Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Aerodynamic loads.
Artykuły w czasopismach na temat „Aerodynamic loads”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych artykułów w czasopismach naukowych na temat „Aerodynamic loads”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj artykuły w czasopismach z różnych dziedzin i twórz odpowiednie bibliografie.
1
Tomasz Lusiak, Andrej Novak, Martin Bugaj i Radovan Madlenak. "Assessment of Impact of Aerodynamic Loads on the Stability and Control of the Gyrocopter Model". Communications - Scientific letters of the University of Zilina 22, nr 4 (1.10.2020): 63–69. http://dx.doi.org/10.26552/com.c.2020.4.63-69.
Pełny tekst źródłaStreszczenie:
Aerodynamic modelling currently relates to development of mathematical models to describe the aerodynamic forces and moments acting on the aircraft. It is a challenging part of aerodynamics that defines a comprehensive approach to using traditional methods and modern techniques to obtain relevant data. The most complicated task for the aerodynamics and flight dynamics is definition, computation and quantification of the aerodynamic description of an object. This paper presents how to determine the aerodynamic load on a gyrocopter and defines the effect on its stability and control. The first step to solution is to develop simpler approximate aerodynamic model - a model that can be used in analysis of aerodynamic load and can represent the aerodynamic properties of the gyrocopter with an acceptable degree of accuracy. Control and stability are very important parts of aircraft characteristics and therefore those characteristics were analyzed in simulation. Finally, the aerodynamic data outputs are assessed in terms of impact of aerodynamic loads on stability and control of the gyrocopter model.
2
Enciu, K., i A. Rosen. "Aerodynamic modelling of fin stabilised underslung loads". Aeronautical Journal 119, nr 1219 (wrzesień 2015): 1073–103. http://dx.doi.org/10.1017/s0001924000011143.
Pełny tekst źródłaStreszczenie:
AbstractBox-like slung loads exhibit periodic yaw response instabilities, while carried externally by a helicopter. When coupled with the slung load longitudinal and lateral pendulum motions, these instabilities result in significant pendulum oscillations of the load. High amplitude oscillations lead in many cases to the limiting of a load’s flight envelope. Using wind tunnel and flight tests, rear mounted fins were previously demonstrated as efficient means for stabilisation of a problematic load. However, the lack of a proper analytical model of the stabilised load’s aerodynamic characteristics, led to a trial and error development process, without an appropriate physical understanding of the stabilisation problem. The present paper describes a method for the aerodynamic modeling of fins stabilised slung loads based on a limited number of simple static wind-tunnel tests. The resulting database is incorporated in a dynamical slung load simulation that shows good agreement with dynamic wind-tunnel tests. The applicability of the proposed method is demonstrated, by the calculation of stabilised loads aerodynamic databases for interim fin inclination angles not covered by tests.
3
Perez-Becker, Sebastian, Francesco Papi, Joseph Saverin, David Marten, Alessandro Bianchini i Christian Oliver Paschereit. "Is the Blade Element Momentum theory overestimating wind turbine loads? – An aeroelastic comparison between OpenFAST's AeroDyn and QBlade's Lifting-Line Free Vortex Wake method". Wind Energy Science 5, nr 2 (15.06.2020): 721–43. http://dx.doi.org/10.5194/wes-5-721-2020.
Pełny tekst źródłaStreszczenie:
Abstract. Load calculations play a key role in determining the design loads of different wind turbine components. To obtain the aerodynamic loads for these calculations, the industry relies heavily on the Blade Element Momentum (BEM) theory. BEM methods use several engineering correction models to capture the aerodynamic phenomena present in Design Load Cases (DLCs) with turbulent wind. Because of this, BEM methods can overestimate aerodynamic loads under challenging conditions when compared to higher-order aerodynamic methods – such as the Lifting-Line Free Vortex Wake (LLFVW) method – leading to unnecessarily high design loads and component costs. In this paper, we give a quantitative answer to the question of load overestimation of a particular BEM implementation by comparing the results of aeroelastic load calculations done with the BEM-based OpenFAST code and the QBlade code, which uses a particular implementation of the LLFVW method. We compare extreme and fatigue load predictions from both codes using sixty-six 10 min load simulations of the Danish Technical University (DTU) 10 MW Reference Wind Turbine according to the IEC 61400-1 power production DLC group. Results from both codes show differences in fatigue and extreme load estimations for the considered sensors of the turbine. LLFVW simulations predict 9 % lower lifetime damage equivalent loads (DELs) for the out-of-plane blade root and the tower base fore–aft bending moments compared to BEM simulations. The results also show that lifetime DELs for the yaw-bearing tilt and yaw moments are 3 % and 4 % lower when calculated with the LLFVW code. An ultimate state analysis shows that extreme loads of the blade root out-of-plane bending moment predicted by the LLFVW simulations are 3 % lower than the moments predicted by BEM simulations. For the maximum tower base fore–aft bending moment, the LLFVW simulations predict an increase of 2 %. Further analysis reveals that there are two main contributors to these load differences. The first is the different way both codes treat the effect of the nonuniform wind field on the local blade aerodynamics. The second is the higher average aerodynamic torque in the LLFVW simulations. It influences the transition between operating modes of the controller and changes the aeroelastic behavior of the turbine, thus affecting the loads.
4
Zhang, Xuyao, Congxin Yang i Shoutu Li. "Influence of the Heights of Low-Level Jets on Power and Aerodynamic Loads of a Horizontal Axis Wind Turbine Rotor". Atmosphere 10, nr 3 (11.03.2019): 132. http://dx.doi.org/10.3390/atmos10030132.
Pełny tekst źródłaStreszczenie:
The influence of the heights of low-level jets (LLJs) on the rotor power and aerodynamic loads of a horizontal axis wind turbine were investigated using the fatigue, aerodynamics, structures, and turbulence code. The LLJ and shear inflow wind fields were generated using an existing wind speed spectral model. We found that the rotor power predicted by the average wind speed of the hub height is higher than the actual power in relatively weak and shallow LLJ inflow conditions, especially when the LLJ height is located inside the rotor-swept area. In terms of aerodynamic loads, when the LLJ height is located inside the rotor-swept area, the root mean square (RMS) rotor thrust coefficient and torque coefficient increase, while the RMS rotor unbalanced aerodynamic load coefficients, including lateral force, longitudinal force, tilt moment, and yaw moment, decreased. This means that the presence of both positive and negative wind shear in the rotor-swept area not only increases the rotor power but also reduces the unbalanced aerodynamic loads, which is beneficial to the operation of wind turbine. Power spectrum analysis shows no obvious difference in the power spectrum characteristics of the rotor torque and thrust in LLJ inflow conditions with different heights.
5
Xiang, Xiao Jun, i Yu Qian. "Numerical Simulation of Unsteady Aerodynamic Loads over an Aircraft". Advanced Materials Research 908 (marzec 2014): 264–68. http://dx.doi.org/10.4028/www.scientific.net/amr.908.264.
Pełny tekst źródłaStreszczenie:
The unsteady aerodynamic loads are the basic of the aeroelastic. This paper focuses on the computation of the unsteady aerodynamic loads for forced periodic motions under different Mach numbers. The flow is modeled using the Euler equations and an unsteady time-domain solver is used for the computation of aerodynamic loads for forced periodic motions. The Euler equations are discretized on curvilinear multi-block body conforming girds using a cell-centred finite volume method. The implicit dual-time method proposed by Jameson is used for time-accurate calculations. Rigid body motions were treated by moving the mesh rigidly in response to the applied sinusoidal motion. For an aircraft model, a validation of the unsteady aerodynamics loads is first considered. Furthermore, a study for understanding the influence of different Mach number was conducted. A reverse of the trend of hysteretic loops can be observed with the increasing of the Mach number.
6
Anil, Mary, i Deepa Varkey. "Recent Progress in Aerodynamics for Aeroelastic Analysis". International Journal for Research in Applied Science and Engineering Technology 10, nr 6 (30.06.2022): 2890–93. http://dx.doi.org/10.22214/ijraset.2022.44475.
Pełny tekst źródłaStreszczenie:
Abstract: Aerodynamics has gained considerable popularity in the aerospace industry. Based on the characteristics of a structure, aerodynamic behavior varies from structure to structure. A reliable aeroelastic analysis requires accurate capture of aerodynamic forces. To produce accurate aerodynamic loads, it is necessary to develop an appropriate aerodynamic model. A review of various approaches to aerodynamic modeling for aeroelastic analysis of diverse wing configurations is presented in this paper. The study covers a wide range of finite element software platforms used in the aeroelastic analysis in various flow regimes.
7
Li, Yun Feng. "Loads Calculation of Pitch Bearing of Wind Turbine". Advanced Materials Research 148-149 (październik 2010): 479–84. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.479.
Pełny tekst źródłaStreszczenie:
Loads calculation process for pitch bearing of wind turbine was presented. The aerodynamic of the rotor was analyzed by using momentum theory and blade element theory firstly; then the aerodynamic loads, the gravitational loads and the centrifugal loads of the pitch bearing were calculated along each axis of the bearing coordinate system; thirdly, all the loads of each direction of the pitch bearing load were composed into three loads, they are radial, axial and tilting moment loads. A calculation example was given at last.
8
He, Pan, i Jian Xia. "Study on the Influence of Low-Level Jet on the Aerodynamic Characteristics of Horizontal Axis Wind Turbine Rotor Based on the Aerodynamics–Controller Interaction Method". Energies 15, nr 8 (7.04.2022): 2709. http://dx.doi.org/10.3390/en15082709.
Pełny tekst źródłaStreszczenie:
Accurate prediction of the aerodynamic characteristics of wind rotors subjected to various wind profiles is of considerable importance in the aerodynamics and structural design of wind turbines. As a very complex atmospheric phenomenon, the impact of a low-level jet (LLJ) on the aerodynamic characteristics of wind rotors is becoming more and more significant with the increase in wind turbine height. Additionally, during calculating the aerodynamic characteristics of the wind rotor, the known wind speed, rotor speed, and blade-pitch angle are generally required. However, when the wind profile is in the LLJ condition, it is difficult to determine the blade-pitch angle and rotor speed. Therefore, in this paper, the blade-element-momentum (BEM) method is exploited by considering the coupling with the generator-torque controller and blade-pitch controller. In order to solve the problem of the unknown rotor speed and blade-pitch angle under the LLJ condition, a C++ code is developed. Then, the influence of the LLJ on the aerodynamic characteristics of the wind rotor is exclusively examined. The research results show that the calculation method can precisely evaluate the rotor speed, blade-pitch angle, and aerodynamic characteristics of the wind rotor. The influence of the LLJ on the aerodynamic loads of the wind rotor is greater than that of the wind shear. When the LLJ is placed inside the rotor swept area, the aerodynamic loads of the blade exhibit two local maximums and local minimums with the variation of the azimuth angle in a rotation period. The closer the LLJ height is to the hub height, the greater the average aerodynamic loads of the wind rotor are, and the smaller the amplitude of aerodynamic loads of the blade is relative to the average value. When the LLJ height is positioned outside the rotor swept area, the change law of the aerodynamic loads of the blade would be similar to that of the wind subjected to a very strong wind shear inflow. This study provides a crucial reference for a more rational assessment of the aerodynamic characteristics of wind turbines under the action of complex wind profiles, as well as revealing the influence of the LLJ on the aerodynamic characteristics of wind turbines.
9
Liu, Jun, Zhengqi Gu, Taiming Huang, Shuya Li, Ledian Zheng i Kai Sun. "Coupled analysis of the unsteady aerodynamics and multi-body dynamics of a small car overtaking a coach". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, nr 14 (22.02.2019): 3684–99. http://dx.doi.org/10.1177/0954407019831559.
Pełny tekst źródłaStreszczenie:
The severe additional aerodynamic loads that are generated on a small car when overtaking a coach have an adverse effect on the car handling stability and its safety. In this article, a two-way coupling of the unsteady aerodynamics and multi-body dynamics is performed in order to study the mutual interactions of a car in an overtaking maneuver with a coach. The unsteady aerodynamic interactions are obtained by using SST (Menter) K-Omega Detached Eddy Simulation and overset mesh technology. The aerodynamics couple the multi-body dynamics, taking into account the effects of the transverse spacing and the cross winds. To validate the necessity of the two-way coupling method, a one-way coupling of the aerodynamics to the vehicle motion is also conducted. Finally, by comparing the aerodynamic loads and the dynamic response of the overtaking car in different overtaking maneuvers between one- and two-way coupling, the results show that it should be considered with two-way coupling analyses of the car while overtaking a coach, particularly under the severe conditions of a lower transverse spacing or the crosswinds.
10
Zeng, Xiaohui, Han Wu, Jiang Lai i Hongzhi Sheng. "Hunting stability of high-speed railway vehicles on a curved track considering the effects of steady aerodynamic loads". Journal of Vibration and Control 22, nr 20 (9.08.2016): 4159–75. http://dx.doi.org/10.1177/1077546315571986.
Pełny tekst źródłaStreszczenie:
Aerodynamic loads may have effects on the hunting stability, and the factor of curved track makes it more complicated. Therefore, considering the steady aerodynamic loads generated by crosswind and airflow in the opposite advancing direction of train, the hunting stability of high-speed railway vehicle on a curved track is studied in this paper. The changes of gravitational restoring force and creep coefficients which are caused by aerodynamic loads are considered, and the change of equilibrium position due to aerodynamic loads, centrifugal force and the factor of curved track is also in consideration. A mathematical model of a high-speed railway vehicle during curve negotiation with aerodynamic loads is set up. A program based on the model is written and verified. Using this program, the linear critical speed considering the effects of aerodynamic loads is determined by the eigenvalue analysis. This paper investigates the critical speeds in three aerodynamic conditions. Considering the aerodynamic loads, the dependence of critical speed on curve radius and super-elevation is analyzed, and the impact of aerodynamic loads on instability mode is analyzed as well. In addition, this paper obtains the dominant factors affecting critical speed and the variation tendency of critical speed with primary longitudinal stiffness by orthogonal experiments. The results show that the critical speed decreases or increases while the wind is blowing to outer rail or inner rail respectively. The aerodynamic loads produce obvious effects on the instability mode. The variation tendency of critical speed dependence on curve radius in the conditions with aerodynamic loads keeps consistent with the case without aerodynamic loads. It is seen from the orthogonal experiments that, aerodynamic loads and curve radius are the dominant factors affecting linear critical speed of vehicle on a curved track, and the linear critical speed decreases with the increasing of primary longitudinal stiffness.
11
Srivastava, Nilabh, Peter T. Tkacik i Russell G. Keanini. "Ascending rockets as macroscopic self-propelled Brownian oscillators". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, nr 2148 (12.09.2012): 3965–94. http://dx.doi.org/10.1098/rspa.2012.0273.
Pełny tekst źródłaStreszczenie:
High-fidelity numerical experiments and theoretical modelling are used to study the dynamics of a sounding-rocket-scale rocket, subject to altitude-dependent random wind and nozzle side loads and deterministic aerodynamic loading. This paper completes a series of studies that showed that Ornstein–Uhlenbeck (OU) rotational dynamics arise when random nozzle side loads dominate wind and aerodynamic loading. In contrast to the earlier work, this paper elucidates that under conditions where aerodynamic, wind and nozzle side loads are comparable, the rocket behaves as stochastic Brownian oscillator. The Brownian oscillator model allows straightforward interpretation of the complex rotational dynamics observed: three dynamical regimes—each characterized by differing balances between nozzle-side-load-induced torques, spring-like aerodynamic torques and mass flux damping torques—characterize rocket ascent. Further, the paper illuminates that in the limit where wind and aerodynamic loads are small, random mass flux variations exponentially amplify side-load-induced rotational stochasticity. In this practical limit, pitch/yaw dynamics are described by a randomly damped OU process; an exact solution of the associated Fokker–Planck equation can be obtained and used to compute, e.g. time-dependent pitch/yaw rate means and variances.
12
Zhang, Hui, Jie Li i Qiong Liu. "Flight Loads Analysis of a Maneuvering Transport Aircraft". Advanced Materials Research 1016 (sierpień 2014): 460–64. http://dx.doi.org/10.4028/www.scientific.net/amr.1016.460.
Pełny tekst źródłaStreszczenie:
The paper provides a method applicable for the determination of flight loads for maneuvering aircraft, in which aerodynamic loads are calculated based on doublet lattice method, which contains three primary steps. Firstly, non-dimensional stability and control derivative coefficients are obtained through solving unsteady aerodynamics in subsonic flow based on a doublet lattice technical. These stability and control derivative coefficients are used in second step. Secondly, the simulation of aircraft dynamic maneuvers is completed utilizing fourth order Runge-Kutta method to solve motion equations in different maneuvers to gain response parameters of aircraft due to the motion of control surfaces. Finally, the response results calculated in the second step are introduced to the calculation of aerodynamic loads. Thus, total loads and loads distribution on different components of aircraft are obtained. According to the above method, abrupt pitching maneuvers, rolling maneuvers and yawing maneuvers are investigated respectively.
13
Qian, Yu, Jun Li Yang, Xiao Jun Xiang i Ming Qiang Chen. "Numerical Simulation of Unsteady Aerodynamic Loads over an Aerofoil in Transonic Flow". Advanced Materials Research 644 (styczeń 2013): 275–78. http://dx.doi.org/10.4028/www.scientific.net/amr.644.275.
Pełny tekst źródłaStreszczenie:
The unsteady aerodynamic loads are the basic of the aeroelasitc. This paper focuses on the computation of the unsteady aerodynamic loads for forced periodic motions under high subsonic Mach numbers. The flow is modeled using the Euler equations and an unsteady time-domain solver is used for the computation of aerodynamic loads for forced periodic motions. The Euler equations are discretized on curvilinear multi-block body conforming girds using a cell-centred finite volume method. The implicit dual-time method proposed by Jameson is used for time-accurate calculations. Rigid body motions were treated by moving the mesh rigidly in response to the applied sinusoidal motion. For NACA 0012 airfoil, a validation of the unsteady aerodynamics loads is first considered. Furthermore, a study for understanding the influence of motion parameters, the Mach number, mean angle of incidence, reduced frequency, amplitude, was also conducted. A reverse of the trend of hysteretic loops can be observed with the increasing of the Mach number. Nonlinear hysteretic loops are turned up when increasing the amplitude and the reduced frequency during the applied pitch sinusoidal motion.
14
Lai, Yung-Cheng (Rex), i Christopher P. L. Barkan. "Options for Improving the Energy Efficiency of Intermodal Freight Trains". Transportation Research Record: Journal of the Transportation Research Board 1916, nr 1 (styczeń 2005): 47–55. http://dx.doi.org/10.1177/0361198105191600108.
Pełny tekst źródłaStreszczenie:
Intermodal trains are typically the fastest trains operated by North American freight railroads. Ironically, these trains tend to have the poorest aerodynamic characteristics. Because of constraints imposed by equipment design and diversity, intermodal trains incur greater aerodynamic penalties and increased fuel consumption than other trains. Improving the loading patterns of intermodal trains has the potential to improve aerodynamic characteristics and thus fuel efficiency. Train aerodynamics and resistance analyses were conducted on several alternative intermodal train-loading configurations. Matching intermodal loads with cars of an appropriate length reduces the gap length between loads and thereby improves airflow. Filling empty slots with empty containers or trailers also reduces aerodynamic resistance and improves energy efficiency, despite the additional weight penalty and consequent increase in bearing and rolling resistance. Depending on the particular train configuration, train resistance can be lowered by as much as 27% and fuel savings by 1 gal/mi per train.
15
Niven, A. J., i S. W. Tait. "A new approach to the third order calibration of internal strain gauge balances used for aerodynamic load measurement". Aeronautical Journal 104, nr 1041 (listopad 2000): 501–8. http://dx.doi.org/10.1017/s0001924000017875.
Pełny tekst źródłaStreszczenie:
Abstract With respect to wind tunnel aerodynamic load measurement, an internal strain gauge balance (often referred to as a sting balance) is essentially a compact load cell designed to fit within a cavity of the aerodynamic body and form a link between the model and a fixed ground point via a sting support system. The structure of an internal strain gauge balance is designed to incorporate a series of planar surfaces such that the deflection of each surface is predominantly induced by a unique aerodynamic load. Strain gauges, mounted on groups of surfaces in a Wheatstone bridge arrangement produce output signals proportional to the applied aerodynamic loads. A strain gauge balance is calibrated by applying known loads, measuring the bridge outputs and then formulating an equation which relates the two variables together. Although calibration techniques are well established, reservations have been recently expressed concerning the ability of the associated calibration equation to satisfactorily model the response of the balance when subjected to a six component aerodynamic loading. This generally accepted calibration equation (referred to here as the traditional equation) results in a quadratic approximation to the behaviour of the output signals with applied loads, whereas a more appropriate variation would be cubic. Other limitations of the traditional calibration equation are that the behaviour of the balance to two simultaneously applied loads is based upon limited combinations of the two applied loads, and that the acquisition of the required loads from the strain gauge signals is frequently based upon an approximate matrix inversion method. The proposed calibration equation, described within this paper, models the behaviour of the sting balance to the third order, takes account of all possible combinations of two simultaneously applied loads, and avoids the use of an approximate matrix inversion when deriving the desired aerodynamic loading from the signal outputs. It is also shown that the proposed method may be used to determine the interaction of all possible combinations of up to three simultaneously applied loads.
16
Zeng, Xiao-Hui, Jiang Lai i Han Wu. "Hunting Stability of High-Speed Railway Vehicles Under Steady Aerodynamic Loads". International Journal of Structural Stability and Dynamics 18, nr 07 (lipiec 2018): 1850093. http://dx.doi.org/10.1142/s0219455418500931.
Pełny tekst źródłaStreszczenie:
With the rising speed of high-speed trains, the aerodynamic loads become more significant and their influences on the hunting stability of railway vehicles deserve to be considered. Such an effect cannot be properly considered by the conventional model of hunting stability analysis. To this end, the linear hunting stability of high-speed railway vehicles running on tangent tracks is studied. A model considering the steady aerodynamic loads due to the joint action of the airflow facing the moving train and the crosswind, is proposed for the hunting stability analysis of a railway vehicle with 17 degrees of freedom (DOF). The key factors considered include: variations of the wheel–rail normal forces, creep coefficients, gravitational stiffness and angular stiffness due to the actions of the aerodynamic load, which affects the characteristics of hunting stability. Using the computer program developed, numerical calculations were carried out for studying the behavior of the linear hunting stability of vehicles under steady aerodynamic loads. The results show that the aerodynamic loads have an obvious effect on the linear critical speeds and instability modes. The linear critical speed decreases monotonously as the crosswind velocity increases, and the influences of pitch moment and lift force on the linear critical speed are larger than the other components of the aerodynamic loads.
17
Gennaretti, M., i C. Ponzi. "Finite-state aerodynamic modelling for gust load alleviation of wing–tail configurations". Aeronautical Journal 103, nr 1021 (marzec 1999): 147–58. http://dx.doi.org/10.1017/s0001924000064964.
Pełny tekst źródłaStreszczenie:
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.
18
Yin, F. F., J. J. Chen, X. K. Li, Z. L. Ye, W. Tang, X. Shen i X. J. Guo. "A blade element momentum model for dual-rotor wind turbines considering inter-rotor velocity interferences". Journal of Physics: Conference Series 2265, nr 4 (1.05.2022): 042058. http://dx.doi.org/10.1088/1742-6596/2265/4/042058.
Pełny tekst źródłaStreszczenie:
Abstract A blade element momentum model for predicting the aerodynamic performance of dual-rotor wind turbines (DRWTs) as an aerodynamic design tool is introduced in this paper. The model considers the inter-rotor axial velocity reduction and the tangential velocity components in the front rotor’s wake to model the inter-rotor velocity interferences for the inflow velocity as the input of the BEM theory. A DRWT with two NREL 5MW rotors is studied using the present model and CFD simulations. Results from the two methods show good agreements with each other in the trends of power, thrust, and aerodynamic loads on the blades despite the error in near-tip regions. The present DRWT configurations have lower optimum tip speed ratios and a wider range of high-CP speeds. The maximum efficiency of the present turbine is improved by only 5%, indicating that a dedicated blade design for DRWT aerodynamics is required to enhance power output and lower the aerodynamic loads.
19
Gennaretti, M., i G. Bernardini. "Aeroelastic response of helicopter rotors using a 3D unsteady aerodynamic solver". Aeronautical Journal 110, nr 1114 (grudzień 2006): 793–801. http://dx.doi.org/10.1017/s0001924000001664.
Pełny tekst źródłaStreszczenie:
The prediction of blade deflections and vibratory hub loads concerning helicopter main rotors in forward flight is the objective of this work. They are determined by using an aeroelastic model derived through the coupling between a nonlinear blade structural model and a boundary integral equation solver for three-dimensional, unsteady, potential aerodynamics. The Galerkin method is used for the spatial integration, whereas the periodic blade response is determined by a harmonic balance approach. This aeroelastic model yields a unified approach for aeroelastic response and blade pressure prediction that may be used for aeroacoustic purposes, with the possibility of including effects from both blade-vortex interaction and multiple-body aerodynamic interaction. Quasi-steady aerodynamic models with wake-inflow from the three-dimensional aerodynamic solver are also applied, in order to perform a comparative study. Numerical results show the capability of the aeroelastic tool to evaluate blade response and vibratory hub loads for a helicopter main rotor in level flight conditions, and examine the sensitivity of the predictions on the aerodynamics model used.
20
Petrone, Nicola, Matteo Capuzzo, Erik De Paoli i Nicola Biliato. "The Measurement of Aerodynamic Loads using Dynamometric Load Cells". ATZautotechnology 4, nr 3 (maj 2004): 56–59. http://dx.doi.org/10.1007/bf03246829.
Pełny tekst źródła
21
Ma, Kaichao, Changhong Tang, Jianye Zhang, Xiaofei Niu i Qingzhi Fan. "Flight Load Design of Nacelle of Carrier-Based Propeller Transport Aircraft". Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, nr 6 (grudzień 2020): 1249–56. http://dx.doi.org/10.1051/jnwpu/20203861249.
Pełny tekst źródłaStreszczenie:
The carrier-based propeller transport aircraft has a compact layout, where the large nacelle in size and weight is sensitive to propeller slipstream, and thus calls for sophisticated flight load design studies, which are still insufficient considering domestic experience. In detail, the design methods on aerodynamic load, inertial load, gyrostatic moment, as well as studies on design criteria and maneuver simulation technology are shown for a reference aircraft. The design range applied to this nacelle's flight load is firstly determined by understanding and selecting the design criteria. The typical loadcases of the nacelle are derived from aircraft maneuver simulation. The data of pressure distribution under a series of propeller slipstream strengths is obtained by CFD method. The Design Loads and Design Loadcases of the nacelle are calculated and selected. The effects of the propeller slipstream are compared in an example of the increment on aerodynamic load in a maneuver. The results show that the Design Loads of the nacelle are obtained from the abrupt pitching maneuver under the maximum normal load factor (Nz), the yawing maneuver under the Design Dive Speed(VD), and the maximum propeller pull under the maximum landing weight; the transverse loads of the nacelle are dominated by the aerodynamic load, and the normal loads are dominated by the inertial load, in which the inertial force exceeds the aerodynamic force by 4 times under the extreme circumstances. In some manoeuvres or status, the total aerodynamic force of the whole nacelle is increased by above 90% due to propeller slipstream; the front part of the nacelle which is close to the propeller sees a much bigger increment.
22
Amrutheswara Krishnamurthy i Dr.Suresh Nagesh. "Aerodynamic Effect on Stability and Lift Characteristics of an Elevated Sedan Car". ARAI Journal of Mobility Technology 2, nr 2 (13.05.2022): 205–13. http://dx.doi.org/10.37285/ajmt.1.2.6.
Pełny tekst źródłaStreszczenie:
There is a strong interaction between air and vehicle components. Aerodynamics plays a significant role in a vehicle's fuel efficiency. The contact patch load between the tire and road is directly related to the vehicle load. In this research, the lift forces generated due to the additional wing attached to the car model with different spans and heights of the wing location from the car body is considered for study. The loads due to change in Angle of Attack (AOA) and their effect on the tire loads are studied. The upward vertical force produced from aerodynamic loads reduces the wheel load of the car virtually. A tire's coefficient of friction would decrease with upward vertical force. This balance load implies that a lightweight car would make more efficient use of its tires than a heavier car. ANSYS Fluent is used for the Computational Fluid Dynamics (CFD) study. The validation of airflow characteristics, lift and drag forces from simulations are done with wind tunnel testing data. Varying the angle of attack, wingspan, height between the car and the wing's lower surface, one can increase the capacity of the payload by 10% or fuel efficiency by 10% to 20%.
23
Cicolani, L. S., J. G. A. da Silva, E. P. N. Duque i M. B. Tischler. "Unsteady aerodynamic model of a cargo container for slung-load simulation". Aeronautical Journal 108, nr 1085 (lipiec 2004): 357–68. http://dx.doi.org/10.1017/s0001924000005170.
Pełny tekst źródłaStreszczenie:
Abstract The problem of simulation models capable of predicting the aerodynamic instability of helicopter slung-load cargo containers and bluff bodies is addressed. Instability for these loads is known to depend on unsteady frequency-dependent aerodynamics, but simulation models that include the unsteady aerodynamics do not currently exist. This paper presents a method for generating such models using computational fluid dynamics (CFD) to generate forced-oscillation aerodynamic data and frequency domain system identification techniques to generate a frequency response from the CFD data and to identify a transfer function fit to the frequency response. The method is independent of the responsible flow phenomenon and is expected to apply to bluff-bodies generally. Preliminary results are presented for the case of the 6- by 6- by 8-ft CONEX (container express) cargo container. The present work is based on two-dimensional (2D) aerodynamic data for the CONEX side force and yaw moment generated by a forced oscillation in which frequency is varied smoothly over the range of interest. A first-order rational polynomial transfer function is found adequate to fit the aerodynamics, and this is shown to provide a good match with flight test data for the yawing motion of the CONEX.
24
Pei, Xi, Min Xu i Dong Guo. "Aeroelastic-Acoustics Numerical Simulation Research". Applied Mechanics and Materials 226-228 (listopad 2012): 500–504. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.500.
Pełny tekst źródłaStreszczenie:
The generation of aerodynamic noise of aircraft in flight is due to dynamical system and aerodynamic .The response of aircraft subjected to High acoustic loads and aerodynamic loads can produce fatigue and damage. In this paper a new Aeroelastic- Acoustics which adds acoustic loads in aeroelastic is presented. The emphasis of the study is the discipline of displacement and load of the flexible structure under the unsteady aerodynamic, inertial, elastic and aero-acoustic. The CFD/CSD/CAA coupling is used to simulate rockets cabin. Sound generated by a rocker is predicted numerically from a Large Eddy simulation (LES) of unsteady flow field. The Lighthill acoustic analogy is used to model the propagation of sound. The structural response of rocket cabin was given. The boundary-layer transition on the pressure side of the cabin is visualized, by plotting to better illustrate the essential interaction between fluctuating pressure and structure.CFD/CSD/CAA coupling compute method is validated in low and middle frequency.
25
Xie, Yonghui, Kun Lu, Le Liu i Gongnan Xie. "Fluid-Thermal-Structural Coupled Analysis of a Radial Inflow Micro Gas Turbine Using Computational Fluid Dynamics and Computational Solid Mechanics". Mathematical Problems in Engineering 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/640560.
Pełny tekst źródłaStreszczenie:
A three-dimensional fluid-thermal-structural coupled analysis for a radial inflow micro gas turbine is conducted. First, a fluid-thermal coupled analysis of the flow and temperature fields of the nozzle passage and the blade passage is performed by using computational fluid dynamics (CFD). The flow and heat transfer characteristics of different sections are analyzed in detail. The thermal load and the aerodynamic load are then obtained from the temperature field and the pressure distribution. The stress distributions of the blade are finally studied by using computational solid mechanics (CSM) considering three cases of loads: thermal load, aerodynamics load combined with centrifugal load, and all the three types of loads. The detailed parameters of the flow, temperature, and the stress are obtained and analyzed. The numerical results obtained provide a useful knowledge base for further exploration of radial gas turbine design.
26
Huang, Taiming, Zhengqi Gu, Chengjie Feng i Wei Zeng. "Transient aerodynamics simulations of a road vehicle in the crosswind condition coupled with the vehicle’s motion". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, nr 5 (11.08.2017): 583–98. http://dx.doi.org/10.1177/0954407017704609.
Pełny tekst źródłaStreszczenie:
The influence of transient aerodynamics on a vehicle in a crosswind and the effect on the vehicle’s motion are investigated by employing fully coupled simulations. The fully coupled method makes the simulation data on the fluid dynamics and on the vehicle dynamics exchange in time. LES are used to investigate the movement of the transient turbulence, and wind tunnel experiments are carried out to validate the numerical method. The vehicle is simplified as a three-degree-of-freedom system which moves in only the horizontal direction. The driver’s reaction is considered when the motion of the vehicle is simulated. The results of fully coupled simulations show that the transient aerodynamic loads have a marked influence on the motion of the vehicle. The transitional method of one-way coupled simulations is also employed to obtain data. The simulation results for the two methods are compared with each other. It is found that there is large difference between the results of the two methods. The maximum side force in fully coupled simulations is about 1.22 times the value obtained by the transitional method, and there is a 0.2 m discrepancy between the peak value of the lateral displacement in fully coupled simulations and the peak value in the transitional method. The results show that the transient aerodynamic loads induced by the unsteady motion of the vehicle have a larger effect on the vehicle’s motion than do the aerodynamic loads from the transitional method. Furthermore, the results also reflect the significance of estimating the transient aerodynamic loads in simulations of the vehicle’s motion.
27
Zyl, L. H. van. "2D and 3D low frequency aerodynamics". Aeronautical Journal 112, nr 1136 (październik 2008): 609–12. http://dx.doi.org/10.1017/s0001924000002578.
Pełny tekst źródłaStreszczenie:
Abstract Unsteady aerodynamic loads on aircraft configurations are used for aeroelastic or flight dynamic analyses. The sources for deriving these loads include strip theory aerodynamics and three-dimensional panel methods. In some applications the behaviour of the unsteady air loads as the frequency approaches zero is important, and it is well known that the behaviour of strip theory aerodynamics employing the exact circulation function differs qualitatively from that of the three-dimensional panel methods such as the subsonic doublet lattice method (DLM). Theoretical results from an earlier study of the low frequency behaviour of the DLM are used here to show the relationship between the DLM and strip theory and the relationship is verified by a numerical example.
28
Sakib, Mohammad Sadman, i D. Todd Griffith. "Parked and operating load analysis in the aerodynamic design of multi-megawatt-scale floating vertical-axis wind turbines". Wind Energy Science 7, nr 2 (24.03.2022): 677–96. http://dx.doi.org/10.5194/wes-7-677-2022.
Pełny tekst źródłaStreszczenie:
Abstract. A good understanding of aerodynamic loading is essential in the design of vertical-axis wind turbines (VAWTs) to properly capture design loads and to estimate the power production. This paper presents a comprehensive aerodynamic design study for a 5 MW Darrieus offshore VAWT in the context of multi-megawatt floating VAWTs. This study systematically analyzes the effect of different, important design variables including the number of blades, aspect ratio and blade tapering in a comprehensive load analysis of both the parked and operating aerodynamic loads including turbine power performance analysis. The number of blades is studied for two- and three-bladed turbines, aspect ratio is defined as ratio of rotor height and rotor diameter and studied for values from 0.5 to 1.5, and blade tapering is applied by means of adding solidity to the blades towards blade root ends, which affects aerodynamic and structural performance. Analyses were carried out using a three-dimensional vortex model named CACTUS (Code for Axial and Cross-flow TUrbine Simulation) to evaluate both instantaneous azimuthal parameters as well as integral parameters, such as loads (thrust force, lateral force and torque loading) and power. Parked loading is a major concern for VAWTs; thus, this work presents a broad evaluation of parked loads for the design variables noted above. This study also illustrates that during the operation of a turbine, lateral loads are on par with thrust loads, which will significantly affect the structural sizing of rotor and platform and mooring components.
29
Shen, Xin, Ping Hu, Jinge Chen, Xiaocheng Zhu i Zhaohui Du. "The unsteady aerodynamics of floating wind turbine under platform pitch motion". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, nr 8 (29.03.2018): 1019–36. http://dx.doi.org/10.1177/0957650918766606.
Pełny tekst źródłaStreszczenie:
The aerodynamic performance of floating platform wind turbines is much more complex than fixed-base wind turbines because of the flexibility of the floating platform. Due to the extra six degrees-of-freedom of the floating platform, the inflow of the wind turbine rotors is highly influenced by the motions of the floating platform. It is therefore of interest to study the unsteady aerodynamics of the wind turbine rotors involved with the interaction of the floating platform induced motions. In the present work, a lifting surface method with a free wake model is developed for analysis of the unsteady aerodynamics of wind turbines. The aerodynamic performance of the NREL 5 MW floating wind turbine under the prescribed floating platform pitch motion is studied. The unsteady aerodynamic loads, the transient of wind turbine states, and the instability of the wind turbine wakes are discussed in detail.
30
Lu, Yaohui, Dewen Zhang, Heyan Zheng, Chuan Lu, Tianli Chen, Jing Zeng i Pingbo Wu. "Analysis of the aerodynamic pressure effect on the fatigue strength of the carbody of high-speed trains passing by each other in a tunnel". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 233, nr 8 (2.11.2018): 783–801. http://dx.doi.org/10.1177/0954409718809469.
Pełny tekst źródłaStreszczenie:
When two high-speed trains pass through a tunnel, the aerodynamic changes are more complex and drastic than in open air owing to the interference of the tunnel wall and the entry effect. The impact on the carbody fatigue strength is very significant in the fatigue reliability design of the carbody. In this paper, the sequential coupling method was used for the first time to study the effect of pressure waves on the fatigue strength in a large-scale and complex carbody structure. The computational fluid dynamics method was used to calculate and analyze the aerodynamic pressure wave of the intersection of the trains in a long and short tunnel. A full-scale finite element shell model of the carbody structure was established. Then, the time integration method was used to convert the transient pressure wave into the aerodynamic loads bearing by the side wall of the carbody. The inhomogeneous stress concentrations at the restraint points were eliminated by the inertial release method; moreover, a finite element analysis of the carbody was carried out under the combined aerodynamic and mechanical loads. The Goodman fatigue strength curve of the aluminum alloy carbody was drawn. The influence of the aerodynamic load on the fatigue strength of the vehicle body was analyzed and compared under the entry effect of the short tunnel. The results show that the aerodynamic load of the short tunnel has a significant impact on the fatigue strength of the carbody owing to the train's entry effect. The safety factor of the fatigue strength is 15% less than that of the long tunnel aerodynamic load. In this paper, computational fluid dynamics and finite element method were used to analyze and evaluate the impact of the pressure wave on the fatigue strength of the carbody, which is of great reference value in the structural design of the carbody subjected to complex aerodynamic loads.
31
Kowaleczko, Grzegorz, i Andrzej Leśniczak. "Modelling of Helicopter Main Rotor Aerodynamic Loads in Manoeuvres". Journal of KONES 26, nr 4 (1.12.2019): 273–84. http://dx.doi.org/10.2478/kones-2019-0118.
Pełny tekst źródłaStreszczenie:
AbstractThe article discusses the method of modelling of the helicopter main rotor aerodynamic loads during steady state flight and manoeuvres. The ability to determine these loads was created by taking into account the motion of each blade relative to the hinges and was a result of the applied method of aerodynamic loads calculating. The first part of the work discusses the basic relationships that were used to build the mathematical model of helicopter flight. The focus was also on the method of calculating of the aerodynamic forces generated by the rotor blades. The results of simulations dedicated to the “jump to hover” manoeuvre were discussed, showing the possibilities of analysing aerodynamic loads occurring in unsteady flights. The main rotor is considered separately in an “autonomous” way and treated as a source of averaged forces and moments transferred to the hub. The motion of individual blades is neglected, and their aerodynamic characteristics are radically simplified. The motion of individual blades is neglected, and their aerodynamic characteristics are radically simplified. This can lead to significant errors when attempting to model dynamic helicopter manoeuvres. The more complex model of helicopter dynamics is discussed.
32
Kim i Kwon. "Effect of Platform Motion on Aerodynamic Performance and Aeroelastic Behavior of Floating Offshore Wind Turbine Blades". Energies 12, nr 13 (30.06.2019): 2519. http://dx.doi.org/10.3390/en12132519.
Pełny tekst źródłaStreszczenie:
In the present study, a numerical framework for predicting the aerodynamic performance and the aeroelastic behavior of floating offshore wind turbine rotor blades involving platform motion was developed. For this purpose, the aerodynamic and structural analyses were conducted simultaneously in a tightly coupled manner by exchanging the information about the aerodynamic loads and the elastic blade deformations at every time step. The elastic behavior of the turbine rotor blades was described by adopting a structural model based on the Euler-Bernoulli beam. The aerodynamic loads by the rotor blades were evaluated by adopting a blade element momentum theory. The numerical simulations were conducted when the platform of the wind turbine independently moves in each of the six degrees-of-freedom directions consisting of heave, sway, surge, roll, pitch, and yaw. It was observed that flexible blades exhibit complicated vibratory behaviors when they are excited by the aerodynamic, inertia, and gravitational forces simultaneously. It was found that the load variation caused by the platform surge or pitch motion has a significant influence on the flapwise and torsional deformations of the rotor blades. The torsional deformation mainly occurs in the nose-down direction, and results in a reduction of the aerodynamic loads. It was also found that the flapwise root bending moment is mainly influenced by the platform surge and pitch motions. On the other hand, the edgewise bending moment is mostly dictated by the gravitational force, but is not affected much by the platform motion.
33
Han, Y., S. Q. Shu i D. Tan. "Numerical Simulation on Aerodynamic Characteristics of Road Vehicles on Bridges under Cross Winds". Advanced Materials Research 774-776 (wrzesień 2013): 241–47. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.241.
Pełny tekst źródłaStreszczenie:
The aerodynamic force coefficients of road vehicles under wind loads depend on not only the shapes of vehicles but also those of infrastructures, such as a bridge. Therefore, study of the aerodynamic characteristics of road vehicles considering the interaction of aerodynamic forces between the road vehicles and bridge is necessary for predicting the performance of vehicle under wind loads properly. This paper studies aerodynamic characteristics of road vehicles when vehicles run on bridges under cross winds using the CFD method. The dependence of aerodynamic forces on vehicle speeds, the interaction of aerodynamic forces between the vehicles and bridges and the influence of the turbulence are investigated by different simulation cases.
34
Zdravkov, Lyubomir A. "Wind loads on girder bridges". Challenge Journal of Structural Mechanics 8, nr 1 (24.03.2022): 9. http://dx.doi.org/10.20528/cjsmec.2022.01.002.
Pełny tekst źródłaStreszczenie:
Bridges are facilities that are in exploitation outdoor. Often the wind is the leading horizontal force in the transverse direction. Therefore the bridges have received the due attention in the standards for wind loading. Unfortunately, in all available standards for wind load on the bridges, one, summarized value of the aerodynamic coefficient is indicated. It is related to the entire cross-section of the facility. There is no differentiation for the individual longitudinal girders and/or roadway. Information about the specific wind pressure on each of the bridge’s element is required for the correct design of their supporting systems, whether they are framed or braced type. To fill this gap, the author has built several models of bridges with longitudinal girders, using a Computational Fluid Dynamics (CFD) analysis. Through them he determined the values of the aerodynamic coefficients for each of the bridge girders under the roadway and the cross-section of the bridge as a whole. Conclusions are summarized and the results clearly show the values of the aerodynamic coefficients for the whole section of the bridge are with 50-60% lower than the ones reported for the windward girder.
35
Guerrero, Alex, i Robert Castilla. "Aerodynamic Study of the Wake Effects on a Formula 1 Car". Energies 13, nr 19 (5.10.2020): 5183. http://dx.doi.org/10.3390/en13195183.
Pełny tekst źródłaStreszczenie:
The high complexity of current Formula One aerodynamics has raised the question of whether an urgent modification in the existing aerodynamic package is required. The present study is based on the evaluation and quantification of the aerodynamic performance on a 2017 spec. adapted Formula 1 car (the latest major aerodynamic update) by means of Computational Fluid Dynamics (CFD) analysis in order to argue whether the 2022 changes in the regulations are justified in terms of aerodynamic necessities. Both free stream and flow disturbance (wake effects) conditions are evaluated in order to study and quantify the effects that the wake may cause on the latter case. The problem is solved by performing different CFD simulations using the OpenFoam solver. The significance and originality of the research may dictate the guidelines towards an overall improvement of the category and it may set a precedent on how to model racing car aerodynamics. The studied behaviour suggests that modern F1 cars are designed and well optimised to run under free stream flows, but they experience drastic aerodynamic losses (ranging from −23% to 62% in downforce coefficients) when running under wake flows. Although the overall aerodynamic loads are reduced, there is a fuel efficiency improvement as the power that is required to overcome the drag is smaller. The modern performance of Ground Effect by means of vortices management represent a very unique and complex way of modelling modern aerodynamics, but at the same time notably compromises the performance of the cars when an overtaking maneuver is intended.
36
Bednarz, Arkadiusz, Krzysztof Puchała, Michał Sałaciński i Volodymyr Hutsaylyuk. "Numerical Investigation of the Influence of Aerodynamic Loads on the Resonant Frequency of a Compressor Blade Made of EI-961 Alloy". Materials 15, nr 23 (25.11.2022): 8391. http://dx.doi.org/10.3390/ma15238391.
Pełny tekst źródłaStreszczenie:
The aim of this work was to numerically determine the influence of aerodynamic loads on the value of the resonant frequency of the compressor blade. The object of the research was the 1st stage compressor blade of the PZL-10W engine. As part of the research, analytical calculations of the resonance frequency were performed and compared with the literature ones (first, second, and third forms of forced vibrations). In the next step of the investigation, a computational model of the compressor stage (fluid domain and rotors) was built and FSI analysis was performed. This analysis was based on CFD modeling of the state of aerodynamic loads on the blade surfaces, and then these values were imported as external loads for the structural analysis, which was the basis for the modal analysis, in which the resonant frequency of the first three vibration modes was determined. As part of the analyzes, both the influence of aerodynamic loads and the rotational speed of the compressor rotor were verified. Thus, it was possible to evaluate the influence of both the rotational speed (and the arising centrifugal force) and the influence of the emerging aerodynamic load. The results obtained will allow for the assessment of the impact of the aforementioned operating conditions of the aircraft engine on the resonance frequency, which in turn may translate into the durability of critical components of the aircraft engine.
37
Hancock, G. J., i J. S. Y. Lam. "Part 4 — Two dimensional dynamic stall". Aeronautical Journal 91, nr 902 (luty 1987): 72–88. http://dx.doi.org/10.1017/s0001924000050776.
Pełny tekst źródłaStreszczenie:
Summary An axiomatic aerodynamic model has been developed for the general motion of a two dimensional aerofoil as it passes in and out of stall, which gives realistic unsteady loads as compared to experimental values. A non-linear set of aerodynamic derivatives with time delays have been derived from the axiomatic aerodynamics. ‘Actual’ and ‘predicted’ dynamic responses of an aerofoil, spring restrained in torsion, following an impulsive input show similar trends, including limit cycle oscillations, although there is a slight difference in frequency and a difference in the magnitude of the initial impulse required to trigger the limit cycle.
38
Paulauskas, Vytautas, Donatas Paulauskas i Joep Wijffels. "SHIP SAFETY IN OPEN PORTS". TRANSPORT 24, nr 2 (30.06.2009): 113–20. http://dx.doi.org/10.3846/1648-4142.2009.24.113-120.
Pełny tekst źródłaStreszczenie:
Ports and terminals open to prevailing winds can cause problems to moored ships with a high freeboard. Such ships, i.e. ship and berth mooring systems, have to deal with significant aerodynamic loads.This paper addresses the theoretical approach of the influence of aerodynamic loads on a mooring system for ship and investigates whether windscreens can reduce aerodynamic loads on ships in ports.
39
Brahimi, M. T., i I. Paraschivoiu. "Darrieus Rotor Aerodynamics in Turbulent Wind". Journal of Solar Energy Engineering 117, nr 2 (1.05.1995): 128–36. http://dx.doi.org/10.1115/1.2870839.
Pełny tekst źródłaStreszczenie:
The earlier aerodynamic models for studying vertical axis wind turbines (VAWT’s) are based on constant incident wind conditions and are thus capable of predicting only periodic variations in the loads. The purpose of the present study is to develop a mode capable of predicting the aerodynamic loads on the Darrieus rotor in a turbulent wind. This model is based on the double-multiple streamtube method (DMS) and incorporates a stochastic wind model The method used to simulate turbulent velocity fluctuations is based on the power spectral density. The problem consists in generating a region of turbulent flow with a relevant spectrum and spatial correlation. The first aerodynamic code developed is based on a one-dimensional turbulent wind model. However, since this model ignores the structure of the turbulence in the crossflow plane, an extension to three dimensions has been made. The computer code developed, CARDAAS, has been used to predict aerodynamic loads for the Sandia-17m rotor and compared to CARDAAV results and experimental data. Results have shown that the computed aerodynamic loads have been improved by including stochastic wind into the aerodynamic model.
40
Balalaev, V. A., A. A. Kammer, G. Kh Mindich i V. A. Tsimbalyuk. "Measurement of low-frequency nonsteady aerodynamic loads". Strength of Materials 25, nr 3 (marzec 1993): 220–23. http://dx.doi.org/10.1007/bf00776869.
Pełny tekst źródła
41
Zhou, Yin, Tracy Kijewski i Ahsan Kareem. "Aerodynamic Loads on Tall Buildings: Interactive Database". Journal of Structural Engineering 129, nr 3 (marzec 2003): 394–404. http://dx.doi.org/10.1061/(asce)0733-9445(2003)129:3(394).
Pełny tekst źródła
42
Aldoss, Taha K., i Mohamed A. Kotb. "Aerodynamic Loads on a Stationary Savonius Rotor". JSME international journal. Ser. 2, Fluids engineering, heat transfer, power, combustion, thermophysical properties 34, nr 1 (1991): 52–55. http://dx.doi.org/10.1299/jsmeb1988.34.1_52.
Pełny tekst źródła
43
MARK, MELVIN. "AERODYNAMIC TORQUE LOADS ON ROTATING RADAR REFLECTORS". Journal of the American Society for Naval Engineers 66, nr 4 (18.03.2009): 953–55. http://dx.doi.org/10.1111/j.1559-3584.1954.tb05942.x.
Pełny tekst źródła
44
Dong, Yehong, Yewen Chen, Hao Liu, Shuni Zhou, Yuanxiang Ni, Chang Cai, Teng Zhou i Qing’an Li. "Review of Study on the Coupled Dynamic Performance of Floating Offshore Wind Turbines". Energies 15, nr 11 (27.05.2022): 3970. http://dx.doi.org/10.3390/en15113970.
Pełny tekst źródłaStreszczenie:
Floating offshore wind turbines (FOWT) have attracted more and more attention in recent years. However, environmental loads on FOWTs have higher complexity than those on the traditional onshore or fixed-bottom offshore wind turbines. In addition to aerodynamic loads on turbine blades, hydrodynamic loads also act on the support platform. A review on the aerodynamic analysis of blades, hydrodynamic simulation of the supporting platform, and coupled aero- and hydro-dynamic study on FOWTs, is presented in this paper. At present, the primary coupling method is based on the combination of BEM theory and potential flow theory, which can simulate the performance of the FOWT system under normal operating conditions but has certain limitations in solving the complex problem of coupled FOWTs. The more accurate and reliable CFD method used in the research of coupling problems is still in its infancy. In the future, multidisciplinary theories should be used sufficiently to research the coupled dynamics of hydrodynamics and aerodynamics from a global perspective, which is significant for the design and large-scale utilization of FOWT.
45
Cumbo, Roberta, Tommaso Tamarozzi, Pavel Jiranek, Wim Desmet i Pierangelo Masarati. "State and Force Estimation on a Rotating Helicopter Blade through a Kalman-Based Approach". Sensors 20, nr 15 (28.07.2020): 4196. http://dx.doi.org/10.3390/s20154196.
Pełny tekst źródłaStreszczenie:
The interaction between the rotating blades and the external fluid in non-axial flow conditions is the main source of vibratory loads on the main rotor of helicopters. The knowledge or prediction of the produced aerodynamic loads and of the dynamic behavior of the components could represent an advantage in preventing failures of the entire rotorcraft. Some techniques have been explored in the literature, but in this field of application, high accuracy can be reached if a large amount of sensor data and/or a high-fidelity numerical model is available. This paper applies the Kalman filtering technique to rotor load estimation. The nature of the filter allows the usage of a minimum set of sensors. The compensation of a low-fidelity model is also possible by accounting for sensors and model uncertainties. The efficiency of the filter for state and load estimation on a rotating blade is tested in this contribution, considering two different sources of uncertainties on a coupled multibody-aerodynamic model. Numerical results show an accurate state reconstruction with respect to the selected sensor layout. The aerodynamic loads are accurately evaluated in post-processing.
46
Han, Yan, Ye Liu, Peng Hu, CS Cai, Guoji Xu i Jiaying Huang. "Effect of unsteady aerodynamic loads on driving safety and comfort of trains running on bridges". Advances in Structural Engineering 23, nr 13 (5.06.2020): 2898–910. http://dx.doi.org/10.1177/1369433220924794.
Pełny tekst źródłaStreszczenie:
In order to investigate the effects of unsteady aerodynamic loads on the driving safety and comfort of trains running on bridges, a three-dimensional and multi-body system model of train–track–bridge was established and the dynamic responses of the coupling system were calculated by combining the finite element software ANSYS with the multi-body dynamics software SIMPACK. The driving safety and comfort of a train running on a bridge under steady and unsteady aerodynamic loads were compared and analyzed. The effects of different crosswind speeds on the driving safety of the train running on the bridge under unsteady aerodynamic loads were studied. It is found that the index values of the driving safety and comfort of the train at the speed of 200–300 km/h without the wind loads are smaller (meaning safer) than those of the train under the wind loads. When the average speed of crosswind is 20 m/s, the driving safety assessment results of the train are better and its comfort assessment results are more conservative with considering the unsteady aerodynamic loads than the steady wind load case. When the average speed of crosswind is smaller than 10 m/s and the train speed is 250 km/h, the driving safety and comfort of the train on the bridge meet the requirements, and the level of stability can reach “good” or above. Through the analysis of driving safety of the train on the bridge under different crosswind speeds, the threshold values of safe driving were obtained, which can provide a better basis for the safe operation of trains on bridges.
47
Viswanath, P. R., i S. R. Patil. "Aerodynamic characteristics of delta wing–body combinations at high angles of attack". Aeronautical Journal 98, nr 975 (maj 1994): 159–70. http://dx.doi.org/10.1017/s0001924000049848.
Pełny tekst źródłaStreszczenie:
AbstractAn experimental study investigating the aerodynamic characteristics of generic delta wing-body combinations up to high angles of attack was carried out at a subsonic Mach number. Three delta wings having sharp leading edges and sweep angles of 50°, 60° and 70° were tested with two forebody configurations providing a variation of the nose fineness ratio. Measurements made included six-component forces and moments, limited static pressures on the wing lee-side and surface flow visualisation studies. The results showed symmetric flow features up to an incidence of about 25°, beyond which significant asymmetry was evident due to wing vortex breakdown, forebody vortex asymmetry or both. At higher incidence, varying degrees of forebody-wing vortex interaction effects were seen in the mean loads, which depended on the wing sweep and the nose fineness ratio. The vortex breakdown on these wings was found to be a gradual process, as implied by the wing pressures and the mean aerodynamic loads. Effects of forebody vortex asymmetry on the wing-body aerodynamics have also been assessed. Comparison of Datcom estimates with experimental data of longitudinal aerodynamic characteristics on all three wing-body combinations indicated good agreement in the symmetric flow regime.
48
Liu, Mengjuan, Han Wu, Junqi Xu, Xiaohui Zeng, Bo Yin i Zhanzhou Hao. "Research on sliding mode controller of the high-speed maglev train under aerodynamic load". Advances in Mechanical Engineering 14, nr 10 (październik 2022): 168781322211278. http://dx.doi.org/10.1177/16878132221127857.
Pełny tekst źródłaStreszczenie:
The high-speed maglev train will be subjected to extremely obvious aerodynamic load and instantaneous aerodynamic impact during passing another train, which brings significant challenges to the train’s suspension stability and safe operation. It’s necessary to consider the influence of aerodynamic load and shock waves in the design of suspension control algorithms. Traditional proportion integration differentiation (PID) control cannot follow the change of vehicle parameters or external disturbance, which is easy to cause suspension fluctuation and instability. To improve the suspension stability and vibration suppression of the high-speed maglev train under aerodynamic load and impact, we design a siding mode controller introducing the primary suspension’s deformation to replace the aerodynamic load on the electromagnet. Furthermore, we establish the train’s dynamic simulation model with three vehicles and compare the designed controller and the PID controller for their performance in controlling the model suspension stability in the presence of the train operating in open air. Simulation results show that the sliding mode control (SMC) method proposed in this paper can effectively restrain the electromagnet fluctuation of the train under aerodynamic loads.
49
Fadlalla, Amin, Ahmet Sahin, Hassen Ouakad i Haitham Bahaidarah. "Aeroelastic analysis of straight-bladed vertical axis wind turbine blade". FME Transactions 50, nr 3 (2022): 512–25. http://dx.doi.org/10.5937/fme2203512f.
Pełny tekst źródłaStreszczenie:
To prevent flutter phenomena in a wind turbine, minimize vibration and increase the blades' life, a systematic analysis is required to investigate the effects between the cyclic aerodynamic loads and the structural performance of the turbine. A dynamic analysis of a straight-bladed vertical axis wind turbine (SB-VAWT) blade is investigated in this paper, and a simplified approach for the energy equations of an Eulerian beam subjected to twist and transverse bending deflections is introduced. The aerodynamic loads are estimated using the double multiple stream tube models. They are introduced into the dynamic model in the aeroelastic coupling, where the structural displacements are fed back to update the aerodynamic loads by utilizing the average acceleration method for the numerical integration of the equations. Reduced order modeling is then imposed based on the first modes of vibration. It is found that the structural displacement has little effect on the aerodynamic loads, and SBVAWTs experience higher transverse displacements compared with those in curved-blade VAWTs.
50
Schafhirt, Sebastian, i Michael Muskulus. "Decoupled simulations of offshore wind turbines with reduced rotor loads and aerodynamic damping". Wind Energy Science 3, nr 1 (21.02.2018): 25–41. http://dx.doi.org/10.5194/wes-3-25-2018.
Pełny tekst źródłaStreszczenie:
Abstract. Decoupled load simulations are a computationally efficient method to perform a dynamic analysis of an offshore wind turbine. Modelling the dynamic interactions between rotor and support structure, especially the damping caused by the rotating rotor, is of importance, since it influences the structural response significantly and has a major impact on estimating fatigue lifetime. Linear damping is usually used for this purpose, but experimentally and analytically derived formulas to calculate an aerodynamic damping ratio often show discrepancies to measurement and simulation data. In this study decoupled simulation methods with reduced and full rotor loads are compared to an integrated simulation. The accuracy of decoupled methods is evaluated and an optimization is performed to obtain aerodynamic damping ratios for different wind speeds that provide the best results with respect to variance and equivalent fatigue loads at distinct output locations. Results show that aerodynamic damping is not linear, but it is possible to match desired output using decoupled models. Moreover, damping ratios obtained from the empirical study suggest that aerodynamic damping increases for higher wind speeds.