Journal articles on the topic 'Gust analysis'
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Knoop, Helge, Felix Ament, and Björn Maronga. "A generic gust definition and detection method based on wavelet-analysis." Advances in Science and Research 16 (July 29, 2019): 143–48. http://dx.doi.org/10.5194/asr-16-143-2019.
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Abstract. Wind gusts can have destructive effects on many structures and objects deemed valuable to humans. The aviation industry, for example, views gusts as a major hazard. Their destructive effect is proportional to the momentum that a specific gust imposes onto an object. The actual definition of a gust has a strong influence on how its impact can be quantified. Existing gust definitions, however, are largely based on fixed parameters describing shape requirements and thresholds and are often developed only for specific use cases. These gust definitions do not provide a direct link to the physical impact a particular gust has on a structure or object. The overall goal of this study is to provide such a direct link. The application of a wavelet-analysis to a turbulence-resolving wind velocity signal allows for the localization of signal amplitudes in the period as well as in the time domain. In this paper, we use wavelet-analysis in order to develop a straight-forward method of deriving information about gusts from a wind velocity signal. In order to define what a particular gust might be, we suggest the specification of a characteristic period and amplitude in the time-domain. We define a generic gust as a section of a wind velocity signal, where the wavelet-analysis detects that characteristic amplitude to be matched or exceeded within that characteristic period. The characteristic amplitudes and periods are generic and span a two-dimensional space of generic gust definitions. The method can be applied to turbulence resolving simulation data as well as high-resolution wind velocity measurement data. It can detect gusts of any shape, it is unbiased regarding any specific use case and invariant to changes of the mean wind. We provide a detailed description of the method, its capabilities and demonstrate its application to high resolution wind velocity measurement data.
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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.
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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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Yan, Bowen, Pakwai Chan, Qiusheng Li, Yuncheng He, Ying Cai, Zhenru Shu, and Yao Chen. "Characterization of Wind Gusts: A Study Based on Meteorological Tower Observations." Applied Sciences 12, no. 4 (February 17, 2022): 2105. http://dx.doi.org/10.3390/app12042105.
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Accurate information on wind gusts is of critical importance to various practical problems. In this study, observational wind data from high-frequency response (i.e., at a sampling rate of 10 Hz), ultrasonic anemometers instrumented at four different heights (i.e., 10 m, 40 m, 160 m, 320 m) on a weather tower were collected. The observation site featured a typical suburban condition, with no significant obstacles in the immediate proximity. The data were analyzed to identify a total of twelve descriptors of wind gusts, and to find the parent distributions that estimate these parameters well via regression analysis. The results show that the gust parameters in the context of gust magnitude and amplitude with units are best fit by the Weibull model, while non-dimensional parameters in terms of gust factor and peak factor are reasonably assessed by the log-logistic distribution. The uplift time and gust nonsymmetric factor generally exhibit a lognormal distribution, while the Gamma distribution can describe the gust length scale, uplift magnitude and passage time. It is also shown that gust factors increase linearly along with turbulence intensity. Nevertheless, empirical linear formulas given in previous studies tend to over-predict. For the vertical structure of gust descriptors, it is found that the average wind speed, gust amplitude and gust length scale in 10 min monotonically increase with height, whereas the function relationship of gust amplitude, peak factor, gust factor, turbulence intensity, rise amplitude and falling amplitude tends to decrease with height.
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Martín, M. L., F. Valero, A. Pascual, A. Morata, and M. Y. Luna. "Springtime connections between the large-scale sea-level pressure field and gust wind speed over Iberia and the Balearics." Natural Hazards and Earth System Sciences 11, no. 1 (January 21, 2011): 191–203. http://dx.doi.org/10.5194/nhess-11-191-2011.
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Abstract. This paper investigates, by means of Singular Value Decomposition analysis, the springtime relationships between the mean sea-level pressure field over the North Atlantic and the regional wind gusts over the Iberian Peninsula, identifying the main atmospheric circulation patterns linked to gust wind speed anomaly configurations. The statistical significance of the obtained modes is investigated by means of Monte Carlo approach. The analysis highlighted that the covariability is dominated by two main large-scale features of the atmospheric circulation over the North Atlantic. The first mode relates to Iberian gust wind speeds to the Scandinavian pattern (SCAND), linking the large-scale pattern to above-normal wind gusts. The second covariability mode, associated with the North Atlantic Oscillation (NAO) pattern, correlates with maximum wind speeds over Iberia. An enhanced spring NAO pattern is related to positive (negative) wind gust correlations over northern (southern) Iberia. To find true relationships between large-scale atmospheric field and the gust wind speeds, composite maps were built up to give an average atmospheric circulation associated with coherent wind gust variability over Iberia.
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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.
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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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Wang, Linpeng, Yuting Dai, and Chao Yang. "Gust Response Analysis for Helicopter Rotors in the Hover and Forward Flights." Shock and Vibration 2017 (2017): 1–20. http://dx.doi.org/10.1155/2017/8986217.
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Dynamic load due to gust for helicopter rotors directly affects the structural stress and flight performance. In case of gust, it may cause the loss of trust force or the increase of deflection for rotors. In current work, an effective coupled aeroelastic model based on a medium-deflection beam theory and a nonlinear unsteady aerodynamic model in the time domain were constructed. Three types of gust in vertical direction were added in the model. The dynamic response and structural load for helicopter rotors under three types of gust were calculated, respectively. Results indicated that when rotors suffer a gust in hover at downward direction, the thrust force on rotor disk would decrease significantly when the gust amplitude increases, which should be paid attention in the design. Among the three gust types with the same gust strength, the maximum instantaneous shear force due to impulse shape gust is the largest. When the rotors suffer a gust in a forward flight, the shear force at the root of rotors would increase with the gust strength first but then it decreases. More attention should be paid to the decrease of thrust force and the increase of structural load in a forward flight.
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Dai, Yuting, Linpeng Wang, Chao Yang, and Xintan Zhang. "Dynamic Gust Load Analysis for Rotors." Shock and Vibration 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/5727028.
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Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.
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Szwed, Piotr, Paweł Rzucidło, and Tomasz Rogalski. "Estimation of Atmospheric Gusts Using Integrated On-Board Systems of a Jet Transport Airplane—Flight Simulations." Applied Sciences 12, no. 13 (June 22, 2022): 6349. http://dx.doi.org/10.3390/app12136349.
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Currently, quite accurate measurements of atmospheric gusts are carried out by airport systems only in the vicinity of the runways. There is a still open issue of availability of information about real wind gusts at cruising altitudes and during approach at a considerable distance from the airfield. Standard on-board systems of a jet transport airplane provide some information which is desirable to have knowledge of how flight parameters reflect real gust parameters and their impact on the aircraft dynamics. The paper proposes an algorithm for headwind gust magnitude estimation in relation to aircraft response. The analysed estimation algorithms assume the use of data available from the existing on-board systems only without the employment of any extra sensors or ground and satellite systems. In this way, many problems caused by different structures, configurations, and ways of installation of additional sensors and structural changes are rejected. The algorithms use the classical method for estimation of wind parameters as well as a linear longitudinal model of aircraft dynamics, taking into account the influence of wind gusts. Data fusion was realised with the use of three filtration methods. Results were evaluated to select the most accurate method of the estimation. Test data were obtained from advanced flight simulation. The experimental scenario considered a flight of a passenger twin-engine jet airplane through a layer of programmed gusts. The results of the flight simulations allowed us to determine the accuracy of the proposed gust estimation algorithms in reference to the ideal wind-speed data analysis obtained directly from the simulation environment (with the accuracy of the simulation process). The use of the proposed gust estimation algorithms may provide more accurate signal for integrated on-board systems, especially for wind shear detection and sped-up response time of flight control systems, protecting aircrafts against the adverse impact of encountered wind shear or gusts, e.g., auto-thrust or auto-throttle systems. The dedicated algorithm presented in the paper may increase the safety level of take-off and approach phases in gusty conditions and also during significant changes in wind speed at cruising altitudes in the case of crossing the area of jet stream occurrence.
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Yao, Gang, Mingpu Wang, and Yang Yang. "The safety analysis of transportation vehicles carrying prefabricated units under the action of gusts." MATEC Web of Conferences 259 (2019): 03001. http://dx.doi.org/10.1051/matecconf/201925903001.
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The prefabricated-unit industry has developed rapidly and the safety of vehicles carrying prefabricated units has received extensive attention. In order to evaluate the safety of vehicles carrying prefabricated units under the action of gusts, the roughness of road surfaces was simulated by the sinusoid superposition method. Furthermore, the wind load was simulated by the harmonic synthesis method. The analysis model of the 13-DOF vehicle was established, and the wind-vehicle-road system was formed. In addition, the safety of the vehicles carrying prefabricated units under gusts was analyzed. It is demonstrated that when a vehicle encounters a sudden gust during driving, lateral deviation of the body will occur. The contact force on the windward side wheel will drop sharply and the wheel is easy to get off the ground, which decides whether a rollover accident happens or not. It sheds light on the safety analysis for ultra-wide and overweight vehicles under gust action.
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Jing, Zhiwei, and Chu Tang. "Dynamic Response Analysis of the Aircraft Exposed to the Lateral Travelling Gust." Journal of Physics: Conference Series 2364, no. 1 (November 1, 2022): 012024. http://dx.doi.org/10.1088/1742-6596/2364/1/012024.
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Abstract The travelling gust from detonation is an interesting and severe excitation for a flying aircraft, and it is characterized by high emanating speed and takes strong energy. Previous investigations on the dynamic response characteristics of the aircraft in the tail-on or head-on travelling gust have been carried out. This paper focuses on the lateral travelling gust and its influence on the dynamic response of the aircraft. Based on conventional flight dynamics equations, the dynamics modelling and simulation technique of the rigid aircraft exposed to the lateral travelling gust is established. By employing the static pressure distributions, one quasi-steady aerodynamics computation method is presented to determine the aerodynamic force and moment on the aircraft in the travelling gust. Simulation results show that the approach presented in this paper is effective and can deal with the engineering requirement. Results also indicate that the enveloping process of the travelling gust increases the aerodynamic moment of the x-axis significantly and subsequently influences the dynamic responses along the x-axis.
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Cheng, Chad Shouquan, Guilong Li, Qian Li, Heather Auld, and Chao Fu. "Possible Impacts of Climate Change on Wind Gusts under Downscaled Future Climate Conditions over Ontario, Canada." Journal of Climate 25, no. 9 (May 2012): 3390–408. http://dx.doi.org/10.1175/jcli-d-11-00198.1.
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Hourly/daily wind gust simulation models and regression-based downscaling methods were developed to assess possible impacts of climate change on future hourly/daily wind gust events over the province of Ontario, Canada. Since the climate/weather validation process is critical, a formal model result verification process has been built into the analysis to ascertain whether the methods are suitable for future projections. The percentage of excellent and good simulations among all studied seven wind gust categories ranges from 94% to 100% and from 69% to 95%, respectively, for hourly and daily wind gusts, for both model development and validation. The modeled results indicate that frequencies of future hourly/daily wind gust events are projected to increase late this century over the study area under a changing climate. For example, across the study area, the annual mean frequency of future hourly wind gust events ≥28, ≥40, and ≥70 km h−1 for the period 2081–2100 derived from the ensemble of downscaled eight-GCM A2 simulations is projected to be about 10%–15%, 10%–20%, and 20%–40% greater than the observed average during the period 1994–2007, respectively. The corresponding percentage increase for future daily wind gust events is projected to be <10%, ~10%, and 15%–25%. Inter-GCM-model and interscenario uncertainties of future wind gust projections were quantitatively assessed. On average, projected percentage increases in frequencies of future hourly/daily wind gust events ≥28 and ≥40 km h−1 are about 90%–100% and 60%–80% greater than inter-GCM-model–interscenario uncertainties, respectively. For wind gust events ≥70 km h−1, the corresponding projected percentage increases are about 25%–35% greater than the interscenario uncertainties and are generally similar to inter-GCM-model uncertainties.
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Manwaring, S. R., and D. C. Wisler. "Unsteady Aerodynamics and Gust Response in Compressors and Turbines." Journal of Turbomachinery 115, no. 4 (October 1, 1993): 724–40. http://dx.doi.org/10.1115/1.2929308.
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A comprehensive series of experiments and analyses was 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 ongoing 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 unsteady component of the blade loading: (1) a classical flat-plate analysis, (2) a two-dimensional linearized flow analysis with a ‘frozen gust’ model, (3) a two-dimensional linearized flow analysis with a “distorted gust” model, (4) a two-dimensional linearized Euler analysis, and (5) a two-dimensional nonlinear 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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Lin, Tsung-Yueh, Chun-Yu Yang, Shiu-Wu Chau, and Jen-Shiang Kouh. "Dynamic Amplification of Gust-Induced Aerodynamic Loads Acting on a Wind Turbine during Typhoons in Taiwan." Journal of Marine Science and Engineering 9, no. 4 (March 24, 2021): 352. http://dx.doi.org/10.3390/jmse9040352.
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Typhoons, such as Soudelor, which caused the collapse of several onshore wind turbines in 2015, pose a considerable challenge to Taiwan’s wind energy industry. In this study the characteristics of the aerodynamic loads acting on a wind turbine due to wind gusts in a typhoon are studied with a view to providing a proper definition of the S-Class wind turbine proposed in International Electrotechnical Commission (IEC) 61400-1. Furthermore, based on analysis of wind data during typhoons, as obtained from the meteorological mast in the Zhangbin coastal area, an extreme wind speed and gust model corresponding to the typhoon wind conditions in Taiwan are herein proposed. Finally, the flow fields around a parked wind turbine experiencing both an unsteady gust and a steady extreme wind were simulated by a numerical approach. Numerical results show that the aerodynamic shear force and overturning moment acting on the target wind turbine in a steady wind are significantly lower than those under an unsteady gust. The gust-induced amplification factors for aerodynamic loadings are then deduced from numerical simulations of extreme wind conditions.
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Houston, Adam L., and Robert B. Wilhelmson. "Observational Analysis of the 27 May 1997 Central Texas Tornadic Event. Part II: Tornadoes." Monthly Weather Review 135, no. 3 (March 1, 2007): 727–35. http://dx.doi.org/10.1175/mwr3301.1.
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Abstract The 27 May 1997 central Texas tornadic event has been investigated in a two-part observational study. As demonstrated in Part I, the 1D environment associated with this event was unfavorable for significant (≥F2) tornadoes. Yet, the storm complex produced at least six significant tornadoes, including one rated F5 (the Jarrell, Texas, tornado). The purpose of this article is to examine the spatiotemporal interrelationships between tornadoes, preexisting boundaries, antecedent low-level mesocyclones, convective cells, and midlevel mesocyclones. It is shown that each of the six observed tornadoes that produced greater than F0 damage formed along the storm-generated gust front, not along preexisting boundaries. Half of these tornadoes formed on the distorted gust front, the portion of the storm-generated gust front whose orientation was deformed largely by the horizontal shear across the cold front. The remaining three tornadoes developed at the gust front cusp (the persistent gust front inflection located at the northeast end of the gust front distortion). Unlike the tornadoes south of the gust front cusp, these tornadoes are found to be associated with antecedent mesocyclones located in the low levels above the boundary layer. Furthermore, these mesocyclonic tornadoes are found to be larger and more destructive than the three nonmesocyclonic tornadoes. The formation of the Jarrell tornado is found to occur as a nearly stationary convective cell became collocated with a south-southwestward-moving low-level mesocyclone near the gust front cusp—a behavior that resembles the formation of nonsupercell tornadoes. It is argued that the back-building propagation/maintenance of the storm complex enabled this juxtaposition of convective cells with vorticity along the distorted gust front and may have therefore enabled tornado formation. Each of the convective cells without midlevel mesocyclones was found to remain farther from the boundaries than the mesocyclonic cells. Since the cells nearest to the boundaries were longer lived than the remaining cells, it is argued that cells near the boundaries were mesocyclonic because the boundaries yielded cells that were more likely to support temporally coherent midlevel rotation.
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Hoyniak, D., and S. Fleeter. "Forced Response Analysis of an Aerodynamically Detuned Supersonic Turbomachine Rotor." Journal of Vibration and Acoustics 108, no. 2 (April 1, 1986): 117–24. http://dx.doi.org/10.1115/1.3269311.
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High-performance aircraft engine fan and compressor blades are vulnerable to aerodynamically forced vibrations generated by inlet flow distortions due to wakes from upstream blade and vane rows, atmospheric gusts, and maldistributions in inlet ducts. In this paper, an analysis is developed to predict the flow-induced forced response behavior of an aerodynamically detuned rotor operating in a supersonic flow with a subsonic axial component. The aerodynamic detuning is achieved by alternating the circumferential spacing of adjacent rotor blades. The total unsteady aerodynamic loading acting on the blading, due to the convection of the transverse gust past the airfoil cascade and the resulting motion of the cascade, is developed in terms of influence coefficients. This analysis is then utilized to investigate the effect of aerodynamic detuning on the forced response characteristics of a 12-bladed rotor, with Verdon’s Cascade B flow geometry as a uniformly spaced baseline configuration. The results of this study indicate that for forward traveling wave gust excitations, aerodynamic detuning is generally very beneficial, resulting in significantly decreased maximum amplitude blade responses for many interblade phase angles.
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Zhu, Ting, Shenglin Xia, Shiwei He, and Kunshan Huang. "Overload Response Analysis of UAV in Severe Weather." Journal of Physics: Conference Series 2280, no. 1 (June 1, 2022): 012014. http://dx.doi.org/10.1088/1742-6596/2280/1/012014.
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Abstract Turbulence will occur when the aircraft passes through the gust area, which will affect the handling quality and ride quality of the aircraft, increase the bending moment of the wing root and shorten the fatigue life of the structure. At present, in engineering calculation, when the gust load of UAV is considering, the UAV is usually regarded as a rigid body according to the general specification, and the overload response is obtained by solving the dynamic equations of rigid body. The flexibility of UAV is not considered, and the more realistic harsh wind field environment is not considered, so there is a certain deviation between the results and the actual values. Therefore, the gust load was studied considering the aircraft elasticity and the more realistic harsh wind field environment, and compares the calculation results with that considering the standard wind field, and makes a full assessment of the gust overload of UAV. It provides the basis for the design of aircraft structure strength and flight safety, and has important engineering significance.
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Wei, Nathaniel J., Johannes Kissing, Tom T. B. Wester, Sebastian Wegt, Klaus Schiffmann, Suad Jakirlic, Michael Hölling, Joachim Peinke, and Cameron Tropea. "Insights into the periodic gust response of airfoils." Journal of Fluid Mechanics 876 (July 31, 2019): 237–63. http://dx.doi.org/10.1017/jfm.2019.537.
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The unsteady lift response of an airfoil in a sinusoidal gust has in the past been modelled by two different transfer functions: the first-order Sears function and the second-order Atassi function. Previous studies have shown that the Sears function holds in experiments, but recently Cordes et al. (J. Fluid Mech., vol. 811, 2017) reported experimental data that corresponded to the Atassi function rather than the Sears function. In order to clarify the observed discrepancy, the specific differences between these models are isolated analytically. To this end, data and analysis are confined to unloaded airfoils. These differences are related to physical gust parameters, and gusts with these parameters are then produced in wind-tunnel experiments using an active-grid gust generator. Measurements of the unsteady gust loads on an airfoil in the wind tunnel at Reynolds numbers ($Re_{c}$) of $2.0\times 10^{5}$ and $2.6\times 10^{5}$ and reduced frequencies between $0.09$ and $0.42$ confirm that the Sears and Atassi functions differ only in convention: the additional gust component of the Atassi problem can be scaled so that the Atassi function collapses onto the Sears function. These experiments, complemented by numerical simulations of the set-up, validate both models across a range of gust parameters. Finally, the influence of boundary-layer turbulence and the turbulent wake of the gust generator on experimental convergence with model predictions is investigated. These results serve to clarify the conditions under which the Sears and Atassi functions can be applied, and demonstrate that the Sears function can effectively model unsteady forces even when significant fluctuations in the streamwise velocity are present.
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Kim, M. C., A. M. Kabe, and S. S. Lee. "Atmospheric Flight Gust Loads Analysis." Journal of Spacecraft and Rockets 37, no. 4 (July 2000): 446–52. http://dx.doi.org/10.2514/2.3603.
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Jin, Fo Rong, and Wei Rong Wang. "Analysis and Simulation of Meteorological Wind Fields Based on Wavelet Transform." Applied Mechanics and Materials 490-491 (January 2014): 1228–36. http://dx.doi.org/10.4028/www.scientific.net/amm.490-491.1228.
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In this work, we examined the non Gauss distribution characteristic and evolution law of the wavelet coefficient of a gust using wavelet transform; according to the time-frequency characteristic, the wavelet transform coefficients and the energy relations of the target velocity spectra are derived; the wavelet coefficient is generated using the cascade model reflecting the turbulent intermittent; the unsteady gust artificial generation method is established based on inverse wavelet transform; and the arbitrary unsteady fluctuation law can be generated by regulating the coefficient of low frequency. The results show that: the natural gust is in good agreement with Karman wind speed spectrum, meets the turbulence-5 / 3 law in the inertial subrange, and exhibits the nature of intermittence and local self-similarity; the artificial wind sequence based on the inverse wavelet transform method shows similar turbulence statistics with natural gust, with which, the effectiveness of the method is confirmed.
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Miller, Paul W., Alan W. Black, Castle A. Williams, and John A. Knox. "Quantitative Assessment of Human Wind Speed Overestimation." Journal of Applied Meteorology and Climatology 55, no. 4 (April 2016): 1009–20. http://dx.doi.org/10.1175/jamc-d-15-0259.1.
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AbstractHuman wind reports are a vital supplement to the relatively sparse network of automated weather stations in the United States, especially for localized convective winds. In this study, human wind estimates recorded in Storm Data between 1996 and 2013 were compared with instrumentally observed wind speeds from the Global Historical Climatology Network (GHCN). Nonconvective wind events in areas of flat terrain within the continental United States served as the basis for this analysis because of the relative spatial homogeneity of wind fields in these meteorological and geographic settings. The distribution of 6801 GHCN-measured gust factors (GF), defined here as the ratio of the daily maximum gust to the daily average wind, provided the reference upon which human gust reports were judged. GFs were also calculated for each human estimate by dividing the estimated gust by the GHCN average wind speed on that day. Human-reported GFs were disproportionately located in the upper tail of the observed GF distribution, suggesting that humans demonstrate a tendency to report statistically improbable wind gusts. As a general rule of thumb, humans overestimated nonconvective wind GFs by approximately one-third.
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Foster, G. W., and J. G. Jones. "Analysis of atmospheric turbulence measurements by spectral and discretegust methods." Aeronautical Journal 93, no. 925 (May 1989): 162–76. http://dx.doi.org/10.1017/s000192400001695x.
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SummaryDetailed measurements of atmospheric-turbulence velocity have been made by a specially instrumented aircraft at altitudes below one thousand feet over a variety of terrains. These measurements are analysed in terms of power-spectral-density and a statistical-discrete-gust model. To a good approximation, spatial increments in turbulence velocity are shown to satisfy scaling laws implying self-similarity for amplitudes up to about four times their root-mean-square value and over a wide range of scales. A three-parameter relationship is established between two parameters from the statistical-discrete-gust analysis, corresponding respectively to intermittency and gust intensity, and one from the power-spectral representation, related to the average rate of energy dissipation.
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Karan, Haldun, and Kevin Knupp. "Radar and Profiler Analysis of Colliding Boundaries: A Case Study." Monthly Weather Review 137, no. 7 (July 2009): 2203–22. http://dx.doi.org/10.1175/2008mwr2763.1.
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The kinematics of a head-on collision between two gust fronts, followed by a secondary collision between a third gust front and a bore generated by the initial collision, are described using analyses of Weather Surveillance Radar-1988 Doppler (WSR-88D) and Mobile Integrated Profiling System (MIPS) data. Each gust front involved in the initial collision exhibited a nearly north–south orientation and an east–west movement. The eastward-moving boundary was 2°C colder and moved 7 m s−1 faster than the westward-moving boundary. Two-dimensional wind retrievals reveal contrasting flows within each gravity current. One exhibited a typical gravity current flow structure, while the other assumed the form of a gravity wave/current hybrid with multiple vortices atop the outflow. One of the after-collision boundaries exhibited multiple radar finelines resembling a solitary wave shortly after the collision. About 1 h after the initial collision, a vigorous gust front intersected the eastward-moving bore several minutes before both circulations were sampled by the MIPS. The MIPS measurements indicate that the gust front displaced the bore upward into a neutral residual layer. The bore apparently propagated upward even farther to the next stable layer between 2 and 3 km AGL. MIPS measurements show that the elevated turbulent bore consisted of an initial vigorous wave, with updraft/downdraft magnitudes of 3 and −6 m s−1, respectively, followed by several (elevated) waves of decreasing amplitude.
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Kim, Jongyeong, Yongju Kwon, Byeonggug Kang, Joowon Choi, and Soonchul Kwon. "Analysis of the Skyscraper Wind around High-Rise Buildings in Coastal Region, South Korea, during Typhoon ‘Hinnamnor’." Wind 3, no. 1 (February 13, 2023): 64–78. http://dx.doi.org/10.3390/wind3010005.
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High-rise buildings in cities adversely affect wind regimes by changing the air currents in their surrounding areas. In particular, extreme climate phenomena caused by climate change are stronger and more frequent, causing damage in cities. To better understand skyscraper wind behaviors around high-rise buildings, actual measurements are necessary to determine the environmental assessment of the wind effect. In this study, field measurements were performed with five anemometers at five points in the vicinity of a skyscraper called the LCT residential complex (411.6 m tall) surrounded by high-rise buildings in the coastal city of Busan, South Korea during Typhoon Hinnamnor. The gust was 3.7 times stronger, while the maximum 1-min mean wind speed was 3.1 times stronger than those measured at a nearby reference weather station operated by the Korean Meteorological Administration. The characteristics of downward and canyon winds were shown to depend on the spatiotemporal characteristics of the five points. The turbulence intensity declined as the wind speed increased and converged to a certain value. The gust factor also dropped as the wind speed increased and converged to 2.0, and was considered to be the parameter that best represents the intensity of instantaneous gust caused by the skyscraper wind effect. These results suggest that high-rise buildings should be designed with the consideration of gusts twice as strong as the average wind speed. In addition, field measurements should be accompanied in order to respond to the skyscraper wind effect.
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Yang, Shi-Bin, Li-Bao Wang, and Dan Xu. "Computational analysis on actuator failures of flexible aircraft." International Journal of Computational Materials Science and Engineering 07, no. 01n02 (June 2018): 1850014. http://dx.doi.org/10.1142/s2047684118500148.
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A coupled model of aeroservoelasticity and hydraulic actuator used for failure simulation is presented. The mathematical model composites rigid-body modes, elastic modes, control surface modes, unsteady aerodynamic forces and failure models (jam, loss of control (LOC), oscillatory failure, and hydraulic fluid leakage). A clear framework of coupling method of airplane aeroelastic equation and control surface dynamic equation is provided to study the impacts of surface failures on rigid-elastic motion of airplane. The coupled model is shown to be effective in evaluation of gust response in both discrete gust and continuous turbulence conditions compared with results obtained from the 3-order simplified actuator. Examples of gust load alleviation (GLA) system with LOC of ailerons are given. Results show that total loss of function of GLA system is caused by the LOC. With continuous turbulence excitation, the failure loads is several times larger than that without GLA system.
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Quinn, Daniel, Daniel Kress, Eric Chang, Andrea Stein, Michal Wegrzynski, and David Lentink. "How lovebirds maneuver through lateral gusts with minimal visual information." Proceedings of the National Academy of Sciences 116, no. 30 (July 9, 2019): 15033–41. http://dx.doi.org/10.1073/pnas.1903422116.
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Flying birds maneuver effectively through lateral gusts, even when gust speeds are as high as flight speeds. What information birds use to sense gusts and how they compensate is largely unknown. We found that lovebirds can maneuver through 45° lateral gusts similarly well in forest-, lake-, and cave-like visual environments. Despite being diurnal and raised in captivity, the birds fly to their goal perch with only a dim point light source as a beacon, showing that they do not need optic flow or a visual horizon to maneuver. To accomplish this feat, lovebirds primarily yaw their bodies into the gust while fixating their head on the goal using neck angles of up to 30°. Our corroborated model for proportional yaw reorientation and speed control shows how lovebirds can compensate for lateral gusts informed by muscle proprioceptive cues from neck twist. The neck muscles not only stabilize the lovebirds’ visual and inertial head orientations by compensating low-frequency body maneuvers, but also attenuate faster 3D wingbeat-induced perturbations. This head stabilization enables the vestibular system to sense the direction of gravity. Apparently, the visual horizon can be replaced by a gravitational horizon to inform the observed horizontal gust compensation maneuvers in the dark. Our scaling analysis shows how this minimal sensorimotor solution scales favorably for bigger birds, offering local wind angle feedback within a wingbeat. The way lovebirds glean wind orientation may thus inform minimal control algorithms that enable aerial robots to maneuver in similar windy and dark environments.
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Tyner, Bryce, Anantha Aiyyer, Jonathan Blaes, and Donald Reid Hawkins. "An Examination of Wind Decay, Sustained Wind Speed Forecasts, and Gust Factors for Recent Tropical Cyclones in the Mid-Atlantic Region of the United States." Weather and Forecasting 30, no. 1 (February 1, 2015): 153–76. http://dx.doi.org/10.1175/waf-d-13-00125.1.
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Abstract In this study, several analyses were conducted that were aimed at improving sustained wind speed and gust forecasts for tropical cyclones (TCs) affecting coastal regions. An objective wind speed forecast analysis of recent TCs affecting the mid-Atlantic region was first conducted to set a benchmark for improvement. Forecasts from the National Digital Forecast Database were compared to observations and surface wind analyses in the region. The analysis suggests a general overprediction of sustained wind speeds, especially for areas affected by the strongest winds. Currently, National Weather Service Weather Forecast Offices use a software tool known as the Tropical Cyclone Forecast/Advisory (TCM) wind tool (TCMWindTool) to develop their wind forecast grids. The tool assumes linear decay in the sustained wind speeds when interpolating the National Hurricane Center 12–24-hourly TCM product to hourly grids. An analysis of postlandfall wind decay for recent TCs was conducted to evaluate this assumption. Results indicate that large errors in the forecasted wind speeds can emerge, especially for stronger storms. Finally, an analysis of gust factors for recent TCs affecting the region was conducted. Gust factors associated with weak sustained wind speeds are shown to be highly variable but average around 1.5. The gust factors decrease to values around 1.2 for wind speeds above 40 knots (kt; 1 kt = 0.51 m s−1) and are in general insensitive to the wind direction, suggesting local rather than upstream surface roughness largely dictates the gust factor at a given location. Forecasters are encouraged to increase land reduction factors used in the TCMWindTool and to modify gust factors to account for factors including the sustained wind speed and local surface roughness.
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Bergström, Hans. "A statistical analysis of gust characteristics." Boundary-Layer Meteorology 39, no. 1-2 (April 1987): 153–73. http://dx.doi.org/10.1007/bf00121872.
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O’Donnell, Cathal W., Mahdi Ebrahimi Salari, and Daniel J. Toal. "A Study on Directly Interconnected Offshore Wind Systems during Wind Gust Conditions." Energies 15, no. 1 (December 27, 2021): 168. http://dx.doi.org/10.3390/en15010168.
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An investigation of the effects of wind gusts on the directly interconnected wind generators is reported, and techniques toward the mitigation of the wind gust negative influences have been proposed. Using a directly interconnected system approach, wind turbine generators are connected to a single synchronous bus or collection grid without the use of power converters on each turbine. This bus can then be transformed for transmission onshore using High Voltage Alternating Current, Low-Frequency Alternating Current or High Voltage Direct Current techniques with shared power conversion resources onshore connecting the farm to the grid. Analysis of the potential for instability in transient conditions on the wind farm, for example, caused by wind gusts is the subject of this paper. Gust magnitude and rise time/fall time are investigated. Using pitch control and the natural damping of the high inertial offshore system, satisfactory overall system performance and stability can be achieved during these periods of transience.
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Ayton, Lorna J., and N. Peake. "Interaction of turbulence with the leading-edge stagnation point of a thin aerofoil." Journal of Fluid Mechanics 798 (June 3, 2016): 436–56. http://dx.doi.org/10.1017/jfm.2016.326.
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An asymptotic model is constructed to analyse the interaction of turbulence generated far upstream with a thin elliptic-nosed solid body in uniform flow. The leading-edge stagnation point causes significant deformation of incident vorticity, and hence our analysis focuses on the region of size scaling with the nose radius close to the stagnation point. Rapid distortion theory is used to separate the flow field generated by a single unsteady gust perturbation into a convective non-acoustic part, containing the evolution of the upstream vortical disturbance, and an acoustic part generated by the interaction of the vorticity with the solid surface, as is typical in gust–aerofoil interaction theory. Using single-frequency gust response solutions, along with a von Kármán energy spectrum, we find the turbulent pressure spectrum generated by homogeneous isotropic turbulence incident from far upstream. Both high- and low-frequency gusts are considered to allow approximations to be found for the turbulent pressure spectra close to the leading edge, and far from the body close to the incident stagnation streamline. Good agreement is shown between the asymptotic results for the near- and far-field leading-edge turbulent pressure spectra and recent experimental findings.
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Selby, Robert G., and Robert B. Dryburgh. "A comparison of the gust factor method and the patch load method of analysis of guyed towers." Canadian Journal of Civil Engineering 23, no. 4 (August 1, 1996): 862–71. http://dx.doi.org/10.1139/l96-894.
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The Canadian standard CAN/CSA-S37-94 "Antennas, towers and antenna supporting structures" (S37) has introduced as an appendix a quasi-dynamic method of analysis. This patch load method yields a more realistic pattern of forces in a guyed tower, but S37 contains no firm guidelines as to when this new method is required over the conventional static gust factor approach. This paper describes various comparative studies that were made to determine the conditions under which the normally used gust factor approach does not give sufficiently acceptable results so that patch load analyses are required. Results of the parametric studies and the analyses of a large number of actual towers showed that leg loads in the upper few spans tended to be about 15% larger on average in a patch load analysis. Face shears at the guy supports were also about 15% higher on average in the patch load method. The studies revealed no strong trends between the patch load and gust factor correlation and the tower parameters, although there were slight trends suggesting that a patch load analysis was warranted if the tower height was greater than 250 m, the aspect ratio was greater than 120, or the drag area exceeded 2.0 m2/m. The presence of a cantilever accentuated the margin between the results of the two methods. Key words: guyed towers, analysis, wind loading, dynamic effects, patch load, gust factor.
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Wang, Wei, Zhigang Zhang, Guanghua He, and Weijie Mo. "Numerical Analysis of the Effects of Periodic Gust Flow on the Wake Structure of Ventilated Supercavities." Journal of Marine Science and Application 20, no. 1 (March 2021): 34–45. http://dx.doi.org/10.1007/s11804-021-00192-4.
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AbstractA computational model is established to investigate the effects of a periodic gust flow on the wake structure of ventilated supercavities. The effectiveness of the computational model is validated by comparing with available experimental data. Benefited from this numerical model, the vertical velocity characteristics in the entire flow field can be easily monitored and analyzed under the action of a gust generator; further, the unsteady evolution of the flow parameters of the closed region of the supercavity can be captured in any location. To avoid the adverse effects of mounting struts in the experiments and to obtain more realistic results, the wake structure of a ventilated supercavity without mounting struts is investigated. Unsteady changes in the wake morphology and vorticity distribution pattern of the ventilated supercavity are determined. The results demonstrate that the periodic swing of the gust generator can generate a gust flow and, therefore, generate a periodic variation of the ventilated cavitation number σ. At the peak σ, a re-entrant jet closure appears in the wake of the ventilated supercavity. At the valley σ, a twin-vortex closure appears in the wake of the ventilated supercavity. For the forward facing model, the twin vortex appears as a pair of centrally rolled-up vortices, due to the closure of vortex is affected by the structure. For the backward facing model, however, the twin vortex appears alternately as a pair of centrally rolled-up vortices and a pair of centrally rolled-down vortices, against the periodic gust flow.
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Kurbatova, Maria, Konstantin Rubinstein, Inna Gubenko, and Grigory Kurbatov. "Comparison of seven wind gust parameterizations over the European part of Russia." Advances in Science and Research 15 (November 19, 2018): 251–55. http://dx.doi.org/10.5194/asr-15-251-2018.
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Abstract. Wind gusts are extreme events which can cause severe damage. Gusts can reach significant values even during medium winds. However, numerical atmospheric models are designed to reproduce average wind speed, not gusts. There are several approaches to estimating wind gusts. Seven different methods are applied to WRF-ARW model output. Results are compared to high-frequency wind speed measurements using ultrasonic anemometers and temperature profiler measurement at the same point in Moscow. Data gathered from synoptic station network over the European part of Russia were also included in the analysis to increase the statistics. None of the wind gust estimation methods shows best results at every skill score. The proposed hybrid method shows good balance between the probability of detection and the false alarm ratio estimates.
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Clark, J. B., M. C. Kim, and A. M. Kabe. "Statistical Analysis of Atmospheric Flight Gust Loads Analysis Data." Journal of Spacecraft and Rockets 37, no. 4 (July 2000): 443–45. http://dx.doi.org/10.2514/2.3602.
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RICCO, PIERRE. "The pre-transitional Klebanoff modes and other boundary-layer disturbances induced by small-wavelength free-stream vorticity." Journal of Fluid Mechanics 638 (October 20, 2009): 267–303. http://dx.doi.org/10.1017/s0022112009990838.
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The response of the Blasius boundary layer to free-stream vortical disturbances of the convected gust type is studied. The vorticity signature of the boundary layer is computed through the boundary-region equations, which are the rigorous asymptotic limit of the Navier–Stokes equations for low-frequency disturbances. The method of matched asymptotic expansion is employed to obtain the initial and outer boundary conditions. For the case of forcing by a two-dimensional gust, the effect of a wall-normal wavelength comparable with the boundary-layer thickness is taken into account. The gust viscous dissipation and upward displacement due to the mean boundary layer produce significant changes on the fluctuations within the viscous region. The same analysis also proves useful for computing to second-order accuracy the boundary-layer response induced by a three-dimensional gust with spanwise wavelength comparable with the boundary-layer thickness. It also follows that the boundary-layer fluctuations of the streamwise velocity match the corresponding free-stream velocity component. The velocity profiles are compared with experimental data, and good agreement is attained.The generation of Tollmien–Schlichting waves by the nonlinear mixing between the two-dimensional unsteady vorticity fluctuations and the mean flow distortion induced by localized wall roughness and suction is also investigated. Gusts with small wall-normal wavelengths generate significantly different amplitudes of the instability waves for a selected range of forcing frequencies. This is primarily due to the disparity between the streamwise velocity fluctuations in the free stream and within the boundary layer.
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Myers, Matthew R., and E. J. Kerschen. "Influence of incidence angle on sound generation by airfoils interacting with high-frequency gusts." Journal of Fluid Mechanics 292 (June 10, 1995): 271–304. http://dx.doi.org/10.1017/s0022112095001522.
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A theoretical model is developed for the sound generated when a convected vortical or entropic gust encounters an airfoil at non-zero angle of attack. The theory is based on a linearization of the Euler equations about the steady subsonic flow past the airfoil. High-frequency gusts, whose wavelengths are short compared to the airfoil chord, but long compared to the displacement of the mean-flow stagnation point from the leading edge, are considered. The analysis utilizes singular-perturbation techniques and involves four asymptotic regions. Local regions, which scale on the gust wavelength, are present at the airfoil leading and trailing edges. Behind the airfoil a ‘transition’ region, which is similar to the transition zone between illuminated and shadow zones in optical problems, is present. In the outer region, far away from the airfoil edges and wake, the solution has a geometric-acoustics form. The primary sound generation is found to be concentrated in the local leading-edge region. The trailing edge plays a secondary role as a scatterer of the sound generated in the leading-edge region. Parametric calculations are presented which illustrate that moderate levels of airfoil steady loading can significantly affect the sound field produced by airfoil–gust interactions.
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Prasad, D., and J. M. Verdon. "A Three-Dimensional Linearized Euler Analysis of Classical Wake/Stator Interactions: Validation and Unsteady Response Predictions." International Journal of Aeroacoustics 1, no. 2 (August 2002): 137–63. http://dx.doi.org/10.1260/147547202760236941.
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A comprehensive validation of the linearized Euler analysis, LINFLUX, for wake/blade row interaction is carried out. The flow configuration is that of the benchmark problem for rotor-stator interaction proposed at the Third Computational Aeroacoustics Workshop. It consists of an unstaggered, annular, flat-plate blade row excited by the vortical gusts associated with the wakes shed from an upstream rotor. The numerical results for the unsteady pressure responses of the stator are compared with semi-analytic lifting surface and lifting line solutions. The validation is first conducted for narrow-annulus flows, where the numerical results are shown to agree well with classical two-dimensional solutions over a range of frequencies. We then carry out a detailed comparison of the three-dimensional LINFLUX results with the lifting surface results of Namba and Schulten for a blade row with a hub-to-tip ratio of 0.5. This study encompasses gust excitation frequencies for which the stator responses vary from cut off to propagating, as well as gusts with varying degrees of spanwise variation. The numerical and semi-analytical analyses yield results for the stator pressure response, including the complex amplitudes of the propagating and least attenuated, evanescent, pressure modes that are in very good agreement. The effect of increasing the spanwise phase variation of the gust is generally, but not necessarily, to reduce the power associated with the acoustic response of the blade row. A comparison of the present numerical results with those obtained from a stripwise application of classical linear theory reveals that the latter approach can be erroneous and, therefore, of questionable applicability to realistic turbomachinery unsteady flows.
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Gennaretti, M., and C. Ponzi. "Finite-state aerodynamic modelling for gust load alleviation of wing–tail configurations." Aeronautical Journal 103, no. 1021 (March 1999): 147–58. http://dx.doi.org/10.1017/s0001924000064964.
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Abstract A finite-state aerodynamics methodology is proposed for the analysis of the forces generated by a gust. To illustrate and assess the methodology, gust-response and gust-alleviation applications are included. Finite-state aerodynamics denotes a technique to approximate aerodynamic loads so as to yield an aircraft model of the type ẋ = Ax + Bu (state-space formulation). In this paper, a finite-state formulation is proposed to include the presence of a gust. The aerodynamic loads to be approximated are evaluated here by using a frequency-domain boundary-element formulation; the flow is assumed to be irrotational except for a zero-thickness vortex layer (wake). The gust-alleviation application consists of determining a control law for reducing the response to a vertical gust disturbance, as measured by the centre of mass acceleration. Two optimal-control approaches are considered for the synthesis of the control law: one uses the classical linear-quadratic regulator (LQR), whereas the second includes the additional feed-forward of the gust velocity ahead of the aircraft. Deflections of ailerons and elevators are assumed to be the control variables. Numerical results deal with responses to both a deterministic ‘1 – cosine’ gust distribution and a stochastic von Kármán spectrum. They indicate that the finite-state aerodynamic model proposed is capable of approximating, with a high level of accuracy, both the aerodynamic loads induced by the aircraft kinematics variables and those induced by the control variables, over a wide frequency range.
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Paulsen, B. M., and J. L. Schroeder. "An Examination of Tropical and Extratropical Gust Factors and the Associated Wind Speed Histograms." Journal of Applied Meteorology and Climatology 44, no. 2 (February 1, 2005): 270–80. http://dx.doi.org/10.1175/jam2199.1.
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Abstract A gust factor, defined as the ratio between a peak wind gust and mean wind speed over a period of time, can be used along with other statistics to examine the structure of the wind. Gust factors are heavily dependent on upstream terrain conditions (roughness), but are also affected by transitional flow regimes (specifically, changes in terrain and the distance from the upstream terrain change to the measuring device), anemometer height, stability of the boundary layer, and, potentially, the presence of deep convection. Previous studies have yielded conflicting results regarding differences in gust factors that might exist between winds generated by tropical cyclones and those generated by extratropical systems. Using high-resolution wind speed data collected from both landfalling tropical cyclones and extratropical systems, two databases of wind characteristics were developed. Gust factors from tropical cyclone and extratropical winds were examined, summarized, and compared. Further analysis was conducted to examine and compare the characteristics of the associated tropical and extratropical wind speed histograms. As expected, the mean gust factor was found to increase with increasing upstream surface roughness. Some differences were observed between data from the tropical environment and the extratropical environment. Mean gust factors from the tropical regime were found to be higher than mean gust factors from the extratropical environment within each roughness regime and the wind speed histograms generated from data from the two environments indicated some differences.
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Vacev, Todor, Stanko Brčić, Andrija Zorić, Miloš Milić, Ivan Nešović, and Slobodan Ranković. "Static and dynamic approach to the analysis of wind gusts in case of a tower H=110 m." Gradjevinski materijali i konstrukcije 64, no. 3 (2021): 201–5. http://dx.doi.org/10.5937/grmk2103201v.
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Steel lattice towers have large application in meteorology, and are regularly exposed to loads difficult to determine reliably, like wind and ice, and especially wind gusts and accompanied structural vibrations. EN 1993-3-1 treats such structures and requires checking of vibrations, but does not supply methodology for it, neither allowed values for deformation and vibrations. The paper presents analysis of a tower 110 m high using the Finite Element Method (FEM), in case of wind gust, for iced and non-iced structure, both statically and dynamically. The results were compared and recommendations for future treatment of such sensitive structures were given.
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Potter, Brian E., and Jaime R. Hernandez. "Downdraft outflows: climatological potential to influence fire behaviour." International Journal of Wildland Fire 26, no. 8 (2017): 685. http://dx.doi.org/10.1071/wf17035.
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Sudden wind shifts caused by atmospheric gust fronts can lead to firefighter entrapments and fatalities. In this study, we describe the physical processes involved in the related phenomena of convective downdrafts, gust fronts and downbursts. We focus on the dominant process, evaporative cooling in a dry surface layer, as characterised by the measure known as downdraft maximum available potential energy (DMAPE). We present a climatological analysis of DMAPE for the coterminous United States, developed from the Climate Forecast System Reanalysis data for the period 1979–2008. Diurnal and seasonal patterns are described. We conclude with a discussion of the implications and limitations of the analysis and DMAPE as an indicator of gust front strength or downburst occurrence.
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Wang, Yanru, Yongguang Li, Chuanxiong Zhang, Xu Wang, Guangyu Fan, Qianqian Qi, and Bin Fu. "Analysis of Turbulence Parameters of Typhoon Morakot along the Southeast Coast of China." Applied Sciences 12, no. 10 (May 21, 2022): 5218. http://dx.doi.org/10.3390/app12105218.
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The southeast coastal region of China is frequently affected by typhoons. The observation station was chosen to be located on the roof of Wenzhou University’s architectural engineering building to collect real-time wind speed data during the landfalling of Typhoon Morakot to investigate the properties of the near-ground wind field of typhoons. The turbulence characteristics of the near-ground wind and its variation with time intervals are analyzed on the basis of real-time measured data. The results show that the turbulence intensity only changes with the mean wind speed under relatively low wind speeds. The gust factors exhibit a scattered distribution under low wind speeds and tend to cluster together when the wind speed exceeds 8 m/s. With increasing time intervals, the turbulence intensity and the gust factor gradually decrease. The relationship between turbulence intensity and gust factor is obtained by the measured data and then compared with the empirical formulas. The peak factor remains constant while the mean wind speed changes, but diminish as the time intervals rise. The turbulence integral scale of typhoons slightly increases with the increasing mean wind speed, and its value falls between 70 and 150.
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Lasauskas, E. "Influence of sailplane wing-bending flexibility on ‘1- Cosine’ gust loads." Aeronautical Journal 120, no. 1234 (October 3, 2016): 1943–55. http://dx.doi.org/10.1017/aer.2016.99.
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ABSTRACTSimultaneous modelling of aerodynamics, structure and flight dynamics is used to predict the gust loads on a model of 18-metre wingspan sailplane that includes bending flexibility. The ASWING software is used to analyse the time history of the wing-bending moment and the shear force at the wing root for the design gust speed and for the design maximum speed at different wavelengths of a ‘1-Cosine’ gust. Maximum values from the time history were compared with certification requirements for rigid sailplanes. The analysis revealed that wing-bending flexibility reduces the loads.
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Afgan, Imran, Sofiane Benhamadouche, Xingsi Han, Pierre Sagaut, and Dominique Laurence. "Flow over a flat plate with uniform inlet and incident coherent gusts." Journal of Fluid Mechanics 720 (February 27, 2013): 457–85. http://dx.doi.org/10.1017/jfm.2013.25.
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AbstractThe flow over a flat plate at a Reynolds number of 750 is numerically investigated via fine large-eddy simulation (LES), first at normal ($90\textdegree $) and then at oblique ($45\textdegree $) incidence flow direction with a uniform steady inlet. The results are in complete agreement with the direct numerical simulation (DNS) and experimental data, thereby serving as a validation for the present simulations. For the normal ($90\textdegree $) uniform inflow case, coherent vortices are alternately shed from both leading edges of the plate, whereas for the oblique ($45\textdegree $) uniform inflow case the vortices shed from the two sides of the plate interact strongly resulting in a quasi-periodic force response. The normal flat plate is then analysed with an incident gust signal with varying amplitude and time period. For these incident coherent gust cases, a reference test case with variable coherent inlet is first studied and the results are compared to a steady inlet simulation, with a detailed analysis of the flow behaviour and the wake response under the incident gust. Finally, the flat plate response to 16 different gust profiles is studied. A transient drag reconstruction for these incident coherent gust cases is then presented based on a frequency-dependent transfer function and phase spectrum analysis.
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Siegmund, Nicole, Juan E. Panebianco, Fernando Avecilla, Laura A. Iturri, Michael Sommer, Daniel E. Buschiazzo, and Roger Funk. "From Gustiness to Dustiness—The Impact of Wind Gusts on Particulate Matter Emissions in Field Experiments in La Pampa, Argentina." Atmosphere 13, no. 8 (July 25, 2022): 1173. http://dx.doi.org/10.3390/atmos13081173.
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This study delivers the first empirical data-driven analysis of the impact of turbulence induced gustiness on the fine dust emissions from a measuring field. For quantification of the gust impact, a new measure, the Gust uptake Efficiency (GuE) is introduced. GuE provides a percentage of over- or under-proportional dust uptake due to gust activity during a wind event. For the three analyzed wind events, GuE values of up to 150% could be found, yet they significantly differed per particle size class with a tendency for lower values for smaller particles. In addition, a high-resolution correlation analysis among 31 particle size classes and wind speed was conducted; it revealed strong negative correlation coefficients for very small particles and positive correlations for bigger particles, where 5 μm appears to be an empirical threshold dividing both directions. We conclude with a number of suggestions for further investigations: an optimized field experiment setup, a new particle size ratio (PM1/PM0.5 in addition to PM10/PM2.5), as well as a comprehensive data-driven search for an optimal wind gust definition in terms of soil erosivity.
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An, Chao, Chao Yang, Changchuan Xie, and Yang Meng. "Gust Load Alleviation including Geometric Nonlinearities Based on Dynamic Linearization of Structural ROM." International Journal of Aerospace Engineering 2019 (May 12, 2019): 1–20. http://dx.doi.org/10.1155/2019/3207912.
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This paper describes a framework for an active control technique applied to gust load alleviation (GLA) of a flexible wing, including geometric nonlinearities. Nonlinear structure reduced order model (ROM) and nonplanar double-lattice method (DLM) are used for structural and aerodynamic modeling. The structural modeling method presented herein describes stiffness nonlinearities in polynomial formulation. Nonlinear stiffness can be derived by stepwise regression. Inertia terms are constant with linear approximation. Boundary conditions and kernel functions in the nonplanar DLM are determined by structural deformation to reflect a nonlinear effect. However, the governing equation is still linear. A state-space equation is established in a dynamic linearized system around the prescribed static equilibrium state after nonlinear static aeroelastic analysis. Gust response analysis can be conducted subsequently. For GLA analysis, a classic proportional-integral-derivative (PID) controller treats a servo as an actuator and acceleration as the feedback signal. Moreover, a wind tunnel test has been completed and the effectiveness of the control technology is validated. A remote-controlled (RC) model servo is chosen in the wind tunnel test. Numerical simulation results of gust response analysis reach agreement with test results. Furthermore, the control system gives GLA efficacy of vertical acceleration and root bending moment with the reduction rate being over 20%. The method described in this paper is suitable for gust response analysis and control strategy design for large flexible wings.
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Friedrich, Katja, David E. Kingsmill, and Carl R. Young. "Misocyclone Characteristics along Florida Gust Fronts during CaPE." Monthly Weather Review 133, no. 11 (November 1, 2005): 3345–67. http://dx.doi.org/10.1175/mwr3040.1.
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Abstract Multiple-Doppler radar and rawinsonde data are used to examine misocyclone characteristics along gust fronts observed during the Convection and Precipitation/Electrification (CaPE) project in Florida. The objective of this study is to investigate the observational representativeness of previous numerical simulations of misocyclones by employing a consistent analysis strategy to 11 gust fronts observed in the same region. The investigation focuses on the intensity range of misocyclones and their organization along gust fronts; the relationship between misocyclone intensity and horizontal wind shear, vertical wind shear, and static stability; and the relationship between misocyclones and convection initiation. The intensity of misocyclones, as indicated by the maximum values of vertical vorticity, varied from 2.8 × 10−3 to 13.9 × 10−3 s−1, although all but one case exhibited values less than 6.4 × 10−3 s−1. Organized misocyclone patterns were only found along small segments of gust fronts. Within those segments misocyclones were spaced between 3 and 7 km. Results show that the intensity of misocyclones was most closely related to the strength of horizontal wind shear across the gust front. The relationship between misocyclone intensity and vertical wind shear and static stability was not as clear. Although convection was initiated along the gust front in 7 of the 11 cases, those regions were not collocated with or in close proximity to misocyclones.
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Guo, Dong, Min Xu, and Shilu Chen. "Nonlinear Gust Response Analysis of Free Flexible Aircraft." International Journal of Intelligent Systems and Applications 5, no. 2 (January 3, 2013): 1–15. http://dx.doi.org/10.5815/ijisa.2013.02.01.
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Habeeb Faidh-Allah, Majid, and Adawiya Ali Hamzah. "Vibration Analysis of Aircraft Wing under Gust Load." Journal of Engineering and Applied Sciences 14, no. 11 (November 30, 2019): 3571–74. http://dx.doi.org/10.36478/jeasci.2019.3571.3574.
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Lee, Sung Su, and Jun Yeong Kim. "Spatial and Temporal Analysis of Thunderstorm Wind Gust." Journal of Korea Spatial Information Society 21, no. 4 (August 31, 2013): 1–6. http://dx.doi.org/10.12672/ksis.2013.21.4.001.
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Herisanu, Nicolae, Vasile Marinca, Gheorghe Madescu, and Florin Dragan. "Dynamic Response of a Permanent Magnet Synchronous Generator to a Wind Gust." Energies 12, no. 5 (March 9, 2019): 915. http://dx.doi.org/10.3390/en12050915.
Full textAbstract:
In this paper, a new analytical approach is proposed to investigate the electrical and mechanical behavior of a low-power permanent magnet synchronous generator (PMSG) in the presence of a wind gust. The proposed model for the wind gust and wind power system was analytically investigated using the optimal auxiliary functions method (OAFM), which has proven to be a reliable tool. The reaction of the system to a wind gust was explicitly obtained, which is useful for stability analysis, protection issues, and risk assessment concerning the PMSG. A substantial reduction of computations in analytically analysing a complicated dynamical system is ensured by this new approach, through some auxiliary functions and convergence-control parameters.