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Статті в журналах з теми "Main fairing"
1
Mehta, Rakhab C. "Computational Fluid Dynamics Analysis and Design of Payload Shroud of Satellite Launch Vehicle." Scholars Journal of Engineering and Technology 10, no. 4 (April 5, 2022): 16–34. http://dx.doi.org/10.36347/sjet.2022.v10i04.001.
Повний текст джерелаАнотація:
The main focus of the present paper is to computational fluid dynamics analysis and design of payload fairing of satellite launch vehicle at freestream Mach number range of 0.6 - 3.0. Initially, time-dependent compressible three-dimensional Euler equations are solved employing a finite volume discretization method with a multi-stage Runge-Kutta time-stepping scheme to compute surface pressure and aerodynamic coefficients at various payload fairing and at angle of attack up to 5o with an increment of 1o. Payload fairing dimensions are selected that satisfies permissible structure load on satellite launch vehicle. Detailed flowfield simulation is carried out on the selected payload fairing employing axisymmetric compressible Reynolds-average Navier-Stokes equations to assess unsteady flowfield characteristics. The numerical simulations are used to locate terminal shock on the payload fairing at transonic Mach number. Unsteady flow characteristics are used to compute acoustic load. Shock standoff distances at supersonic speeds are tabulated and compared with the analytical solution. Schlieren images and oil flow pictures are compared with experimental results and in good agreement. Aerodynamic shape optimization of satellite launch vehicle payload fairing shape has been performed to satisfy structural load at maximum drag and dynamic pressure.
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Wang, Hua Ming, Han Xing Zhao, Yong Jia Dai, and Xiao Song Rui. "Experimental Research on Effect of Hot Works on Mechanical Performance of Ship Steel Plate." Advanced Materials Research 311-313 (August 2011): 1859–62. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.1859.
Повний текст джерелаАнотація:
Hot works is an important method for fairing the ship steel plate to improve the quality of shipbuilding, while the mechanical performance of the ship steel plate may be affected during the fairing process, which could result to some safe problems on the structural strength. DH32 high-strength ship steel plate, which is a kind of widely used material in shipbuilding industry, is taken as an object of the present experimental study. Some main parameters of the plate’s mechanical property through hot-works treatment for different times are investigated systematically. Through analyzing the variation of the mechanical properties, some conclusions are drawn and some useful suggestions put forward.
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Зайцев, Борис Филиппович, Татьяна Владимировна Протасова, Дмитрий Васильевич Клименко, Дмитрий Васильевич Акимов та Владимир Николаевич Сиренко. "ДИНАМИЧЕСКИЙ АНАЛИЗ КОМПОЗИТНОГО ОБТЕКАТЕЛЯ РАКЕТЫ ПРИ ОТДЕЛЕНИИ С УЧЕТОМ РАССЛОЕНИЯ СТРУКТУРЫ". Aerospace technic and technology, № 8 (31 серпня 2020): 19–26. http://dx.doi.org/10.32620/aktt.2020.8.03.
Повний текст джерелаАнотація:
The dynamic processes in the rocket fairing when the pyrotechnic separation system is triggered are considered. The fairing construction is mixed and includes composite and metal elements. The main composite construction element is a fiberglass shell with regular and irregular winding zones. The speed acceleration required to separate the fairing occurs under the action of impulse pressure from the powder gases in the pyrotechnic system. The displacement of the fairing is made up of displacements of the movement as a rigid whole along its axis and vibrations caused by deformations. The calculation of the fairing movement is carried out according to a three-dimensional FEM model using software that uses a topologically regular discretization system. The problem solution in time is performed according to the implicit Wilson finite-difference scheme. When studying the fairing dynamics, it is allowed to break the structure of the shell in the form of lamination, which in the FEM scheme is modeled by a special method. A cut with double nodes is created on the surface of the proposed lamination along topological planes by transforming the finite element mesh. Modification of the stiffness matrix and mass matrix for the transformed mesh is performed based on the created information base of degenerate finite elements and formalized matrix operations. In numerical studies, two types of lamination from irregular zones of fiberglass winding are considered – the internal location from the flange and edge location with access to the fairing free edge. The results of calculating vibrations along the sides of lamination and data on the redistribution of dynamic stresses due to lamination are presented. Radial and axial displacements when passing through the lamination surface discontinue, the magnitude of which for internal lamination is much less, which is explained by the compression of deformation for this case, in contrast to the lamination that goes to the boundary. When estimating the relative axial displacements, the component of the displacement of a rigid whole, determined by a separate calculation, was excluded. The maximum radial displacements during lamination from the edge reach 3 mm, which is one and a half times higher than for an undamaged shell. Axial stresses are maximal from the action of inertial forces during acceleration. Its redistribution over the layers is significantly greater for the edge lamination, for which the maximum values increase almost two times concerning the undamaged shell, which determines this type of lamination as more dangerous.
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Westgaard, Geir, and Horst Nowacki. "Construction of Fair Surfaces Over Irregular Meshes." Journal of Computing and Information Science in Engineering 1, no. 4 (October 1, 2001): 376–84. http://dx.doi.org/10.1115/1.1433484.
Повний текст джерелаАнотація:
This paper describes the process of constructing a fair, open or closed C1 surface over a given irregular curve mesh. The input to the surface construction consists of point and/or curve data which are individually marked to be interpolated or approximated and are arranged according to an arbitrary irregular curve mesh topology (Fig. 1). The surface constructed from these data will minimize flexibly chosen fairness criteria. The set of available fairness criteria is able to measure surface characteristics related to curvature, variation of curvature, and higher order surface derivatives based on integral functionals of quadratic form derived from the second, third and higher order parametric derivatives of the surface. The choice is based on the desired shape character. The construction of the surface begins with a midpoint refinement decomposition of the irregular mesh into aggregates of patch complexes in which the only remaining type of building block is the quadrilateral Be´zier patch of degrees 4 by 4. The fairing process may be applied regionally or to the entire surface. The fair surface is built up either in a single global step or iteratively in a three stage local process, successively accounting for vertex, edge curve and patch interior continuity and fairness requirements. This surface fairing process will be illustrated by two main examples, a benchmark test performed on a topological cube, resulting in many varieties of fair shapes for a closed body, and a practical application to a ship hull surface for a modern container ship, which is subdivided into several local fairing regions with suitable transition pieces. The examples will demonstrate the capability of the fairing approach of contending with irregular mesh topologies, dealing with multiple regions, applying global and local fairing processes and will illustrate the influence of the choice of criteria upon the character of the resulting shapes.
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Bur'yanov, M. A., I. V. Chervyakov, and A. I. Bur'yanov. "The influence of the properties of materials used to make the working bodies of the stripper header on the quality of the performed process." Traktory i sel hozmashiny 85, no. 3 (June 15, 2018): 54–61. http://dx.doi.org/10.17816/0321-4443-66401.
Повний текст джерелаАнотація:
The aim of the inveatigations is to develop the main provisions of the procedure for determining the influence of material properties on the example of steel and ultra-high molecular weight polyethylene (UHMW PE) when they are used to fabricate or cover the outer and inner surfaces of the fairing and the combing teeth of the header, on the quality of the process performed by it. The dependencies and regularities that are integral parts of the previously developed mathematical model of the process of combing grain crops with a single-barrel header are used in the article. As a result of solving the equations, data on the normal and tangential components of the speed of movement of the ear and grain after contact with the test surfaces were obtained. Upon contact with the external surface of the fairing that material would be preferred which the movement along is accompanied by a lower value of the frictional force. During a rebound from the combing tooth and the inner surface of the fairing, the best material is the speed of rebound of the grain from which is higher. The value of the normal forces pressing the ear of winter wheat to the contacting surface was determined in an experimental plant simulating the process of combing the reaper. The coefficient of static friction and motion and the coefficient of recovery upon contact with the surfaces of steel and UHMW PE ears and winter wheat’s grains were determined at its moisture content of 9 %. It has been established that at a header speed of 3 m/s, the frictional force pressing the ear to the outer surface of the fairing from UHMW PE is 1,75 times less than on the steel. After contact with the tooth, the rebound speed of the grain is higher, if it is made of steel. For the accepted characteristics of the harvested plants and the operating conditions of the header, when the grains come into contact with the inner surface of the fairing from the UHMW PE within the friction angle, the loss of grain velocity after the collision is less than on the steel, with the exception of contact with direct impact. Compensation for the reduction in speed within a direct impact on the inner surface of the fairing which is made of UHMW PE can be achieved by varying the angle of inclination of the combing teeth on the drum.
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Escartí-Guillem, Mara S., Luis M. García-Raffi, and Sergio Hoyas. "URANS Analysis of a Launch Vehicle Aero-Acoustic Environment." Applied Sciences 12, no. 7 (March 25, 2022): 3356. http://dx.doi.org/10.3390/app12073356.
Повний текст джерелаАнотація:
Predicting and mitigating acoustic levels become critical because of the harsh acoustic environment during space vehicle lift-off. This paper aimed to study the aero-acoustic environment during a rocket lift-off. The sound propagation within a launch event was studied using dedicated computational fluid dynamics (CFD). The resolution of all the phenomena that occur is unfeasible. We discuss the turbulence simplification and propose a feasible simulation through an unsteady Reynolds-averaged Navier–Stokes (URANS) model. The results were validated with experimental data showing a good correlation near the fairing surface and an improvable accuracy in the far field. To assess noise generation, the main shock waves were identified, and the evolution of the generated sound pressure was assessed. Moreover, vertical directivity was revealed by data analysis of the pressure field surrounding the fairing.
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Zhang, Yadong, Jiye Zhang, Tian Li, Liang Zhang, and Weihua Zhang. "Research on Aerodynamic Noise Reduction for High-Speed Trains." Shock and Vibration 2016 (2016): 1–21. http://dx.doi.org/10.1155/2016/6031893.
Повний текст джерелаАнотація:
A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H) acoustic analogy. An analysis of noise reduction methods based on the main noise sources was performed. An aerodynamic noise model for a full-scale high-speed train, including three coaches with six bogies, two inter-coach spacings, two windscreen wipers, and two pantographs, was established. Several low-noise design improvements for the high-speed train were identified, based primarily on the main noise sources; these improvements included the choice of the knuckle-downstream or knuckle-upstream pantograph orientation as well as different pantograph fairing structures, pantograph fairing installation positions, pantograph lifting configurations, inter-coach spacings, and bogie skirt boards. Based on the analysis, we designed a low-noise structure for a full-scale high-speed train with an average sound pressure level (SPL) 3.2 dB(A) lower than that of the original train. Thus, the noise reduction design goal was achieved. In addition, the accuracy of the aerodynamic noise calculation method was demonstrated via experimental wind tunnel tests.
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Habib, Zulfiqar, and Manabu Sakai. "FAIRING ARC SPLINE AND DESIGNING BY USING CUBIC BÉZIER SPIRAL SEGMENTS." Mathematical Modelling and Analysis 17, no. 2 (April 1, 2012): 141–60. http://dx.doi.org/10.3846/13926292.2012.655787.
Повний текст джерелаАнотація:
This paper considers how to smooth three kinds of G 1 biarc models, the C-, S-, and J-shaped transitions, by replacing their parts with spiral segments using a single cubic Bézier curve. Arc spline is smoothed to G 2continuity. Use of a single curve rather than two has the benefit because designers and implementers have fewer entities to be concerned. Arc spline is planar, tangent continuous, piecewise curves made of circular arcs and straight line segments. It is important in manufacturing industries because of its use in the cutting paths for numerically controlled cutting machinery. Main contribution of this paper is to minimize the number of curvature extrema in cubic transition curves for further use in industrial applications such as non-holonomic robot path planning, highways or railways, and spur gear tooth designing.
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Kondratiev, A. V., and V. O. Kovalenko. "Optimization of design parameters of the main composite fairing of the launch vehicle under simultaneous force and thermal loading." Kosmìčna nauka ì tehnologìâ 25, no. 4 (2019): 3–21. http://dx.doi.org/10.15407/knit2019.04.003.
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Zhang, Wei, and Zheng Wang. "Design and Implementation of a CAD Software System for Hull Lines." Applied Mechanics and Materials 668-669 (October 2014): 1343–46. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.1343.
Повний текст джерелаАнотація:
A CAD software system for hull lines based on .NET is introduced in terms of system construction and principle. The system adopts a 3D V-shaped fairing computing model, which sufficiently considers the consistency of lines offsets in three different projection planes. By means of tree structure for parametric hull lines and 3-dimensional modeling technology, the system supports total-process-design of hull lines. Such a system not only can draw main parameter table, lines offsets table and lines plan grid automatically, support interactive design and synchronous adjustment for hull lines, but also can cut the hull synchronously and produce the 3-dimensional model of the hull. The implementation of this CAD software system for hull lines improves the hull design efficiency and quality.
Дисертації з теми "Main fairing"
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Деберний, Михайло Богданович. "Магнітно-абразивне оброблення головного обтікача макету ракети". Master's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/46136.
Повний текст джерелаАнотація:
На основі аналізу питання недостатнього захисту від безпілотних
літальних апаратів з допогомогою комплексів радіоелектронної боротьби,
визначено, що в багатьох країнах використовують малокаліберні боєприпаси
з програмованим підривачем.
В процесі створення проекту було розроблено модель головного обтікача
ракети, проаналізовано та спроектовано форму поверхні обтікача, а також
оброблено носову частину спеціальним методом.
Виготовлено макет головного обтікача ракети необхідної форми.Based on the analysis of the issue of insufficient protection against unmanned aerial vehicles with the help of electronic warfare systems, it was determined that in many countries small-caliber munitions with a programmable detonator are used. In the process of creating the project, a model of the main fairing of the rocket was developed, the shape of the fairing surface was analyzed and designed, and the bow was processed by a special method. A model of the main fairing of the rocket of the required shape has been made.
Книги з теми "Main fairing"
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Fairy houses of the Maine coast. Camden, ME: Down East, 2010.
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Owens, Robin D. Enchanted no more. New York: Luna, 2011.
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Copyright Paperback Collection (Library of Congress), ed. A faerie tale. New York: Jove Books, 1998.
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A lady and her magic. Naperville, Ill: Sourcebooks Casablanca, 2012.
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Copyright Paperback Collection (Library of Congress), ed. Beguiled: A Queen of the Otherworld novel. New York: New American Library, 2009.
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Mazzuca, Debbie. Warrior of the isles. New York: Zebra Books/Kensington Pub., 2011.
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Copyright Paperback Collection (Library of Congress), ed. As you wish. New York: Tor, 2011.
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Lady of light and shadows: Tairen Soul. Waterville, Me: Thorndike Press, 2008.
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Husk, Shona. The outcast prince. Naperville, Ill: Sourcebooks Casablanca, 2013.
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Waters, Heather. Destiny's Warrior. New York: Penguin Group USA, Inc., 2008.
Знайти повний текст джерелаЧастини книг з теми "Main fairing"
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Barklage, Alexander, and Rolf Radespiel. "Interaction of Wake and Propulsive Jet Flow of a Generic Space Launcher." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 129–43. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_8.
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Abstract This work investigates the interaction of the afterbody flow with the propulsive jet flow on a generic space launcher equipped with two alternative nozzle concepts and different afterbody geometries. The flow phenomena are characterized by experimental measurements and numerical URANS and LES simulations. Investigations concern a configuration with a conventional truncated ideal contour nozzle and a configuration with an unconventional dual-bell nozzle. In order to attenuate the dynamic loads on the nozzle fairing, passive flow control devices at the base of the launcher main body are investigated on the configuration with TIC nozzle. The nozzle Reynolds number and the afterbody geometry are varied for the configuration with dual-bell nozzle. The results for integrated nozzles show a shift of the nozzle pressure ratio for transition from sea-level to altitude mode to significant lower levels. The afterbody geometry is varied including a reattaching and non-reattaching outer flow on the nozzle fairing. Investigations are performed at supersonic outer flow conditions with a Mach number of $$Ma_\infty =3$$. It turns out, that a reattachment of the outer flow on the nozzle fairing leads to an unstable nozzle operation.
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Hendrickx, Anne, and Thomas Kanga-Tona. "Ein transparentes Modell für einen fairen Preis für innovative Arzneimittel in Europa." In Arzneimittel-Kompass 2021, 155–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2021. http://dx.doi.org/10.1007/978-3-662-63929-0_11.
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Zusammenfassung Zusammenfassung Das empfindliche Gleichgewicht zwischen Bezahlbarkeit von Arzneimitteln, Nutzen für Gesundheitssysteme und Patient:innen sowie Einnahmen für die Pharmafirmen hat sich zugunsten letzterer eingependelt. Die europäischen Gesundheitssysteme tun sich schwer damit, Patient:innen zeitnahen Zugang zu neuartigen Arzneimitteln zu ermöglichen, weil deren hohe Preise nicht gerechtfertigt sind. Wie aber verschafft man den Patient:innen Zugang und setzt dabei gleichzeitig Anreize für die Pharmaindustrie, in neue Arzneimittel zu investieren, die die Patient:innen auch wirklich brauchen? In ihrem Modell für eine faire Preisfestsetzung in Europa plädiert die Association Internationale de la Mutualité (AIM) für eine aktivere Rolle der Preisfestsetzungs- und Erstattungsbehörden in Europa bei der Definition und Festsetzung „fairer“ Preise für innovative Arzneimittel. Alternativ zum bisherigen Value-based Pricing schlägt die AIM einen einfachen, aber effektiven Algorithmus vor, der auf die zugrunde liegenden Kosten und den therapeutischen Nutzen abstellt. Wenn man den Gewinn auf ein vernünftiges Maß beschränken und gleichzeitig relevante Innovationen honorieren würde, dann könnte man die Arzneimittelpreise senken und den Patient:innen einen besseren Zugang zu diesen Medikamenten verschaffen. Mit ihrem Modell für eine faire Preisfestsetzung in Europa leistet die AIM einen Beitrag zu einer zentralen Debatte, die die Gesundheitssysteme weltweit in den kommenden Jahren beschäftigen wird.
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Roychoudhury, Suparna. "Epilogue." In Phantasmatic Shakespeare, 191–204. Cornell University Press, 2018. http://dx.doi.org/10.7591/cornell/9781501726552.003.0008.
Повний текст джерелаАнотація:
Why has Shakespeare’s sensitivity to the cognitive discourse of imagination not been noticed before? In A Midsummer Night’s Dream, Theseus’ speech on imagination is followed by the play-within-play of “Pyramus and Thisbe” enacted by Bottom and the other “rude mechanicals”; it shows that Shakespeare was interested in the mechanical applications of imagination, its cognitive uses in playmaking. But this interest was obscured by Enlightenment and Romantic thinkers, who prized the fairies above the mechanicals: Shakespeare was remade from a man of the theater into a visionary poet; imagination was remade from a mechanism of the mind into a mystical force of creativity. It is time to recuperate the scientific and epistemological background of Shakespeare’s interest in imagination, whose crucial achievement was to bring the complexities of cognitive theory into the realm of art.
Тези доповідей конференцій з теми "Main fairing"
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Law, Yun Zhi, Tan Jui Hang Benjamin, and Rajeev K. Jaiman. "Parametric Investigation and Mechanism of Low-Drag Fairing Devices for Suppressing Vortex-Induced Vibration." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54853.
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It is well known that fairing devices are better alternatives than helical strakes due to their low-drag performance while suppressing vortex-induced vibration (VIV). Our objective is to present a systematic numerical study to understand the hydrodynamic performance and physical mechanism of fairing configurations and then propose a new device for suppressing VIV and reducing drag force. In this work, we simplify our investigation by allowing the cylinder-fairing system to oscillate in cross-flow direction without rotation. Firstly, we present a set of simulations of vortex-induced vibration for Short Crab Claw (SCC) fairings [1] with different nondimensional length (Lf/D), where Lf is the length of fairing and D denotes the diameter of cylinder. To establish the relation between the length of fairing and the performance with respect to VIV suppression and drag reduction, we consider the length ratio Lf/D = 1.25, 1.50, 2.00. The underlying VIV suppression mechanism is investigated with the aid of force and amplitude variations, wake flow structures and frequency ratios. Our results show that the SCC fairing with longer length performs better by suppressing the amplitude up to 84% and reduces the drag coefficient by 40%. This finding implies that by offsetting the vortices shed away from the main cylinder, it lowers the influence of vortex interactions, which leads to the suppression of VIV and net reduction in the drag force generation. Based on this mechanism, we propose a new design of fairing, namely the “Hinged C-shaped”, which consists of a thin splitter plate (connected at the base of main cylinder) bifurcating into a C-shaped geometry after a certain distance. Through our numerical study on its hydrodynamic performance, it is shown to be efficient with respect to VIV suppression and drag reduction. To understand the VIV suppression physics, the numerical study is conducted in two-dimension for the cylinder-fairing mounted elastically with mass ratio m* = 2.6 and the damping ξ = 0.001 at low Reynolds number. We further demonstrate the performance of the new fairing device in three-dimension at sub-critical Reynolds number.
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de Kock, J. P., N. Janse van Rensburg, S. Kruger, and R. F. Laubscher. "Aerodynamic Optimization in Light Weight Solar Vehicle Design." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38053.
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Solar car racing has created a competitive platform for research into alternative energies, particularly the utilization of solar energy. This paper reports on a numerical optimization of the vehicle body shape, utilizing Computational Fluid Dynamics (CFD). Optimization and validation of the body shape, fairing position, body-and-fairing fillet blend, fairing leading edge curvature, driver position and canopy design were considered. For the purposes of this study, the fairing and driver position optimization will be discussed as a case study to illustrate the design and optimization methodology with the improved product of area and the coefficient of drag (ACd) values recorded. The algorithms developed and procedures followed to adapt the design of the vehicle are presented. The algorithms applied relied on comparing designs based on evaluating shape function curves representing the normalized (body length) sectional area of the body under consideration. With the aid of numerical analysis software and applying the design optimization algorithm by evaluating ACd, it was possible to optimize the shape of the main wing and the placement of the fairings and the driver compartment/canopy. The results of the CFD simulation showed there was a direct correlation between the drag coefficient and the shape function. By utilizing this methodology, significant improvements to the coefficient of drag could be realized. A reduction of 31% in the coefficient of drag was achieved by moving the centered driver position to the side. This design change then also contributed to an energy saving of 442.6 Watt at a speed of 100km/h.
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Abeysinghe, Amal, Julia Whitmire, Daniel Nesthus, Jeffery Moe, and Gene Stuczynski. "QTD 2 (Quiet Technology Demonstrator 2) Main Landing Gear Noise Reduction Fairing Design and Analysis." In 13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference). Reston, Virigina: American Institute of Aeronautics and Astronautics, 2007. http://dx.doi.org/10.2514/6.2007-3456.
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Koganei, Reiko, Shigemasa Ando, Qinzhong Shi, and Ichiro Hagiwara. "The Elucidation of Mechanism of Local Sound Pressure Increase Phenomenon." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-2764.
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Payloads of satellite are exposed on the severe acoustic environment at the process of lift-off and supersonic zone of a launcher. This acoustic environment excites the payload in high pressure and broad frequency band of random acoustical excitation, which may cause serious damage to the structures or instruments of the spacecraft inside. Space instruments are designed and verified to the acoustic environment by ground reverberant acoustic chamber in order to specify random vibration level at component interface and to verify the payloads are working in function and the structure does not have structural damage. The present load sound pressure specification assumes that the sound pressure interior fairing is uniformly distributed. In spacecraft system acoustic tests, local pressure increase occurs in the narrow gap between spacecraft primal structure and components facing toward the fairing wall. This acoustical environment load to the components differs from that the components were tested alone and the flight acoustic environment may not be actually simulated in the ground testing. It is important to clarify the mechanism of sound pressure increase in the narrow gap in order to predict the level of sound pressure increase. In this study, we focus to the investigation of the mechanism by basic experiment including acoustic testing and vibration modal survey. It is clarified that the main reason of the phenomenon is dominated by the acoustic cavity on the appropriate boundary condition rather than structure vibration. And more, we predict the frequency at which the sound pressure increase at the narrow gap and compare analysis results with experiment results by using Boundary Element Method (BEM).
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Johnson, Marty, Ozer Sacarcelik, and Tony Harris. "Weight Optimized Structural and Acoustic Actuators for the Control of Sound Transmission Into Rocket Payload Compartments." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61205.
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The reduction of sound transmission into rocket payload compartments is a challenging application for active control due to the broadband nature of the disturbance, the large structural and acoustic space and the very high acoustic levels required. The exterior acoustic field that drives the payload fairing at liftoff is typically in the order of 145dB and the active control system must be able to counteract this high drive level using lightweight actuators. This paper is concerned with the development of structural and acoustic actuators for this application with the emphasis on maximum output level in the 60–200Hz bandwidth for a given actuator weight. The electromagnetic structural actuators are based on powerful rare earth magnets in a two degree of freedom arrangement. It is shown that a two degree of freedom arrangement allows the output in the bandwidth of interest to be increased over a simple one degree of freedom arrangement. The design is termed a distributed active vibration absorber or DAVA as the second degree of freedom is provided by a light and distributed foam element that allows easy attachment and low stress concentration on the structure. The two degree of freedom arrangement also acts as a natural low pass filter to naturally remove unwanted spillover at higher frequencies. The acoustic component is also based on powerful rare earth magnets, however the two degree of freedom arrangement used for the structural actuator is no longer of interest. The main concern is in the reduction of the speaker and cabinet weight. It is shown that careful design of the speaker and cabinet can lead to large reductions in weight without loss of performance. Data taken from an active control experiment on a large composite cylinder, coupled with data from the characterization of the actuators will be used to determine the total actuator weight needed for control in a typical launch environment.
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di Mare, Luca, Mauro Carnevale, Max E. Rife, Davendu Kulkarni, and Richard Northall. "Modelling and Design of LPC Components With Semi-Analytical Models: Part II — Design of Optimal OGV Cascades." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90481.
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Abstract The growth in diameter of turbofan engines exacerbates problems related to the interaction of the Outlet Guide Vanes (OGV), pylon and intake because it reduces the ratio between components gaps and disturbance wavelength. The main components of this interaction are the potential fields generated by the intake and by structural components in the bypass, the pylon and the Radial Drive Fairing (RDF). The OGV bladerow and the fan are immersed in these potential fields and suffer performance degradation as well as integrity issues as a result. Simple actuator-disc analysis shows that a uniform OGV cascade amplifies the effect of the pylon potential flow. Therefore, a number of methods have been proposed over the years to compute OGV exit flow angle patterns that result in an approximately circumferentially uniform static pressure field at fan exit. Within actuator disc approximations, the determination of the optimal exit flow angle pattern can be accomplished analytically but little information is obtained on how the geometry of the vanes ought to be modified. Consequently, it is not difficult to generate by this method OGV cascades that stall or choke locally. More recent contributions use CFD computations coupled to optimization methods to determine OGV patterns that reduce the distortion at the fan exit, while minimising some measure of OGV loss. Whilst in principle more rational, these methods encounter practical difficulties due the computational power needed to obtain reliable loss estimates while exploring large design spaces. In this paper the view is taken that the performance of the OGV bladerow can be preserved during the optimization process if the loading distribution of each vane is made to match the loading distribution of the nominal vane (i.e. the aerodynamic design intent with axisymmetric inlet and exit flow). As loading distributions are readily available from inviscid-type analysis, the generation of optimal OGV patterns can be accomplished with very reasonable computational expense using a method based on the model described in part I of this paper.
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Murayama, Mitsuhiro, Yuzuru Yokokawa, Kazuomi Yamamoto, and Tohru Hirai. "Numerical Simulation of a Two-Wheel Main Landing Gear with Low-Noise Fairings around Tire-Axle Region." In 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference). Reston, Virigina: American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-2279.
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