Статті в журналах з теми "Aerodynamic angle"
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1
Tripathi, Manish, Mahesh M. Sucheendran, and Ajay Misra. "Experimental analysis of cell pattern on grid fin aerodynamics in subsonic flow." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 3 (September 5, 2019): 537–62. http://dx.doi.org/10.1177/0954410019872349.
Повний текст джерелаАнотація:
Grid fins consisting of a lattice of high aspect ratio planar members encompassed by an outer frame are unconventional control surfaces used on numerous missiles and bombs due to their enhanced lifting characteristics at high angles of attack and across wider Mach number regimes. The current paper accomplishes and compares the effect of different grid fin patterns on subsonic flow aerodynamics of grid fins by virtue of the determination of their respective aerodynamic forces. Furthermore, this study deliberates the impact of gap variation on aerodynamics of different patterns. Results enunciate enhanced aerodynamic efficiency, and lift slope for web-fin cells and single diamond patterns compared to the baseline model. Moreover, the study indicates improved aerodynamic performance for diamond patterns with higher gaps by providing elevated maximum lift coefficient, delayed stall angle, and comparable drag at lower angles. The study established the presence of an additional effect termed as the inclination effect alongside the cascade effect leading to deviations with respect to lift, stall, and aerodynamic efficiency amongst different gap variants of the individual patterns. Thus, optimization based on the aerodynamic efficiency, stall angle requirements, and construction cost by optimum pattern and gap selection can be carried out through this analysis, which can lead to elevated aerodynamic performance for grid fins.
2
Sun, Xiao-Ying, Tian-E. Li, Guo-Chang Lin, and Yue Wu. "A study on the aerodynamic characteristics of a stratospheric airship in its entire flight envelope." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 5 (August 2, 2017): 902–21. http://dx.doi.org/10.1177/0954410017723358.
Повний текст джерелаАнотація:
Aerodynamic characteristics of a stratospheric airship in its entire flight envelope, including take-off, ascending, cruising, descending, and landing, is an important part of its research topic. In this paper, experiments of wind pressure measurement on a 1/30-scale stratospheric airship model were carried out to obtain a better assessment of the aerodynamic characteristics during the cruising process. Based on the wind pressure distribution, the effects of pitch angle, yaw angle, and combined angles (pitch angle and yaw angle acted simultaneously) on the aerodynamics of the airship were analyzed. In addition, the contributions of different portions of the airship hull (namely head, middle, and tail) to the aerodynamic forces and moments were discussed. The experimental results imply that the tail portion is the main contributor to pressure drag force. The combined angles significantly increase aerodynamic forces and rolling moment, and the rolling moment produced by the middle portion accounts for the major proportion. Secondly, the computational fluid dynamics method was verified and employed to study the aerodynamic characteristics of the full-scale model in its entire flight envelope based on the decision of the wind environment parameters and attitude. As a main result, it can be concluded that, more attention should be paid to the airship when it is located in the troposphere and near the ground with an inclined take-off angle.
3
Taiming, Huang, Zhuang Xiaodong, Wan Zhongmin, and Gu Zhengqi. "Experimental and numerical investigations of the vehicle aerodynamic drag with single-channel rear diffuser." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 8 (February 7, 2020): 2216–27. http://dx.doi.org/10.1177/0954407019893849.
Повний текст джерелаАнотація:
The main purpose of this paper is to reveal the drag reduction mechanism of single-channel rear diffuser on the vehicle aerodynamic drag and to obtain the relationship between the structure parameters of rear diffuser and the vehicle aerodynamic drag. The influence of the single-channel rear diffuser on the aerodynamic drag is studied using the Reynolds-averaged method with the 25° slant Ahmed model. The accuracy of the numerical method is validated by means of a wind tunnel test. The aerodynamic performance of the Ahmed model with different vertical diffuser angles, lateral diffuser angles, and channel widths is discussed. The results demonstrate that the vortex location will be influenced by the vertical diffuser angle, and with the vortex core approaching to the model, the aerodynamic drag will increase. The aerodynamic drag reaches the minimum value with a vertical diffuser angle of 10.46°. Moreover, the aerodynamic drag decreases with increasing channel width. Finally, the aerodynamic drag can be reduced by 5.3%, when the vertical diffuser angle, lateral diffuser angle, and channel width are 10.46°, 0°, and 351 mm, respectively.
4
Baigang, Mi, and Yu Jingyi. "An Improved Nonlinear Aerodynamic Derivative Model of Aircraft at High Angles of Attack." International Journal of Aerospace Engineering 2021 (September 8, 2021): 1–12. http://dx.doi.org/10.1155/2021/5815167.
Повний текст джерелаАнотація:
The classical aerodynamic derivative model is widely used in flight dynamics, but its application is extremely limited in cases with complicated nonlinear flows, especially at high angles of attack. A modified nonlinear aerodynamic derivative model for predicting unsteady aerodynamic forces and moments at a high angle of attack is developed in this study. We first extend the higher-order terms to describe the nonlinear characteristics and then introduce three more influence parameters, the initial angle of attack, the reduced frequency, and the oscillation amplitude, to correct the constant aerodynamic derivative terms that have higher-order polynomials for these values. The improved nonlinear aerodynamic derivative model was validated by using the NACA 0015 airfoil and the F-18 model. The results show that the improved model has a higher prediction ability at high angles of attack and has the ability to predict the aerodynamic characteristics of other unknown states based on known unsteady aerodynamic data, such as the initial angle of attack, reduced frequency, and oscillation amplitude.
5
Xiang, Jinwu, Kai Liu, Daochun Li, Chunxiao Cheng, and Enlai Sha. "Unsteady aerodynamic characteristics of a morphing wing." Aircraft Engineering and Aerospace Technology 91, no. 1 (January 7, 2018): 1–9. http://dx.doi.org/10.1108/aeat-04-2017-0101.
Повний текст джерелаАнотація:
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.
6
Hu, Haode, and Dongli Ma. "Airfoil Aerodynamics in Proximity to Wavy Ground for a Wide Range of Angles of Attack." Applied Sciences 10, no. 19 (September 27, 2020): 6773. http://dx.doi.org/10.3390/app10196773.
Повний текст джерелаАнотація:
Wing-in-ground craft often encounter waves when flying over the sea surface, and the ground effect is more complicated than that of flat ground. Therefore, the aerodynamic characteristics of the NACA 4412 airfoil in proximity to wavy ground for a wide range of angles of attack is studied by solving the Reynolds Averaged Navier–Stokes equations. The validation of the numerical method is carried out by comparing it with the experimental data. The results show that the aerodynamic coefficients will fluctuate periodically when the airfoil moves over wavy ground at a small ride height. Except for the angle of attack of 0°, the fluctuation trend of aerodynamic coefficients at other angles of attack is the same. The analysis of aerodynamic fluctuation amplitude found that the medium angle of attack should be selected as the design cruise angle of attack for wing-in-ground craft. The time-averaged aerodynamic coefficients in the case of wavy ground are almost the same as those of flat ground. Hence, wavy ground mainly causes a fluctuation in aerodynamic coefficients. Considering the difference between aerodynamic coefficients at the angle of attack of 0° and at other angles of attack, the flow field structure at an angle of attack of 0° and 4° is analyzed. The results reveal the aerodynamic characteristics of the airfoil moving over wavy ground, which gives a deeper understanding of the ground effect in the conditions of wavy surface/ground. This has a certain guiding significance for the design of wing-in-ground craft.
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Zhang, Yanqi, and Zhaoming Zhang. "Unsteady Aerodynamic Characteristics of Antenna Rotating in Different Elevation Angles." International Journal of Antennas and Propagation 2021 (July 26, 2021): 1–16. http://dx.doi.org/10.1155/2021/5503330.
Повний текст джерелаАнотація:
The aerodynamic characteristics of radar antennas should be considered in computing their wind resistance and designing pedestal servo systems. In this paper, the aerodynamic characteristics of a flat plate antenna with azimuthal rotation are explored using a wind tunnel, and the effects of the antenna elevation angle and reduced frequency on the aerodynamic coefficients are analyzed. The corresponding results of numerical simulation are given to compare with the experimental results. The variation of aerodynamic coefficients with respect to the azimuth angle is found to depend on the reduced frequency and the antenna elevation angle. When the increase in antenna elevation angle is slight, the mean and root mean square values of the aerodynamic coefficients are not monotonic with respect to increases in elevation angle and may increase at individual elevation angles. When the elevation angle increases significantly, the mean, maximum, and root mean square values of the aerodynamic coefficients all significantly decrease. The simulation results are in good agreement with the experimental results, which verify the feasibility of using unsteady numerical simulations to obtain the flow field structure when the antenna is rotating. This approach allows the influence mechanism of the elevation angle change on the aerodynamic characteristics of the rotating antenna to be identified.
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Wang, Xu, Yuanhao Qian, Zengshun Chen, Xiao Zhou, Huaqiang Li, and Hailin Huang. "Numerical studies on aerodynamics of high-speed railway train subjected to strong crosswind." Advances in Mechanical Engineering 11, no. 11 (November 2019): 168781401988727. http://dx.doi.org/10.1177/1687814019887270.
Повний текст джерелаАнотація:
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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HUANG, DA, and GENXIN WU. "INVESTIGATION OF SUITABILITY FOR THE LINEAR SUPERPOSITION MODEL." Modern Physics Letters B 19, no. 28n29 (December 20, 2005): 1631–34. http://dx.doi.org/10.1142/s0217984905010086.
Повний текст джерелаАнотація:
An aircraft model was tested at the 3-meter low speed wind tunnel as it was oscillated with large amplitude. The unsteady aerodynamic behavior was acquired during the oscillation in yawing, rolling and yawing-rolling. The lateral-directional dynamic derivative was obtained using the mathematic model of unsteady aerodynamics and the dynamic derivative simulation. According to the principle of linear superposition, the unsteady aerodynamic parameters of the model about yaw-roll coupled motion can be obtained by the quasi-steady aerodynamic model and the result was compared with the experimental test. It was found that for the quasi-steady aerodynamic model the unsteady aerodynamic characteristic was in agreement with the test at the middle and large angle of attack (for example α ≤ 45°), but was opposite at the extremely large angle of attack (α > 45°).
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Kang, Chang-kwon, and Wei Shyy. "Analytical model for instantaneous lift and shape deformation of an insect-scale flapping wing in hover." Journal of The Royal Society Interface 11, no. 101 (December 6, 2014): 20140933. http://dx.doi.org/10.1098/rsif.2014.0933.
Повний текст джерелаАнотація:
In the analysis of flexible flapping wings of insects, the aerodynamic outcome depends on the combined structural dynamics and unsteady fluid physics. Because the wing shape and hence the resulting effective angle of attack are a priori unknown, predicting aerodynamic performance is challenging. Here, we show that a coupled aerodynamics/structural dynamics model can be established for hovering, based on a linear beam equation with the Morison equation to account for both added mass and aerodynamic damping effects. Lift strongly depends on the instantaneous angle of attack, resulting from passive pitch associated with wing deformation. We show that both instantaneous wing deformation and lift can be predicted in a much simplified framework. Moreover, our analysis suggests that resulting wing kinematics can be explained by the interplay between acceleration-related and aerodynamic damping forces. Interestingly, while both forces combine to create a high angle of attack resulting in high lift around the midstroke, they offset each other for phase control at the end of the stroke.
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Kumar, Gaurav, Chanfiou Ahmed Mboreha, and Yahya Al-fakih. "Numerical simulations on the aerodynamics of the Ahmed body at different slant angles." International Journal of Advanced Engineering Research and Applications 6, no. 03 (July 31, 2020): 55–71. http://dx.doi.org/10.46593/ijaera.2020.v06i03.002.
Повний текст джерелаАнотація:
In this research, the aerodynamic behavior of Ahmed’s body with slant angles of 0°, 30° and 60° is studied using ANSYS FLUENT CFD code. The flow conditions for all cases were same while the rear slant angle is varied for Ahmed’s body. The aerodynamic parameters; lift coefficient and drag coefficient were focused mainly to analyze the flow behavior, it tells the aerodynamics efficiency. The time dependent transient simulation is run to study the behavior of fluid flow. As the Reynold’s number lied 5x105in turbulent regime so to accurately capture the turbulent effects, k-epsilon two equation model with
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Yu, Jing Mei, Yan Hong Yu, and Pan Pan Liu. "Horizontal Axis Wind Turbine Numerical Simulation of Two Dimensional Angle of Attack." Advanced Materials Research 619 (December 2012): 111–14. http://dx.doi.org/10.4028/www.scientific.net/amr.619.111.
Повний текст джерелаАнотація:
wind power is the most effective form of wind energy utilization, modern large-scale wind turbine with horizontal axis wind mainly. Horizontal axis wind turbine aerodynamic performance calculation of the wind turbine aerodynamics research hot spot, is a wind turbine aerodynamic optimization design and calculation of critical load. Horizontal axis wind turbine airfoil aerodynamic performance of the wind turbine operation characteristics and life plays a decisive role". Using Fluent software on the horizontal axis wind turbine numerical simulation, analysis of the United States of America S809NREL airfoil aerodynamic characteristics of different angles of attack numerical simulation, analyzes the different angles of attack in the vicinity of the pressure, velocity distribution. By solving the two-dimensional unsteady, compressible N-S equations for the calculation of wind turbine airfoil S809used the characteristics of flow around. N-S equation in body-fitted coordinate system is given, with the Poisson equation method to generate the C grid.
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Zhang, Lin, Xiong Li, Xin Wang, Long Chen, and Tianyu Zhao. "Performance and Biomechanics in the Flight Period of Ski Jumping: Influence of Ski Attitude." Biology 11, no. 5 (April 27, 2022): 671. http://dx.doi.org/10.3390/biology11050671.
Повний текст джерелаАнотація:
The performance of ski jumping is underpinned by multi-disciplinary principles, in which the aerodynamics of the ski dominates the flying distance and affects the biomechanics of the athletes’ ankle during the flight period. Conventional research on this topic was supported by wind tunnel experiments. Here, the aerodynamics of a full-scale ski jumping ski was calculated via Computational Fluid Dynamics (CFD) methods and good agreement with experimental data was achieved. The impacts of the angle of attack, yaw angle, and roll angle on the aerodynamic performance are explained. The inclusion of yaw angle can enhance the lift generation, which originates from the formation of a tilted multi-vortex system and the induced low-pressure footprints on the upper surface of the ski. Our results thus establish a database for the aerodynamic forces and moments of the ski and the associations between our findings and the skills in ankle control are discussed.
14
Wang, Qiang, Kangping Liao, and Qingwei Ma. "The Influence of Tilt Angle on the Aerodynamic Performance of a Wind Turbine." Applied Sciences 10, no. 15 (August 4, 2020): 5380. http://dx.doi.org/10.3390/app10155380.
Повний текст джерелаАнотація:
Aerodynamic performance of a wind turbine at different tilt angles was studied based on the commercial CFD software STAR-CCM+. Tilt angles of 0, 4, 8 and 12° were investigated based on uniform wind speed and wind shear. In CFD simulation, the rotating motion of blade was based on a sliding mesh. The thrust, power, lift and drag of the blade section airfoil at different tilt angles have been widely investigated herein. Meanwhile, the tip vortices and velocity profiles at different tilt angles were physically observed. In addition, the influence of the wind shear exponents and the expected value of turbulence intensity on the aerodynamic performance of the wind turbine is also further discussed. The results indicate that the change in tilt angle changes the angle of attack of the airfoil section of the wind turbine blade, which affects the thrust and power of the wind turbine. The aerodynamic performance of the wind turbine is better when the tilt angle is about 4°. Wind shear will cause the thrust and power of the wind turbine to decrease, and the effect of the wind shear exponents on the aerodynamic performance of the wind turbine is significantly greater than the expected effect of the turbulence intensity. The main purpose of the paper was to study the effect of tilt angle on the aerodynamic performance of a fixed wind turbine.
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He, Pan, and Jian Xia. "Study on the Influence of Low-Level Jet on the Aerodynamic Characteristics of Horizontal Axis Wind Turbine Rotor Based on the Aerodynamics–Controller Interaction Method." Energies 15, no. 8 (April 7, 2022): 2709. http://dx.doi.org/10.3390/en15082709.
Повний текст джерелаАнотація:
Accurate prediction of the aerodynamic characteristics of wind rotors subjected to various wind profiles is of considerable importance in the aerodynamics and structural design of wind turbines. As a very complex atmospheric phenomenon, the impact of a low-level jet (LLJ) on the aerodynamic characteristics of wind rotors is becoming more and more significant with the increase in wind turbine height. Additionally, during calculating the aerodynamic characteristics of the wind rotor, the known wind speed, rotor speed, and blade-pitch angle are generally required. However, when the wind profile is in the LLJ condition, it is difficult to determine the blade-pitch angle and rotor speed. Therefore, in this paper, the blade-element-momentum (BEM) method is exploited by considering the coupling with the generator-torque controller and blade-pitch controller. In order to solve the problem of the unknown rotor speed and blade-pitch angle under the LLJ condition, a C++ code is developed. Then, the influence of the LLJ on the aerodynamic characteristics of the wind rotor is exclusively examined. The research results show that the calculation method can precisely evaluate the rotor speed, blade-pitch angle, and aerodynamic characteristics of the wind rotor. The influence of the LLJ on the aerodynamic loads of the wind rotor is greater than that of the wind shear. When the LLJ is placed inside the rotor swept area, the aerodynamic loads of the blade exhibit two local maximums and local minimums with the variation of the azimuth angle in a rotation period. The closer the LLJ height is to the hub height, the greater the average aerodynamic loads of the wind rotor are, and the smaller the amplitude of aerodynamic loads of the blade is relative to the average value. When the LLJ height is positioned outside the rotor swept area, the change law of the aerodynamic loads of the blade would be similar to that of the wind subjected to a very strong wind shear inflow. This study provides a crucial reference for a more rational assessment of the aerodynamic characteristics of wind turbines under the action of complex wind profiles, as well as revealing the influence of the LLJ on the aerodynamic characteristics of wind turbines.
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Tang, Wei, and Bi-Feng Song. "Transitional flight equilibrium and performance study for the X-NMRL tail-sitter VTOL MAV." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 8 (August 19, 2018): 3056–77. http://dx.doi.org/10.1177/0954410018794731.
Повний текст джерелаАнотація:
An investigation on transitional flight equilibrium, performance analysis and parameter impacts is conducted in a conversion corridor, based on the proposed X-NMRL tail-sitter Vertical Takeoff and Landing Micro Air Vehicles (VTOL MAVs). Dependent on a propulsion model, aerodynamic model and physical control model, a nonlinear mathematical transitional model of the vehicle dynamics was constructed with consideration of the velocity, angle of attack, thrust, control surface deflection and pitching angle. The momentum theory and estimation method are applied to simulated propeller slipstream effects on aerodynamics, and an aerodynamic model for all regions of angles of attack and velocities is built. The nonlinear indefinite high-order dynamic model is solved by the improved Newton iteration algorithm. The corridor of the pitching angle or flight-path angle to the velocity reveals that the boundaries are mainly governed by the stalling performance, full throttle thrust and zero thrust, respectively. The performance corridor indicates different performance parameter variations under different conditions of steady climbing, cruising and descending states. Additionally, the performance for a steady transitional strategy can be illustrated to some extent. In terms of the parameter impacts, the increasing max propulsive power, supplied voltage, and decreasing total weight can widen the transitional corridor effectively, and the changes in the aerodynamics will only move the boundaries toward the same direction. These results will benefit transitional vehicle designs and control designs.
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Soldatkin, V. M., V. V. Soldatkin, E. S. Efremova, and B. I. Miftachov. "Models for Generating and Processing of Signals of the Panoramic Sensor of Aerodynamic Angle and True Airspeed." Mekhatronika, Avtomatizatsiya, Upravlenie 22, no. 8 (August 20, 2021): 442–48. http://dx.doi.org/10.17587/mau.22.442-448.
Повний текст джерелаАнотація:
The importance of information about the true airspeed and aerodynamic angles of aircraft and replenishment of arsenal of their measuring means with only electronic design scheme, low weight and cost, providing a panoramic measurement of the gliding angle is noted. It is shown that traditional measuring means of true airspeed of AP, which implement the aerodynamic and vane measuring methods of parameters of incoming air flow, using receivers and sensors distributed over the fuselage, have a complex design, significant weight and cost, and limited ranges of measuring aerodynamic angles, which limits their use on small-sized aircraft plane. The integrated sensor of aerodynamic angle and true airspeed, which implements a vortex method for measuring the parameters of incoming air flow, is considered. A single fixed flow receiver simplifies the design, and the time-frequency primary informative signals reduce the errors of instrumentation channel. The limited range of measurement of the gliding angle limits the use of the sensor on small AP. The integrated sensor of aerodynamic angle and true airspeed, which implements the ion-mark method for measuring the parameters of incoming air flow, is considered. The sensor provides a panoramic measurement of aerodynamic angle using receivers distributed in the measurement plane. But the multichannel measuring circuit significantly complicates the design, increases the weight and cost of the sensor, which limits its use on small-sized aircraft plane. The functional scheme of the original panoramic purely electronic sensor of the aerodynamic angle and true airspeed with one fixed receiver of the incoming air flow and ultrasonic instrumentation channels is revealed. Analytical models of the formation, processing and determination of the aerodynamic angle and true airspeed using frequency, time-pulse and phase informative signals are obtained. The analysis of the variants of used informative signals determines the prospects of using of the panoramic sensor with frequency informative signals on small-sized aircraft plane, in which there are no methodological errors from the influence of the ambient temperature when changing the flight altitude.
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Vaidhye, Rahul. "Blade Design and Performance Analysis of Wind Turbine." International Journal for Research in Applied Science and Engineering Technology 10, no. 6 (June 30, 2022): 2220–27. http://dx.doi.org/10.22214/ijraset.2022.44217.
Повний текст джерелаАнотація:
Abstract: This paper reviews the design optimization of wind turbine blades through investigating the design methods and analyzing the performance of the blades. The current research work in this area include wind turbine blade geometric design and optimization, aerodynamics analysis, wind turbine blade structural design and dynamics analysis. Blade geometric design addresses the design parameters, including airfoils and their aerodynamic coefficients, attack angles, design tip speed ratio, design and/or rated wind speed, rotor diameter, blade aerodynamic shape with chord length and twist distributions, so that the blade achieves an optimum powerperformance. The geometry of the blade is an aerodynamic shape with nonlinear chord and twist distribution, which can be obtained based on the BEM theory with respect to given aerofoil with known aerodynamic coefficients. In terms of blade aerodynamics analysis, there are four types of aerodynamic models which can be used to predict the aerodynamic performance of blades, including blade element momentum (BEM) model, lifting panel and vortex model, actuator line model, and computational fluid dynamics (CFD) model. Among the four, computational fluid dynamics (CFD) model has been used to calculate the aerodynamic effect on the bladeairfoil. Critical Reynolds number and constant wind speed has been considered during analysis under different turbulence models Viz, spallart-almaras, k-epsilon, invicid flow. During investigation it is observed that only k- epsilon showed efficient results than others and 14 degree angle of attack (AOA) is the optimum value at which there is much lift coefficient and minimum drag
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Kouser, Taiba, Yongliang Xiong, Dan Yang, and Sai Peng. "Direct Numerical Simulations on the three-dimensional wake transition of flows over NACA0012 airfoil at Re = 1000." International Journal of Micro Air Vehicles 13 (January 2021): 175682932110556. http://dx.doi.org/10.1177/17568293211055656.
Повний текст джерелаАнотація:
For micro air vehicles (MAV), the precise prediction of aerodynamic force plays an important role. The aerodynamic force of a comparative low Reynold number (Re) vehicle tends to be affected by the different flow modes. In this paper, the aerodynamic performance of a three-dimensional NACA0012 airfoil is studied numerically. A range of angles of attack ( α) 0°−25° and Reynolds number 1000 is considered. Mean and fluctuating coefficients of aerodynamic forces around NACA0012 airfoil are analyzed for different wake modes. The difference of aerodynamic forces between two and three-dimensional simulations are compared. The results show that the wake remains steady two-dimensional for lower angles of attack. At α = 9°, Von Karman vortex pattern is noticed. Flow transition to three-dimensional as the angle of attack increases from α = 13°. 3D wake is found to be stable with parallel shedding mode for 14°-17°. However, these modes become finer with the gradual increase in angle of incidence. While, wake loses its three-dimensional stability to chaotic with gradual increment in angle of attack afterwards.
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Li, Daochun, Qichen Liu, Yining Wu, and Jinwu Xiang. "Design and analysis of a morphing drag rudder on the aerodynamics, structural deformation, and the required actuating moment." Journal of Intelligent Material Systems and Structures 29, no. 6 (September 20, 2017): 1038–49. http://dx.doi.org/10.1177/1045389x17730910.
Повний текст джерелаАнотація:
The split drag rudder is an important yawing control device for the tailless flying-wing aircraft. In this article, a new morphing drag rudder is proposed based on the chordwise continuous variable camber technology. The designs of the structure and actuation system are first presented. A comparative study on the aerodynamics of the morphing and traditional drag rudders is performed numerically. The results show that the morphing drag rudder experiences a larger aerodynamic drag than the traditional one at small angles of attack. The analysis on the structural deformation and the required actuating moment at zero angle of attack are performed. The results show that the deformation due to the aerodynamic load increases more and more slowly with the angle of deflection. Besides, the relationship between the required actuating moment and the trailing edge deformation is linear, which indicates the applicability of using morphing drag rudder for yawing control.
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Wang, Ruochen, Guoxin Zhang, Pei Ying, and Xiaoping Ma. "Effects of Key Parameters on Airfoil Aerodynamics Using Co-Flow Jet Active Flow Control." Aerospace 9, no. 11 (October 26, 2022): 649. http://dx.doi.org/10.3390/aerospace9110649.
Повний текст джерелаАнотація:
The Co-Flow Jet (CFJ) technique is an effective way to enhance the aerodynamics of airfoils. The present study is to comprehensively investigate the effects of CFJ key parameters, viz., the jet momentum coefficient, the injection slot location, the injection slot size, the suction slot location, the suction slot size, and the suction slot angle, on the airfoil aerodynamic characteristics based on the numerical method of Reynolds Averaged Navier-Stokes (RANS) equations coupled with the Spalart-Allmaras (S-A) turbulence model. The numerical method is validated by a CFJ6415 airfoil case, and a relatively good agreement with the experiment is achieved. The results show that a larger jet momentum coefficient is more conducive to lift enhancement, drag reduction, and stall margin enlargement. However, a relatively smaller jet momentum coefficient could increase the corrected aerodynamic efficiency at small angles of attack. The variation of the injection slot location is barely influential to the lift coefficient. With the increase of the injection slot size, the power coefficient first decreases and then increases, and the corrected aerodynamic efficiency first increases and then decreases. The drag coefficient increases monotonously as the suction slot location moves downstream. Furthermore, a relatively smaller suction slot size or a larger suction slot angle could better reduce the drag and enhance the CFJ airfoil aerodynamics.
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Zhu, Tianci, and Wenhui Li. "Numerical study of the trailing vehicle length on train aerodynamics under crosswind." AIP Advances 13, no. 2 (February 1, 2023): 025366. http://dx.doi.org/10.1063/5.0131877.
Повний текст джерелаАнотація:
Limited by the wind tunnel size, a one-and-a-half train model is generally adopted during the test to represent the realistic long tandem. Thus, the reasonable arrangement of the trailing vehicle length is of significance for experimental accuracy. In this work, the aerodynamic performance of trains with different trailing vehicle lengths subjected to crosswind was studied using the improved detached eddy simulation method combined with the shear–stress–transport k– ω turbulence model. The 1/8th scaled high-speed trains with five trailing lengths were proposed, and the aerodynamic differences were evaluated at yaw angles ranging from β = 0° to β = 60°. The numerical method was validated by the previous wind tunnel test. Results show that the aerodynamics and flow patterns of the L a = 0.50 and the benchmark are highly relevant. The downstream dummy vehicle length has the greatest effect on aerodynamic coefficients at a higher yaw angle ( β > 30°), especially at β = 60°, whereas the effects become insignificant at a lower yaw angle ( β < 30°). For various L a lengths, notable discrepancy appears at the leeward and top side where large vortexes shed off from the roof. The larger contributions to the lateral force and lift force coefficients are mainly due to these areas. A suitable length of L a = 0.50 is therefore recommended to obtain more accurate aerodynamics of a long train set.
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Faulkner, Steve H., and Philippa Jobling. "The Effect of Upper-Body Positioning on the Aerodynamic–Physiological Economy of Time-Trial Cycling." International Journal of Sports Physiology and Performance 16, no. 1 (January 1, 2021): 51–58. http://dx.doi.org/10.1123/ijspp.2019-0547.
Повний текст джерелаАнотація:
Purpose: Cycling time trials (TTs) are characterized by riders’ adopting aerodynamic positions to lessen the impact of aerodynamic drag on velocity. The optimal performance requirements for TTs likely exist on a continuum of rider aerodynamics versus physiological optimization, yet there is little empirical evidence to inform riders and coaches. The aim of the present study was to investigate the relationship between aerodynamic optimization, energy expenditure, heat production, and performance. Methods: Eleven trained cyclists completed 5 submaximal exercise tests followed by a TT. Trials were completed at hip angles of 12° (more horizontal), 16°, 20°, 24° (more vertical), and their self-selected control position. Results: The largest decrease in power output at anaerobic threshold compared with control occurred at 12° (−16 [20] W, P = .03; effect size [ES] = 0.8). There was a linear relationship between upper-body position and heat production (R2 = .414, P = .04) but no change in mean body temperature, suggesting that, as upper-body position and hip angle increase, convective and evaporative cooling also rise. The highest aerodynamic–physiological economy occurred at 12° (384 [53] W·CdA−1·L−1·min−1, ES = 0.4), and the lowest occurred at 24° (338 [28] W·CdA−1·L−1·min−1, ES = 0.7), versus control (367 [41] W·CdA−1·L−1·min−1). Conclusion: These data suggest that the physiological cost of reducing hip angle is outweighed by the aerodynamic benefit and that riders should favor aerodynamic optimization for shorter TT events. The impact on thermoregulation and performance in the field requires further investigation.
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Lee, Sang Woo, Yong Beom Kim, and Joon Sik Lee. "Flow Characteristics and Aerodynamic Losses of Film-Cooling Jets With Compound Angle Orientations." Journal of Turbomachinery 119, no. 2 (April 1, 1997): 310–19. http://dx.doi.org/10.1115/1.2841114.
Повний текст джерелаАнотація:
Oil-film flow visualizations and three-dimensional flow measurements using a five-hole probe have been conducted to investigate the flow characteristics and aerodynamic loss distributions of film-cooling jets with compound angle orientations. For a fixed inclination angle of the injection hole, measurements are performed at various orientation angles to the direction of the mainstream in the case of three velocity ratios of 0.5, 1.0, and 2.0. Flow visualizations for the velocity ratio of 2.0 show that the increase in the orientation angle furnishes better film coverage on the test surface, but gives rise to large flow disturbances in the mainstream. A near-wall flow model has been proposed based on the surface flow visualizations. It has also been found from the flow measurements that as the orientation angle increases, a pair of count-errotating vortices turn to a single strong one, and the aerodynamic loss field is closely related to the secondary flow. Even in the case of the velocity ratio of 2.0, aerodynamic loss is produced within the jet region when the orientation angle is large. Regardless of the velocity ratio, the mass-averaged aerodynamic loss increases with increasing orientation angle, the effect of which on aerodynamic loss is pronounced when the velocity ratio is large.
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Tanasheva, N. K., A. R. Bakhtybekova, A. Zh Tleubergenova, L. L. Minkov, S. A. Bolegenova, N. N. Shuyushbaeva, and B. A. Toktarbaev. "Influence of a rough surface on the aerodynamic characteristics of a rotating cylinder." Bulletin of the Karaganda University. "Physics" Series 103, no. 3 (September 30, 2021): 52–59. http://dx.doi.org/10.31489/2021ph3/52-59.
Повний текст джерелаАнотація:
The article considers the influence of the relative roughness of a cylindrical blade on aerodynamic characteristics. It is known that the operation basis of blades under consideration is the Magnus effect, which is characterized by appearance of a lifting force (Magnus force), when the cylinders rotate in a transverse flow. This force is used to rotate the wind wheel, similar to lifting force, but can have a much larger value when selecting optimal conditions, both geometric and aerodynamic. The authors conducted a comparative analysis of cylinder layout with a relative roughness (0.005 ÷ 0.02). Experimental studies of aerodynamics process of rotating cylinders were carried out in the aerodynamic laboratory using the T-1-M wind tunnel at an air flow value of 5 to 15 m/s. Graphs of dependences of rotating cylinder's lifting force and drag force on the changing air flow velocity and on relative roughness, k/d, are obtained. For further study experimental cylinder layout’s aerodynamic parameters, the most optimal is the variant with a relative roughness value of 0.02, which had high indicators, was selected. In the course of experimental studies, graphs of the dependence of the values of lift and drag force on the angles of attack of a single rotating cylinder with a rough surface on the speed and angle of attack of the wind flow (0°, 30° and 60°) were obtained. It is established that the effective angle of attack is 0°, at which aerodynamic characteristics’s maximum values were obtained.
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Xin-min, Li, Nie Xiao-chun, Zhu Yong-kun, You Yi, and Yan Zhi-tao. "Wind Tunnel Tests on Aerodynamic Characteristics of Ice-Coated 4-Bundled Conductors." Mathematical Problems in Engineering 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/1628173.
Повний текст джерелаАнотація:
Wind tunnel tests were carried out to obtain the static aerodynamic characteristics of crescent iced 4-bundled conductors with different ice thicknesses, initial ice accretion angles, bundle spaces, and wind attack angles. The test models were made of the actual conductors and have a real rough surface. Test results show that the influence of wake interference on the drag coefficients of leeward subconductors is obvious. The interference angle range is larger than 20° and the drag coefficient curves of leeward subconductors have a sudden decrease phenomenon at some certain wind attack angles. The absolute value of the lift and moment coefficient increases with the increase of the ice thickness. In addition, the galloping of the iced subconductor may occur at the angle of wind attack near ±20° and the wake increases the moment coefficient. The variation of initial ice accretion angle has a significant influence on the aerodynamic coefficients. The aerodynamic coefficient curves exhibit a “moving” phenomenon at different initial ice accretion angles. The bundle spaces have a great influence on the moment coefficient of leeward thin ice-coated conductors. With the increase of ice thickness, the bundle spaces generally have little influence on the aerodynamic coefficients.
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Zhao, Liang, Qingfeng Huang, Xinyan Deng, and Sanjay P. Sane. "Aerodynamic effects of flexibility in flapping wings." Journal of The Royal Society Interface 7, no. 44 (August 19, 2009): 485–97. http://dx.doi.org/10.1098/rsif.2009.0200.
Повний текст джерелаАнотація:
Recent work on the aerodynamics of flapping flight reveals fundamental differences in the mechanisms of aerodynamic force generation between fixed and flapping wings. When fixed wings translate at high angles of attack, they periodically generate and shed leading and trailing edge vortices as reflected in their fluctuating aerodynamic force traces and associated flow visualization. In contrast, wings flapping at high angles of attack generate stable leading edge vorticity, which persists throughout the duration of the stroke and enhances mean aerodynamic forces. Here, we show that aerodynamic forces can be controlled by altering the trailing edge flexibility of a flapping wing. We used a dynamically scaled mechanical model of flapping flight ( Re ≈ 2000) to measure the aerodynamic forces on flapping wings of variable flexural stiffness (EI). For low to medium angles of attack, as flexibility of the wing increases, its ability to generate aerodynamic forces decreases monotonically but its lift-to-drag ratios remain approximately constant. The instantaneous force traces reveal no major differences in the underlying modes of force generation for flexible and rigid wings, but the magnitude of force, the angle of net force vector and centre of pressure all vary systematically with wing flexibility. Even a rudimentary framework of wing veins is sufficient to restore the ability of flexible wings to generate forces at near-rigid values. Thus, the magnitude of force generation can be controlled by modulating the trailing edge flexibility and thereby controlling the magnitude of the leading edge vorticity. To characterize this, we have generated a detailed database of aerodynamic forces as a function of several variables including material properties, kinematics, aerodynamic forces and centre of pressure, which can also be used to help validate computational models of aeroelastic flapping wings. These experiments will also be useful for wing design for small robotic insects and, to a limited extent, in understanding the aerodynamics of flapping insect wings.
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Huang, Han Jie, and Xin Min Li. "Experimental Study on the Influence Factors of Static Aerodynamic Characteristics of Ice-Coated Commonly Used Conductors." Advanced Materials Research 774-776 (September 2013): 1227–31. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.1227.
Повний текст джерелаАнотація:
For conductors commonly used in the high and ultra-high voltage transmission projects, research was conducted on how ice shape, ice thickness, wind speed and angle of attack affect the static aerodynamic characteristics of ice-coated conductor. The ice shape and the shape of ice-coated conductor are both important factors that determine the aerodynamic characteristics of conductor. Sudden increase of lift coefficient may happen at low angle of attack. Wind speed shows less effect on aerodynamic characteristics of ice-coated conductor with streamlined shape than that of conductor with blunt shape. Under most attack angles, aerodynamic coefficients increase as the ice thickness increases. The aerodynamic load on ice-coated conductor does not increase linearly with the diameter of conductor.
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Hu, Xing Jun, Lei Liao, Jing Yu Wang, and Li Min Fu. "Research on Aerodynamic Characteristics of a Simplified SUV Model." Applied Mechanics and Materials 275-277 (January 2013): 603–6. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.603.
Повний текст джерелаАнотація:
The aerodynamics characteristics of square Mira model were researched by simulation, the drag coefficient and the aerodynamic characteristics around model were achieved with analysis of velocity and pressure distribution. Based on results, the angle of rear wind window, the angle of underbody diffuser and the front transition radius were changed, the drag and lift coefficients were achieved. The conclusions provide reference for how to reduce drag coefficient of SUV
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He, Yin Zhi, and Zhi Gang Yang. "Influence of Crosswind to Automobile Interior Aerodynamic Noise." Advanced Materials Research 503-504 (April 2012): 1164–68. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1164.
Повний текст джерелаАнотація:
After a brief introduction about aerodynamic noise generation and transmission mechanisms, the influence of crosswind to vehicle interior aerodynamic noise for a production automobile sedan was investigated through full-scale aeroacoustic wind tunnel tests. Through analysis of sound pressure level of vehicle interior driver ear position and pressure fluctuation level on vehicle side window glass under different yaw angles, the following results are obtained: The frequency characteristics of vehicle interior aerodynamic noise vary as yaw angle changes under one certain wind speed. Whether on the leeside or by windward, sound pressure level increases as yaw angle goes up. Under the same yaw angle, interior noise level on the leeside is higher than that by windward. Test results between pressure fluctuation level on side window glass and vehicle interior aerodynamic noise of driver ear position show good correlation
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Kumar Vandrangi, Seshu. "AERODYNAMIC CHARACTERISTICS OF NACA 0012 AIRFOIL BY CFD ANALYSIS." Journal of Airline Operations and Aviation Management 1, no. 1 (July 25, 2022): 1–8. http://dx.doi.org/10.56801/jaoam.v1i1.1.
Повний текст джерелаАнотація:
The wind turbine's aerodynamic efficiency is heavily influenced by the aerodynamic airfoil blades. It's critical to choose the right aerofoil section for the blade. The angle of attack and its impact on lift and drag forces, such as high lift and low drag or vice versa, are key elements that determine the wind turbine system's efficiency. Using this as inspiration, the NACA 0012 airfoil profile is used to investigate the influence of angle of attack on the aerodynamic performance of wind turbine blades. The airfoil geometry is produced using computational fluid dynamics, according to the National Advisory Committee for Aeronautics (NACA) guidelines. The aerodynamic findings are evaluated in terms of static pressure and velocity distributions, as well as different angles of attack, in this study. The angle of attack increases as the lift/drag ratio decreases, according to the CFD study. Other elements, such as blade backflow turbulence and blade forces, should be addressed when evaluating the aerodynamic performance of NACA aerofoils.
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Yu, Haiyan, Fuyou Xu, Mingjie Zhang, and Aoqiu Zhou. "Experimental Investigation on Glaze Ice Accretion and Its Influence on Aerodynamic Characteristics of Pipeline Suspension Bridges." Applied Sciences 10, no. 20 (October 14, 2020): 7167. http://dx.doi.org/10.3390/app10207167.
Повний текст джерелаАнотація:
Pipeline suspension bridges may experience ice accretion under special atmospheric conditions, and the aerodynamic characteristics of the bridges may be modified by the ice accretion. Under some specific climatic conditions of freezing rain, the dependencies of the ice size and shape on the icing duration and some structural properties (including pipeline diameter, inclination angle of wind hanger, inclination angle and size of section steel, and girder geometry) were experimentally investigated in a refrigerated precipitation icing laboratory. Typical ice accretions on pipelines, wind hangers, section steels, and girders of pipeline suspension bridges are summarized. Then the effects of some selected ice accretions on aerodynamic force coefficients of a bridge girder were further investigated through wind tunnel tests. The ice size and shape on the pipeline were closely related to the pipeline diameter and icing duration. The engineering geometric models of ice accretion on pipelines were extracted. The ice shape and size on wind hangers and section steels changed with their inclination angles. The aerodynamic force coefficients of a girder with ice accretion were much higher than those of an ice-free one. The results can provide references for simulating the ice accretion and further evaluating the effect of ice accretion on the aerodynamics of pipeline suspension bridges.
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Dai, Zhiyuan, Tian Li, Ning Zhou, Jiye Zhang, and Weihua Zhang. "Numerical simulation and optimization of aerodynamic uplift force of a high-speed pantograph." Railway Engineering Science 30, no. 1 (October 6, 2021): 117–28. http://dx.doi.org/10.1007/s40534-021-00258-7.
Повний текст джерелаАнотація:
AbstractAiming at the problem that aerodynamic uplift forces of the pantograph running in the knuckle-downstream and knuckle-upstream conditions are inconsistent, and their magnitudes do not satisfy the corresponding standard, the aerodynamic uplift forces of pantographs with baffles are numerically investigated, and an optimization method to determine the baffle angle is proposed. First, the error between the aerodynamic resistances of the pantograph obtained by numerical simulation and wind tunnel test is less than 5%, which indicates the accuracy of the numerical simulation method. Second, the original pantograph and pantographs equipped with three different baffles are numerically simulated to obtain the aerodynamic forces and moments of the pantograph components. Three different angles for the baffles are −17°, 0° and 17°. Then the multibody simulation is used to calculate the aerodynamic uplift force of the pantograph, and the optimal range for the baffle angle is determined. Results show that the lift force of the baffle increases with the increment of the angle in the knuckle-downstream condition, whereas the lift force of the baffle decreases with the increment of the angle in the knuckle-upstream condition. According to the results of the aerodynamic uplift force, the optimal angle of the baffle is determined to be 4.75° when the running speed is 350 km/h, and pantograph–catenary contact forces are 128.89 N and 129.15 N under the knuckle-downstream and knuckle-upstream operating conditions, respectively, which are almost equal and both meet the requirements of the standard EN50367:2012.
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Ali, Zurriati Mohd, Wahyu Kuntjoro, and Wisnoe Wirachman. "The Effect of Canard to the Aerodynamic Behavior of Blended Wing Body Aircraft." Applied Mechanics and Materials 225 (November 2012): 38–42. http://dx.doi.org/10.4028/www.scientific.net/amm.225.38.
Повний текст джерелаАнотація:
This paper presents a study on the effect of canard setting angle on the aerodynamic characteristic of a Blended Wing Body (BWB). Canard effects to BWB aerodynamic characteristics are not widely investigated. Hence the focus of the study is to investigate the variations of lifts, drags and moments when the angles of attack are varied at different canard setting angles. Wind tunnel tests were performed on BWB aircraft with canard setting angles, ranging from -20˚ to 20˚. Angles of attack, were varied from -10˚ to 10˚. Aspect ratio and canard planform area were kept fixed. All tests were conducted in the subsonic wind tunnel at Universiti Teknologi MARA, at Mach number of 0.1. The streamlines flow, at the upper surface of the canard was visualized using mini tuft. Result shows that the lift coefficient does not change much with different canard setting angles. As expected, the lift coefficient increases with increasing angles of attack at any canard setting angle. In general, the moment coefficient increases as the canard setting angle is increased. The results obtained in this research will be of importance to the understanding of aerodynamic behavior of BWB employing canard in its configuration.
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Liu, Ting Rui, and Yong Sheng Ren. "Vibration of Wind Turbine Blade Modeled as Composite Thin-Walled Closed-Section Structure." Advanced Materials Research 129-131 (August 2010): 23–27. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.23.
Повний текст джерелаАнотація:
Based on a laminated composite structure, vibration and nonlinear stall aeroelastic stability of rotor blades modeled as anisotropic thin-walled closed-section beams are systematically addressed. The analysis is applied to a laminated construction of the circumferentially asymmetric stiffness (CAS) that produces bending-bending-twist coupling. The vibration characteristics of composite beam are determined by the Galerkin Method. The unsteady aerodynamic loads and centrifugal force are integrated with the nolinear aerodynamic model to deal with aeroelastic stability analysis. The influence of some related factors, pretwisted angle, ply-angle rotational speed, and wind speed, is investigated. The paper gives methods of eigenvalue analysis and aeroelastic response, which can determine the stability of the blade forced by the nolinear aerodynamics.
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Kryvokhatko, Illia. "Aerodynamic moment characteristics of tandem-scheme aircraft." MATEC Web of Conferences 304 (2019): 02015. http://dx.doi.org/10.1051/matecconf/201930402015.
Повний текст джерелаАнотація:
Aerodynamic interference between forward and back wings of tandem-scheme aircraft significantly affects its pitch and roll moments. The interference increases roll stability in a narrow range of sideslip angles; there is a kink on the dependence of roll moment coefficient versus sideslip angle (that is not observed for conventional-scheme aircraft). Directional stability is decreased by a dihedral angle of forward wings and winglets on them but is increased by the same factors for back wings. If back wings’ bending is significant, then aerodynamic interference may affect directional stability as well. The vortex system of tandem-wings at a sideslip angle was modeled incorrectly by the used CFD method (solving RANS), and further research is needed. The analytical and experimental methods show a good agreement concerning moment characteristics.
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Lutsenko, A. Y., D. K. Nazarova, and D. M. Slobodyanyuk. "A Study of the Aerodynamic Characteristics of the Rocket Fairing Door Using Conical Means of Passive Stabilization." Proceedings of Higher Educational Institutions. Маchine Building, no. 7 (712) (July 2019): 66–75. http://dx.doi.org/10.18698/0536-1044-2019-7-66-75.
Повний текст джерелаАнотація:
In the article, the aerodynamic characteristics of a detachable fairing door model are investigated with the use of passive stabilization means, which are conical bodies with flexible and rigid connections. Two types of experiments were conducted in a subsonic wind tunnel to determine the balancing angles of attack: a visualization experiment (using a video camera) and a measuring experiment (using the angle sensor). Mathematical flow models and aerodynamic quality values were obtained. The change in the balancing angle of attack and the corresponding aerodynamic quality of the studied combinations with respect to the base model were analyzed. Comparative characteristics of the considered stabilization variants were presented.
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M, JAKUBOWSKI M. "NUMERICAL TESTS OF THE INFLUENCE OF THE TILT ANGLE OF THE MOTORCYCLE WINDSHIELD ON SELECTED AERODYNAMIC PARAMETERS." National Transport University Bulletin 1, no. 50 (2021): 35–45. http://dx.doi.org/10.33744/2308-6645-2021-3-50-035-045.
Повний текст джерелаАнотація:
Jakubowski M. Numerical tests of the influence of the tilt angle of the motorcycle windshield on selected aerodynamic parameters. Visnyk of National Transport University. Series «Technical sciences». Scientific and Technical Collection. – Kyiv: National Transport University, 2021. – Issue 3 (50). Aerodynamic drag is one of the drag forces acting on a vehicle while driving. Above a speed of about 75 km / h, this force becomes dominant, while below a rolling resistance has a greater influence. Aerodynamic drag is the sum of the resistances: body profile (about 60% of the share), vibrations of space (about 15%), friction (about 7%), inductive state (about 18%). At a speed of 100 km / h, the drag is approximately 90% of the total drag on the motorcycle. In the context of vehicle aerodynamics research, wind tunnel measurements are still the most common and widely used, but the evolution of computers in electronic data processing and storage and advances in their computational dynamics make numerical (mathematical) modeling very useful in the research process. Among the various design options, classic motorcycles are popular, they are not equipped with fairings and linings, with geometry, which allows you to ride comfortably with an upright fit. Such vehicles are often modified by users by installing a relatively large motorcycle windshield, which acts as a fairing and protects the rider from air pressure when driving at high speed. Mounting kits allow the angle of inclination of the windshield to be adjusted according to the driver's needs. This angle is one of the many parameters that affect the aerodynamic performance of a motorcycle, including drag. Thus, using such a windshield or a small fairing, it is possible to influence not only fuel consumption, but also the comfort and safety of driving. The article presents the results of simulation tests of the influence of the angle of installation of the windshield of a motorcycle (20, 30 and 40 °) on the aerodynamic characteristics. The analysis covered the velocity distribution in the plane of symmetry of the vehicle, the pressure (air pressure) exerted on the rider and motorcycle, as well as the isobaric surface for the specified pressure values. Low values of aerodynamic drag were obtained for a glass tilt angle of 40 °. A motorcycle in this configuration will consume less fuel while driving, and this also has a corresponding effect on reducing exhaust gas emissions. It should be noted that this angle of inclination of the glass, with the driver's position unchanged, exposes him to greater air pressure, especially when driving at high speed. When it comes to protecting the rider from air currents, the most advantageous configuration is a motorcycle with a 20 ° tilt angle. KEYWORDS: AERODYNAMICS, MOTORCYCLE WINDSHIELD, FAIRING, MOTION RESISTANCE, FUEL CONSUMPTION, COMFORT AND SAFETY OF MOTORCYCLISTS
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Ullah, Tariq, Krzysztof Sobczak, Grzegorz Liśkiewicz, and Amjid Khan. "Two-Dimensional URANS Numerical Investigation of Critical Parameters on a Pitch Oscillating VAWT Airfoil under Dynamic Stall." Energies 15, no. 15 (August 3, 2022): 5625. http://dx.doi.org/10.3390/en15155625.
Повний текст джерелаАнотація:
In this paper, a thorough 2D unsteady computational fluid dynamic analysis was performed on a pitching airfoil to properly comprehend the dynamic stall and aerodynamic forces. The computational software ANSYS Fluent was used to solve the unsteady Reynolds-averaged Navier–Stokes equations. Low Reynolds number flows were modeled using the k-ω shear stress transport turbulence model. Aerodynamic forces, fluid flow structures, and flow separation delay angles were explored as a function of the Reynolds number, reduced frequency, oscillation amplitude, and mean angle of attack. The maximum aerodynamic forces, including lift, drag, and the onset of the dynamic stall, were all influenced by these variables. The critical parameters that influenced the optimum aerodynamic forces and ended up causing dynamic stall delay were oscillation amplitude and mean angle of attack. The stall angle was raised by 9° and 6°, respectively, and a large increment in the lift coefficient was also noted in both cases. Additionally, for the highest Reynolds number, a considerable rise in the maximum lift coefficient of 20% and a 28% drop in drag coefficient were observed, with a 1.5° delay in the stall angle. Furthermore, a significant increase of 33% in the lift force was seen with a rise of 4.5° in the stall angle in the case of reduced frequency.
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Nabawy, Mostafa R. A., and Ruta Marcinkeviciute. "Scalability of resonant motor-driven flapping wing propulsion systems." Royal Society Open Science 8, no. 9 (September 2021): 210452. http://dx.doi.org/10.1098/rsos.210452.
Повний текст джерелаАнотація:
This work aims to develop an integrated conceptual design process to assess the scalability and performance of propulsion systems of resonant motor-driven flapping wing vehicles. The developed process allows designers to explore the interaction between electrical, mechanical and aerodynamic domains in a single transparent design environment. Wings are modelled based on a quasi-steady treatment that evaluates aerodynamics from geometry and kinematic information. System mechanics is modelled as a damped second-order dynamic system operating at resonance with nonlinear aerodynamic damping. Motors are modelled using standard equations that relate operational parameters and AC voltage input. Design scaling laws are developed using available data based on current levels of technology. The design method provides insights into the effects of changing core design variables such as the actuator size, actuator mass fraction and pitching kinematics on the overall design solution. It is shown that system efficiency achieves peak values of 30–36% at motor masses of 0.5–1 g when a constant angle of attack kinematics is employed. While sinusoidal angle of attack kinematics demands more aerodynamic and electric powers compared with the constant angle of attack case, sinusoidal angle of attack kinematics can lead to a maximum difference of around 15% in peak system efficiency.
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Qin, Jie, and Xiao Yan Wang. "Simulation and Analysis for Aerodynamic Characteristics of Flying Object Based on Canard." Applied Mechanics and Materials 127 (October 2011): 415–20. http://dx.doi.org/10.4028/www.scientific.net/amm.127.415.
Повний текст джерелаАнотація:
Change the aerodynamic characteristics of the flying object by controlling the canard deflection and achieve ballistic correction of the flying object. Select different angles of attack to simulate and analyze the changes on aerodynamic performance of the flying object at different flight speed. Study the variation regularity and influence factors of aerodynamic characteristics with the deflection angle and the area of the canard as characteristic parameters.
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Yu, Hu, Bin Tang Yang, Xiao Qing Sun, Xi Wang, and Hang Jie Mo. "Effects of Tunable Angle for Vortex Generators on Aerodynamic Performances of Airfoils." Applied Mechanics and Materials 872 (October 2017): 192–97. http://dx.doi.org/10.4028/www.scientific.net/amm.872.192.
Повний текст джерелаАнотація:
Vortex generators (VGs) are commonly adopted to control the flow separation, and many researches have investigated their effects on the aerodynamic performance of wind turbines. However, nearly no attentions are paid to the VGs’ installation angle. Thus, in this paper, to investigate the effects of the VGs’ installation angle on airfoils, numerical simulations are conducted by CFD on the finite wing of NACA0012. According to the finite airfoil with or without VGs, three-dimensional models are established and numerical simulations are carried out in detail. It could be seen clearly that the VGs’ installation angle produces a significant impact on the aerodynamic performances. For some installation angles, special ranging from 45° to 90°, VGs can improve the lift-drag ratio apparently, even by 34.5%. While angle ranges from 15° to 30°, VGs negatively influence the lift-drag ratio. Furthermore, the fluctuation phenomenon is discussed through analysis of the streamlines and vortices. Based on those results, optimal aerodynamic performances could be achieved by the active control of the VGs’ installation angle.
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Shinde, Yash. "Dimples Effects on a Spoilers Aerodynamics." International Journal for Research in Applied Science and Engineering Technology 9, no. 8 (August 31, 2021): 1851–68. http://dx.doi.org/10.22214/ijraset.2021.37674.
Повний текст джерелаАнотація:
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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Kim, Woo-Yul, Santhosh Senguttuvan, and Sung-Min Kim. "Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode." Processes 8, no. 11 (October 23, 2020): 1338. http://dx.doi.org/10.3390/pr8111338.
Повний текст джерелаАнотація:
The aerodynamic performance of a counter-rotating ducted fan in hover mode is numerically analyzed for different rotor spacings and duct diffusion angles. The design of the counter-rotating fan is inspired by a custom-designed single rotor ducted fan used in a previous study. The numerical model to predict the aerodynamic performance of the counter-rotating ducted fan is developed by adopting the frozen rotor approach for steady-state incompressible flow conditions. The relative angle between the front and the rear rotor is examined due to the usage of the frozen rotor model. The results show that the variation of thrust for the different relative angles is extremely low. The aerodynamic performances are evaluated by comparing the thrust, thrust coefficient, power coefficient, and figure of merit (FOM). The thrust, thrust coefficient, and FOM slightly increase with increasing rotor spacing up to 200 mm, regardless of the duct diffusion angle, and reduce on further increase in the rotor spacing. The duct diffusion angle of 0° generates about 9% higher thrust and increases the FOM by 6.7%, compared with the 6° duct diffusion angle. The duct diffusion angle is highly effective in improving the thrust and FOM of the counter-rotating ducted fan, rather than the rotor spacing.
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Zhou, Haichao, Qingyun Chen, Runzhi Qin, Lingxin Zhang, and Huiyun Li. "Investigation of wheelhouse shapes on the aerodynamic characteristics of a generic car model." Advances in Mechanical Engineering 13, no. 12 (December 2021): 168781402110668. http://dx.doi.org/10.1177/16878140211066842.
Повний текст джерелаАнотація:
As vehicle speed increases, the aerodynamic drag reduction becomes increasingly significant. The aim of this paper is to find out the effects of the wheelhouse shapes on the aerodynamics of an Ahmed body with a 35 slant angle. In this paper, based on the detached-eddy simulation method, the effects of the three classic different wheelhouse on the aerodynamic performance and near wake of the Ahmed body are presented. The mesh resolution and methodology are validated against the published test results. The results show that the front wheelhouse has a significant impact on the aerodynamic performance of the Ahmed body, leading to different aerodynamic drag forces and flow fields. Enlarging the wheelhouse cavity volume could result in a gradual increase in aerodynamic drag coefficients, the ratio of the wheelhouse cavity volume increased by 2.9% and 9.8%, the drag coefficients increased by 2.5% and 4.5% respectively. The increase in aerodynamic drag was primarily caused by flow separation in the large cavity volume wheelhouse.
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Jia, Ya Lei, Zhong He Han, Fu You Li, Ya Kai Bai, and Ji Xuan Wang. "Influence of Flap Deflection Angle on Wind Turbine Airfoil with Trailing Edge Flaps." Advanced Materials Research 977 (June 2014): 222–27. http://dx.doi.org/10.4028/www.scientific.net/amr.977.222.
Повний текст джерелаАнотація:
To improve the ability of capturing the wind energy of wind turbine and shorten the design period is of great importance to designing wind turbine blade. The article established S809 airfoil model with trailing edge flaps, The gap of the frontal subject and trailing edge flap adopt uniform gap structure, this structure will reduce the influence of the gap on aerodynamic characteristics.Using the k-ω Two equation turbulence model , the article calculated aerodynamic performance of S809 with 10% chord length trailing edge flaps under different deflecting angles. Results show that gap between the main body and trailing edge flap has little effect on airfoil aerodynamic performance, however, the deflection Angle of Trailing edge flap have great affect on airfoil aerodynamic performance, when deflection Angle of trailing edge flap is 14 ° degrees ,the lift-to-drag ratio is the largest.
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Kazim, Ali Hussain, Abdullah Hamid Malik, Hammad Ali, Muhammad Usman Raza, Awais Ahmad Khan, Tauseef Aized, and Aqsa Shabbir. "CFD analysis of variable geometric angle winglets." Aircraft Engineering and Aerospace Technology 94, no. 2 (October 15, 2021): 289–301. http://dx.doi.org/10.1108/aeat-10-2020-0241.
Повний текст джерелаАнотація:
Purpose Winglets play a major role in saving fuel costs because they reduce the lift-induced drag formed at the wingtips. The purpose of this paper is to obtain the best orientation of the winglet for the Office National d’Etudes et de Recherches Aérospatiales (ONERA) M6 wing at Mach number 0.84 in terms of lift to drag ratio. Design/methodology/approach A computational fluid dynamics analysis of the wing-winglet configuration based on the ONERA M6 airfoil on drag reduction for different attack angles at Mach 0.84 was performed using analysis of systems Fluent. First, the best values of cant and sweep angles in terms of aerodynamic performance were selected by performing simulations. The analysis included cant angle values of 30°, 40°, 45°, 55°, 60°, 70° and 75°, while for the sweep angles 35°, 45°, 55°, 65° and 75° angles were used. The aerodynamic performance was measured in terms of the obtained lift to drag ratios. Findings The results showed that slight alternations in the winglet configuration can improve aerodynamic performance for various attack angles. The best lift to drag ratio for the winglet was achieved at a cant angle of 30° and a sweep angle of 65°, which caused a 5.33% increase in the lift to drag ratio. The toe-out angle winglets as compared to the toe-in angles caused the lift to drag ratio to increase because of more attached flow at its surface. The maximum value of the lift to drag ratio was obtained with a toe-out angle (−5°) at an angle of attack 3° which was 2.53% greater than the zero-toed angle winglet. Originality/value This work is relatively unique because the cant, sweep and toe angles were analyzed altogether and led to a significant reduction in drag as compared to wing without winglet. The wing model was compared with the results provided by National Aeronautics and Space Administration so this validated the simulation for different wing-winglet configurations.
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Tahani, Mojtaba, Mehran Masdari, and Ali Bargestan. "Aerodynamic performance improvement of WIG aircraft." Aircraft Engineering and Aerospace Technology 89, no. 1 (January 3, 2017): 120–32. http://dx.doi.org/10.1108/aeat-05-2015-0139.
Повний текст джерелаАнотація:
Purpose This paper aims to investigate the aerodynamic characteristics as well as static stability of wing-in-ground effect aircraft. The effect of geometrical characteristics, namely, twist angle, dihedral angle, sweep angle and taper ratio are examined. Design/methodology/approach A three-dimensional computational fluid dynamic code is developed to investigate the aerodynamic characteristics of the effect. The turbulent model is utilized for characterization of flow over wing surface. Findings The numerical results show that the maximum change of the drag coefficient depends on the angle of attack, twist angle and ground clearance, in a decreasing order. Also, it is found that the lift coefficient increases as the ground clearance, twist angle and dihedral angle decrease. On the other hand, the sweep angle does not have a significant effect on the lift coefficient for the considered wing section and Reynolds number. Also, as the aerodynamic characteristics increase, the taper ratio befits in trailing state. Practical implications To design an aircraft, the effect of each design parameter needs to be estimated. For this purpose, the sensitivity analysis is used. In this paper, the influence of all parameter against each other including ground clearance, angle of attack, twist angle, dihedral angle and sweep angle for the NACA 6409 are investigated. Originality/value As a summary, the contribution of this paper is to predict the aerodynamic performance for the cruise condition. In this study, the sensitivity of the design parameter on aerodynamic performance can be estimated and the effect of geometrical characteristics has been investigated in detail. Also, the best lift to drag coefficient for the NACA 6409 wing section specifies and two types of taper ratios in ground effect are compared.
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Lei, Yao, and Jinli Wang. "Aerodynamic Performance of Quadrotor UAV with Non-Planar Rotors." Applied Sciences 9, no. 14 (July 10, 2019): 2779. http://dx.doi.org/10.3390/app9142779.
Повний текст джерелаАнотація:
The mobility of a quadrotor UAV is significantly affected by its aerodynamics, especially when the closely spaced rotors are applied in the multi-rotor system. This paper addresses the aerodynamic modeling of non-planar quadrotor UAV with various rotor spacing (1 d–2 d) and disk plane angle (0–50 deg). The inter-rotor interference and the power models are also proposed in this paper. In order to validate the non-planar model, a series of CFD analyses and experiments were conducted. The obtained results demonstrate that the flow field of the non-planar quadrotor is extremely complicated when the unsteady flow is involved. The pulsation of partial angle of attack and pressure distribution is formed when the blade passes through the vortex. The thrust is increasing significantly along with the tilt angle, resulting from the stronger outflow of the non-planar rotors, which is also leading the power increment. However, the thrust increment is not that obvious when the spacing is larger than 1.4 d. The experiments and the numerical simulation results provide consistent trends and demonstrate the effectiveness of the aerodynamic model of the non-planar quadrotor. The comparison with the traditional planar quadrotor validates that the proposed non-planar quadrotor has better aerodynamic and control performances with a larger power loading.
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Didenko, Anton, Vladislav Borisenko, and Jose Leoro. "Load distribution method in helicopter blade multibody dynamics system." E3S Web of Conferences 258 (2021): 09076. http://dx.doi.org/10.1051/e3sconf/202125809076.
Повний текст джерелаАнотація:
The paper focuses on the loads applied to the helicopter blade cross-sections in the multibody dynamics system. The main objective is to simplify the blade aerodynamics calculation and avoid time-consuming CFD methods. For this reason, the way of computing blade aerodynamics is proposed by using multibody dynamics methods with a linear-elastic blade model. As the primary tool for further research, the MCS Adams software package is selected. Splitting the main rotor blade into a finite number of sections, each having its own average value of installation and coning angles, simplifies the calculation. Afterward, expressions for the total flow velocity around the blade section and its angle of attack are obtained through vector operations. This provides a measure of aerodynamic forces acting on each section in its cross-sectional coordinate system. In conclusion, the article provides the formalized method of aerodynamic force distribution between blade sections in the multibody model as well as the correlation between the flow coordinate system and the blade chord coordinate system.