21. http://dx.doi.org/10.1093/tse/tdz014.
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Abstract High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway development. This paper systematically summarizes the aerodynamic research relating to China’s high-speed railway network. Seven key research advances are comprehensively discussed, including train aerodynamic drag-reduction technology, train aerodynamic noise-reduction technology, train ventilation technology, train crossing aerodynamics, train/tunnel aerodynamics, train/climate environment aerodynamics, and train/human body aerodynamics. Seven types of railway aerodynamic test platform built by Central South University are introduced. Five major systems for a high-speed railway network—the aerodynamics theoretical system, the aerodynamic shape (train, tunnel, and so on) design system, the aerodynamics evaluation system, the 3D protection system for operational safety of the high-speed railway network, and the high-speed railway aerodynamic test/computation/analysis platform system—are also introduced. Finally, eight future development directions for the field of railway aerodynamics are proposed. For over 30 years, railway aerodynamics has been an important supporting element in the development of China’s high-speed railway network, which has also promoted the development of high-speed railway aerodynamics throughout the world.
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Philpot, M. G. "Future challenges for powerplant aerodynamic integration in combat aircraft". Aeronautical Journal 105, nr 1048 (czerwiec 2001): 335–43. http://dx.doi.org/10.1017/s0001924000012227.
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Abstract The operational requirements of modern combat aircraft demand complex engine intake and exhaust systems, capable of working efficiently over a very wide range of flight conditions and throttle settings. In addition to high aerodynamic efficiency and avoidance of high distortion levels at the engine face, these systems must also meet rigorous radar and infra-red signature targets. This paper discusses the implications from the aerodynamics point of view. Examples of technical approaches which seek to balance the sometimes conflicting requirements of aerodynamics and signatures are outlined. The potential offered by in-flight thrust vectoring to enhance flight performance and/or safety is also reviewed and the aerodynamic implications considered. Overall, propulsion integration for combat aircraft presents several challenges to the aerodynamicist, not least the development and validation of improved theoretical design methods capable of analysing the highly complex flows involved.
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Ji, Rui, Yinting Shen i Kai Sheng. "The recent progress and state-of-art applications of aerodynamics for vehicle". Highlights in Science, Engineering and Technology 13 (21.08.2022): 75–81. http://dx.doi.org/10.54097/hset.v13i.1334.
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Transportation is an indispensable part of human beings’ daily life, thus plenty of scholars have focused on improving the energy efficiency of transportation. The application and development of aerodynamics is of paramount importance. In this article, the effects of three types of locomotives on aerodynamic performance of high-speed trains are investigated. In order to lucubrate this topic, the definition of aerodynamics by different scientists is firstly discussed and showed, they basically classify them by three different kinds of ways. Subsequently, the creation of aerodynamics, historical development, and present situation are briefly introduced. In the main part, mathematical model and calculation formula are carried out to ensure which kinds of aerodynamic model is the most suitable among all the designs. Overall, these results offer a guideline for how to design a more effective and practical train head by applying the aerodynamic knowledge and expanding people's use of aerodynamics.
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Hong, Sungchan, Takeshi Asai i Byung Mook Weon. "Surface Patterns for Drag Modification in Volleyballs". Applied Sciences 9, nr 19 (25.09.2019): 4007. http://dx.doi.org/10.3390/app9194007.
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Surface patterns on objects are important in aerodynamics. We show how surface patterns on volleyballs modify their aerodynamic performances. Conventional volleyballs with six panels show different aerodynamic characteristics along transverse and diagonal directions. Interestingly, isotropic surface patterning with hexagons or dimples enables us to achieve isotropic aerodynamics. This result gives insight into surface-mediated flight controls of projectiles through resisting fluid media.
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Bielek, Boris, Daniel Szabó, Josip Klem i Kristína Kaniková. "Application of physical theory of cavity in the construction of double skin facades". Curved and Layered Structures 9, nr 1 (3.11.2021): 40–53. http://dx.doi.org/10.1515/cls-2022-0004.
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Abstract The article deals with the issue of double skin transparent facades as a new technological-operational system of transparent exterior walls. Especially of high-rise buildings, which with its operating modes ingeniously uses a renewable source of solar energy to reduce the energy needs of the building. The basic precondition for the correct function of the double skin facade is its functional aerodynamics in any climatic conditions of the outdoor climate. In the critical state of windlessness, the aerodynamic quantification of a double skin facade is the total aerodynamic resistance of the cavity, which consists of the aerodynamic frictional resistances along the length of the air flow line and local aerodynamic resistances of the cavity. The article analyses the functional aerodynamics on two frequented types of double skin facades with a narrow type and corridor type cavity. At the end it confronts functional aerodynamics with the results of their temperature, aerodynamic and energy regime obtained from in-situ experiments.
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Wang, Junzhe. "Analysis of the Principle and Applications of Aerodynamics of High-speed Railway". Highlights in Science, Engineering and Technology 72 (15.12.2023): 530–35. http://dx.doi.org/10.54097/ymwbxx75.
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With the advancement of science and technology, the railway has become an important breakthrough. Railroads can transport goods and carry people. Aerodynamics has a huge connection to the study of the high-speed railways. On this basis, the subject of this paper is the principle and application analysis of high-speed railway aerodynamics. To be specific, this study introduces the formulas and principles related to aerodynamics, and how some formulae are used in high-speed railways. The research searches for literature related to railway and aerodynamics and finds the current development status of high-speed railway. The paper explains how aerodynamics affect high-speed rail, the way to transform high-speed railways with aerodynamic knowledge. Contemporarily, there are many methods to carry out the simulation and tunnel experiments. This study also introduces some special experiments to solve special problems about high-speed railway. According to the analysis, there are still many aerodynamic problems that people need to solve, and there is room for improvement in high-speed railways.
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Ni, Runzhou. "Research on the application of aerodynamic in cycling". Theoretical and Natural Science 12, nr 1 (17.11.2023): 227–32. http://dx.doi.org/10.54254/2753-8818/12/20230478.
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As a bicycle moves, the rider feels air resistance, which affects speed and the rider's energy expenditure. In cycling races, where the main focus is on increasing speed, modifications to the design of the bike, optimization of the bike's materials, and adjustments to the riding position are often utilized to increase speed and reduce energy expenditure. These optimizations are based on aerodynamic principles, which is one of the practical applications of aerodynamic developments. Therefore, the influence of aerodynamics is becoming more and more important in today's bicycle racing. In this paper, the application of aerodynamics in cycling is studied and analyzed through theoretical analysis and literature review. Based on the experimental study of aerodynamics, the optimization of various parts of the bicycle is analyzed to give riders the advantage and help them to increase their speed. Provides the reader with an initial understanding of the application of aerodynamics in cycling.
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Žilinský, Juraj, i Milan Vanc. "Applied Aerodynamics in Building". Advanced Materials Research 855 (grudzień 2013): 164–67. http://dx.doi.org/10.4028/www.scientific.net/amr.855.164.
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Development of new materials, high strength concrete, steels, composites, new construction techniques and procedures put the Development of new materials, high strength concrete, steels, composites, new construction techniques and procedures put the foundations of a new generation of buildings. With the advent of advanced computer technology, using the finite element method engineers and architects plan and construct buildings that are, high, flexible, thin and lightweight. These buildings, however, are burdened by aerodynamic forces, whose source is wind. Just the action of aerodynamic forces adversely affects their ability to traffic, reducing safety and durability. It is therefore necessary to provide high flexibility structures and maintain their safety. This can only be achieved by means of applied aerodynamics using various types of passive and active components to optimize aerodynamics of buildings.
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Toet, W. "Aerodynamics and aerodynamic research in Formula 1". Aeronautical Journal 117, nr 1187 (styczeń 2013): 1–26. http://dx.doi.org/10.1017/s0001924000007739.
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AbstractThis paper will address the engineering performance differentiators for an F1 car and highlight the difference aerodynamics can make to that performance. It will also consider some basic aerodynamic challenges and the main tools used for aerodynamic exploration by teams.
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Chen, Zhao Jun. "Application of Aerodynamics in the Automotive Repair". Applied Mechanics and Materials 556-562 (maj 2014): 991–95. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.991.
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In the development process of the car, the aerodynamics has a strong impact on the automotive research and design. The initial research of aerodynamics focused on reducing air resistance and improving the car's fuel efficiency. Aerodynamic lift and side forces generated has a significant effect on the stability of cars, and even a threat to the safe driving. With the rapid development of automotive performance, the comfort and security of cars have put forward new and higher requirements, wind noise and airflow pollution generated by the aerodynamics have also emerged. How to reduce the adverse effects on the aerodynamics of cars, which is thought about by not only the people of the design, but also the users and maintenance workers in the car. In the course of vehicle maintenance, arising issues of aerodynamics have been gradually received wide attention.
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Zhang, Jing, Wenwen Kang i Lingyu Yang. "Aerodynamic benefits of boundary layer ingestion for distributed propulsion configuration". Aircraft Engineering and Aerospace Technology 91, nr 10 (4.11.2019): 1285–94. http://dx.doi.org/10.1108/aeat-06-2018-0174.
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Purpose Boundary layer ingestion (BLI) is one of the probable noteworthy features of distributed propulsion configuration (DPC). Because of BLI, strong coupling effects are generated between the aerodynamics and propulsion system of aircraft, leading to the specific lift and drag aerodynamic characteristics. This paper aims to propose a model-based comprehensive analysis method to investigate this unique aerodynamic. Design/methodology/approach To investigate this unique aerodynamics, a model-based comprehensive analysis method is proposed. This method uses a detailed mathematical model of the distributed propulsion system to provide the essential boundary conditions and guarantee the accuracy of calculation results. Then a synthetic three-dimensional computational model is developed to analyze the effects of BLI on the lift and drag aerodynamic characteristics. Findings Subsequently, detailed computational analyses are conducted at different flight states, and the regularities under various flight altitudes and velocities are revealed. Computational results demonstrate that BLI can improve the lift to drag ratio evidently and enable a great performance potentiality. Practical implications The general analysis method and useful regularities have reference value to DPC aircraft and other similar aircrafts. Originality/value This paper proposed a DPS model-based comprehensive analysis method of BLI benefit on aerodynamics for DPC aircraft, and the unique aerodynamics of this new configuration under various flight altitudes and velocities was revealed.
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Xie, Meng, i Xiaoyan Liu. "The influence and application of nonlinear aerodynamics on static derivatives in transonic regime". Journal of Physics: Conference Series 2512, nr 1 (1.05.2023): 012007. http://dx.doi.org/10.1088/1742-6596/2512/1/012007.
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Abstract This paper details two static aeroelastic analysis methods applied to a passenger aircraft model with high aspect ratio wing. The influence of nonlinear aerodynamic force on static aeroelastic derivatives in the transonic regime is analysed. The traditional aerodynamic influence coefficient (AIC) matrix method can produce fast and reliable aerodynamic force and is widely used in aeroelastic analysis. However, the AIC matrix computed by linear aerodynamics will lead to some errors in transonic regime because of the nonlinear effect of aerodynamics. By generating the correction matrices, the AIC matrix is modified, and the accuracy of transonic static aeroelastic correction of aerodynamic data can be improved. The static derivatives are compared to the results of the computational fluid dynamics (CFD) / computational structural (CSD) interaction method.
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Liu, Jun, Zhengqi Gu, Taiming Huang, Shuya Li, Ledian Zheng i Kai Sun. "Coupled analysis of the unsteady aerodynamics and multi-body dynamics of a small car overtaking a coach". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, nr 14 (22.02.2019): 3684–99. http://dx.doi.org/10.1177/0954407019831559.
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The severe additional aerodynamic loads that are generated on a small car when overtaking a coach have an adverse effect on the car handling stability and its safety. In this article, a two-way coupling of the unsteady aerodynamics and multi-body dynamics is performed in order to study the mutual interactions of a car in an overtaking maneuver with a coach. The unsteady aerodynamic interactions are obtained by using SST (Menter) K-Omega Detached Eddy Simulation and overset mesh technology. The aerodynamics couple the multi-body dynamics, taking into account the effects of the transverse spacing and the cross winds. To validate the necessity of the two-way coupling method, a one-way coupling of the aerodynamics to the vehicle motion is also conducted. Finally, by comparing the aerodynamic loads and the dynamic response of the overtaking car in different overtaking maneuvers between one- and two-way coupling, the results show that it should be considered with two-way coupling analyses of the car while overtaking a coach, particularly under the severe conditions of a lower transverse spacing or the crosswinds.
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Tomasz Lusiak, Andrej Novak, Martin Bugaj i Radovan Madlenak. "Assessment of Impact of Aerodynamic Loads on the Stability and Control of the Gyrocopter Model". Communications - Scientific letters of the University of Zilina 22, nr 4 (1.10.2020): 63–69. http://dx.doi.org/10.26552/com.c.2020.4.63-69.
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Aerodynamic modelling currently relates to development of mathematical models to describe the aerodynamic forces and moments acting on the aircraft. It is a challenging part of aerodynamics that defines a comprehensive approach to using traditional methods and modern techniques to obtain relevant data. The most complicated task for the aerodynamics and flight dynamics is definition, computation and quantification of the aerodynamic description of an object. This paper presents how to determine the aerodynamic load on a gyrocopter and defines the effect on its stability and control. The first step to solution is to develop simpler approximate aerodynamic model - a model that can be used in analysis of aerodynamic load and can represent the aerodynamic properties of the gyrocopter with an acceptable degree of accuracy. Control and stability are very important parts of aircraft characteristics and therefore those characteristics were analyzed in simulation. Finally, the aerodynamic data outputs are assessed in terms of impact of aerodynamic loads on stability and control of the gyrocopter model.
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Shinde, Yash. "Dimples Effects on a Spoilers Aerodynamics". International Journal for Research in Applied Science and Engineering Technology 9, nr 8 (31.08.2021): 1851–68. http://dx.doi.org/10.22214/ijraset.2021.37674.
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Abstract: Over the evolution of automobiles, performance, mileage, and grip have dramatically improved. Nevertheless, there have been some improvements, but now the ideal design has been reached for design of engine, airflow & tires, & ergonomics. This means that even very small design improvements could result in high performance enhancements. As fuel is becoming more expensive, the need for improved aerodynamics is becoming more acute. Thus, the purpose of this paper is to examine the effect of golf-like dimples on the aerodynamic properties of a spoiler. As such, numerical calculations and computational fluid dynamics calculations were performed to investigate the impact on aerodynamics and turbulence spoilers with various surface roughness and angle of attack. Based on the recorded data, this test will provide the best information on the appropriate size for the dimple. The data collected on the test model will be used to calculate the drag coefficient, the downforce, and the wake produced at 56 m/s speed, at four different attack angles. Different sizes & depths of dimples will be used to improve the aerodynamics of spoilers, which will improve their downforce, drag force and wake formation. Keywords: spoiler, aerodynamics, dimples, downforce, aerodynamic forces
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Kamruzzaman, Md, Sushil Nepal i Mushfiq Al Arafa. "Aerodynamic Analysis of Micro Aerial Vehicle Rotor Blade at Low Reynolds Number". Asian Journal of Engineering and Applied Technology 10, nr 2 (5.11.2021): 1–10. http://dx.doi.org/10.51983/ajeat-2021.10.2.2953.
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The numerical simulation of micro aerial vehicle (MAV) rotor blade aerodynamics is highly challenging in the field of rotor aerodynamics. The aim of this paper is to present a computational fluid dynamics (CFD) study on the aerodynamics analysis of micro aerial vehicle rotor blade at low-Reynolds number by means of Spalart-Allmaras turbulence model. The KA152313 airfoil, which is dedicated to mid to small-scale rotorcraft, e.g. MAV is chosen to design the rotor blade. The rotor blade was investigated in three different pitch configurations, which are GP13º, GP12º and GP11º and the aerodynamics characteristics are analyzed respectively. The CFD results of the analysis is used to compare the aerodynamic characteristics, e.g. pressure force, shear force and pitching moment on the chord surface of the rotor blades at different pitch configurations.
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Anil, Mary, i Deepa Varkey. "Recent Progress in Aerodynamics for Aeroelastic Analysis". International Journal for Research in Applied Science and Engineering Technology 10, nr 6 (30.06.2022): 2890–93. http://dx.doi.org/10.22214/ijraset.2022.44475.
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Abstract: Aerodynamics has gained considerable popularity in the aerospace industry. Based on the characteristics of a structure, aerodynamic behavior varies from structure to structure. A reliable aeroelastic analysis requires accurate capture of aerodynamic forces. To produce accurate aerodynamic loads, it is necessary to develop an appropriate aerodynamic model. A review of various approaches to aerodynamic modeling for aeroelastic analysis of diverse wing configurations is presented in this paper. The study covers a wide range of finite element software platforms used in the aeroelastic analysis in various flow regimes.
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Wenhui, Yan, i Zhang Kun. "Effects of Stage Spacing on Contra-Rotating Propeller Aerodynamic Interactions". Journal of Physics: Conference Series 2478, nr 12 (1.06.2023): 122013. http://dx.doi.org/10.1088/1742-6596/2478/12/122013.
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Abstract To identify the law of aerodynamic interactions of contra-rotating propellers (CRPs) and improve their aerodynamics, this study investigates the aerodynamic interactions of 4 CRPs (six blades in front and six in back) with different stage spacings using the Reynolds-averaged Navier-Stokes (RANS) equations-based method. The results showed that the CRP whose stage spacing was 0.25 times the propeller diameter delivered the highest average efficiency and that the aerodynamic interactions between the front and rear propellers decreased as the spacing widened, and compared with the rear propeller, the front one was more sensitive to stage spacing due to the aerodynamic interaction-generated thrust fluctuations. It can be seen that stage spacing exerts a significant effect on CRP aerodynamic interactions. Therefore, choosing an appropriate stage spacing in CRP design is of great significance to enhance its aerodynamics.
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Wang, Jianfeng, Hao Li, Yiqun Liu, Tao Liu i Haibo Gao. "Aerodynamic research of a racing car based on wind tunnel test and computational fluid dynamics". MATEC Web of Conferences 153 (2018): 04011. http://dx.doi.org/10.1051/matecconf/201815304011.
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Wind tunnel test and computational fluid dynamics (CFD) simulation are two main methods for the study of automotive aerodynamics. CFD simulation software solves the results in calculation by using the basic theory of aerodynamic. Calculation will inevitably lead to bias, and the wind tunnel test can effectively simulate the real driving condition, which is the most effective aerodynamics research method. This paper researches the aerodynamic characteristics of the wing of a racing car. Aerodynamic model of a racing car is established. Wind tunnel test is carried out and compared with the simulation results of computational fluid dynamics. The deviation of the two methods is small, and the accuracy of computational fluid dynamics simulation is verified. By means of CFD software simulation, the coefficients of six aerodynamic forces are fitted and the aerodynamic equations are obtained. Finally, the aerodynamic forces and torques of the racing car travel in bend are calculated.
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Kafkas, Angelos, i George Lampeas. "Static Aeroelasticity Using High Fidelity Aerodynamics in a Staggered Coupled and ROM Scheme". Aerospace 7, nr 11 (17.11.2020): 164. http://dx.doi.org/10.3390/aerospace7110164.
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Current technology in evaluating the aeroelastic behavior of aerospace structures is based on the staggered coupling between structural and low fidelity linearized aerodynamic solvers, which has inherent limitations, although tried and trusted outside the transonic region. These limitations arise from the assumptions in the formulation of linearized aerodynamics and the lower fidelity in the description of the flowfield surrounding the structure. The validity of low fidelity aerodynamics also degrades fast with the deviation from a typical aerodynamic shape due to the inclusion of various control devices, gaps, or discontinuities. As innovative wings tend to become more flexible and also include a variety of morphing devices, it is expected that using low fidelity linearized aerodynamics in aeroelastic analysis will tend to induce higher levels of uncertainty in the results. An obvious solution to these issues is to use high fidelity aerodynamics. However, using high fidelity aerodynamics incurs a very high computational cost. Various formulations of reduced order models have shown promising results in reducing the computational cost. In the present work, the static aeroelastic behavior of three characteristic aeroelastic problems is obtained using both a full three-dimensional staggered coupled scheme and a time domain Volterra series based reduced order model (ROM). The reduced order model’s ability to remain valid for a wide range of dynamic pressures around a specific Mach number (and Reynolds number regime if viscous flow is considered) and the capability to modify structural parameters such as damping ratios and natural frequencies are highlighted.
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Hong, Sungchan, John Eric Goff i Takeshi Asai. "Effect of a soccer ball’s surface texture on its aerodynamics and trajectory". Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology 233, nr 1 (9.10.2018): 67–74. http://dx.doi.org/10.1177/1754337118794561.
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The effect of a soccer ball’s surface texture on its aerodynamics and flight trajectory is not definitively known. For this study, five soccer balls were used, each having 32 panels with different surface textures. Their aerodynamics were examined via wind-tunnel experiments and then several non-spin trajectories were calculated for each ball. The results showed that the aerodynamic forces acting on a soccer ball change significantly depending on the surface texture of the ball, which in turn influences flight trajectories. The study contributes to an understanding of how a soccer ball’s surface influences the aerodynamics, which may impact the future design and development of soccer balls.
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Chen, Senlin, i Zhenghong Gao. "Unsteady aerodynamics modeling using Volterra series expansed by basis function". MATEC Web of Conferences 198 (2018): 03002. http://dx.doi.org/10.1051/matecconf/201819803002.
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Unsteady aerodynamics modeling must accurately describe nonlinear aerodynamic characteristics in addition to unsteady aerodynamic characteristics. The Volterra series has attracted increasing attention as a powerful tool for nonlinear system modeling. It is essential to incorporate the influence of the second-order Volterra kernel or higher-order kernels to build a nonlinear unsteady aerodynamics model. The main difficulty in the identification of higher-order kernels is that the number of parameters to be identified increases exponentially with the order of a kernel. This paper expands the Volterra kernels with the four-order B-spline wavelet on the interval as the basis function, converts the problem into the solution of low-dimensional equations, and obtains a stable solution. A nonlinear unsteady aerodynamics model is built by identifying the second-order and third-order kernels of the lift, drag, and pitching moment coefficients of the NACA0012 airfoil. Then the model is verified at different reduced frequencies using CFD.
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MATSUMOTO, M., N. SHIRAISHI, M. KITAZAWA, C. KNISELY, H. SHIRATO, Y. KIM i M. TSUJII. "Aerodynamic Behavior of Inclined Circular Cylinders-Cable Aerodynamics". Wind Engineers, JAWE 1988, nr 37 (1988): 103–12. http://dx.doi.org/10.5359/jawe.1988.37_103.
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Matsumoto, M., N. Shiraishi, M. Kitazawa, C. Knisely, H. Shirato, Y. Kim i M. Tsujii. "Aerodynamic behavior of inclined circular cylinders-cable aerodynamics". Journal of Wind Engineering and Industrial Aerodynamics 33, nr 1-2 (marzec 1990): 63–72. http://dx.doi.org/10.1016/0167-6105(90)90021-4.
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Eskandary, Keivan, Morteza Dardel, Mohammad Hadi Pashaei i Abdol Majid Kani. "Effects of Aeroelastic Nonlinearity on Flutter and Limit Cycle Oscillations of High-Aspect-Ratio Wings". Applied Mechanics and Materials 110-116 (październik 2011): 4297–306. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.4297.
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In this study aeroelastic characteristics of long high aspect ratio wing models with structural nonlinearities in quasi-steady aerodynamics flows are investigated. The studied wing model is a cantilever wing with double bending and torsional vibrations and with large deflection ability in according to Dowell-Hodges wing model. This wing model is valid for long, straight and thin homogeneous isotropic beams. Aerodynamics model is based on quasi-steady aerodynamic which is valid for aerodynamic flows in low velocity and without wake, viscosity and compressibility effects. The effect of different parameters such as mass ratios and stiffness ratios on flutter and divergence velocities and limit cycle oscillation amplitudes are carefully studied.
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Unitsky, Anatoli E., Sergey V. Artyushevsky, Vladimir V. Goncharov i Michael I. Tsyrlin. "Aerodynamic optimization of high-speed unimobile of string transport by Unitsky". Innotrans, nr 3 (2022): 3–11. http://dx.doi.org/10.20291/2311-164x-2022-3-3-11.
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The paper describes technical solutions aimed at improving the aerodynamics of vehicles; the engineering specifics of high-speed models of the vehicles of the string transport by Unitsky (uST), their advantages in aerodynamics and ergonomics are presented; the design of unimobile (steel wheeled electric rail car) is proposed, which ensures the configuration of the wheeled vehicle of uST with advanced aerodynamic characteristics and having improved dynamic stability; the methods of analysis of optimal dimensions of the main elements of the unimobile are indicated. The presented data were proven by the results of aerodynamic tests. The results of the research constitute the foundation for the elaboration of the high-speed unimobile - uniflash.
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Poddaeva, Olga Igorevna, i Ilya Vladimirovich Dunichkin. "ARCHITECTURAL-BUILDING AERODYNAMICS". Vestnik MGSU, nr 6 (czerwiec 2017): 602–9. http://dx.doi.org/10.22227/1997-0935.2017.6.602-609.
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This article gives a brief historical digression about the formation of architectural and building aerodynamics as a separate branch of the construction science. The main methods and approaches to the solution of problems of architectural and building aerodynamics are listed; the classification of problems of aerodynamics of structural steel according to the studied objects is given; main peculiarities of the research in selected areas are briefly indicated. The aim of the work is to systematize existing approaches to assessing wind impact on structural steel taking into account some modern international requirements, as well as to choose the optimal method for solving this problem in relation to various structural steel. It is established that, currently, the study about wind impact is especially important for high-rise buildings, structures, and structural steel nonresistant to dynamic loads (long span bridge conduits, gins polarized, thin-shell tubes, etc.), as well as for residential estates with restrained urban conditions. It is necessary to carry-out these aerodynamic studies at the designing stage for the above objects because it is directly related to the issues of reliability and safety.
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Xiang, Jinwu, Kai Liu, Daochun Li, Chunxiao Cheng i Enlai Sha. "Unsteady aerodynamic characteristics of a morphing wing". Aircraft Engineering and Aerospace Technology 91, nr 1 (7.01.2018): 1–9. http://dx.doi.org/10.1108/aeat-04-2017-0101.
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Purpose The purpose of this paper is to investigate the unsteady aerodynamic characteristics in the deflection process of a morphing wing with flexible trailing edge, which is based on time-accurate solutions. The dynamic effect of deflection process on the aerodynamics of morphing wing was studied. Design/methodology/approach The computational fluid dynamic method and dynamic mesh combined with user-defined functions were used to simulate the continuous morphing of the flexible trailing edge. The steady aerodynamic characteristics of the morphing deflection and the conventional deflection were studied first. Then, the unsteady aerodynamic characteristics of the morphing wing were investigated as the trailing edge deflects at different rates. Findings The numerical results show that the transient lift coefficient in the deflection process is higher than that of the static case one in large angle of attack. The larger the deflection frequency is, the higher the transient lift coefficient will become. However, the situations are contrary in a small angle of attack. The periodic morphing of the trailing edge with small amplitude and high frequency can increase the lift coefficient after the stall angle. Practical implications The investigation can afford accurate aerodynamic information for the design of aircraft with the morphing wing technology, which has significant advantages in aerodynamic efficiency and control performance. Originality/value The dynamic effects of the deflection process of the morphing trailing edge on aerodynamics were studied. Furthermore, time-accurate solutions can fully explore the unsteady aerodynamics and pressure distribution of the morphing wing.
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Wang, Xu, Yuanhao Qian, Zengshun Chen, Xiao Zhou, Huaqiang Li i Hailin Huang. "Numerical studies on aerodynamics of high-speed railway train subjected to strong crosswind". Advances in Mechanical Engineering 11, nr 11 (listopad 2019): 168781401988727. http://dx.doi.org/10.1177/1687814019887270.
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Under the action of strong crosswind, the aerodynamic behavior of a rail vehicle at high speed will be changed significantly, which could directly affect the safe operation of the vehicle. With the help of the shape of train used in China, the aerodynamic characteristics of trains with scale of 1:1 is investigated using computational fluid dynamics numerical simulation method, which consists of the variation of aerodynamics force and moment with wind yaw angle, wind speed, train speed, and nose shape. After an initial validation against Baker’s results from wind tunnel test, the numerical model is then used to investigate the aerodynamic characteristics of the trains. The numerical results indicate that lift coefficient of the M train is slightly higher than TMC1 and TMC2 trains. Regardless of aerodynamics force coefficients, TMC1 reaches the maximum at a yaw angle of 75°. Aerodynamics force coefficient increases with both wind speed and train speed, but the change of which is not linear. Comparing aerodynamic force with different geometric dimensions of train nose, it is shown that height–width ratio is insensitive to side force and rolling moment, but sensitive to lift force from the yaw angle 0°–90°. The side force coefficient, as we most concern, is less than other results, when the length–width ratio is 1 and height–width is 0.87.
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Lv, Shi Liang, Ya Sheng Jin i Xin Rui Chen. "Speech Aerodynamics Parameter Extraction Platform". Applied Mechanics and Materials 568-570 (czerwiec 2014): 238–42. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.238.
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The speech aerodynamics signal is one of the most important physiological signal in language research, plays an important role in human phonation process. Recently, there are a lot of equipment for speech aerodynamics signal research, mainly used in the field of medical research. But the supporting software can't satisfy the need of phonetics research. In this paper, according to the need of phonetics research, through the analysis of signal to KAYPENTAX speech aerodynamic devices, and used the MATLAB programming to establish the analysis platform to extracting parameters. The platform can read the NSP format file and output relevant parameters.
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ILIE, Marcel, i Augustin Semenescu. "COMPUTATIONAL STUDIES OF HELICOPTER AERODYNAMICS". Annals of the Academy of Romanian Scientists Series on Engineering Sciences 15, nr 1 (2023): 54–64. http://dx.doi.org/10.56082/annalsarscieng.2023.1.54.
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The present research concerns the helicopter aerodynamics and the blade-vortex interaction phenomenon. The computational studies are carried out using the large-eddy simulation approach for subsonic incompressible flow of Reynolds number Re=1.3x106. The helicopter aerodynamics is dominated by the blade-vortex interaction (BVI) phenomenon which is responsible for noise and vibrations. During the helicopter flight, a tip-vortex filament is formed and its interaction with the advancing blade causes the blade-vortex interaction phenomenon. The study shows that the blade-vortex interaction causes oscillations of the aerodynamic coefficients. Due to the turbulence phenomenon, the oscillations exhibit a non-linear behaviour.
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Guerrero, Alex, i Robert Castilla. "Aerodynamic Study of the Wake Effects on a Formula 1 Car". Energies 13, nr 19 (5.10.2020): 5183. http://dx.doi.org/10.3390/en13195183.
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The high complexity of current Formula One aerodynamics has raised the question of whether an urgent modification in the existing aerodynamic package is required. The present study is based on the evaluation and quantification of the aerodynamic performance on a 2017 spec. adapted Formula 1 car (the latest major aerodynamic update) by means of Computational Fluid Dynamics (CFD) analysis in order to argue whether the 2022 changes in the regulations are justified in terms of aerodynamic necessities. Both free stream and flow disturbance (wake effects) conditions are evaluated in order to study and quantify the effects that the wake may cause on the latter case. The problem is solved by performing different CFD simulations using the OpenFoam solver. The significance and originality of the research may dictate the guidelines towards an overall improvement of the category and it may set a precedent on how to model racing car aerodynamics. The studied behaviour suggests that modern F1 cars are designed and well optimised to run under free stream flows, but they experience drastic aerodynamic losses (ranging from −23% to 62% in downforce coefficients) when running under wake flows. Although the overall aerodynamic loads are reduced, there is a fuel efficiency improvement as the power that is required to overcome the drag is smaller. The modern performance of Ground Effect by means of vortices management represent a very unique and complex way of modelling modern aerodynamics, but at the same time notably compromises the performance of the cars when an overtaking maneuver is intended.
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Capece, V. R., i S. Fleeter. "Experimental Investigation of Multistage Interaction Gust Aerodynamics". Journal of Turbomachinery 111, nr 4 (1.10.1989): 409–17. http://dx.doi.org/10.1115/1.3262288.
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The fundamental flow physics of multistage blade row interactions are experimentally investigated at realistic reduced frequency values. Unique data are obtained that describe the fundamental unsteady aerodynamic interaction phenomena on the stator vanes of a three-stage axial flow research compressor. In these experiments, the effect on vane row unsteady aerodynamics of the following are investigated and quantified: (1) steady vane aerodynamic loading; (2) aerodynamic forcing function waveform, including both the chordwise and transverse gust components; (3) solidity; (4) potential interactions; and (5) isolated airfoil steady flow separation.
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Fakhruddin, Muhammad, Hangga Wicaksono, Fauzan Baananto, Hilmi Iman Firmansyah, Nurlia Pramita Sari, Mochamad Muzaki, Khelvindra Rizky Akbarsyah D i Noveri Dwi Hardyanto. "OPTIMASI AERODINAMIKA BODI MOBIL HEMAT ENERGI KEN DEDES ELECTRIC EVO 3 MENGGUNAKAN METODE COMPUTATIONAL FLUID DYNAMICS (CFD)". Eksergi 17, nr 1 (24.01.2021): 36. http://dx.doi.org/10.32497/eksergi.v17i1.2219.
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Aerodynamics is a branch of science that discusses the movement of an object in the air. Aerodynamics comes from the words aero = air and dynamics = force of motion. The study of air forces is a branch of fluid mechanics. This study is a continuation of the study of hydrodynamics, where the science of the motion of air has a close relationship with other sciences. Physics, mathematics, mechanics, meteorology and others are branches of science that are closely related to aerodynamics. Where in the science of aerodynamics, it discusses the principle of stationary air, specifically about the changes experienced by the air when there is a change in geometry. In this study, CFD analysis was carried out to inspect and optimize the airflow through the energy-efficient car body "Ken dedes Evo 3" Malang State Polytechnic to participate in energy-efficient car competitions by following the regulations and packaging requirements in energy-efficient car contests. The aerodynamic analysis of the energy-efficient car was carried out using the ANSYS simulation software. This aerodynamic research aims to reduce the drag coefficient and lift coefficient of energy-efficient cars. In the end, the energy-efficient car Ken Dedes Electric Evo 3 has an improved drag coefficient of 0.03 and a lift coefficient of 0.034. This is obtained from the simulation only on the car body.
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Cicolani, L. S., J. G. A. da Silva, E. P. N. Duque i M. B. Tischler. "Unsteady aerodynamic model of a cargo container for slung-load simulation". Aeronautical Journal 108, nr 1085 (lipiec 2004): 357–68. http://dx.doi.org/10.1017/s0001924000005170.
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Abstract The problem of simulation models capable of predicting the aerodynamic instability of helicopter slung-load cargo containers and bluff bodies is addressed. Instability for these loads is known to depend on unsteady frequency-dependent aerodynamics, but simulation models that include the unsteady aerodynamics do not currently exist. This paper presents a method for generating such models using computational fluid dynamics (CFD) to generate forced-oscillation aerodynamic data and frequency domain system identification techniques to generate a frequency response from the CFD data and to identify a transfer function fit to the frequency response. The method is independent of the responsible flow phenomenon and is expected to apply to bluff-bodies generally. Preliminary results are presented for the case of the 6- by 6- by 8-ft CONEX (container express) cargo container. The present work is based on two-dimensional (2D) aerodynamic data for the CONEX side force and yaw moment generated by a forced oscillation in which frequency is varied smoothly over the range of interest. A first-order rational polynomial transfer function is found adequate to fit the aerodynamics, and this is shown to provide a good match with flight test data for the yawing motion of the CONEX.
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Chung, Wei-Li, Kuo-Cheng Liu, Hsiu-Feng Chuang, Yi-An Lu, Hsueh-Yu Li, Alice M. K. Wong, Yu-Cheng Pei i Tuan-Jen Fang. "Aerodynamic Performance and Neuromuscular Control in Patients with Unilateral Vocal Fold Paralysis". Diagnostics 12, nr 12 (11.12.2022): 3124. http://dx.doi.org/10.3390/diagnostics12123124.
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Unilateral vocal fold paralysis (UVFP) causes glottal incompetence and poor vocal efficiency. The influence of laryngeal neuromuscular control on aerodynamics in UVFP remains unclear. This study investigated the relationship between laryngeal muscle activities using quantitative laryngeal electromyography (LEMG) and aerodynamics in UVFP. This prospective study recruited patients with UVFP, and the diagnosis was confirmed with videolaryngostroboscopy and LEMG. The patient received aerodynamic assessment and LEMG of the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex and the cricothyroid (CT) muscle. The relationship between quantitative LEMG and aerodynamic parameters was analyzed. A total of 134 UVFP patients without concurrent CT muscle involvement were enrolled. Compared with the normal side, the peak turn frequency of the lesioned side was lower in the TA-LCA (p < 0.001) and CT (p = 0.048) muscles. Stepwise linear regression revealed that the turn ratio of TA-LCA muscles was a robust factor in the decrease in peak expiratory airflow (β = −0.34, p = 0.036), mean airflow during voicing (β = −0.28, p = 0.014), and aerodynamic power (β = −0.42, p = 0.019), and an increase in aerodynamic efficiency (β = 27.91, p = 0.012). In addition, the turn ratio of CT muscles was a potent factor in inducing an increase in aerodynamic resistance (β = 14.93, p = 0.029). UVFP without CT involvement still showed suppression of CT muscles on the lesioned side, suggesting that neurological impairment of the TA-LCA complex could cause asymmetrical compensation of CT muscles, further impeding aerodynamics. The residual function of TA-LCA muscle complexes facilitates less air leakage and power dissipation, enhancing aerodynamic efficiency. On the other hand, the symmetrical compensation of the CT muscles improves aerodynamic resistance.
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Qi, Xiaojing, Yuxin Ou, Hance Zhang i Da Wang. "Efficiency Enhancement Design Approach in the Side Wing of a FSAE Car Utilizing a Shutter-Like Fairing Structure". Applied Sciences 12, nr 13 (28.06.2022): 6552. http://dx.doi.org/10.3390/app12136552.
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Aerodynamical design is one of the critical technologies in race car engineering, and favorable race car aerodynamics is supposed to provide sufficient negative lift force and keep the center of pressure in the vicinity of center of mass. Taking the Formula Society of Automotive Engineers (FSAE) cars as an example, side wing structure is frequently adopted for better grip in the mid-back of short wheelbase, open wheel race cars. This research designs a shutter-like fairing structure and utilizes it to weaken the vorticity and reinforce the pressure of side wing flow field. The sensitivity of side wing aerodynamic efficiency to shutters’ key parameters is analyzed, and optimized shutters’ key parameters for a prototype FSAE race car are obtained through computational fluid dynamics simulations. Results indicate that over 10% enhancement in side wing aerodynamic efficiency can be achieved by applying optimized shutters.
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Musa, Mohamad Nor, Samion Syahrullail i Fairuz Zainal Abidin. "Aerodynamic Analysis on Proton Preve by Experimental". Applied Mechanics and Materials 773-774 (lipiec 2015): 575–79. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.575.
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The purpose of this study is to determine the coefficient drag, CD of the Proton PREVẾ by experimental method using Low Speed Wind Tunnel. All the relevant data are collected through the literature reviews from books and journals. First, the basic thing in aerodynamic is studied. There are two things are concern when studies aerodynamics. They were air flow and vehicle shape which we regard as aerodynamics factor that determine aerodynamic of the vehicle. Fundamental of air flow and vehicle shape is reviewed includes the relationship between air speed with pressure, boundary layer, Reynolds number, drag, lift drag and shape optimization. Wind tunnel is also studied before the experiment. Five selected speed were been tasted during the experiment to determine the CD value.
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Deng, Yong Quan, Tian Li, Yi Sheng Zou, Ji Ye Zhang i Wei Hua Zhang. "Equilibrium Characteristics of High-Speed Train in Crosswind". Applied Mechanics and Materials 275-277 (styczeń 2013): 532–36. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.532.
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A fast approach to high-speed train co-simulation between aerodynamics and train-track coupling dynamics is presented. With this method, the fluid-structure dynamic performances of a high-speed train are simulated with different crosswind velocity and train velocity. The aerodynamic forces and train dynamics are compared under off-line simulation and equilibrium state method. Considering the fluid-structure interaction, there is significant influence on the head aerodynamics and train dynamics. The results show that it is necessary to consider changing attitude in crosswind
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Chen, Jian Zhong, i Pei Qing Liu. "Test Technique Research for the Hinge Moment of a Grid Fin in High Speed Wind Tunnel". Applied Mechanics and Materials 574 (lipiec 2014): 480–84. http://dx.doi.org/10.4028/www.scientific.net/amm.574.480.
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In order to study the test technique for the hinge moment of a grid fin in wind tunnel, a platform based on half model support technique was established in FL-23 and FL-31 wind tunnel in China Aerodynamics Research & Development Center (CARDC). The platform developed a wind tunnel test balance, rudder control system and the aerodynamics measurement system. This test technique was important to optimize aerodynamic configurations of a grid fin, design or evaluate the capability of the rudder control system. Nomenclature
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Wu, Jiarong, i Yiding Wen. "Methods on Adjusting Vehicle’s Shape to Control Air Resistance". Highlights in Science, Engineering and Technology 13 (21.08.2022): 14–20. http://dx.doi.org/10.54097/hset.v13i.1310.
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Wind resistance is usually expressed by the following formula. Fx＝ CdAρv^2 /2. Where Cd is a constant. And A is the contact area between air and car. ρ is air density. v is the velocity. Because of the complex structure, mostly a very specific and accurate model cannot be obtained directly. Instead, engineers will use wind tunnel test to get a practical drag coefficient of a car. In the actual analysis, the influence of wind resistance cannot be ignored in the car dynamic system. Wind resistance is the main factor to counteract traction in the process of high-speed driving. Knowledge and literature about aerodynamics of vehicle is abundant in the world. However, this knowledge is not directly related to car design. Engineers empirically design vehicles in the perspective of aerodynamics based on what they have learnt. This paper will put forward some suggestions on vehicle structure according to the practical application of various aerodynamics. It will simultaneously emphasize how the knowledge in the literature is related to the car design in reality. Engineers can design vehicles combining with aerodynamic theory. In recent years, wedge-shaped vehicles have become the mainstream of design, which is the result of the pursuit of low wind resistance and higher stability. The streamlined body shape conforms to both aerodynamics and mainstream aesthetics. Improving speed and safety while saving energy is the most intuitive manifestation of aerodynamic application in vehicle field.
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Jahn, Ingo, i Peter Jacobs. "Using Meridional Streamline and Passage Shapes to Generate Radial Turbomachinery Geometry and Meshes". Applied Mechanics and Materials 846 (lipiec 2016): 1–6. http://dx.doi.org/10.4028/www.scientific.net/amm.846.1.
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An important aspect for structural and aerodynamics design of radial flow turbomachinery is the definition of the geometry and the generation of meshes for computational analysis. Particularly in the area of computational design and optimization, the way the geometry is defined is important, as it can limit design space. Traditionally, radial compressors and radial turbine rotors are defined using a mechanical design approach. Effectively a hub and shroud profile, followed by a rotorblade geometry are defined and the shape is adjusted in order to meet certain aerodynamic boundary conditions. The current paper presents an alternative approach, in which the overall geometry is defined starting from an aerodynamic requirement. The corresponding rotor and blade geometry is generated automatically, based on certain constraints. The advantage of this approach is the ability to define directly the aerodynamic requirements, which may allow a simpler efficient optimization of the aerodynamics.
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Shen, Xin, Ping Hu, Jinge Chen, Xiaocheng Zhu i Zhaohui Du. "The unsteady aerodynamics of floating wind turbine under platform pitch motion". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, nr 8 (29.03.2018): 1019–36. http://dx.doi.org/10.1177/0957650918766606.
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The aerodynamic performance of floating platform wind turbines is much more complex than fixed-base wind turbines because of the flexibility of the floating platform. Due to the extra six degrees-of-freedom of the floating platform, the inflow of the wind turbine rotors is highly influenced by the motions of the floating platform. It is therefore of interest to study the unsteady aerodynamics of the wind turbine rotors involved with the interaction of the floating platform induced motions. In the present work, a lifting surface method with a free wake model is developed for analysis of the unsteady aerodynamics of wind turbines. The aerodynamic performance of the NREL 5 MW floating wind turbine under the prescribed floating platform pitch motion is studied. The unsteady aerodynamic loads, the transient of wind turbine states, and the instability of the wind turbine wakes are discussed in detail.
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Wiński, Krzysztof, i Adam Piechna. "Comprehensive CFD Aerodynamic Simulation of a Sport Motorcycle". Energies 15, nr 16 (15.08.2022): 5920. http://dx.doi.org/10.3390/en15165920.
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Nowadays, aerodynamics is a key focal point in the vehicle design process. Beyond its direct impact on the performance of a vehicle, it also has significant effects on economics and safety. In the last decade numerical methods, mainly Computational Fluid Dynamics (CFD), have established themselves as a reliable tool that assists in the design process and complements classical tunnel tests. However, questions remain about the possible obtained accuracy, best practices and applied turbulence models. In this paper, we present a comprehensive study of motorcycle aerodynamics using CFD methods which, compared to the most common car aerodynamics analysis, has many specific features. The motorcycle, along with its rider, constitutes a shape with very complex aerodynamic properties. A detailed insight into the flow features is presented with detailed commentary. The front fairing, the front wheel and its suspension were identified as the main contributors to the aerodynamic drag of the motorcycle and its rider. The influence of rider position was also studied and identified as one of the most important elements when considering motorcycle aerodynamics. An extensive turbulence models study was performed to evaluate the accuracy of the most common Reynolds-averaged Navier–Stokes models and novel hybrid models, such as the Scale Adaptive Simulation and the Delayed Detached Eddy Simulation. Similar values of drag coefficients were obtained for different turbulence models with noticeable differences found for k−ϵ models. It was also observed that near-wall treatment affects the flow behaviour near the wheels and windshield but has no impact on the global aerodynamic parameters. In the summary, a discussion about the obtained results was set forth and a number of questions related to specifics of motorcycle CFD simulations were addressed.
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Korolev, E. V., R. R. ZHamalov i V. V. Bernackij. "Age of aerodynamics of automobiles". Izvestiya MGTU MAMI 12, nr 3 (15.09.2018): 40–50. http://dx.doi.org/10.17816/2074-0530-66833.
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The article analyzes the time variation of the values of the coefficient Cx and the aerodynamic factor for passenger vehicles of leading companies. Calculated equations of aerodynamic indexes are presented, both for the whole array of automobiles and for breaking them into classes according to the European classification. The analysis uses aerodynamic indicators of the main types of bodies of vehicles obtained both during road tests and in experiments in wind tunnels with full-scale objects. Examples are given of the discrepancy between aerodynamic indicators and the results of the correlation studies of automobiles produced under different conditions, in different wind tunnels and its comparison with road tests. The reasons for these discrepancies are indicated. Examples are given of the change in aerodynamic indicators from the time of the release of generations of some brands of automobiles. The best and worst vehicles in aerodynamics for all six classes of European classification are indicated. The novelty is the determination of the regularity of the change in aerodynamic parameters, in particular of the aerodynamic factor, for the whole period of development of motorization, which requires the use of a large data set. The results of the analysis are also given. The result of the analysis is the conclusion that the amount of the aerodynamic factor of passenger vehicles is decreasing for the whole time of automobilization with a change in the external form of the body.
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Xie, Dan, Min Xu, Honghua Dai i Tao Chen. "New Look at Nonlinear Aerodynamics in Analysis of Hypersonic Panel Flutter". Mathematical Problems in Engineering 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/6707092.
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A simply supported plate fluttering in hypersonic flow is investigated considering both the airflow and structural nonlinearities. Third-order piston theory is used for nonlinear aerodynamic loading, and von Karman plate theory is used for modeling the nonlinear strain-displacement relation. The Galerkin method is applied to project the partial differential governing equations (PDEs) into a set of ordinary differential equations (ODEs) in time, which is then solved by numerical integration method. In observation of limit cycle oscillations (LCO) and evolution of dynamic behaviors, nonlinear aerodynamic loading produces a smaller positive deflection peak and more complex bifurcation diagrams compared with linear aerodynamics. Moreover, a LCO obtained with the linear aerodynamics is mostly a nonsimple harmonic motion but when the aerodynamic nonlinearity is considered more complex motions are obtained, which is important in the evaluation of fatigue life. The parameters of Mach number, dynamic pressure, and in-plane thermal stresses all affect the aerodynamic nonlinearity. For a specific Mach number, there is a critical dynamic pressure beyond which the aerodynamic nonlinearity has to be considered. For a higher temperature, a lower critical dynamic pressure is required. Each nonlinear aerodynamic term in the full third-order piston theory is evaluated, based on which the nonlinear aerodynamic formulation has been simplified.
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Ye, Ruiqi, Ziming Liu, Jin Cui, Chenyang Wang i Yirong Wu. "Aerodynamic Analysis of Hovering Flapping Wing Using Multi-Plane Method and Quasi-Steady Blade Element Theory". Applied Sciences 14, nr 10 (17.05.2024): 4258. http://dx.doi.org/10.3390/app14104258.
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In the design of flapping-wing micro-size air vehicles capable of hovering, wings serve as the primary source of hovering power, making the analysis of aerodynamics and aerodynamic efficiency crucial. Traditional quasi-steady models treat the wings as single rigid plane, neglecting the deformable characteristics of flexible wings. This paper proposes a multi-plane method that, in conjunction with various design parameters of flexible wings in a two-dimensional plane, analyzes their deformation characteristics under the assumption of multiple planes in three-dimensional space, and describes the deformation of wings during flapping. By combining the quasi-steady aerodynamic model, aerodynamic analysis of the deformed wings can be conducted. The relationship between the slack angle, wing flapping position, and wing deformation are analyzed, along with their effects on aerodynamics and aerodynamic efficiency. Experiments validate the deformation patterns of wings during flapping and compare the simulated aerodynamic forces with measured ones. The results indicate that wing deformation can be accurately described by adjusting the parameters in the multi-plane method and that the aerodynamic analysis using this method closely approximates the average lift results. Additionally, the multi-plane method establishes a connection between wing morphology and aerodynamic forces and efficiency, providing valuable insights for aerodynamic analysis.
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Duncan, Bradley, Luca D’Alessio, Joaquin Gargoloff i Ales Alajbegovic. "Vehicle aerodynamics impact of on-road turbulence". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, nr 9 (10.04.2017): 1148–59. http://dx.doi.org/10.1177/0954407017699710.
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The ultimate target for vehicle aerodynamicists is to develop vehicles that perform well on the road in real-world conditions. On the other hand, vehicle development today is performed mostly in controlled settings, using wind tunnels and computational fluid dynamics with artificially uniform freestream conditions and neglecting real-world effects due to road turbulence from the wind and other vehicles. Turbulence on the road creates a non-uniform and fluctuating flow field in which the length scales of the fluctuations fully encompass the length scales of the relevant aerodynamic flow structures around the vehicle. These fluctuations can be comparable in size and strength with the vehicle’s own wake oscillations. As a result, this flow environment can have a significant impact on the aerodynamic forces and on the sensitivity of these forces to various shape changes. Some aerodynamic devices and integral design features can perform quite differently from the way in which they do under uniform freestream conditions. In this paper, unsteady aerodynamics simulations are performed using the lattice Boltzmann method on a detailed representative automobile model with several design variants, in order to explore the effect of on-road turbulence on the aerodynamics and the various mechanisms that contribute to these effects.
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Zhang, Zhe, Qiang Wang, Shida Song, Chengchun Zhang, Luquan Ren i Yingchao Zhang. "Joint Research on Aerodynamic Characteristics and Handling Stability of Racing Car under Different Body Attitudes". Energies 15, nr 1 (5.01.2022): 393. http://dx.doi.org/10.3390/en15010393.
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With the rapid development of FSAE, the speed of racing cars has increased year by year. As the main research content of racing cars, aerodynamics has received extensive attention from foreign teams. For racing cars, the aerodynamic force on the aerodynamic device ultimately acts on the tires through the transmission of the body and the suspension. When the wheel is subjected to the vertical load generated by the aerodynamic device, the ultimate adhesion capacity of the wheel is improved. Under changing conditions, racing wheels can withstand greater lateral and tangential forces. Therefore, the effects of aerodynamics have a more significant impact on handling stability. The FSAE racing car of Jilin University was taken as the research object, and this paper combines the wind tunnel test, the numerical simulation and the dynamics simulation of the racing system. The closed-loop design process of the aerodynamics of the FSAE racing car was established, and the joint study of aerodynamic characteristics and handling stability of racing car under different body attitudes was realized. Meanwhile, the FSAE car was made the modification of aerodynamic parameter on the basis of handling stability. The results show that, after the modification of the aerodynamic parameters, the critical speed of the car when cornering is increased, the maneuverability of the car is improved, the horoscope test time is reduced by 0.525 s, the downforce of the car is increased by 11.39%, the drag is reduced by 2.85% and the lift-to-drag ratio is increased by 14.70%. Moreover, the pitching moment is reduced by 82.34%, and the aerodynamic characteristics and aerodynamic efficiency of the racing car are obviously improved. On the basis of not changing the shape of the body and the aerodynamic kit, the car is put forward to shorten the running time of the car and improve the comprehensive performance of the car, so as to improve the performance of the car in the race.