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Статті в журналах з теми "Gust Loading"
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Cheng, P. W., and W. A. A. M. Bierbooms. "Extreme Gust Loading for Wind Turbines during Operation." Journal of Solar Energy Engineering 123, no. 4 (July 1, 2001): 356–63. http://dx.doi.org/10.1115/1.1413218.
Повний текст джерелаАнотація:
One of the extreme load cases treated in the wind turbine certification is the extreme gust loading during operation. In the certification codes, it is treated in a deterministic way. A method of generating stochastic extreme gusts that includes the turbulence properties of the wind is described in this paper. For the moment, only the horizontal along wind direction of the wind speed is considered. The stochastic gusts are used to determine the gust responses. The gust responses are processed together with the probability density of the gust amplitude and mean wind speed to obtain the gust response distribution. Different distribution types, namely Rayleigh, Weibull, and Gumbel distributions, are applied to fit the distribution of the extreme gust responses. The estimated distributions are analyzed with statistical methods to determine the required number of simulations to obtain a reliable estimate of the statistical parameters of the distribution. The resulting structural responses to the stochastic gusts are compared to the gust response to the extreme operating gust specified in the IEC (International Electrotechnical Commission) design standard. The results show that the extreme gust response can differ significantly depending on the control concept. The response of the deterministic gust proposed in the IEC design code can also deviate considerably from the response of the stochastic gust depending on the turbine configuration. The aim of this work is to provide a rational approach to determine the extreme gust response. This theoretical method has not yet been verified with extensive measurements.
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Letson, Frederick, Rebecca J. Barthelmie, Weifei Hu, and Sara C. Pryor. "Characterizing wind gusts in complex terrain." Atmospheric Chemistry and Physics 19, no. 6 (March 25, 2019): 3797–819. http://dx.doi.org/10.5194/acp-19-3797-2019.
Повний текст джерелаАнотація:
Abstract. Wind gusts are a key driver of aerodynamic loading, especially for tall structures such a bridges and wind turbines. However, gust characteristics in complex terrain are not well understood and common approximations used to describe wind gust behavior may not be appropriate at heights relevant to wind turbines and other structures. Data collected in the Perdigão experiment are analyzed herein to provide a foundation for improved wind gust characterization and process-level understanding of flow intermittency in complex terrain. High-resolution observations from sonic anemometers and vertically pointing Doppler lidars are used to conduct a detailed study of gust characteristics with a specific focus on the parent distributions of nine gust parameters (that describe velocity, time, and length scales), their joint distributions, height variation, and coherence in the vertical and horizontal planes. Best-fit distributional forms for varying gust properties show good agreement with those from previous experiments in moderately complex terrain but generate nonconservative estimates of the gust properties that are of key importance to structural loading. Probability distributions of gust magnitude derived from vertically pointing Doppler lidars exhibit good agreement with estimates from sonic anemometers despite differences arising from volumetric averaging and the terrain complexity. Wind speed coherence functions during gusty periods (which are important to structural wind loading) are similar to less complex sites for small vertical displacements (10 to 40 m), but do not exhibit an exponential form for larger horizontal displacements (800 to 1500 m).
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Länger-Möller, Annika. "Simulation of transient gusts on the NREL 5 MW wind turbine using the URANS solver THETA." Wind Energy Science 3, no. 2 (July 6, 2018): 461–74. http://dx.doi.org/10.5194/wes-3-461-2018.
Повний текст джерелаАнотація:
Abstract. A procedure to propagate longitudinal transient gusts through a flow field by using the resolved-gust approach is implemented in the URANS solver THETA. Both the gust strike of a 1−cos() gust and an extreme operating gust following the IEC 61400-1 standard are investigated on the generic NREL 5 MW wind turbine at rated operating conditions. The impact of both gusts on pressure distributions, rotor thrust, rotor torque, and flow states on the blade are examined and quantified. The flow states on the rotor blade before the gust strike at maximum and minimum gust velocity are compared. An increased blade loading is detectable in the pressure coefficients and integrated blade loads. The friction force coefficients indicate the dynamic separation and re-attachment of the flow during the gust. Moreover, a verification of the method is performed by comparing the rotor torque during the extreme operating gust to results of FAST rotor code.
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Yigili, I., M. A. Andirin, M. T. Akpolat, O. Baskan, M. Percin, and O. Uzol. "Design of a gust generator and comparison of model wind turbine and porous disc wake flows in a transverse gust." Journal of Physics: Conference Series 2265, no. 2 (May 1, 2022): 022108. http://dx.doi.org/10.1088/1742-6596/2265/2/022108.
Повний текст джерелаАнотація:
Abstract This paper outlines the similarities and differences between the wake characteristics of a porous disc and model wind turbine under transverse gust loading which is generated via a two-vane wind tunnel gust generator. Phase-locked two-dimensional two-component (2D2C) particle image velocimetry (PIV) measurements show that the capability of a porous disc in representing a wind turbine increases under gust loading. Compared to the uniform inflow case, normalized streamwise velocity plots of the porous disc and model turbine are in a better agreement under gusty inflow condition particularly in the near wake region. Comparison of the wake centerlines reveals a similar wavy wake pattern with no significant phase lag suggesting that the gust dynamics is the dominant factor in the determination of the wake dynamics.
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Berger, Frederik, Lars Neuhaus, David Onnen, Michael Hölling, Gerard Schepers, and Martin Kühn. "Experimental analysis of the dynamic inflow effect due to coherent gusts." Wind Energy Science 7, no. 5 (September 8, 2022): 1827–46. http://dx.doi.org/10.5194/wes-7-1827-2022.
Повний текст джерелаАнотація:
Abstract. The dynamic inflow effect describes the unsteady aerodynamic response to fast changes in rotor loading due to the inertia of the wake. Fast changes in turbine loading due to pitch actuation or rotor speed transients lead to load overshoots. The phenomenon is suspected to be also relevant for gust situations; however, this was never shown, and thus the actual load response is also unknown. The paper's objectives are to prove and explain the dynamic inflow effect due to gusts, and compare and subsequently improve a typical dynamic inflow engineering model to the measurements. An active grid is used to impress a 1.8 m diameter model turbine with rotor uniform gusts of the wind tunnel flow. The influence attributed to the dynamic inflow effect is isolated from the comparison of two experimental cases. Firstly, dynamic measurements of loads and radially resolved axial velocities in the rotor plane during a gust situation are performed. Secondly, corresponding quantities are linearly interpolated for the gust wind speed from lookup tables with steady operational points. Furthermore, simulations with a typical blade element momentum code and a higher-fidelity free-vortex wake model are performed. Both the experiment and higher-fidelity model show a dynamic inflow effect due to gusts in the loads and axial velocities. An amplification of induced velocities causes reduced load amplitudes. Consequently, fatigue loading would be lower. This amplification originates from wake inertia. It is influenced by the coherent gust pushed through the rotor like a turbulent box. The wake is superimposed on that coherent gust box, and thus the inertia of the wake and consequently also the flow in the rotor plane is affected. Contemporary dynamic inflow models inherently assume a constant wind velocity. They filter the induced velocity and thus cannot predict the observed amplification of the induced velocity. The commonly used Øye engineering model predicts increased gust load amplitudes and thus higher fatigue loads. With an extra filter term on the quasi-steady wind velocity, the qualitative behaviour observed experimentally and numerically can be caught. In conclusion, these new experimental findings on dynamic inflow due to gusts and improvements to the Øye model enable improvements in wind turbine design by less conservative fatigue loads.
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Cheney, Jorn A., Jonathan P. J. Stevenson, Nicholas E. Durston, Jialei Song, James R. Usherwood, Richard J. Bomphrey, and Shane P. Windsor. "Bird wings act as a suspension system that rejects gusts." Proceedings of the Royal Society B: Biological Sciences 287, no. 1937 (October 21, 2020): 20201748. http://dx.doi.org/10.1098/rspb.2020.1748.
Повний текст джерелаАнотація:
Musculoskeletal systems cope with many environmental perturbations without neurological control. These passive preflex responses aid animals to move swiftly through complex terrain. Whether preflexes play a substantial role in animal flight is uncertain. We investigated how birds cope with gusty environments and found that their wings can act as a suspension system, reducing the effects of vertical gusts by elevating rapidly about the shoulder. This preflex mechanism rejected the gust impulse through inertial effects, diminishing the predicted impulse to the torso and head by 32% over the first 80 ms, before aerodynamic mechanisms took effect. For each wing, the centre of aerodynamic loading aligns with the centre of percussion, consistent with enhancing passive inertial gust rejection. The reduced motion of the torso in demanding conditions simplifies crucial tasks, such as landing, prey capture and visual tracking. Implementing a similar preflex mechanism in future small-scale aircraft will help to mitigate the effects of gusts and turbulence without added computational burden.
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Naaim-Bouvet, Florence, Mohamed Naaim, Hervé Bellot, and Kouichi Nishimura. "Wind and drifting-snow gust factor in an Alpine context." Annals of Glaciology 52, no. 58 (2011): 223–30. http://dx.doi.org/10.3189/172756411797252112.
Повний текст джерелаАнотація:
AbstarctWind-transported snow is a common phenomenon in cold windy areas, creating snowdrifts and contributing significantly to the loading of avalanche release areas. It is therefore necessary to take into account snowdrift formation both in terms of predicting and controlling drift patterns. Particularly in an Alpine context, drifting snow is a nonstationary phenomenon, which has not been taken into account in physical modeling carried out in wind tunnels or in numerical simulations. Only a few studies have been conducted to address the relation between wind gusts and drifting-snow gusts. Consequently, the present study was conducted at the Lac Blanc pass (2700ma.s.l.) experimental site in the French Alps using a snow particle counter and a cup anemometer in order to investigate drifting-snow gusts. First, it was shown that the behavior of the wind gust factor was coherent with previous studies. Then the definition of wind gust factor was extended to a drifting-snow gust factor. Sporadic drifting-snow events were removed from the analysis to avoid artificially high drifting-snow gust factors. Two trends were identified: (1) A high 1 s peak and a mean 10 min drifting-snow gust factor, greater than expected, were observed for events that exhibited a gamma distribution on the particle width histogram. The values of drifting-snow gust factors decreased with increasing gust duration. (2) Small drifting-snow gusts (i.e. smaller than or of the same order of magnitude as wind gusts) were also observed. However, in this case, they were systematically characterized by a snow particle size distribution that differed from the two-parameter gamma probability density function.
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Zhou, Yin, and Ahsan Kareem. "Gust Loading Factor: New Model." Journal of Structural Engineering 127, no. 2 (February 2001): 168–75. http://dx.doi.org/10.1061/(asce)0733-9445(2001)127:2(168).
Повний текст джерела
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Solari, Giovanni. "Turbulence Modeling for Gust Loading." Journal of Structural Engineering 113, no. 7 (July 1987): 1550–69. http://dx.doi.org/10.1061/(asce)0733-9445(1987)113:7(1550).
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Verheij, F. J., J. W. Cleijne, and J. A. Leene. "Gust modelling for wind loading." Journal of Wind Engineering and Industrial Aerodynamics 42, no. 1-3 (October 1992): 947–58. http://dx.doi.org/10.1016/0167-6105(92)90101-f.
Повний текст джерелаДисертації з теми "Gust Loading"
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MYERS, MATTHEW RONALD. "EFFECT OF AIRFOIL MEAN LOADING ON HIGH-FREQUENCY GUST INTERACTION NOISE (AEROACOUSTICS, FAN, TURBOMACHINERY)." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184032.
Повний текст джерелаАнотація:
This dissertation investigates the effect of airfoil steady loading on the sound generated by the interaction of an isolated, zero-thickness airfoil with a high-frequency convected disturbance. The analysis is based on a linearization of the inviscid equations of motion about a nonuniform mean flow. The mean flow is assumed to be two-dimensional and subsonic. Throughout most of the dissertation, we assume that the Mach number is 0(1), though in one section we concentrate on the leading-edge region and study the behavior of the sound field as the Mach number tends to zero. The small parameter representing the amount of airfoil camber and incidence angle, and the large parameter representing the ratio of airfoil chord to disturbance wavelength, are utilized in a singular perturbation analysis. The analysis shows that essentially all of the sound is generated at the leading and trailing edges, in regions the size of the disturbance wavelength. The solution in the local-leading-edge region reveals several sound-generating mechanisms which do not exist for an airfoil with no mean loading. These mechanisms are not present at the trailing edge; the trailing edge is important only as a scatterer of the sound produced at the leading edge. The propagation of sound away from the airfoil edges is described by geometric acoustics, with the amplitude varying on the scale of the airfoil chord and the phase varying on the much smaller scale of the disturbance wavelength. In addition, a diffraction-type transition region exists downstream of the airfoil. Calculations of radiated acoustic power show that the sound field depends strongly on Mach number, gust characteristics, and airfoil steady loading. Small changes in these properties can produce large changes in radiated power levels. Most importantly, we find that the amount of power radiated correlates very well with the strength of the mean flow around the leading edge.
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Horwich, Elizabeth Ann. "Unsteady response of a two-dimensional hydrofoil subject to high reduced frequency gust loading." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12408.
Повний текст джерелаАнотація:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1993, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1993.Includes bibliographical references (leaves 111-112).
by Elizabeth Ann Horwich.
M.S.
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McWilliam, S. "Response statistics under the action of first and second order wave forces and wind gust loading." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240898.
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Delpero, Philip Mario. "Investigation of flows around a two dimensional hydrofoil subject to a high reduced frequency gust loading." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13132.
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Pělucha, Jiří. "Výpočet zatížení kluzáku HPH 2 Twin Shark." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229315.
Повний текст джерелаАнотація:
The object of diploma thesis is a loading determination for strength calculation of HPH 2 Twin Shark glider matching the requirements of Certification Specification for Sailplanes (CS-22). Loading of the wing, tail section, fuselage and undercarriage is determined in this work.
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Kozelský, Martin. "Konstrukční návrh letounu Avia BH534 v ultralehkém provedení." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229316.
Повний текст джерелаАнотація:
The object of the diploma thesis is a preparation of fundamental bases for realization aerofoils of the replica of the biplane aircraft BH534 Avia. The preambule of the work balances replica against the real historic aircraft. As next the basic aerodynamics characteristics, construction of aerofoils and strenght calculation of the aerofoils are described.
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Hobday, Claire Louise. "Effect of guest uptake and high pressure on Zn- and Zr- metal-organic frameworks." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29527.
Повний текст джерелаАнотація:
Porous materials are essential to our everyday lives, for example as an effective catalyst in the cracking of crude oil, or as water softeners in washing powder. When developing novel functional porous materials, it is necessary to fully understand their structure-property relationships to maximise their ability to be used in industrially relevant settings. This thesis aims to understand the mechanical and adsorption properties of a class of porous solids metal-organic frameworks (or MOFs), which have many potential applications owing to their tuneable structures. Due to the inherent 3-D crystalline structure of MOFs, a wide range crystallographic techniques were used to determine structure-property relationships. To achieve maximum in-depth structural knowledge, both classical and quantum theoretical approaches were also applied to complement the understanding of both the energetics and structural details. Chapters One and Two begin with an overview of the state of the art studies carried out on MOFs, focusing on the use of high-pressure crystallography to understand their properties. In addition, there is emphasise on the importance of complementary computational methods that are used in the characterisation of MOFs. In Chapter Three, an isostructural series of MOFs (zeolitic imidazolate frameworks, or ZIFs) were studied for methanol adsorption by employing both experimental and molecular simulation techniques. These frameworks are gating materials, where the imidazole linker rotates upon adsorption of guest, and it was found that through ligand substitution the gate opening angle and onset pressure to gating could be tuned. By using high-pressure Xray crystallography the structure of the ZIFs were studied upon the uptake of guest and the degree of ring rotation quantified. In combination with periodic DFT and grand canonical Monte Carlo simulations the energy barrier to rotation and energies of adsorption could be calculated, respectively. Chapter Four focuses on one ZIF in particular, ZIF-8 ((Zn6(MeIm)12, MeIm = 2- methylimidazole) and details the adsorption of a selection of gases into the pores. The experimental method of cryogenic gas loading into a diamond anvil cell in this chapter is novel to MOFs. This method, in combination with molecular crystallography, is used to determine the structural response of the framework to guest-uptake as well as the crystallographic positions of the adsorption sites. In combination with in silico methods, the adsorption energies of guest-sites could be calculated, detailing which interactions drive the gating behaviour. The method of cryogenic loading highlighted how extreme conditions can be used to extract useful information about structural behaviour of MOFs on uptake of gas molecules into the pores, and when used in combination with computational methods, we have a powerful tool to analyse both positions and energies of adsorption sites. With this information, progress can be made in developing MOFs to maximize favourable interactions and lead to the development of MOFs with better selective gas storage properties. Chapter Five focuses on the synthesis and characterisation of the physical properties of a series of Zr-containing MOFs, called UiO-MOFs. The high valency of Zr(IV) and 12-fold coordination of the metal cluster in these materials, are associated with high shear and bulk moduli, which surpass those of other MOFs. A combination of single-crystal nano-indentation, high-pressure X-ray diffraction studies, density functional theory (DFT) calculations, and first-principles molecular dynamics (MD) simulations were used to determine the compressibility, elasticity and hardness of these materials, whose mechanical robustness was correlated to their different structural features, in-particular, how using non-linear linkers between the metal clusters stabilises the framework to compression. Chapter Six expands upon the series of Zr-MOFs in Chapter Five, and looks at how the mechanical properties of these MOFs are affected upon increasing the linker length. The experimentally determined elastics modulus of one of the frameworks, UiO-sdc (Zr6O4(OH)4(sdc)6 where sdc =4,4’-stillbene dicarboxylate), was found to lie above those of other highly porous MOFs. In addition, the elastic modulus was found to decrease linearly as a function of increasing the linker length, extending the structure-property relationships determined in Chapter Five.
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Maxwell, Rhianne Morgan Le. "Modifying the Mineral Profile of Crickets (Acheta domesticus) Using a Supplemented Diet." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1907.
Повний текст джерелаАнотація:
Captive insectivores may consume invertebrates as all, or part of their overall diet. The challenge with feeding captive insectivores involves the limited number of invertebrate species that are commercially available, and the lack of key nutrients provided by these insects. Among these insects, a naturally occurring low concentration of calcium and an inverse calcium to phosphorus ratio may put insectivores at the risk of developing hypocalcemia. A strategy to correct this nutrient imbalance involves supplementing the insect diet with high concentrations of targeted nutrients – a term referred to as gut-loading. Current industry guidelines recommend feeding a supplemented diet for 48 to 72 h before offering the insect to an insectivore. In the present study, the mineral profile of adult crickets (Acheta domesticus) offered a maintenance diet (1.58% Ca, DMB) are compared to crickets offered a supplemented diet (11.32% Ca, DMB) over 120 h. The supplemented diet produced a cricket with significantly higher calcium concentration compared to the maintenance diet. The calcium concentration of crickets offered the supplemented diet was highest at 48 h (0.63%), but did not achieve a 1:1 Ca:P ratio nor meet the lowest reported nutrient requirements of carnivorous reptiles, omnivorous reptiles, or an insectivorous bird at various life stages. Although the supplemented diet improved the whole body calcium concentration in feeder crickets, the crickets do not provide adequate calcium, iron, or manganese to meet the requirement of insectivores. As evidenced by the current study, the supplemented crickets are not recommended to serve as the sole source of nutrition for an insectivore.
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Mukherjee, Indrajit. "Aeroelasticity of Flapping Wings towards Micro Air Vehicle Applications." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4311.
Повний текст джерелаАнотація:
Studies have revealed that insect like flapping flight can serve as a benchmark in designing Micro Aerial Vehicles (MAV) owing to its power efficiency and high maneuverability. Primarily envisioned as agents facilitating in surveillance and reconnaissance missions, flapping wing-based MAV (FWMAV) can also be employed for a host of other applications ranging from _re fighting, rescue missions and biochemical sensing. Recently, few prototypes of FWMAV have successfully been realized owing to the recent technological progress. However, the present state of the art is still at a nascent stage and the ultimate goal of designing fully autonomous FWMAVs appears staggering, which demands contemporaneous developments in several disciplines. In particular, being the sources of lift generation, propulsion and maneuvers, the flexible wings of FWMAVs need special attention for the successful design of this class of vehicles. To this end, the development of a low dimensional aeroelastic framework describing the interaction of the flexible wing structures of FWMAVs with the surrounding fluid medium has special importance as it would guide the synthesis of control laws - a key step towards the development of autonomous FWMAVs. The work embodied in this thesis essentially presents two low dimensional analytical models describing the aeroelasticity of a flexible insect wing undergoing the flapping light. The analytical models can serve as a ready-to-use framework for obtaining responses of insect-like flexible flapping wing under different operating fight conditions.
After a brief introduction on the topic followed by a thorough survey of relevant literatures in Chapter 1, Chapter 2 presents a framework for quasi-steady aeroelasticity of a flapping wing structure in hover, which essentially is the first part of the dissertation. For this purpose, the revised quasi-steady aerodynamics model of Sane and Dickinson is used after making suitable modifications to the model to accommodate the effect of wing flexibility. The idealized flapping kinematics parameterized by the wing-sweep angle and the angle of attack is prescribed at the wing root. The flexible wing structure is idealized as the bending-torsion coupled Hodges-Dowell beam. Ramifications are made to the existing beam model to describe the time varying pitching motion of the insect wing. The bending displacement and the twist are the two unknowns to be solved for. One term approximation of the bending displacement and twist are made respectively in terms of the first bending mode of Euler-Bernoulli beam and the first torsional mode of circular bar with each expression having one multiplicative unknown coefficient. The Rayleigh-Ritz method is then taken recourse to wherein the expressions of the kinetic energy, the potential energy and the virtual work due to the aerodynamic loads are obtained in terms of the unknown coefficients of the bending and torsion expressions. An ordering scheme is invoked which segregates terms within the expressions energy and virtual work having different orders of magnitude, thereby retaining only the significant terms. The governing equation of motion of the coupled system is obtained using the Lagrange's method.
Notwithstanding the conciseness of the quasi-steady model, the second part of the study, comprising of Chapters 3-6, focuses on the development of a full unsteady aeroelastic model of insect fight, which would essentially capture the underlying complex ow physics keeping the same structural model earlier developed. Chapter 3 and 4 discuss the development of an unsteady blade element theory for the aerodynamics of insect flight based on the finite state air-load theory by D.A. Peters. The motivation stems from the requirement of a low order aerodynamics model, which can be developed from the first principle unlike most of the existing theories that are constructed empirically. Chapter 3 reports the development of the quasi-steady framework. The model developed is validated against the Robofly data. The framework is then used to model the forward flight of a rigid wing. The simplest case of locomotion along a straight line in one principal direction is considered. Chapter 4 reports the development of a wake model. For this purpose, the three-dimensional Peter-He inflow model is adapted to describe the wake shed by the wing and, more importantly, for modeling the interaction of wing with the wake shed during previous wingbeat cycles. A time domain formulation with ten wake states is developed based on the Peter-He inflow theory. The modularity of the finite state framework air-load theory allows us to incorporate the effect of the shed wake by coupling it with the quasi-steady framework developed in chapter 3. Once the unsteady framework is developed, the unsteady lift force computed is again validated with the Robofly data. Noteworthy to mention that chapter 4 presents the first ever attempt to adapt the formulation of Peter-He inflow theory for the wake modeling of insect-like flapping flight. Chapter 5 presents a low-dimensional aeroelastic framework based on the unsteady blade element theory developed in the previous two chapters. The finite state blade element theory is modified at the outset to incorporate the effect of wing flexibility by introducing variables such as the velocity of the wing flapping and the angular velocity due to wing pitching. The wing model used for the quasi-steady aeroelasticity analysis is used again. Virtual work done due to the aerodynamics loads is computed. The energy expressions are obtained similarly to the quasi-steady problem enumerated in chapter 2. Procedures similar to that of Chapter 2 is followed to arrive at the governing equations of motion. Simulations for both the quasi-steady and unsteady cases are carried out and lift forces obtained from each case is compared with one another and with the rigid wing lift data obtained from the finite state aerodynamics. Responses of a flapping wing structure under gust load are very important owing to the light weight and diminutive size of the vehicle. Chapter 6 presents the framework for obtaining aeroelastic responses of the wing in hover when impinged with the wind gust, which is modeled as a transient velocity pulse acting vertically to the wing surface. Different standard forms of global gust-pulse are considered. This is for the first time that a low-dimensional framework for obtaining aeroelastic response under gust is being reported. Apart from being an useful tool for stability analysis and synthesis of control laws, the low dimensional aeroelastic models introduced in the dissertation may also provide useful insights into the complex physics of the flapping flight.
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Attard, Lydia. "The Development and Evaluation of a Gut-loading Diet for Feeder Crickets Formulated to Provide a Balanced Nutrient Source for Insectivorous Amphibians and Reptiles." Thesis, 2013. http://hdl.handle.net/10214/6653.
Повний текст джерелаАнотація:
In captivity the diversity of prey items for obligate insectivores is limited and nutritionally inadequate, leading to nutrient deficiencies. Zoological institutions utilize gut-loading, an insect supplementation technique, to compensate for these nutrient shortcomings.
This study developed a gut-loading diet (GLD) to enhance the nutritive quality of the domestic house cricket (Acheta domestica) for insectivorous amphibians and reptiles, with the requisite that it also met cricket foraging and palatability needs.
Gut-loaded cricket analysis established its effectiveness such that the targeted level of most nutrients required by the end consumers were met after consuming the diet for 24 hrs (Ca:P of 1.127; vitamin A (retinyl acetate) level of 12,607 IU/kg; vitamin E level of 342 IU/kg and a linoleic fatty acid level of 4.62%), peaking at 2 days for some and remained above targeted amounts for at least 4 days. A list of cricket gut-loading optimization husbandry procedures has also been recommended.
Книги з теми "Gust Loading"
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W. G. J. 't Hart. Fatigue damage in composites under different loading conditions. Amsterdam: National Aerospace Laboratory, 1988.
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Response of the alliance 1 proof-of-concept airplane under gust loads. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 2001.
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Publishing, Furr Corp. Retirement Loading: Retirement Guest Book ~ Keepsake Memory Book, Guestbook for Retirement Party Family and Friends to Write In. Independently Published, 2019.
Знайти повний текст джерелаЧастини книг з теми "Gust Loading"
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Kerschen, E. J., and M. R. Myers. "Influence of Airfoil Mean Loading on Convected Gust Interaction Noise." In Aero- and Hydro-Acoustics, 13–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82758-7_2.
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"Equations for Gust Response Factors." In Guidelines for Electrical Transmission Line Structural Loading, 113–18. Reston, VA: American Society of Civil Engineers, 2009. http://dx.doi.org/10.1061/9780784410356.apf.
Повний текст джерелаТези доповідей конференцій з теми "Gust Loading"
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Weaver, Matthew M., and Stanford Fleeter. "Turbine Rotor Generated Forcing Functions for Flow Induced Vibrations." In ASME 1994 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/94-gt-328.
Повний текст джерелаАнотація:
A series of experiments are performed to investigate the effect of steady loading on the unsteady aerodynamic gust forcing functions generated by turbine rotor blade rows and the validity of the vortical and potential gust splitting techniques. Both the downstream vortical-potential gusts and, for the first time, the upstream generated potential gust are considered. Note that these upstream gusts are in fact the potential field of the rotor and not the nozzle wakes. This is accomplished by measuring the downstream and upstream unsteady forcing functions generated by the first stage rotor of the low speed research turbine over a range of steady loading levels. These forcing functions are then split into vortical and potential gusts utilizing both the V-Method using only velocity data and the P-Method which also incorporates unsteady static pressure data. The results clearly show an increase in potential effects for the downstream gust forcing functions with increased blade loading. The rotor blade gusts upstream of the first rotor are theoretically purely potential gusts since no vorticity can be conducted upstream. These potential disturbances do not appear to be a function of the blade loading. The results of the linear theory splitting show that both splitting methods have discrepancies in their recombined forcing functions. The V-Method either under or over estimates the unsteady static pressure and has trouble duplicating the phase. The P-Method tends to skew the recombined velocity in the lift force direction. The upstream potential gusts posed a particular problem for the splitting, with neither method able to fully reconcile the measured pressure and velocity perturbations.
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Henderson, Gregory H., and Sanford Fleeter. "Cascade Vortical Gust Response Including Steady Loading Effects." In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-370.
Повний текст джерелаАнотація:
A series of experiments are performed to investigate the effect of steady loading and separated flow on the unsteady vortical gust response of both low and high solidity blade rows, including the effects of airfoil camber. This is accomplished utilizing a unique single stage turbomachine research facility in which the flow is not generated by the blading but rather by an additional fan. This provides the ability to quantify the steady or mean performance of the stator row over a range of steady loading levels both with and without unsteady flow effects. In particular, for a particular mean stator angle-of-attack, the steady and mean aerodynamic performance are determined in a steady flow and also in an unsteady flow generated by a rotor composed of perforated plates at the same mean operating condition. This enables the stator vane row dynamic stall conditions to be identified. The unsteady aerodynamic response of both symmetric and cambered stator vanes configured as low and high solidity stator vane rows is then investigated over a range of mean angle-of-attack values, including attached and separated flows with dynamic stall.
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Cheng, P., and W. Bierbooms. "Extreme gust loading for wind turbines during operation." In 20th 2001 ASME Wind Energy Symposium. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2001. http://dx.doi.org/10.2514/6.2001-45.
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Mara, T. G. "Updated Gust Response Factors for Transmission Line Loading." In Electrical Transmission and Substation Structures 2015. Reston, VA: American Society of Civil Engineers, 2015. http://dx.doi.org/10.1061/9780784479414.037.
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Manwaring, Steven R., and Sanford Fleeter. "Rotor Blade Unsteady Aerodynamic Gust Response to Inlet Guide Vane Wakes." In ASME 1991 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/91-gt-129.
Повний текст джерелаАнотація:
A series of experiments are performed in an extensively instrumented axial flow research compressor to investigate the fundamental flow physics of wake generated periodic rotor blade row unsteady aerodynamics at realistic values of the reduced frequency. Unique unsteady data are obtained which describe the fundamental unsteady aerodynamic gust interaction phenomena on the first stage rotor blades of a research axial flow compressor generated by the wakes from the Inlet Guide Vanes. In these experiments, the effects of steady blade aerodynamic loading and the aerodynamic forcing function, including both the transverse and chordwise gust components, and the amplitude of the gusts, are investigated and quantified.
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Manwaring, S. R., and D. C. Wisler. "Unsteady Aerodynamics and Gust Response in Compressors and Turbines." In ASME 1992 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/92-gt-422.
Повний текст джерелаАнотація:
A comprehensive series of experiments and analyses were performed on compressor and turbine blading to evaluate the ability of current, practical, engineering/analysis models to predict unsteady aerodynamic loading of modern gas turbine blading. This is part of an on-going effort to improve methods for preventing blading failure. The experiments were conducted in low-speed research facilities capable of simulating the relevant aerodynamic features of turbomachinery. Unsteady loading on compressor and turbine blading was generated by upstream wakes and, additionally for compressors, by a rotating inlet distortion. Fast-response hot-wire anemometry and pressure transducers embedded in the airfoil surfaces were used to determine the aerodynamic gusts and resulting unsteady pressure responses acting on the airfoils. This is the first time that gust response measurements for turbines have been reported in the literature. Several different analyses were used to predict the gust response of the blading: (1) a classical flat-plate analysis, (2) a 2-D linearized flow analysis with a “frozen gust” model, (3) a 2-D linearized flow analysis with a “distorted gust” model, (4) a 2-D linearized Euler analysis, and (5) a 2-D non-linear Euler analysis. Also for the first time, a detailed comparison of these analyses methods is made and the importance of properly accounting for both vortical and potential disturbances is demonstrated. The predictions are compared with experiment and their abilities assessed to help guide designers in using these prediction schemes.
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S., Borgersen, and Yazdani S. "Dynamic Response Characteristics of Steel Tanks under Wind Gust Loading." In Modern Methods and Advances in Structural Engineering and Construction. Singapore: Research Publishing Services, 2011. http://dx.doi.org/10.3850/978-981-08-7920-4_s2-s19-cd.
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Frey, Kuk Kim, and Sanford Fleeter. "Combined-Simultaneous Gust and Oscillating Compressor Blade Unsteady Aerodynamics." In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-414.
Повний текст джерелаАнотація:
Experiments are performed in a 3-stage axial flow research compressor to investigate and quantify the simultaneous-combined gust and motion induced unsteady aerodynamic response of compressor 1st stage rotor blades. The gust response unsteady aerodynamics are experimentally modeled with a 2/rev forcing function. The torsion mode unsteady aerodynamics are investigated utilizing an experimental influence coefficient technique in conjunction with a unique drive system. Combined gust and oscillating unsteady aerodynamics are obtained by superposition of the separate oscillating blade row and the gust response unsteady aerodynamics. Simultaneous gust and motion induced unsteady aerodynamic response are obtained by driving the torsion mode oscillation in the presence of the 2/Rev forcing function. The effects of steady loading are quantified, with airfoil oscillation amplitude effects also studied. The combined unsteady aerodynamics establish the applicability limitations of the superposition principle at high oscillation amplitudes and high loading. In addition, the gust-blade motion phase angle is identified as a key parameter, with the accuracy of forced response prediction and the alteration of blade row stability due to gust interaction dependent on the gust-blade motion phase.
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Henderson, Gregory H., and Sanford Fleeter. "Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 1 — Forcing Functions." In ASME 1992 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/92-gt-174.
Повний текст джерелаАнотація:
The fundamental gust modeling assumption is investigated by means of a series of experiments performed in the Purdue Annular Cascade Research Facility. The unsteady periodic flow field is generated by rotating rows of perforated plates and airfoil cascades. In this paper, the measured unsteady flow fields are compared to linear-theory gust requirements, with the resulting unsteady gust response of a downstream stator cascade correlated with linear theory predictions in an accompanying paper. The perforated-plate forcing functions closely resemble linear-theory forcing functions, with the static pressure fluctuations small and the periodic velocity vectors parallel to the downstream mean-relative flow angle over the entire periodic cycle. In contrast, the airfoil forcing functions exhibit characteristics far from linear-theory gusts, with the alignment of the velocity vectors and the static pressure fluctuation amplitudes dependent on the rotor-loading condition, rotor solidity and the inlet mean-relative flow angle. Thus, these unique data clearly show that airfoil wakes, both compressor and turbine, are not able to be modeled with the boundary conditions of current state-of-the-art linear unsteady aerodynamic theory.
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KERSCHEN, E., and M. MYERS. "A parametric study of mean loading effects on airfoil gust interaction noise." In 11th Aeroacoustics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1987. http://dx.doi.org/10.2514/6.1987-2677.
Повний текст джерелаЗвіти організацій з теми "Gust Loading"
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Nixon, David, and Keh L. Tzuoo. Prediction of Gust Loadings and Alleviation at Transonic Speeds. Fort Belvoir, VA: Defense Technical Information Center, March 1986. http://dx.doi.org/10.21236/ada167748.
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