Thematische Bibliographien / Wing local calculations

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Auswahl der wissenschaftlichen Literatur zum Thema „Wing local calculations“

Autor: Grafiati

Veröffentlicht am 28. Juni 2021

Zuletzt aktualisiert am 5. Februar 2022

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Zeitschriftenartikel zum Thema "Wing local calculations"

Davis, M. J. „Microvascular control of capillary pressure during increases in local arterial and venous pressure“. American Journal of Physiology-Heart and Circulatory Physiology 254, Nr. 4 (01.04.1988): H772—H784. http://dx.doi.org/10.1152/ajpheart.1988.254.4.h772.

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The extent to which capillary hydrostatic pressure might be protected from increases in local arterial and venous pressure was examined in the wing microcirculation of unanesthetized pallid bats (Antrozous pallidus). Arterial inflow and venous outflow pressures to the wing were elevated using a box technique to increase pressure around the body of the animal in steps of 12 mmHg between 0 and +60 mmHg for 3-min periods. During this time, hydrostatic pressure, diameter, and red cell velocity in single microvessels were continuously recorded. All branching orders of arterioles constricted significantly during increases in box pressure (Pb), while capillaries and venules dilated. First-order arteriole and venule pressures increased 1:1 with Pb. Capillary pressures increased by only a fraction of Pb up to +36 mmHg, but at higher Pb, the change in capillary pressure was equivalent to the change in Pb. Calculations of vascular resistance indicate that changes in both pre- and postcapillary resistance in this tissue act to prevent increases in capillary pressure during moderate, but not during large, increases in arterial and venous pressure.

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Sato, M., und A. Azuma. „The flight performance of a damselfly Ceriagrion melanurum Selys“. Journal of Experimental Biology 200, Nr. 12 (01.01.1997): 1765–79. http://dx.doi.org/10.1242/jeb.200.12.1765.

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The local circulation method was applied to the free forward flight of the damselfly Ceriagrion melanurum Selys. The kinematic data used in the calculations were obtained by analyzing video-taped images of damselflies in free flight in a transparent container. The inclination of the stroke plane was smaller and the flapping amplitude was larger than those of dragonflies reported in other studies on odonate flight. However, the phase shift between the fore- and hindwings agreed with none of the previously reported patterns for damselflies: the forewings lead the hindwings by approximately a quarter-period. The calculated forces were within the expected range of error. The muscle-mass-specific power was between 40 and 80 W kg-1. The vorticity distribution of trailing and shed vortices in the wake was also analyzed. Strong trailing vortices were observed at the wing tips, whereas shed vortices were concentrated near the wing root as the stroke switched direction.

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Гребеников, А. Г., und Д. Ю. Жиряков. „АНАЛІЗ СИЛ ФУНКЦІОНУВАННЯ ВІД’ЄМНОЇ ЧАСТИНИ КРИЛА ЛІТАКА ТРАНСПОРТНОЇ КАТЕГОРІЇ“. Open Information and Computer Integrated Technologies, Nr. 89 (23.03.2021): 4–20. http://dx.doi.org/10.32620/oikit.2020.89.01.

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Each experimental design department has experience in determining design and operational loads for a given type of aircraft. The reliability of the data on the loading of a particular structural element determines the success of the aircraft being created. This is often confidential information. Much work has been investigated to improve the fatigue life of wing structural elements. With the development of integrated design methods, aircraft structure design can be performed in the shortest time, and with high technical excellence. In most cases, the fatigue life of wing elements is determined from the nominal stresses in the element. For a longitudinal structure set, it is customary to perform fatigue calculations directly using normal stresses in the element. For a more detailed specification of the fatigue life, it is necessary to have a general and local stress-strain state of a given structure. A feature of the work is to analyze the spectrum of loads acting on the wing console during a typical flight. The influence of high-lift devises (slats, flaps) on the shear forces and torque moment of the wing was analyzed. It has been shown that with the extensions high-lift devices, there is a significant increase in torque. These articles will make it possible to obtain the stress distribution of the detachable part of the wing under all operating modes. This, in turn, leads to a more thorough prediction of fatigue life. Since some operating loads can significantly change the distribution of the stress-strain state in the design element, and in turn change the fatigue life. The structural elements of the wing, in particular the attachment points for the high-lift devices, operate in a complex-stressed state. This complicates the process of predicting the fatigue life of these elements. To obtain a competitive aircraft, it is necessary to develop new methods of wing design with widespread use of integrated systems. This will contribute to obtaining a more optimal and perfect wing design

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Ruban, A. I., T. Bernots und M. A. Kravtsova. „Linear and nonlinear receptivity of the boundary layer in transonic flows“. Journal of Fluid Mechanics 786 (30.11.2015): 154–89. http://dx.doi.org/10.1017/jfm.2015.587.

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In this paper we analyse the process of the generation of Tollmien–Schlichting waves in a laminar boundary layer on an aircraft wing in the transonic flow regime. We assume that the boundary layer is exposed to a weak acoustic noise. As it penetrates the boundary layer, the Stokes layer forms on the wing surface. We further assume that the boundary layer encounters a local roughness on the wing surface in the form of a gap, step or hump. The interaction of the unsteady perturbations in the Stokes layer with steady perturbations produced by the wall roughness is shown to lead to the formation of the Tollmien–Schlichting wave behind the roughness. The ability of the flow in the boundary layer to convert ‘external perturbations’ into instability modes is termed the receptivity of the boundary layer. In this paper we first develop the linear receptivity theory. Assuming the Reynolds number to be large, we use the transonic version of the viscous–inviscid interaction theory that is known to describe the stability of the boundary layer on the lower branch of the neutral curve. The linear receptivity theory holds when the acoustic noise level is weak, and the roughness height is small. In this case we were able to deduce an analytic formula for the amplitude of the generated Tollmien–Schlichting wave. In the second part of the paper we lift the restriction on the roughness height, which allows us to study the flows with local separation regions. A new ‘direct’ numerical method has been developed for this purpose. We performed the calculations for different values of the Kármán–Guderley parameter, and found that the flow separation leads to a significant enhancement of the receptivity process.

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FEDOROV, A. V., N. D. MALMUTH und V. G. SOUDAKOV. „Supersonic scattering of a wing-induced incident shock by a slender body of revolution“. Journal of Fluid Mechanics 585 (07.08.2007): 305–22. http://dx.doi.org/10.1017/s0022112007006714.

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The lift force acting on a slender body of revolution that separates from a thin wing in supersonic flow is analysed using Prandtl–Glauert linearized theory, scattering theory and asymptotic methods. It is shown that this lift is associated with multi-scattering of the wing-induced shock wave by the body surface. The local and global lift coefficients are obtained in simple analytical forms. It is shown that the total lift is mainly induced by the first scattering. Contributions from second, third and higher scatterings are zero in the leading-order approximation. This greatly simplifies calculations of the lift force. The theoretical solution for the flow field is compared with numerical solutions of three-dimensional Euler equations and experimental data at free-stream Mach number 2. There is agreement between the theory and the computations for a wide range of shock-wave strength, demonstrating high elasticity of the leading-order asymptotic approximation. Theoretical and experimental distributions of the cross-sectional normal force coefficient agree satisfactorily, showing robustness of the analytical solution. This solution can be applied to the moderate supersonic (Mach numbers from 1.2 to 3) multi-body interaction problem for crosschecking with other computational or engineering methods.

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Brazier, Jean-Philippe, Frédéric Moens und Philippe Bardoux. „Spatial Stability Analysis of a Flap Side Edge Vortex“. International Journal of Aeroacoustics 4, Nr. 1-2 (Januar 2005): 37–47. http://dx.doi.org/10.1260/1475472053730066.

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The flap side edge vortex is suspected to contribute to aerodynamic noise generation. Using a temporal stability analysis, Khorrami and Singer have shown that unstable modes could exist in this vortex. Due to the convective nature of this instability, a spatial analysis is more suitable. This is the subject of the present work. The mean flow past a 2D wing with a half-span flap has been computed with a steady 3D Navier-Stokes code. Then, local linear stability calculations are performed in several planes perpendicular to the vortex axis. The vortex is assumed axisymmetric and modelled with Batchelor's analytical vortex. Using Gaster's relation, the spatial amplification rate is calculated, giving by integration the relative amplitude of the fluctuations. Some low-frequency fluctuations are seen to be preferentially amplified by the vortex, but the amplifications remain small, so that this mechanism alone should not produce important noise in this particular configuration, where the flap deflection angle is moderate.

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Крашаница, Юрий Александрович, und Дмитрий Юрьевич Жиряков. „Аэродинамический профиль в трансзвуковом потоке газа“. Aerospace technic and technology, Nr. 2 (28.04.2021): 20–27. http://dx.doi.org/10.32620/aktt.2021.2.03.

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The subject of investigation in this article is transonic flow. This is a condition in which local speeds of sound are appears on the wing surface, even at the subsonic speed of the nonturbulent flow. As a result, at a certain speed of the incoming flow, the flow regime around the aerodynamic surface will change sharply, which in turn changes the aerodynamic characteristics. Aerodynamic surfaces of the most transport category airplane experience transonic airflow during flight. The goal of the investigation is to study aerodynamic characteristics using numerical methods. The use of numerical methods in the design of aircraft structures is used more and more often to determine the optimal parameters for given operating conditions. This contributes to obtaining a more optimal and perfect design. In this article, we carried out a numerical analysis of the aerodynamic characteristics of airfoils in the transonic flow case using the CAE system CFD ANSYS. As a result of the research, the distributions of the pressure coefficients over the profile surface were obtained. The nature of the flow is obtained, which is similar to the picture of the pressure coefficients for transonic flow in the published sources of this topic. In the area of the middle of the profile, a shock-wave is observed. As a result, the flow around the airfoil changes, which contributes to a change in aerodynamic characteristics. The behavior of the aerodynamic drag and lift coefficients depending on the speed of the Mach number is considered. Also, the position of the center of pressure was analyzed at various velocities of the nonturbulent flow. The calculation was carried out at the cruising altitude of a medium-range aircraft of 11 km. For the calculations, we used the characteristics of the air temperature, the pressure of a given height from the table of the standard atmosphere.

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Secco, Ney Rafael, und Bento Silva de Mattos. „Artificial neural networks to predict aerodynamic coefficients of transport airplanes“. Aircraft Engineering and Aerospace Technology 89, Nr. 2 (06.03.2017): 211–30. http://dx.doi.org/10.1108/aeat-05-2014-0069.

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Purpose Multidisciplinary design frameworks elaborated for aeronautical applications require considerable computational power that grows enormously with the utilization of higher fidelity tools to model aeronautical disciplines like aerodynamics, loads, flight dynamics, performance, structural analysis and others. Surrogate models are a good alternative to address properly and elegantly this issue. With regard to this issue, the purpose of this paper is the design and application of an artificial neural network to predict aerodynamic coefficients of transport airplanes. The neural network must be fed with calculations from computational fluid dynamic codes. The artificial neural network system that was then developed can predict lift and drag coefficients for wing-fuselage configurations with high accuracy. The input parameters for the neural network are the wing planform, airfoil geometry and flight condition. An aerodynamic database consisting of approximately 100,000 cases calculated with a full-potential code with computation of viscous effects was used for the neural network training, which is carried out with the back-propagation algorithm, the scaled gradient algorithm and the Nguyen–Wridow weight initialization. Networks with different numbers of neurons were evaluated to minimize the regression error. The neural network featuring the lowest regression error is able to reduce the computation time of the aerodynamic coefficients 4,000 times when compared with the computing time required by the full potential code. Regarding the drag coefficient, the average error of the neural network is of five drag counts only. The computation of the gradients of the neural network outputs in a scalable manner is possible by an adaptation of back-propagation algorithm. This enabled its use in an adjoint method, elaborated by the authors and used for an airplane optimization task. The results from that optimization were compared with similar tasks performed by calling the full potential code in another optimization application. The resulting geometry obtained with the aerodynamic coefficient predicted by the neural network is practically the same of that designed directly by the call of the full potential code. Design/methodology/approach The aerodynamic database required for the neural network training was generated with a full-potential multiblock-structured code. The training process used the back-propagation algorithm, the scaled-conjugate gradient algorithm and the Nguyen–Wridow weight initialization. Networks with different numbers of neurons were evaluated to minimize the regression error. Findings A suitable and efficient methodology to model aerodynamic coefficients based on artificial neural networks was obtained. This work also suggests appropriate sizes of artificial neural networks for this specific application. We demonstrated that these metamodels for airplane optimization tasks can be used without loss of fidelity and with great accuracy, as their local minima might be relatively close to the minima of the original design space defined by the call of computational fluid dynamics codes. Research limitations/implications The present work demonstrated the ability of a metamodel with artificial neural networks to capture the physics of transonic and subsonic flow over a wing-fuselage combination. The formulation that was used was the full potential equation. However, the present methodology can be extended to model more complex formulations such as the Euler and Navier–Stokes ones. Practical implications Optimum networks reduced the computation time for aerodynamic coefficient calculations by 4,000 times when compared with the full-potential code. The average absolute errors obtained were of 0.004 and 0.0005 for lift and drag coefficient prediction, respectively. Airplane configurations can be evaluated more quickly. Social implications If multidisciplinary optimization tasks for airplane design become more efficient, this means that more efficient airplanes (for instance less polluting airplanes) can be designed. This leads to a more sustainable aviation. Originality/value This research started in 2005 with a master thesis. It was steadily improved with more efficient artificial neural networks able to handle more complex airplane geometries. There is a single work using similar techniques found in a conference paper published in 2007. However, that paper focused on the application, i.e. providing very few details of the methodology to model aerodynamic coefficients.

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AZUMA, AKIRA, SOICHI AZUMA, ISAO WATANABE und TOYOHIKO FURUTA. „Flight Mechanics of a Dragonfly“. Journal of Experimental Biology 116, Nr. 1 (01.05.1985): 79–107. http://dx.doi.org/10.1242/jeb.116.1.79.

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The steady slow climbing flight of a dragonfly, Sympetrum frequens, was filmed and analysed. By using the observed data, the mechanical characteristics of the beating wings were carefully analysed by a simple method based on the momentum theory and the blade element theory, and with a numerical method modified from the local circulation method (LCM), which has been developed for analysing the aerodynamic characteristics of rotary wings. The results of calculations based on the observed data show that the dragonfly performs low speed flight with ordinary airfoil characteristics, instead of adopting an abnormally large lift coefficient. The observed phase advance of the hindwing, Δδ1 ≃ 80° can be fully explained by the present theoretical calculation. Similarly, the spanwise variation of the airloading and the time variations of the horizontal force, vertical force, pitching moment and torque or power can be definitely estimated within a reasonable range of accuracy in comparison with the flight data. The distribution of loading between the fore and hind pairs of wings is also clarified by the calculations.

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Cao, Xiao, Pei Pei Peng, Hai Zhou und Xu Cheng. „Technology of Wind Power Forecasting Accuracy Assessment and Curtail Quantity Estimation with Power Capacity Limited“. Applied Mechanics and Materials 672-674 (Oktober 2014): 280–85. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.280.

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Eastern Inner Mongolia is by now one of the areas with the most rapid development of wind power in China. There exists mismatching between wind power supply ability and level of local economy. Thus, wind farms will be inevitability partly involved in peak shaving. The researches on accuracy assessment on wind power forecasting and estimation of power rationing quantity on condition of wind power curtail contribute to provide effective data evidence for scheduling and dispatching operations. In this paper, a new method for accuracy assessment on wind power forecasting and estimation of power rationing quantity through calculating theoretical power were presented first. Then, the algorithm of theoretical power calculation was presented. Case study proved the feasibility and effectiveness of the method. The conclusion indicated that the method has feasible and objective mean for accuracy assessment on wind power forecasting on condition of wind power curtail, which can provide objective and accurate theoretical and data support for dispatching and scheduling operations on condition of wind power curtail.

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Mehr Quellen

Dissertationen zum Thema "Wing local calculations"

Chabada, Martin. „Návrh křídla letounu UAV v kategorii do 600 kg“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442849.

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The main aim of the this diploma thesis is the wing design of the UAV aircraft, including the appropriate material choice, calculation of the wing load and also strength analysis. Other goals include the design of the location and volume of fuel tanks, as well as the design of wingspan reduction after landing.

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Buchteile zum Thema "Wing local calculations"

„(GE/m**3). According to this definition one odour unit is the amount of odorants in one cubic meter of air at odour thres hold level. The new definition is a real concentration and gives a better form of input parameter for dispersion models. On the basis of guideline VDI 3881 parts 1, 2, and 3 ringtests were carried out with different odorants. The results can be summerized as follows: -The dispersion of results varies and depends on the compo sition of the participants and on problems of sampling and preparation of odorous sample. Lower dispersion is obtained when results with obvious errors in application of guide lines or with large deviations from mean value are excluded. -Participants of the Netherlands get systematically lower threshold values than the others. The reason has to be investigated. -All findings of the ringtests lead to the conclusion that it is possible to determine odour thresholds which do not differ by more than factor 10. At present another ringtest is in preparation. This test will be carried out in summer 1985. The French collegues will also participate in this test. Experience of all ringtests will be reported in part 4 of guideline VDI 3881. Guideline VDI 3882 deals with the determination of odour intensity and hedonic tone. The members of the working group "odorous substances" assume that odour threshold and odour concentration are insufficient for the characterization of odorous perception. They recommend to judge the odour inten sity and the hedonic tone by category estimation. Moreover, it is their opinion that the odour determination with olfacto meters is not suitable to assess odour in ambient air. There fore they are preparing two guidelines dealing with these problems. Guideline VDI 3883 gives instructions on the regis tration of nuisance by interviews with nearby residents of emitting plants or inhabitants of industrial areas. Addition ally guideline VDI 3940 describes the determination of odour in ambient air by inspection panels based on the following idea: During constant conditions as to the class of weather, wind speed, and wind direction each local point is charac terized by a frequency of odour perception representing the probability to perceive an odour. The situation at a local point will be have to determine the portion of a year with a frequency of odorous perception greater than 5 % in a random test. Both guidelines, VDI 3882 and 3940, should give corres ponding results. Guideline VDI 3781 part 5 completes the complex of odour determination and judgement with the calculation of disper sion models. The calculation methode and odour determination by panelists should give comparable results. The following summery can be given. Odour measurements with olfactometers is only a small part of the whole field of odour determination in ambient air and the measurement of odour nuisance must be approached in the near future with appropriate urgency.“ In Odour Prevention and Control of Organic Sludge and Livestock Farming, 76–94. CRC Press, 1986. http://dx.doi.org/10.1201/9781482286311-30.

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Konferenzberichte zum Thema "Wing local calculations"

Florea, Razvan V., Dmytro Voytovych, Gregory Tillman, Mark Stucky, Aamir Shabbir, Om Sharma und David J. Arend. „Aerodynamic Analysis of a Boundary-Layer-Ingesting Distortion-Tolerant Fan“. In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94656.

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The paper describes the aerodynamic CFD analysis that was conducted to address the integration of an embedded-engine (EE) inlet with the fan stage. A highly airframe-integrated, distortion-tolerant propulsion preliminary design study was carried out to quantify fuel burn benefits associated with boundary layer ingestion (BLI) for “N+2” blended wing body (BWB) concepts. The study indicated that low-loss inlets and high-performance, distortion-tolerant turbomachines are key technologies required to achieve a 3–5% BLI fuel burn benefit relative to a baseline high-performance, pylon-mounted, propulsion system. A hierarchical, multi-objective, computational fluid dynamics-based aerodynamic design optimization that combined global and local shaping was carried out to design a high-performance embedded-engine inlet and an associated fan stage. The scaled-down design will be manufactured and tested in NASA’s 8′×6′ Transonic Wind Tunnel. Unsteady calculations were performed for the coupled inlet and fan rotor and inlet, fan rotor and exit guide vanes. The calculations show that the BLI distortion propagates through the fan largely un-attenuated. The impact of distortion on the unsteady blade loading, fan rotor and fan stage efficiency and pressure ratio is analyzed. The fan stage pressure ratio is provided as a time-averaged and full-wheel circumferential-averaged value. Computational analyses were performed to validate the system study and design-phase predictions in terms of fan stage performance and operability. For example, fan stage efficiency losses are less than 0.5–1.5% when compared to a fan stage in clean flow. In addition, these calculations will be used to provide pretest predictions and guidance for risk mitigation for the wind tunnel test.

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Joubert, H., und M. Goutines. „Use of CFD Methods to Design Engine Nacelles“. In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-117.

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The challenge for current and future nacelles of commercial engines is to obtain: -low transonic drag in cruise condition, -low weight and reduced dimensions without reducing the low speed operating domain (maximum incidence, crosswind, etc) and low noise level. This paper explains how various designs can be improved by using modern numerical methods. Concerning air inlets, 3D Euler code and boundary layer code are used for prediction of divergence Mach number and drag in cruise conditions. Low speed behaviour is also obtained for various flight conditions which cause high local incidences on air inlet sections. Attention is mainly focused on attached flow limits. CFD method calibrations based on existing tests results are needed for that work. Bypass and core nozzle design use axisymmetric Navier-Stokes calculations for the prediction of thrust and flow coefficients relative values. This calculation also helps on development of adequate designs of the throat region and provides detailed analysis of the core nozzle flowfield including interaction of outer cold jet. These methods are applied to the design of an advanced nacelle for a high bypass ratio engine. This nacelle is equiped with an original core cowl doors thrust reverser. Consequently the nacelle length and weight have been significantly reduced. The main numerical results obtained on this nacelle are presented including some results for the installation of this nacelle under a wing.

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Ramrakhyani, Deepak S., George A. Lesieutre, Mary Frecker und Smita Bharti. „Parallel Genetic Algorithm for Design of Morphing Cellular Truss Structures“. In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82751.

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A parallel genetic algorithm is developed for the design of morphing aircraft structures using tendon actuated compliant truss. The wing structure in this concept is made of solid members and cables. The solid members are connected through compliant joints so that they can be deformed relatively easily without storing much strain energy in the structure. The structure is actuated using cables to deform into a required shape. Once the structure is deformed, the cables are locked and hence carry loads. Previously an octahedral unit cell made of cables and truss members was developed to achieve the required shape change of a morphing wing developed at NASA. It was observed that a continuously deformable truss structure with required morphing capability can be achieved by a cellular geometry tailored to local strain deformation. A wing structure made of these unit cells was sized for a representative aircraft and was found to be suitable. This paper describes the development of new unit cell designs that fit the morphing requirements using topology optimization. A ground structure approach is used to set up the problem. A predetermined set of points is selected and the members are connected in between the neighboring nodes. Each member in this ground structure has four possibilities, 1) a truss member, 2) a cable that morphs the structure into a required shape, 3) a cable that is antagonistic and brings it back to the original shape 4) a void, i.e., the member doesn’t exist in the structure. This choice is represented with a discrete variable. A parallel genetic algorithm is used as an optimization approach to optimize the variables in the ground structure to get the best structural layout. The parallelization is done using a master slave process. A fitness function is used to calculate how well a structural layout fits the design requirements. In general, a unit cell that has lesser deflection under external loads and higher deflection under actuation has a higher fitness value. Other requirements such as having fewer cables and achieving a required morphing shape are also included in the fitness function. The finite element calculations in the fitness function can be done using either linear or nonlinear analysis. The paper discusses the different ways of formulating the fitness function and the results thereof.

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Ma, Youjie, Hulong Wen, Xuesong Zhou, Ji Li und Haishan Yang. „Calculation and study of two-dimensional parameter local bifurcation boundary in wind power system stability model based on continuation method“. In 2009 World Non-Grid-Connected Wind Power and Energy Conference (WNWEC 2009). IEEE, 2009. http://dx.doi.org/10.1109/wnwec.2009.5335808.

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Xu, Guanpeng, und Lakshmi N. Sankar. „Application of a Viscous Flow Methodology to the NREL Phase VI Rotor“. In ASME 2002 Wind Energy Symposium. ASMEDC, 2002. http://dx.doi.org/10.1115/wind2002-30.

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A numerical technique has been developed for efficiently simulating fully three-dimensional viscous fluid flow around horizontal axis wind turbines (HAWT). In this approach, the viscous region surrounding the blades is modeled using 3-D unsteady Navier-Stokes equations. The inviscid region away from the boundary layer and the wake is modeled using potential flow. The concentrated vortices that emanate from the blade tip are treated as piecewise straight line segments that are allowed to deform and convect at the local flow velocity. Biot-Savart law is used to estimate the velocity field associated with these vortices. Calculations are presented under axial wind conditions for a NREL two-bladed rotor, known as the Phase VI rotor, tested at the NASA Ames Research Center. Good agreement with the measurements is found. The computed results are used to develop improved engineering models for the loss of lift at the blade tip, and for the delay in the stall angle at inboard locations. The improved models are incorporated in a blade element-momentum (BEM) analysis to study the post-stall behavior of a three-bladed rotor tested at NREL.

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Holley, Brian M., Sandor Becz und Lee S. Langston. „Measurement and Calculation of Turbine Cascade Endwall Pressure and Shear Stress“. In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-68256.

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The complex three-dimensional fluid flow on the endwall in an axial flow turbine blade or vane passage has been extensively investigated and reported on in turbomachinery literature. The aerodynamic loss producing mechanisms associated with the endwall flow are still not fully understood or quantitatively predictable. To better quantify wall friction contributions to endwall aerodynamic loss, low Mach number wind tunnel measurement of skin friction coefficients have been made on one endwall of a large scale cascade of high pressure turbine airfoils, at engine operating Reynolds numbers. Concurrently, predictive calculations of the endwall flow shear stress have been made using a computational fluid dynamics (CFD) code. Use of the oil film interferometry skin friction technique is described and applied to the endwall, to measure local skin friction coefficients and shear stress directions on the endwall. These are correlated with previously reported measured local endwall pressure gradients. The experimental results are discussed and compared to the CFD calculations, to answer questions concerning endwall aerodynamic loss predictive ability.

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Wu, Nan, Na Xue und Xinjian Liu. „Research on the Influence of Complex Terrain on Atmospheric Dispersion After Accident“. In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81378.

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Emergency condition should be evaluated during the siting of Nuclear Power Plants (NPP). One of the criteria is the capability of emergency evacuation for the purpose of protecting the NPP staff and public. Exposure dose received by evacuees is a key factor to evaluate the effectiveness of emergency evacuation, which can be characterized by the atmospheric dispersion factors over the evacuation paths. Gaussian plume model is usually applied in the atmospheric dispersion factor calculation for NPPs. However, for some NPP sites with complex terrain like mountain and lake which has significant influence on the local flow field and the nuclides transportation, the calculations based on Gaussian model will not be accurate enough for the evaluation of the evacuation capability. In such cases, Computational Fluid Dynamics (CFD) method with fine calculation grids and rich physical models can be used in the atmospheric dispersion modeling of small-scale region, to get much more accurate results. This paper is devoted to the research on the impact of these complex terrain on atmospheric dispersion with CFD method. The local atmospheric dispersion around a NPP site located on an island is modeled, where there is a mountain on the way of evacuation. For the limitation of the geographic barrier, two evacuation paths, which are located closely with small difference in direction, are planned along different sides of the mountain. Utilizing STAR-CCM+ CFD software, local atmospheric dispersion factors are fine simulated under six worse wind directions. Based on the simulation results, the impact of the mountain on the flow field and of the radiological plume on the evacuation paths is analyzed. Results show that due to the blocking effect of the mountain, those two evacuation paths have little probability to be simultaneously covered by the radiological plume. By the choosing of suitable routes during the evacuation, the radiological risk of public is acceptable and emergency evacuation can be carried out effectively. These results also demonstrate that CFD modeling method is effective in the evaluation of local atmospheric dispersion over complex terrain, which can be applied in the analysis of emergency evacuation of NPP sites with complex terrain.

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Martinez, Michaël, und Sébastien Montalvo. „Detailed Finite Element Modeling of a High Capacity Mooring Steel Wire Rope: Calculation of the Stress Concentration Near the Connection“. In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18170.

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Abstract The mooring of floating platforms is an important challenge for the offshore industry. It is an important part of the design engineering and, often, a critical point for the fatigue life assessment. A solution that could improve the fatigue life is to directly connect the mooring rope to the platform, without an intermediate chain. However this solution is not widespread and the behavior of a rope near such a connection is little known. The present paper proposes to better understand this behavior, thanks to a detailed finite element model of the rope. The study case is a steel wire rope directly connected to a floating wind turbine. A local finite element model of the rope has been built, where the wires are individually modeled with beam elements. One end of the rope is clamped, simulating the connection, while tension and cyclic bending oscillations are applied to the other end. A localized bending takes place near the connection, leading to stress concentration in the wires. The stress concentration and the local contact forces are calculated for each wire. These data are important entry parameters for a local failure or fatigue analysis. This latter is however not presented here. Despite IFPEN experience in the development of local finite element models of steel wire ropes, it is the first time that such a high capacity rope (MBL = 12 500 kN) is modeled. This is challenging because of the large diameter of the rope and the large number of wires. However this modeling approach is very valuable for such ropes, because the experimental tests are rare and very expensive.

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Koop, Arjen, SeongMo Yeon, Kai Yu, Sebastien Loubeyre, Wei Xu, Jerry Huang, Vimal Vinayan, Madhusuden Agrawal und Jang Kim. „Development and Verification of Modeling Practice for CFD Calculations to Obtain Current Loads on FPSO“. In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19173.

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Abstract Current loads are important input parameters for mooring studies. To accurately predict the motions of moored vessels these quantities should be determined with confidence in the values. Traditionally, these quantities have been determined using model tests in water basins or in wind tunnels. With recent advancements in CFD modeling, the offshore industry has started using CFD as an alternative tool to compute current loads on FPSO’s. In order to help adopt CFD as a widely accepted tool, there is a need to develop confidence in CFD predictions. Therefore, a practical CFD Modeling Practice is developed within the Reproducible Offshore CFD JIP. The Modeling Practice describes the geometry modeling, computational mesh, model set-up and post-processing for these types of CFD calculations. This Modeling Practice is verified and validated by five independent verifiers against model test data, such that reproducible and accurate results can be obtained by following the Modeling Practice. This paper provides an overview of the developed Modeling Practice and the calculated CFD results from the verifiers. The CFD Modeling Practice is benchmarked against available model test results for a barge-type and a tanker-shaped FPSO. By following this Modeling Practice, the CFD predictions for CY and CMZ are within 10% from all verifiers and within 10% from the model test results. Larger differences may be obtained for CX, depending on local grid resolution and turbulence model used, but also due to larger experimental uncertainty for this quantity.

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Bexten, Thomas, Manfred Wirsum, Björn Roscher, Ralf Schelenz, Georg Jacobs, Daniel Weintraub und Peter Jeschke. „Optimal Operation of a Gas Turbine Cogeneration Unit With Energy Storage for Wind Power System Integration“. In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76688.

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Many energy supply systems around the world are currently undergoing a phase of transition characterized by a continuing increase in installed renewable power generation capacities. The inherent volatility and limited predictability of renewable power generation pose various challenges for an efficient system integration of these capacities. One approach to manage these challenges is the deployment of small-scale dispatchable power generation and storage units on a local level. In this context, gas turbine cogeneration units, which are primarily tasked with the provision of power and heat for industrial consumers, can play a significant role if they are equipped with a sufficient energy storage capacity allowing for a more flexible operation. The present study investigates a system configuration which incorporates a heat-driven industrial gas turbine interacting with a wind farm providing volatile renewable power generation. The required energy storage capacity is represented by an electrolyzer and a pressure vessel for intermediate hydrogen storage. The generated hydrogen can be reconverted to electricity and process heat by the gas turbine. The corresponding operational strategy for the overall system aims at an optimal integration of the volatile wind farm power generation on a local level. The study quantifies the impact of selected system design parameters on the quality of local wind power system integration that can be achieved with a specific set of parameters. In addition, the impact of these parameters on the reduction of CO2 emissions due to the use of hydrogen as gas turbine fuel is quantified. In order to conduct these investigations, detailed steadystate models of all required system components were developed. These models enable accurate simulations of the operation of each component in the complete load range. The calculation of the optimal operational strategy is based on an application of the Dynamic Programming algorithm. Based on this model setup, the operation of the overall system configuration is simulated for each investigated set of design parameters for a one-year period. The simulation results show that the investigated system configuration has the ability to significantly increase the level of local wind power integration. The parameter variation reveals distinct correlations between the main design parameters of the storage system and the achievable level of local wind power integration. Regarding the installed electrolyzer power consumption capacity, smaller additional benefits of capacity increases can be identified at higher levels of power consumption capacity. Regarding the geometrical volume of the hydrogen storage, it can be determined that the storage volume loses its limiting character on the operation of the electrolyzer at a characteristic level. The additional investigation of the CO2 emission reduction reveals a direct correlation between the level of local wind power integration and the achievable level of CO2 emission reduction.

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