Zeitschriftenartikel: „Wing test“

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Heryawan, Yudi, Hoon Cheol Park, Nam Seo Goo, Kwang Joon Yoon und Yung Hwan Byun. „Structural Design, Manufacturing, and Wind Tunnel Test of a Small Expandable Wing“. Key Engineering Materials 306-308 (März 2006): 1157–62. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.1157.

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This paper describes design, manufacturing, and wind tunnel test of a motor-driven small-scale expandable wing for MAV class vehicles. The bird-like expandable wing has been developed for investigating the influence of aspect ratio change on the lift and drag of the wing. As a typical bird wing, the wing is separated into inner and outer wings. The wing model consists of the linkage system made of carbon composite strip/rod and the remaining part covered with carbon composite sheet and multiple LIPCAs (Lightweight Piezo-Composite Actuators) mimicking wing feathers. The LIPCA actuator was used to control wing camber, which created additional lift. Wind tunnel tests were conducted to investigate the changes in lift and drag during wing folding and expansion, and to observe the influence of LIPCA actuation on the wing. In the tests, effects of the wing fold/expansion and actuation of LIPCA on changes in lift and drag were quantitatively identified.

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Siliang, Du, und Tang Zhengfei. „The Aerodynamic Behavioral Study of Tandem Fan Wing Configuration“. International Journal of Aerospace Engineering 2018 (30.10.2018): 1–14. http://dx.doi.org/10.1155/2018/1594570.

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The fan wing aircraft is a new concept based on a new principle, especially its wing which is based on a unique aerodynamic principle. A fan wing can simultaneously generate lift and thrust. In order to further improve its aerodynamic characteristics without changing its basic geometric parameters, two fan wings are installed along the longitudinal body, which is the composition of a tandem fan wing aircraft. Through numerical simulation, the lift and thrust of the fan wings were calculated with the distance, height, and installation angle of the front and rear fan wings changed, and the aerodynamic characteristic interaction rule between the front and rear fan wings was analyzed. In addition, the wind test model of a tandem fan wing was designed, and the results of the wind tunnel test and numerical calculation results were compared to verify the preliminary setup. The results show that at a certain height, distance, and installation angle, aerodynamic characteristics of a tandem fan wing have more advantages compared to the single fan wing. Therefore, the tandem fan wing aircraft’s advantages have good prospects for development and application.

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Teo, Z. W., T. H. New, Shiya Li, T. Pfeiffer, B. Nagel und V. Gollnick. „Wind tunnel testing of additive manufactured aircraft components“. Rapid Prototyping Journal 24, Nr. 5 (09.07.2018): 886–93. http://dx.doi.org/10.1108/rpj-06-2016-0103.

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Purpose This paper aims to report on the physical distortions associated with the use of additive manufactured components for wind tunnel testing and procedures adopted to correct for them. Design/methodology/approach Wings of a joined-wing test aircraft configuration were fabricated with additive manufacturing and tested in a subsonic closed-loop wind tunnel. Wing deflections were observed during testing and quantified using image-processing procedures. These quantified deflections were then incorporated into numerical simulations and results had agreed with wind tunnel measurement results. Findings Additive manufacturing provides cost-effective wing components for wind tunnel test components with fast turn-around time. They can be used with confidence if the wing deflections could be accounted for systematically and accurately, especially at the region of aerodynamic stall. Research limitations/implications Significant wing flutter and unsteady deflections were encountered at higher test velocities and pitch angles. This reduced the accuracy in which the wing deflections could be corrected. Additionally, wing twists could not be quantified as effectively because of camera perspectives. Originality/value This paper shows that additive manufacturing can be used to fabricate aircraft test components with satisfactory strength and quantifiable deflections for wind tunnel testing, especially when the designs are significantly complex and thin.

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Tsushima, Natsuki, Kenichi Saitoh, Hitoshi Arizono und Kazuyuki Nakakita. „Structural and Aeroelastic Studies of Wing Model with Metal Additive Manufacturing for Transonic Wind Tunnel Test by NACA 0008 Example“. Aerospace 8, Nr. 8 (25.07.2021): 200. http://dx.doi.org/10.3390/aerospace8080200.

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Additive manufacturing (AM) technology has a potential to improve manufacturing costs and may help to achieve high-performance aerospace structures. One of the application candidates would be a wind tunnel wing model. A wing tunnel model requires sophisticated designs and precise fabrications for accurate experiments, which frequently increase manufacturing costs. A flutter wind tunnel testing, especially, requires a significant cost due to strict requirements in terms of structural and aeroelastic characteristics avoiding structural failures and producing a flutter within the wind tunnel test environment. The additive manufacturing technique may help to reduce the expensive testing cost and allows investigation of aeroelastic characteristics of new designs in aerospace structures as needed. In this paper, a metal wing model made with the additive manufacturing technique for a transonic flutter test is studied. Structural/aeroelastic characteristics of an additively manufactured wing model are evaluated numerically and experimentally. The transonic wind tunnel experiment demonstrated the feasibility of the metal AM-based wings in a transonic flutter wind tunnel testing showing the capability to provide reliable experimental data, which was consistent with numerical solutions.

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Rogalla, Svana, Liliana D'Alba, Ann Verdoodt und Matthew D. Shawkey. „Hot wings: thermal impacts of wing coloration on surface temperature during bird flight“. Journal of The Royal Society Interface 16, Nr. 156 (Juli 2019): 20190032. http://dx.doi.org/10.1098/rsif.2019.0032.

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Recent studies on bird flight propose that hotter wing surfaces reduce skin friction drag, thereby improving flight efficiency (lift-to-drag ratio). Darker wings may in turn heat up faster under solar radiation than lighter wings. We used three methods to test the impact of colour on wing surface temperature. First, we modelled surface temperature based on reflectance measurements. Second, we used thermal imaging on live ospreys ( Pandion haliaetus ) to examine surface temperature changes with increasing solar irradiance. Third, we experimentally heated differently coloured wings in a wind tunnel and measured wing surface temperature at realistic flight speeds. Even under simulated flight conditions, darker wings consistently became hotter than pale wings. In white wings with black tips, the temperature differential produced convective currents towards the darker wing tips that could lead to an increase in lift. Additionally, a temperature differential between wing-spanning warm muscles and colder flight feathers could delay the flow separation above the wing, increasing flight efficiency. Together, these results suggest that wing coloration and muscle temperature both play important roles in modulating wing surface temperature and therefore potentially flight efficiency.

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Zafirov, Dimo, und Hristian Panayotov. „Joined-wing test bed UAV“. CEAS Aeronautical Journal 6, Nr. 1 (07.10.2014): 137–47. http://dx.doi.org/10.1007/s13272-014-0134-z.

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Kumar, G. C. Vishnu, und M. Rahamath Juliyana. „Design and Analysis of Flapping Wing“. Applied Mechanics and Materials 110-116 (Oktober 2011): 3495–99. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.3495.

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This paper the optimum wing planform for flapping motion is investigated by measuring the lift and drag characteristics. A model is designed with a fixed wing and two flapping wings attached to its trailing edge. Using wind tunnel tests are conducted to study the effect of angle of attack (smoke flow visualization technique). The test comprises of measuring the aerodynamic forces with flapping motion and without it for various flapping frequencies and results are presented. It can be possible to produce a micro air vehicle which is capable of stealthy operations for defence requirements by using these experimental data.

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Khaghaninia, S., S. Mohammadi, A. Srafrazi, K. Nejad und R. Zahiri. „Geometric Morphometric Study on Geographic Dimorphism of Coding Moth Cydia Pomonella (Lepidoptera, Tortricidae) from North West of Iran“. Vestnik Zoologii 45, Nr. 5 (01.01.2011): e-20-e-28. http://dx.doi.org/10.2478/v10058-011-0028-z.

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Geometric Morphometric Study on Geographic Dimorphism of Coding MothCydia Pomonella(Lepidoptera, Tortricidae) from North West of IranDuring years 2003-2004, nine geographical populations of codling moth Cydia pomonella (Linnaeus) from 4 north western provinces of Iran were collected. By preparing 575 images from fore wings and 564 from hind wings, a total of 15 and 11 landmarks were determined for fore and hind wings, respectively. With transforming of landmark's geometrical data into partial warp scores, 26 and 18 scores were obtained for fore and hind wings, respectively. Canonical correlation analysis (CCA) revealed significant correlation between environmental parameters and wing shape variables. Among environmental parameters, wind speed showed the highest correlation with wing shape variables whereas, the correlation between latitude, relative humidity as well as amount of precipitation and wing shape variables was low. Considering the effect of various environmental parameters on wing shape, wind speed was determined as important parameter affecting geographic dimorphism. Among the populations collected from different regions, two geographic population pairs; Meshkinshahr-Mahneshan and Zandjan-Khoramdareh were selected as representative of low and high windy regions, respectively. Relative warp analysis (RWA) of fore and hind wings shape variables in the areas with high and low wind showed shorter and wider fore wings as well as slender and narrower hind wings in populations from high windy regions compared with populations from low wind regions. Centroid size of fore and hind wings in high windy area populations were smaller compared with those from low windy ones as revealed by t-test. The results showed aerodynamic shape and small size of wings are as adapted traits for powerful flight and its control in high windy regions.

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Streit, T., und C. Hoffrogge. „DLR transonic inverse design code, extensions and modifications to increase versatility and robustness“. Aeronautical Journal 121, Nr. 1245 (11.10.2017): 1733–57. http://dx.doi.org/10.1017/aer.2017.101.

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ABSTRACTThe DLR inverse design code computes the wing geometry for a prescribed target pressure distribution. It is based on the numerical solution of the integral inverse transonic small perturbation (TSP) equations. In this work, several extensions and modifications of the inverse design code are described. Results are validated with corresponding redesign test cases. The first modification concerns applications for high transonic Mach numbers or cases with strong shocks. The introduced modifications enable converged design solutions for cases where the original method failed. The second modification is the extension of the code to general non-planar wings. Previously, the design code was restricted to non-planar wing designs with small dihedral or to nacelle design. A third modification concerns aerofoil/wings designed for wind-tunnel design. In order to design a swept wing between two wind-tunnel walls, the solution method was extended to two symmetry planes. The introduced extensions and modifications have increased the robustness and range of applicability of the inverse design code.

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Zhang, Ming Lu, Yi Ren Yang und Zhi Yong Lu. „Unsteady Characteristics over Dynamic Delta Wings“. Applied Mechanics and Materials 128-129 (Oktober 2011): 350–53. http://dx.doi.org/10.4028/www.scientific.net/amm.128-129.350.

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A study of flow and frequency characteristics of the leading-edge vortices over a delta wing undergoing pitching up-stop motions is presented. The experiments with the dynamic delta wings were conducted in a water channel and a wind tunnel respectively. Among them, the test of the flow visualization was completed in the water channel with the delta wing with pitching up-stop motions. The result shows that in the case of pitching up-stop movement the vortex breakdown position is dependent on the range of incidence at which the wing is subject to pitching up-stop and the reduced frequency k (k=c/2U∞). Analysis of the pressure signal measured in the wind tunnel shows when the delta wing is subject to pitching-up the nondimensional spiral wave frequency at nominal incidence in post-breakdown is higher than that at corresponding static state and the bigger the k is, the higher the nondimensional spiral wave frequency is. The same conclusion is fitted with different sweep delta wing.

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Combes, S. A., und T. L. Daniel. „Shape, flapping and flexion: wing and fin design for forward flight“. Journal of Experimental Biology 204, Nr. 12 (15.06.2001): 2073–85. http://dx.doi.org/10.1242/jeb.204.12.2073.

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SUMMARY Both kinematics and morphology are critical determinants of performance in flapping flight. However, the functional consequences of changes in these traits are not yet well understood. Traditional aerodynamic studies of planform wing shape have suggested that high-aspect-ratio wings generate more force per area and perform more efficiently than low-aspect-ratio wings, but these analyses may neglect critical components of flapping flight such as unsteady fluid dynamics and wing or fin flexion. In this paper, we use an unsteady potential flow analysis that incorporates wing flexion to test predictions of optimal wing shape under varying degrees of unsteady motion and wing flexion. We focus on forward flapping flight and examine the effects of wing/fin morphology and movements on thrust generation and efficiency. We test the model by comparing our predictions with kinematic data derived from the aquatic flight of the ratfish Hydrolagus colliei. Our analyses show that aspect ratio and the proportion of area in the outer one-fifth of the wing can characterize wing shape in terms of aero- or hydrodynamic performance. By comparing the performance of wings that vary in these two parameters, we find that traditional predictions of optimal wing shape are valid only under limited circumstances (when flapping frequency is low, wings are stiff or wings are tapered at the tips). This indicates a complex relationship between locomotor traits and performance and helps explain the diversity of wing kinematics and morphologies observed in nature.

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Bauknecht, Andŕe, Xing Wang, Jan-Arun Faust und Inderjit Chopra. „Wind Tunnel Test of a Rotorcraft with Lift Compounding“. Journal of the American Helicopter Society 66, Nr. 1 (01.01.2021): 1–16. http://dx.doi.org/10.4050/jahs.66.012002.

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Rotorcraft flight speed is limited by compressibility effects on the advancing blade side and decreasing lift potential on the retreating blade side. It may thus be beneficial to employ a hingeless rotor to generate additional lift with the advancing blade and compensate the resulting rolling moment with a fixed wing on the retreating blade side. This concept is a form of "lift compounding" that appears to show enormous potential. The present paper presents results of a wind tunnel test with a slowed, hingeless rotor and single fixed wing on the retreating blade side. Based on rotor test stand data and flow field measurements, the impact of operational and rotor parameters on system performance and aerodynamics is examined, mutual interaction effects between rotor and fixed wing are analyzed, and dominant flow structures are characterized in the reverse flow region on the retreating blade side. Flow field analysis reveals a reverse flow entrance vortex that freely convects through the reverse flow region and rivals the blade tip vortices in strength. Contrary to previous beliefs, this vortex originates from upstream of the reverse flow region and only its detachment from the rotor blade is related to entering this region. The combination of finite rolling moment trim and aft shaft tilt significantly increases rotor lift coefficient and corresponding peak lift-to-drag ratio of the compound rotorcraft. Results are compared with predictions from a comprehensive rotor analysis that is expanded to cover the main effects of the added fixed wing and is able to reproduce general performance trends of the rotorcraft. The present study highlights that adding a single fixed wing and hingeless rotor to a high-speed rotorcraft could significantly improve its performance.

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Bond, Vanessa L., Robert A. Canfield, Maria da Luz Madruga Santos Matos, Afzal Suleman und Maxwell Blair. „Joined-Wing Wind-Tunnel Test for Longitudinal Control via Aftwing Twist“. Journal of Aircraft 47, Nr. 5 (September 2010): 1481–89. http://dx.doi.org/10.2514/1.41140.

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Yu, Li, Bin Bin Lv, Hong Tao Guo, Yu Yan, Xing Hua Yang und Jian Guo Luo. „Research on Transonic Wind Tunnel Flutter Test for a Wing Model“. Advanced Materials Research 1006-1007 (August 2014): 26–29. http://dx.doi.org/10.4028/www.scientific.net/amr.1006-1007.26.

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This paper adopts self-designed wing model to conduct flutter test on subsonic and transonic, and obtains flutter characteristic of the model, and the test results are used for calibration and verification of flutter procedures. The sub-critical extrapolation is used to obtain the flutter sub-critical parameters and the direct observation method is used to obtain comparison of results. Error of results obtained by the two approaches does not exceed 5%, and validates reliability of the sub-critical prediction approach in continuous adjusted dynamic pressure flutter test.

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Ölçmen, Semih M., und Roger L. Simpson. „Influence of Passive Flow-Control Devices on the Pressure Fluctuations at Wing-Body Junction Flows“. Journal of Fluids Engineering 129, Nr. 8 (23.02.2007): 1030–37. http://dx.doi.org/10.1115/1.2746917.

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The effectiveness of passive flow-control devices in eliminating high surface rms pressure fluctuations at the junction of several idealized wing/body junction flows was studied. Wall-pressure fluctuation measurements were made using microphones along the line of symmetry at the wing/body junction of six different wing shapes. The wings were mounted on the wind tunnel floor at a zero degree angle-of-attack. The six wing shapes tested were: a 3:2 semi-elliptical-nosed NACA 0020 tailed generic body shape (Rood wing), a parallel center-body model, a tear-drop model, a Sandia 1850 model, and NACA 0015 and NACA 0012 airfoil shapes. Eight different fence configurations were tested with the Rood wing. The two double-fence configurations were found to be the most effective in reducing the pressure fluctuations. Two of the single fence types were nearly as effective and were simpler to manufacture and test. For this reason one of these single fence types was selected for testing with all of the other wing models. The best fence flow-control devices were found to reduce rms wall-pressure fluctuations by at least 61% relative to the baseline cases.

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Mat, Shabudin, I. Shah Ishak, Khidzir Zakaria und Z. Ajis Khan. „Manufacturing Process of Blended Delta-Shaped Wing Model“. Advanced Materials Research 845 (Dezember 2013): 971–74. http://dx.doi.org/10.4028/www.scientific.net/amr.845.971.

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Aerodynamicists have long acknowledged the blended wing body (BWB) aircraft design could produce great aerodynamic advantages due to the integration of the delta wing structure with the thick center body. Therefore the wind tunnel test campaign is crucial to gain information of the flow field that governs the delta-shaped wing which has frequently baffled the aerodynamicists. In such, the wind tunnel test required acceptable quality of delta-shaped wing model for results validity. Consequently, the manufacturing process as well as the selection of the appropriate machinery tools, must be wisely designed and performed. The modular 3D concept in associating with CAD/CAM technology was utilised in the process. Finally, the actual flow cycle of manufactures blended BWB aircraft model was sucessfully established. The objective of this paper is to highlight those complexity manufacturing process and techniques involved in order to produce a good blended delta-shaped wind tunnel model.

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Tjahjowidodo, Tegoeh, und Shian Lee. „Tendon-Sheath Mechanisms in Flexible Membrane Wing Mini-UAVs: Control and Performance“. International Journal of Aerospace Engineering 2017 (2017): 1–18. http://dx.doi.org/10.1155/2017/8181743.

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Flexible membrane wings (FMWs) are known for two inherent advantages, that is, adaptability to gusty airflow as the wings can flex according to the gust load to reduce the effective angle of attack and the ability to be folded for compact storage purposes. However, the maneuverability of UAV with FMWs is rather limited as it is impossible to install conventional ailerons. The maneuver relies only on the rudders. Some applications utilize torque rods to warp the wings, but this approach makes the FMW become unfoldable. In this research, we proposed the application of a tendon-sheath mechanism to manipulate the wing shape of UAV. Tendon-sheath mechanism is relatively flexible; thus, it can also be folded together with the wings. However, its severe nonlinearity in its dynamics makes the wing warping difficult to control. To compensate for the nonlinearity, a dedicated adaptive controller is designed and implemented. The proposed approach is validated experimentally in a wind tunnel facility with imitated gusty condition and subsequently tested in a real flight condition. The results demonstrate a stable and robust wing warping actuation, while the adaptive washout capability is also validated. Accurate wing warping is achieved and the UAV is easily controlled in a real flight test.

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Jiang, Shan, Yong Hu, Qiang Li, Hongde Wang, Yang Lin, Xiaoqin Zhou und Qiang Liu. „The Noise-Reduction Characteristics of Microstructure of Dragonfly Wing Leading Vein“. Applied Sciences 11, Nr. 7 (26.03.2021): 2970. http://dx.doi.org/10.3390/app11072970.

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Dragonfly wings have many excellent functions, such as superhydrophobic, fatigue resistance, anti-reflection, etc. However, there are few reports on the low noise flight of dragonfly wings. For this reason, the microgeometry of dragonfly wings was studied in this paper to reveal the mechanism of low-noise flight of dragonfly leading veins. The micromorphology of dragonfly wings was observed by scanning electron microscopy. It was found that the leading-edge veins of dragonfly wings have a triangular prism-like serrated structure, which has been proven to have the effect of improving aeroacoustics. According to the principle of scale law of flying organisms, a bionic model with the leading-edge microstructure of dragonfly’s front wing was established, and computational fluid dynamics (CFD) analysis of serration bionic microstructure was carried out. The effects of geometric parameters, such as height, width and overall amplification factor of microstructure on aeroacoustics were obtained. The distribution of pressure fluctuation on the surface of the bionic wing was also analyzed in this paper. It was found that the serrated microstructure can significantly suppress the noise generation in the mid-frequency band. Finally, wind tunnel tests were simulated using a designed low-noise rotating test platform. The test results confirmed that the serration microstructure has certain noise-reduction characteristics.

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Pelehach, Laura. „On a Wing and a Test Tube“. Laboratory Medicine 28, Nr. 4 (01.04.1997): 283–84. http://dx.doi.org/10.1093/labmed/28.4.284.

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AOKI, Y., T. ISHIKAWA, S. TAKEDA, Y. HAYAKAWA, A. HARADA und H. KIKUKAWA. „Fatigue test of lightweight composite wing structure“. International Journal of Fatigue 28, Nr. 10 (Oktober 2006): 1109–15. http://dx.doi.org/10.1016/j.ijfatigue.2006.02.017.

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Coton, F. N., R. A. McD. Galbraith und R. B. Green. „The effect of wing planform shape on dynamic stall“. Aeronautical Journal 105, Nr. 1045 (März 2001): 151–59. http://dx.doi.org/10.1017/s0001924000092071.

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AbstractThis paper examines the dynamic stalling of three wing planforms and characterises the main features of the stalling process in each case. The particular data were obtained during a three year research programme in the Department of Aerospace Engineering, University of Glasgow to collect high-resolution unsteady pressure data on the dynamic stalling characteristics of finite wing planforms. In this study, which was motivated by the pressing need for a greater understanding of the strongly three-dimensional effects in the tip region of helicopter rotors, the three wing planforms considered were a straight rectangular wing, a rectangular wing with swept tips and a delta wing. The initial test programme was followed by a further three years of detailed analysis and interpretation of the test data. Results from this analysis are presented in the present paper for cases in which the wings were subject to ramp motions.

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Lees, John J., Grigorios Dimitriadis und Robert L. Nudds. „The influence of flight style on the aerodynamic properties of avian wings as fixed lifting surfaces“. PeerJ 4 (20.10.2016): e2495. http://dx.doi.org/10.7717/peerj.2495.

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The diversity of wing morphologies in birds reflects their variety of flight styles and the associated aerodynamic and inertial requirements. Although the aerodynamics underlying wing morphology can be informed by aeronautical research, important differences exist between planes and birds. In particular, birds operate at lower, transitional Reynolds numbers than do most aircraft. To date, few quantitative studies have investigated the aerodynamic performance of avian wings as fixed lifting surfaces and none have focused upon the differences between wings from different flight style groups. Dried wings from 10 bird species representing three distinct flight style groups were mounted on a force/torque sensor within a wind tunnel in order to test the hypothesis that wing morphologies associated with different flight styles exhibit different aerodynamic properties. Morphological differences manifested primarily as differences in drag rather than lift. Maximum lift coefficients did not differ between groups, whereas minimum drag coefficients were lowest in undulating flyers (Corvids). The lift to drag ratios were lower than in conventional aerofoils and data from free-flying soaring species; particularly in high frequency, flapping flyers (Anseriformes), which do not rely heavily on glide performance. The results illustrate important aerodynamic differences between the wings of different flight style groups that cannot be explained solely by simple wing-shape measures. Taken at face value, the results also suggest that wing-shape is linked principally to changes in aerodynamic drag, but, of course, it is aerodynamics during flapping and not gliding that is likely to be the primary driver.

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Xu, Xin, Qiang Li, Dawei Liu, Keming Cheng und Dehua Chen. „Geometric Effects Analysis and Verification of V-Shaped Support Interference on Blended Wing Body Aircraft“. Applied Sciences 10, Nr. 5 (28.02.2020): 1596. http://dx.doi.org/10.3390/app10051596.

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A special V-shaped support for blended wing body aircraft was designed and applied in high-speed wind tunnel tests. In order to reduce the support interference and explore the design criteria of the V-shaped support, interference characteristics and geometric parameter effects of V-shaped support on blended wing body aircraft were numerically studied. According to the numerical results, the corresponding dummy V-shaped supports were designed and manufactured, and verification tests was conducted in a 2.4 m × 2.4 m transonic wind tunnel. The test results were in good agreement with the numerical simulation. Results indicated that pitching moment of blended wing body aircraft is quite sensitive to the V-shaped support geometric parameters, and the influence of the inflection angle is the most serious. To minimize the pitching moment interference, the straight-section diameter and inflection angle should be increased while the straight-section length should be shortened. The results could be used to design special V-shaped support for blended wing body aircraft in wind tunnel tests, reduce support interference, and improve the accuracy of test results.

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Shi, Pengtao, Jihai Liu, Yingsong Gu, Zhichun Yang und Pier Marzocca. „Full-Span Flying Wing Wind Tunnel Test: A Body Freedom Flutter Study“. Fluids 5, Nr. 1 (16.03.2020): 34. http://dx.doi.org/10.3390/fluids5010034.

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Aiming at the experimental test of the body freedom flutter for modern high aspect ratio flexible flying wing, this paper conducts a body freedom flutter wind tunnel test on a full-span flying wing flutter model. The research content is summarized as follows: (1) The full-span finite element model and aeroelastic model of an unmanned aerial vehicle for body freedom flutter wind tunnel test are established, and the structural dynamics and flutter characteristics of this vehicle are obtained through theoretical analysis. (2) Based on the preliminary theoretical analysis results, the design and manufacturing of this vehicle are completed, and the structural dynamic characteristics of the vehicle are identified through ground vibration test. Finally, the theoretical analysis model is updated and the corresponding flutter characteristics are obtained. (3) A novel quasi-free flying suspension system capable of releasing pitch, plunge and yaw degrees of freedom is designed and implemented in the wind tunnel flutter test. The influence of the nose mass balance on the flutter results is explored. The study shows that: (1) The test vehicle can exhibit body freedom flutter at low airspeeds, and the obtained flutter speed and damping characteristics are favorable for conducting the body freedom flutter wind tunnel test. (2) The designed suspension system can effectively release the degrees of freedom of pitch, plunge, and yaw. The flutter speed measured in the wind tunnel test is 9.72 m/s, and the flutter frequency is 2.18 Hz, which agree well with the theoretical results (with flutter speed of 9.49 m/s and flutter frequency of 2.03 Hz). (3) With the increasing of the mass balance at the nose, critical speed of body freedom flutter rises up and the flutter frequency gradually decreases, which also agree well with corresponding theoretical results.

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Breen, John E., Michael E. Kreger, Christopher D. White und Gordon C. Clark. „Field evaluation and model test of a composite wing-girder bridge“. Canadian Journal of Civil Engineering 14, Nr. 6 (01.12.1987): 753–62. http://dx.doi.org/10.1139/l87-113.

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This paper presents the key observations and conclusions from the evaluation of an innovative "loose-fit" composite, post-tensioned concrete wing-girder bridge proposed for an elevated interstate highway expansion in an urban environment. The evaluation program included both testing to destruction of a 1/2-scale model of a partial span as well as construction monitoring and field testing at service load levels of a full-scale prototype two-span bridge. Results of both construction measurements and loading tests were compared with analytical predictions. Laboratory tests showed the composite behavior of the wing-girder joint to be fully effective and a high level of load transfer between wings to be present. Recommendations for modification of the prototype design are made to improve constructibility, durability, structural performance, and economy. Key words: box girder, bridge, post-tensioned, prestressed concrete, reinforcement, stresses, temperature, tendons.

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Kim, Kijoon, Seungkeun Kim, Jinyoung Suk, Jongmin Ahn, Nakwan Kim und Byoung-Soo Kim. „Flight test of flying-wing type unmanned aerial vehicle with partial wing-loss“. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, Nr. 5 (21.02.2018): 1611–28. http://dx.doi.org/10.1177/0954410018758497.

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This paper investigates experimental evaluation via flight tests for applying adaptive neural network controller to a flying-wing type unmanned aerial vehicle experiencing partial wing-loss. For this, six-degree-of-freedom numerical model is constructed taking into account damage-induced changes to the unmanned aerial vehicle in aerodynamic coefficients, mass, center of gravity, and moments of inertia. Numerical simulations are performed to investigate the flight dynamics change and to verify the performance of the neural network based controller. During the flight test, main wing-loss is artificially generated by 22% or 33% area moment. The flight test verifies that the damaged unmanned aerial vehicle shows drastic roll behavior with the unstable longitudinal response, and the neural network based adaptive controller combined with feedback linearization successfully compensates for the wing damage.

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Cutts, C., und J. Speakman. „ENERGY SAVINGS IN FORMATION FLIGHT OF PINK-FOOTED GEESE“. Journal of Experimental Biology 189, Nr. 1 (01.04.1994): 251–61. http://dx.doi.org/10.1242/jeb.189.1.251.

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Fifty-four skeins of pink-footed geese (Anser brachyrhynchus) were photographed from directly underneath to eliminate the effects of perspective distortion, and the wing-tip spacings (the distance between adjacent birds' wing tips perpendicular to the flight path at maximum wingspan) and depths (the distance between adjacent birds' body centres parallel to the flight path) were measured at the same time as local wind speeds. The photographs were used to test for savings in induced power from wing positioning relative to the predicted positions of vortices generated by other wings, using a theoretical model. The mean wing-tip spacing corresponded to a saving in induced power of 14 %, less than one-third of the maximum possible. The saving in total power might be as low as 2.4 %. The high variation in wing-tip spacing suggests that pink-footed geese found difficulty maintaining position and thus adopted a strategy of flying outboard of the optimal position that maximises savings. This may minimise the risk of straying into a zone where savings are negative. There was a significant correlation between depth and wing-tip spacing, supporting an alternative communication hypothesis, whereby the birds position themselves to obtain maximum information on their neighbour's position. In high winds, there was little change in wing-tip spacing variation but a decrease in depth variation, suggesting a shift towards more regularly spaced skeins.

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I. Ismail, N., H. Yusoff, Hazim Sharudin, Arif Pahmi, H. Hafi und Mahadzir M.M. „Lift distribution of washout twist morphing MAV wing“. International Journal of Engineering & Technology 7, Nr. 4.13 (09.10.2018): 89. http://dx.doi.org/10.14419/ijet.v7i4.13.21337.

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Micro Air Vehicle, or also commonly known as MAV, is a miniature aircraft that has been gaining interest in the industry. MAV is defined as a flying platform with 15cm wingspan and operates at a speed of around 10m/s. Recently, MAV has been exposed with the latest development and link towards the biologically-inspired designs such as morphing wing. Twist morphing wing is one of the latest MAV wing design developments. The application of Twist Morphing (TM) on MAV wing has been previously known to produce better aerodynamic performance. Previous study in washin TM wing has shown a promising possibility of generating higher lift force. Despite the benevolent performance exhibited by the washin TM wing, the lift distribution for the washout type of TM MAV is relatively unknown and still open to be explored. This is probably due to the lack of experimental test rig to produce the washout twist morphing motion on the MAV wing. Therefore, this research aims to produce a special test rig for washout TM wing that is compatible for wind tunnel experimental testing. By using the special test rig, the experimental investigation on the lift performance of washout TM MAV wing can be done. Based on the wing deformation results, it clearly shows that the proposed test rig is capable to produce up to 19.5mm tip deflection at the morphing point, which is also resulting in a significant morphing motion. Higher morphing force induces larger morphing motion. Based on the lift distribution results, they show that the morphing motion has significantly affected the overall lift distribution on the MAV wing. The morphing motion on TM wing has produced at least 17.6% and 5.33% lower CL and CLmax magnitude, respectively, with the membrane wing especially at the pre-stall region. However, the TM wing is still able to maintain the stall angle similar to the baseline wing at αstall= 31°. By maintaining high αstall value with lower CL and CLmax magnitude, TM wing produces more agility for the MAV maneuverability that will be useful for indoor mission or obstacle avoidance flight.

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Zhu, Xiao-Jun, und Feng Li. „Exploration on application of dredging thermal protection in the leading edge of the wing“. International Journal of Modern Physics B 34, Nr. 14n16 (20.04.2020): 2040105. http://dx.doi.org/10.1142/s0217979220401050.

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Aiming at the severe aerodynamic heating problem in the leading edge of the hypersonic vehicle, in order to ensure the sharp shape of the leading edge of the wing, a dredging thermal protection structure is proposed, and the built-in high-temperature heat pipe structure is used to provide thermal protection for the leading edge of the wing. By means of numerical simulation and arc wind tunnel test, the dredging thermal protection structure of the leading edge of the wing is analyzed, and the thermal protection effect of the built-in high-temperature heat pipe is obtained. The numerical results show that under certain thermal conditions, the temperature at the leading edge of the wing decreases by 304 K, and the minimum temperature of the tail increases by 130 K. The heat flow is dredged from the high-temperature zone to the low-temperature zone, and the thermal load of the leading edge of the wing is weakened. The same result can be obtained by the arc wind tunnel test, which verifies the accuracy of the numerical method and the feasibility of the dredging thermal protection structure with high-temperature heat pipe embedded in the leading edge of the wing.

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Pan, Chun Xiang, Xiao Yan Qi, Guang Zhao und Xu Zhuo Guo. „The Test and Analysis of Nano Mechanical Properties for Dragonfly Wing“. Applied Mechanics and Materials 574 (Juli 2014): 271–74. http://dx.doi.org/10.4028/www.scientific.net/amm.574.271.

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nanomechanical testing system in this paper has been applied to get elastic modulus and hardness of dragonfly wing, and showing their gradient changes along the wing, and also analyzing the mechanical properties in nanodimension. It is significant to make a further research for specific biological functions of dragonfly wing.

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Liu, Yang, Pan Zeng und Li Ping Lei. „Experimental Study on the Stability Properties of Different Design of Tandem Wing Airship Models“. Applied Mechanics and Materials 457-458 (Oktober 2013): 1611–14. http://dx.doi.org/10.4028/www.scientific.net/amm.457-458.1611.

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This paper introduces a set of new design for the tandem wing airship, which the angular position between the front wing and tail wing are at 0o and 45o. Through the Wind Tunnel Platform test on the scaled models, lift-drag force for each configuration at different speed and mooring point was obtained and the aerodynamic performance and stability properties were analyzed. The results indicate that the tandem wing models have considerable higher aerodynamic characteristic and maintain a better stabilizability. The effect on longitudinal and yaw moment are relating to the mooring point, angle and position of the tandem wing. Result of this study could provide a new approach in designing an efficient tandem wing airship.

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Kulhánek, Robert. „Identification of a degradation of aerodynamic characteristics of a paraglider due to its flexibility from flight test“. Aircraft Engineering and Aerospace Technology 91, Nr. 6 (10.06.2019): 873–79. http://dx.doi.org/10.1108/aeat-06-2018-0162.

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Purpose Aerodynamics of paragliders is very complicated aeroelastic phenomena. The purpose of this work is to quantify the amount of aerodynamic drag related to the flexible nature of a paraglider wing. Design/methodology/approach The laboratory testing on scaled models can be very difficult because of problems in the elastic similitude of such a structure. Testing of full-scale models in a large facility with a large full-scale test section is very expensive. The degradation of aerodynamic characteristics is evaluated from flight tests of the paraglider speed polar. All aspects of the identification such as pilot and suspension lines drag and aerodynamics of spanwise chambered wings are discussed. The drag of a pilot in a harness was estimated by means of wind tunnel testing, computational fluid dynamics (CFD) solver was used to estimating smooth wing lift and drag characteristics. Findings The drag related to the flexible nature of the modern paraglider wing is within the range of 4-30 per cent of the total aerodynamic drag depending on the flight speed. From the results, it is evident that considering only the cell opening effect is sufficient at a low-speed flight. The stagnation point moves forwards towards the nose during the high speed flight. This causes more pronounced deformation of the leading edge and thus increased drag. Practical implications This paper deals with a detailed analysis of specific paraglider wing. Although the results are limited to the specific geometry, the findings help in the better understanding of the paraglider aerodynamics generally. Originality/value The data obtained in this paper are not affected by any scaling problems. There are only few experimental results in the field of paragliders on scaled models. Those results were made on simplified models at very low Reynolds number. The aerodynamic drag characteristics of the pilot in the harness with variable angles of incidence and Reynolds numbers have not yet been published.

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Xu, Xin, Dawei Liu, Keming Cheng und Dehua Chen. „Design and experimental validation of a specialized pressure-measuring rake for blended wing body aircraft’s unconventional inner flow channel“. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, Nr. 15 (06.07.2020): 2186–96. http://dx.doi.org/10.1177/0954410020938971.

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The internal drag of the unconventional inner flow channel of blended wing body aircraft must be measured accurately to correct the air intake effect of the blended wing body flow-through model in wind tunnel tests. In this study, the pressure distribution of the inner flow channel under the interaction of internal and external flows was obtained through numerical simulation. A specialized pressure-measuring rake was designed based on the numerical results, and a validation test was conducted in a 2.4 m × 2.4 m transonic wind tunnel. Compared with the flow in traditional inlets/nozzles, the flow in the unconventional inner channel in the current research is asymmetric, the distortion index is higher, and the internal drag is more sensitive to flow changes. The wind tunnel test results have a good correlation with the numerical results, and the repeatability of the test results is satisfactory, indicating that the measurement accuracy and precision of the pressure-measuring rake are acceptable. The design method of the specialized rake is feasible, and it can be used to guide the measurement of complex flow in unconventional inner flow channels of blended wing body aircraft.

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Yuan, Yan, und Le Cao. „Design of New Double-Wing Product Drop Test Machine“. Applied Mechanics and Materials 608-609 (Oktober 2014): 206–9. http://dx.doi.org/10.4028/www.scientific.net/amm.608-609.206.

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In order to simulate the free-fall motion of package, a new double-wing product drop test machine was designed. The lifting motion of the test bed was realized by the cooperation between rolling screw and stepping motor, while the opening and closing of double wing was realized by the coordinating transmission of guide rail and lead screw pair. Compared to similar products sold in the market, the new double-wing product drop test machine is low in cost, simple in structure, convenient in processing, stable in performance and beautiful in appearance. It can satisfy the demands of packing companies and academic institution, with practical application and promotion value.

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Curtis, David H., Mark F. Reeder, Craig E. Svanberg, Richard G. Cobb und Gregory H. Parker. „Flapping Wing Micro Air Vehicle Bench Test Setup“. International Journal of Micro Air Vehicles 4, Nr. 1 (März 2012): 51–77. http://dx.doi.org/10.1260/1756-8293.4.1.51.

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Iyas, Mahzan Muhammad, Muhamad Sallehuddin, Mat Ali Mohamed Sukri und Mansor Mohd Shuhaimi. „Wind Tunnel Testing of Composite Wing Flutter Speed due to Control Surface Excitation“. Applied Mechanics and Materials 315 (April 2013): 359–63. http://dx.doi.org/10.4028/www.scientific.net/amm.315.359.

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Flutter is a dynamic instability problem represents the interaction among aerodynamic forces and structural stiffness during flight. The study was conducted to investigate whether deflecting the control surface will affect the flutter speed and the flutter frequency. A wind tunnel test was performed using a flat plate wing made of composite material. It was found that by deflecting the control surface at 45°, the wing entered flutter state at wind speed of 28.1 m/s instead of 33.4 m/s. In addition, the flutter frequency also reduced from 224.52 Hz to 198.96 Hz. It was concluded that by deflecting the control surface, the wing experienced flutter at lower speed and frequency.

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Pak, Chan-gi, und Shun-fat Lung. „Flutter Analysis of Aerostructures Test Wing with Test Validated Structural Dynamic Model“. Journal of Aircraft 48, Nr. 4 (Juli 2011): 1263–72. http://dx.doi.org/10.2514/1.c031257.

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Lu, Bo, Bin Bin Lv, Li Yu, Hong Tao Guo, Yu Yan und Xi Ping Kou. „Design and Application of an all Moving Wing Model Limiting and Locking Device“. Advanced Materials Research 753-755 (August 2013): 1031–34. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.1031.

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To effectively excite the all moving wing flutter model and limiting or quick locking model in case of bigger amplitude of the model, an excitation and limiting and locking device is designed for the high-speed wind tunnel flutter test model. This paper introduces the structure arrangement, control principle and strategy of this device. The wind tunnel flutter test indicates that this device can enhance the SNR of the test data, improve the boundary prediction precision of flutter, prevent the model from entering the flutter divergence state and protect the model and wind tunnel test equipment.

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Syaifuddin, Moh, Hoon Cheol Park, Kwang Joon Yoon und Nam Seo Goo. „Design and Test of Flapping Device Mimicking Insect Flight“. Key Engineering Materials 306-308 (März 2006): 1163–68. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.1163.

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This paper addresses detail design and demonstration of an insect-mimicking flappingwing mechanism composed of LIPCA (Lightweight Piezo-Composite Actuator) and linkage system that can amplify the actuation displacement of LIPCA. The angular amplification of the linkage system can provide various flapping angles by adjusting the actuation point of the LIPCA. The device can generate flapping frequency ranging from 5 to 50 Hz depending on weight of the wing and linkages. Flapping tests using different wing mass, area, and aspect ratio were performed to investigate the flapping performance. The test results were described and compared with the estimation. It was found that changes in wing mass, area, and aspect ratio result in significant variation of natural flapping-frequency.

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YAMAMOTO, Kohei, und Osamu KOBAYASHI. „1204 Wind Tunnel Test on Lift-Drag Characteristics of Wing in Formation Flight“. Proceedings of Conference of Hokuriku-Shinetsu Branch 2014.51 (2014): _1204–1_—_1204–2_. http://dx.doi.org/10.1299/jsmehs.2014.51._1204-1_.

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Liu, Yi, Changchuan Xie, Chao Yang und Jialin Cheng. „Gust response analysis and wind tunnel test for a high-aspect ratio wing“. Chinese Journal of Aeronautics 29, Nr. 1 (Februar 2016): 91–103. http://dx.doi.org/10.1016/j.cja.2015.12.013.

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Hu, Yi Huai, Xiang Ming Zeng und Song Yue Li. „Research on the Aerodynamic Characteristics of Ellipse Wing Sail“. Advanced Materials Research 347-353 (Oktober 2011): 2249–54. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.2249.

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A kind of novel airfoil sail is proposed in this paper based on the research of traditional arc wing sails. The aerodynamic characteristic- the lift coefficient and drag coefficient is numerically calculated with FLUENT 6.0 and the results are verified by wind tunnel test. It is proved that the aerodynamic characteristic of the novel sail is much better than the arc wing sail.

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Ouyang, Yan, Kaichun Zeng, Xiping Kou, Yingsong Gu und Zhichun Yang. „Experimental and Numerical Studies on Static Aeroelastic Behaviours of a Forward-Swept Wing Model“. Shock and Vibration 2021 (10.06.2021): 1–12. http://dx.doi.org/10.1155/2021/5535192.

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The static aeroelastic behaviours of a flat-plate forward-swept wing model in the vicinity of static divergence are investigated by numerical simulations and wind tunnel tests. A medium fidelity model based on the vortex lattice method (VLM) and nonlinear structural analysis is proposed to calculate the displacements of the wing structure with large deformation. Follower forces effect and geometric nonlinearity are considered to calculate the deformation of the wing by finite element method (FEM). In the wind tunnel tests, the divergence dynamic pressure is predicted by the Southwell method, and the static aeroelastic displacement is measured by a photogrammetric method. The results obtained by the medium fidelity model calculations show reasonable agreement with wind tunnel test results. A high fidelity model based on coupled computational fluid dynamics (CFD) and computational structural dynamics (CSD) predicts better results of the wing tip displacement when the freestream dynamic pressure is approaching the divergence dynamic pressure.

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Wada, Daichi, und Masato Tamayama. „Wing Load and Angle of Attack Identification by Integrating Optical Fiber Sensing and Neural Network Approach in Wind Tunnel Test“. Applied Sciences 9, Nr. 7 (08.04.2019): 1461. http://dx.doi.org/10.3390/app9071461.

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The load and angle of attack (AoA) for wing structures are critical parameters to be monitored for efficient operation of an aircraft. This study presents wing load and AoA identification techniques by integrating an optical fiber sensing technique and a neural network approach. We developed a 3.6-m semi-spanned wing model with eight flaps and bonded two optical fibers with 30 fiber Bragg gratings (FBGs) each along the main and aft spars. Using this model in a wind tunnel test, we demonstrate load and AoA identification through a neural network approach. We input the FBG data and the eight flap angles to a neural network and output estimated load distributions on the eight wing segments. Thereafter, we identify the AoA by using the estimated load distributions and the flap angles through another neural network. This multi-neural-network process requires only the FBG and flap angle data to be measured. We successfully identified the load distributions with an error range of −1.5–1.4 N and a standard deviation of 0.57 N. The AoA was also successfully identified with error ranges of −1.03–0.46° and a standard deviation of 0.38°.

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Hainsworth, F. Reed. „Wing movements and positioning for aerodynamic benefit by Canada geese flying in formation“. Canadian Journal of Zoology 67, Nr. 3 (01.03.1989): 585–89. http://dx.doi.org/10.1139/z89-084.

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Wing tip spacing (the distance between wing tips of adjacent birds at maximum span, perpendicular to the flight path), depth (distance between adjacent birds along the flight path), wing beat frequencies, and extreme relative wing positions were measured for Canada geese (Branta canadensis) flying in V formations to test for use of variation in trailing wing tip vortex positions produced by wing movements. Use of vertical vortex position variation requires similarity in wing beat frequency. An average of only 48% of 73 birds in eight formations had frequencies similar to those of the bird ahead during migratory flight (difference ≤ 0.1 beat/s). Birds whose wing beat frequency was similar to that of the bird ahead differed in depth based on whether wings were in or out of phase. Use of horizontal vortex position variation involves variation in wing tip spacing with depth, which was observed, but variation was high and median wing tip spacing was less for birds with similar wing beat frequencies to the bird ahead in only two of eight formations. Induced power saving may be limited by unpredictable moves of birds ahead and by ability to track trailing vortex positions.

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., Sutrisno, Febryanto Nugroho, Yogi Adi Pratama, Sigit Iswahyudi und Setyawan Bekti Wibowo. „Sukhoi SU-47 Berkut and Eurofighter Typhoon Models Flow Visualization and Performance Investigation Using GAMA Water Tunnel“. Modern Applied Science 13, Nr. 2 (03.01.2019): 21. http://dx.doi.org/10.5539/mas.v13n2p21.

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Changes and modifications to the wings of fighter aircraft were carried out, one of which was the forward swept wing which was a moderate wing that continues to develop. There were also types of delta wings that had been applied to many fighter planes. Both types of aircraft wings had certainly different aerodynamic characteristics. This research would study the flow visualization that occurs in the aircraft model body to determine the aerodynamic characteristics of the forward swept wing and delta wing. This study used a water tunnel to observe the aerodynamic flow and forces that occurred in both types of wings. This visualization test used similar aircraft models: SU-47 Berkut and Eurofighter Typhoon. The results provided flow visualization, coefficient of lift (Cl), and coefficient of drag (Cd) which showed that the stall that occurred on the aircraft model similar to the SU-47 Berkut occurred at an angle of attack (AoA) 500 with a Cl max value of 2.66. Meanwhile, the Eurofighter Typhoon stall model occurred at an angle of attack 450 with a Cl max value of 1.48.

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Hua, Xin, Wei Shao, Chun Hua Zhang und Zhi Qiang Zhang. „Based on Imitation Seagull Airfoil UVA Wing Numerical Simulation“. Applied Mechanics and Materials 271-272 (Dezember 2012): 791–96. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.791.

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Wing aircraft is one of the major components to generate lift, in today's energy shortage, design the high lift-to-drag ratio wing is the goal pursued by, The author in the exploration of bionic airfoil aerodynamic characteristics on the basis of, which will be applied to straight wing design so as to improve the aerodynamic performance of aircraft.Our research mainly includes two aspects: first, the use of imitation seagull airfoil and NACA4412 airfoil are designed into the straight wing. The use of FLUENT software in Re=300000condition carries on the numerical simulation results show that the ratio of gull wing airfoil than NACA4412 lift coefficient increased by 13%, while the lift to drag ratio,is improved by 46.83%. Then, using the similarity principle, the wing scale, was tested in a wind tunnel test, the results obtained with the simulation are consistent. Airfoil design for the design of high performance wing opened a new way.

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Phillips, Nathan, Kevin Knowles und Richard J. Bomphrey. „Petiolate wings: effects on the leading-edge vortex in flapping flight“. Interface Focus 7, Nr. 1 (06.02.2017): 20160084. http://dx.doi.org/10.1098/rsfs.2016.0084.

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The wings of many insect species including crane flies and damselflies are petiolate (on stalks), with the wing planform beginning some distance away from the wing hinge, rather than at the hinge. The aerodynamic impact of flapping petiolate wings is relatively unknown, particularly on the formation of the lift-augmenting leading-edge vortex (LEV): a key flow structure exploited by many insects, birds and bats to enhance their lift coefficient. We investigated the aerodynamic implications of petiolation P using particle image velocimetry flow field measurements on an array of rectangular wings of aspect ratio 3 and petiolation values of P = 1–3. The wings were driven using a mechanical device, the ‘Flapperatus’, to produce highly repeatable insect-like kinematics. The wings maintained a constant Reynolds number of 1400 and dimensionless stroke amplitude Λ * (number of chords traversed by the wingtip) of 6.5 across all test cases. Our results showed that for more petiolate wings the LEV is generally larger, stronger in circulation, and covers a greater area of the wing surface, particularly at the mid-span and inboard locations early in the wing stroke cycle. In each case, the LEV was initially arch-like in form with its outboard end terminating in a focus-sink on the wing surface, before transitioning to become continuous with the tip vortex thereafter. In the second half of the wing stroke, more petiolate wings exhibit a more detached LEV, with detachment initiating at approximately 70% and 50% span for P = 1 and 3, respectively. As a consequence, lift coefficients based on the LEV are higher in the first half of the wing stroke for petiolate wings, but more comparable in the second half. Time-averaged LEV lift coefficients show a general rise with petiolation over the range tested.

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Mikhalyov, Semyon, Andrey Dunaevsky, Leonid Teperin, Roman Vasilyev und Andrey Redkin. „Effects of Propeller Slipstream of Distributed Electric Propulsion on the Wing-Flap System“. MATEC Web of Conferences 304 (2019): 02018. http://dx.doi.org/10.1051/matecconf/201930402018.

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The studies are aimed at investigating the mechanism to ensure the high lift by installing propellers in front of the wing and using interference effects. The model of the wing section of a regional STOL aircraft with DEPSis considered. The wing section is equipped with a trailing edge device (Fowler flap) and DEPS consisting of motors with propellers. Parametric and experimental studies of the interaction between DEPS propellers and the regional STOL aircraft wing-flap system were carried out. The development and verification of aerodynamic calculation method for the wing section at low Reynolds numbers were performed. The comparison with the wind tunnel test data obtained at TSAGI was made. It was found that: - for fixed power of propellers there is an optimal propeller diameter ensuring maximum increase in the wing section lift; - at low thrust the total lift weakly depends on DEPS inclination angle.

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Hart, K., und M. Bienz. „A test for cell autonomy, based on di-cistronic messenger translation“. Development 122, Nr. 3 (01.03.1996): 747–51. http://dx.doi.org/10.1242/dev.122.3.747.

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We have devised a test for cell autonomy of a gene that is switched on ectopically in a clone of cells, allowing us to ask whether the wild-type activity of this gene can influence neighbouring cells. To switch on the test gene, we used the yeast FRT system, and marked the FRT-generated cell clone by co-expressing beta-galactosidase. Co-expression is achieved by a stretch of 5′ untranslated mRNA from the homeotic gene Ultrabithorax (Ubx), which is inserted between the two coding sequences. We show that this Ubx sequence mediates efficient and reliable di-cistronic mRNA translation in wing imaginal discs of Drosophila. Applying our test to Ubx, we find that ectopic Ubx in wing discs strictly coincides with beta-galactosidase expression. Consequently, wing cells are transformed into cells that appear to be intermediates between wing and haltere cells, contesting the view that homeotic genes act as binary switches.

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