Дисертації з теми "Blade motion"

Dissertation (Ph.D. in Aeronautical and Astronautical Engineering) Naval Postgraduate School, June 1999.
"June 1999". Dissertation supervisor(s): E. Roberts Wood. Includes bibliographical references (p. 81). Also available online.

This PhD research investigated the influence of turbulence effects on the vibration behaviour of wind turbines. A small laboratory scale wind turbine test facility was developed with special purpose instrumentation and sensors. Experimental investigations of the vibration behaviour of the turbine demonstrated the complexity of the displacements of the main rotor shaft and the strain at the roots of the rotor blade. This research will assist in the ongoing development of improved failure detection mechanisms.

Three-dimensional design and three-dimensional CFD analysis of a compressor rotor stage are performed. The design methodology followed is based on a mean line analysis and a radial equilibrium phase. The radial equilibrium is established at a selected number of radii. NACA 65 series airfoils are selected and stacked according to the experimental data available. The CFD methodology applied is based on a three-dimensional, finite difference, compressible flow Euler solver that includes the source terms belonging to rotational motion. The accuracy of the solver is shown by making use of two different test cases. The CFD solution of the designed geometry predicts the static pressure rises and flow turning angles to a good degree of accuracy.

Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, March 2003.
Thesis advisor(s): Garth V. Hobson, Raymond P. Shreeve. Includes bibliographical references (p. 81-82). Also available online.

Робота виконана у Тернопільському національному технічному університеті імені Івана Пулюя Міністерства освіти і науки України. Захист відбувся “ 27 ” січня 2015 року о “ 14 ” годині на засіданні спеціалізованої вченої ради Д 58.052.02 в Тернопільському національному технічному університеті імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56, аудиторія 79.
Удосконалення конструктивної схеми доочисника головок коренеплодів, який забезпечує підвищення показників надійності та якості виконання технологічного процесу, можливо досягти шляхом розроблення гичкозрізуючого пристрою з активним плоским ножем. Перевагою запропонованого конструктивного рішення, порівняно з активним дисковим ножем, є підвищена експлуатаційна надійність, значно менша маса та простота виготовлення.
Дисертацію присвячено питанням підвищення ефективності та надійності технологічного процесу дообрізування залишків гички з головок коренеплодів цукрових буряків на основі обґрунтування конструктивно-технологічних параметрів механізму дообрізувача гички активного типу. Теоретично досліджено: процес взаємодії активного плоского ножа з головками коренеплодів при режимі різання з ковзанням; НДС ножа при приведенні у рух; модель руху дообрізувача гички з активним робочим органом по рядках коренеплодів цукрових буряків; коефіцієнт ковзання в системі “коренеплід – плоский ніж”. Експериментально досліджено залежність сили різання головок цукрових буряків активним плоским ножем від робочої швидкості бурякозбирального агрегату; зворотно-поступальної швидкості ножа та товщини його леза; діаметра коренеплодів. Встановлено корозійний вплив на функціональну здатність конструкційних матеріалів ножів середовища соку цукрових буряків. Застосування запропонованої конструкції дообрізувача активного типу дозволить підвищити ефективність та надійність процесу доочищення головок коренеплодів цукрових буряків від залишків гички.
The thesis is dedicated to the problem of improving the efficiency and reliability of technological topping the residual tops of sugar beet crowns taking into consideration the structural and technological parameters of an active type topper. The following aspects are theoretically researched: interaction of an active flat knife with the root beet crowns in mode of cutting with sliding; tensely deformed status of that knife when moving; model of moving the topper with active working bodies along sugar root beets rows; coefficient of sliding in the system “root – flat knife”. The dependence of sugar beet crowns cutting force by means of active flat knife on the working speed of a beet harvester, as well as on the knife reciprocating speed, knife blade thickness, root diameter, is developed experimentally. The corrosion effect of beet juice on functional capability of knife structural materials is researched. The use of active type topper design will improve the efficiency and reliability of toping the sugar beet crowns.

Denna uppsats har gjorts i syfte att undersöka relationerna som finns mellan den filmtekniska aspekten av tempo och porträttering av manlig intimitet. Musikvideon till låten Territory av The Blaze analyseras genom en filmsemiotisk analys ur ett genusperspektiv. Metoden utformas efter hur aktivitet är representerat genom icke-verbal kommunikation för att läsa av vart intimitet uppstår och uteblir. Kommunikations- och genusteorier appliceras sedan på materialet för att se hur det påverkas av valet att skildra representationen med slow-motion eller normalt tempo. Användningen av slow-motion bidrar till att sakta ner i narrativet där den manliga intimiteten kan liknas till det sätt som kvinnor vanligtvis porträtteras genom Mulveys teorier gällande den manliga blicken.
The purpose of this essay is to analyze the relations between the use of pace and representation of masculine intimacy. The music video to the song Territory by The Blaze is observed through a gender perspective in a film semiotic analysis. The method involves how intimacy is represented through non-verbal communication. The material will be analyzed through theories involving communication and gender identity to see how it is affected by pace. This leads to the result of a conclusion that slowing down the narrative contributes to a representation of male intimacy to have resemblance to how women are portrayed according to Mulvey’s theories about the Male gaze.

Gli otto Quaderni in Ottavo, scritti da Kafka tra la fine del 1916 e l'inizio del 1918, rappresentano con la loro eterogeneità stilistica e tematica una fonte preziosa per la ricerca kafkiana: non solo, collocandosi all'altezza di una svolta fondamentale nella biografia dell'autore, offrono una testimonianza autentica e sincera del legame tra "vita" e "scrittura" e del loro parallelo sviluppo, ma presentano anche, in quanto luogo di sperimentazione, elementi utili per un'analisi della genesi testuale. Ciò che la mia tesi si propone è da un lato una lettura cronologica e lineare degli otto quaderni, che permetta di seguire l'evolversi della scrittura e del pensiero di Kafka nel periodo in esame, dall'altro un confronto sincronico con gli scritti privati, che mettendo in luce rielaborazioni e corrispondenze tematiche, getti le basi per una nuova interpretazione dei nuclei metaforici sviluppati in questa particolare fase creativa.

碩士
國立臺灣大學
工程科學及海洋工程學研究所
102
The offshore wind turbine will be influenced by the couple of aerodynamics and hydrodynamics.The selection of floating platform will directly affect the generating power of the wind turbine. The floating system of the OC3-Hywind and the OC4 DeepCwind is applied in this paper. Through the Blade Element Momentum theory evaluate the power curve of NREL-5MW wind turbine and compare to the NREL data. It shows two of them have similar power curve, but they have about 7.64% difference in the rating velocity condition. When we consider the real wind turbine control system in the pitch motion, the average power is no longer that high anymore. Within the motion of turbine, it causes the power of turbine have the same period as the motion of turbine. In this paper, coupling the Blade Element Momentum (BEM) and computational Fluid Dynamics model (CFD) to evaluate two type of floating wind turbine, spar and semisubmersible wind turbine. Under the wave height 4m and period 10s, it shows that the semisubmersible type floating wind turbine has lower power loss than the spar type of wind turbine. This simulation case is verified with the reference. According to this research present a suitable wave condition to reduce the power loss for both of the floating wind turbine. If the wave period is less than 8.4s, so the spar type floating wind turbine has been recommended. But if the wave period is larger than 10 s and the wave is just like calm sea state, the semisubmersible floating wind turbine will be better.

Vibration related issues like flutter can significantly limit the performance of aircraft engines and cause unwarranted cost and time overruns. The increased demand for more powerful yet compact engines has resulted in the use of relatively thin and long blade rows, which are more susceptible to such vibration related issues. Flutter refers to an aeroelastic instability in which the motion of the blade interacts with the flow to generate the unsteady fluid loads that can sustain or possibly grow its oscillations, which can ultimately lead to structural failure. The severe consequences that follow the phenomenon of flutter has triggered substantial interest in flutter studies. Linear cascades that represent a particular span section of the rotor have proven to be a reliable tool for such flutter studies. Although several studies pertaining to flutter have been reported in the literature, only a few of them have concentrated on linking the flutter characteristics to the corresponding unsteady flow field around the blade. With this in mind, in the present work, detailed experimental study of bending mode flutter in two representative cascades, one operating in stalled conditions at low Reynolds number (∼ 104) incompressible flow, and the other at transonic conditions has been carried out. The main focus of the work is on simultaneous measurements of flutter characteristics and the unsteady flow field around the blade that can help in understanding the unsteady flow features that contribute to flutter. The blade oscillations are forced and the flutter characteristics are deduced in terms of the energy transfer to the blade from the measured unsteady loads, and the flow field is measured with the help of PIV in both the cases, in addition to high-speed shadowgraphy for the transonic case. In the low Reynolds number cascade case, three blades in the cascade were oscillated with arbitrary phase difference between adjacent blades referred to as Inter Blade Phase Angle (IBPA). The response of the flow to these imposed oscillations is measured in terms of unsteady loads on the central blade in the cascade, and this is used to quantify the mean energy transfer to the blade from the fluid over an oscillation cycle. The parameters varied in this case include the reduced frequency (k) (up to 0.1) and the Inter Blade Phase Angle (IBPA), the latter being varied from +180◦ to −180◦ in steps of 45◦. The experiments were conducted at three different post stall incidence angles of the blades in the cascade to assess the influence of blade loading on flutter behaviour. In each case, IBPA and k have been varied and contours plots of the excitation have been obtained in the plane of IBPA and k, showing the region of excitation, with the results indicating that most of the excitation occurs around IBPA of +90◦. Fluid excitation at lower k values for specific IBPA cases of +45◦ and +90◦ was observed, indicating the influence of reduced frequency (k) and Inter Blade Phase Angle (IBPA) on cascade stability. Also, an increased blade loading is observed to significantly increase the extent of excitation or damping. To understand the contribution from oscillating adjacent blades, experiments involving a single blade oscillating in a cascade have also been performed. PIV measurements at different IBPA values show that there exists significant differences in the phase of the separated unsteady shear layer dynamics with respect to the blade motion between excitation (flutter) and damping (no flutter) cases. The PIV measurements also clearly show the effect of the time-varying inter-blade spacing on the shear layer dynamics, with the shear layer tending to separate at instances when there is a large inter-blade spacing, compared to the instances when the inter-blade spacing is small, this being important for cases with different IBPA values. For the transonic cascade case, in order to facilitate flutter studies at flow conditions that are realistic to aircraft engine components, a new blow-down transonic cascade facility has been developed as part of the present work. The facility is equipped with a mechanism that can oscillate the central blade in the cascade at realistic reduced frequency (k) of about 0.1. The parameters varied in this case include the reduced frequency (k) up to 0.1 and the static pressure ratio (SPR) across the cascade. The SPR in these transonic cases alters the passage shock position, which is seen to have a large effect on the corresponding flutter characteristics of the blade. Four SPR cases of 1.05, 1.25, 1.35 and 1.55 are considered for flutter studies of which the first three have a passage shock, while the SPR = 1.55 case corresponds to an unstarted cascade with a detached shock at the leading edge. The experimental results indicate striking differences in the flutter behaviour between the started and unstarted cascade cases. While both the cases show excitation at lower k values (k ≈ 0.05), in the unstarted cascade, an additional regime of huge excitation is observed at relatively higher k values, with the excitation values in this case being about an order of magnitude higher that that at lower k values. A large PIV data set has been obtained simultaneously with unsteady loads in select cases. High-speed shadowgraphy visualizations have also been carried out at different reduced frequencies for both a started cascade case with passage shock, and an unstarted cascade case with a detached leading edge shock. The results indicate that the shocks oscillate in response to the blade motions, with the phase between the shock motion and the blade motion being dependent on the reduced frequency and SPR. In particular, differences are seen in the phase of the shock motion with respect to the blade motion between the excitation and damping cases, and also between started and unstarted cascade cases. These measurements also show striking differences in the shock phase between the two excitation cases of the unstarted cascade case, indicating differences in the underlying mechanisms responsible for the two excitation regimes observed at lower and higher frequencies, respectively. Specifically, when the blade is at the suction side extreme location, the detached leading edge shock is found to be located upstream of its mean location in the low frequency excitation case, while the shock is located downstream of the mean location at the higher frequency excitation regime. In summary, the measurements indicate that the unsteady shear layer and its phase relation with the blade motion is the deciding factor for stall flutter at low Reynolds numbers, while it is the phase of the unsteady shock motions with respect to the blade motion that is crucial in the transonic cascade case.
GATET initiative of AR&DB and GTRE

碩士
國立成功大學
航空太空工程學系碩博士班
93
The purpose of this thesis is to build a wind turbine model and perform the motion simulation and dynamic analysis. In motion simulation part, we used FAST to model a 1.5MW, three-bladeed, up-wind, horizontal-axis wind turbine model and exported this model into ADAMS. ADAMS can generate a graphics output file which may be to view an animation of the motion simulation. The analysis results compared with FAST and ADAMS are obtained good agreements in this case. 　In dynamic analysis, we built a full-scale wind turbine blade model into the F.E.A software ANSYS, then applied the aerodynamic load which is from FAST analysis result into the blade we built. We could obtain stress distributions, deflections and nature frequencies of the wind turbine blade. It is useful for the construction of the methodology of designing and analysis mode for wind turbine blades.

碩士
逢甲大學
材料與製造工程所
95
In order to investigate the phenomenon that liner motion will become rotational motion when subjects fall. We use rectangular blades with different aspect-ratios and vary the angles of the blades in the experiment. We observe the effect of air resistance and the efficiency of the energy transformation on the aspect-ratios and the angles of the wings when the blades fall. We let the vanes with the aspect-ratio of 1.5:1, 1.75:1, 2.0:1, 2.5:1 and 3.0:1 collocated with angles of 30˚, 60˚ and 90˚ fall from 2.5 meters and observe the changing phenomenon of the motion. The result shows that, if we take the same blade and vary the angle gradually, the bigger the angle is, the slower the speed of rotation is. Besides, the resistance of the difference of the pressure to the blade goes greater, and the efficiency of the energy transformation increases. The blade with wider breadth of the wings takes much time to fall in a certain distance. Therefore, the falling speed slows down, the resistance increases, and the efficiency of the energy conversion goes down. Moreover, the rectangle blade with longer length of the wings takes much falling time. The falling speed goes slower, but the whirling speed is faster. So, the resistance causing the difference of the pressure increases and raises the efficiency of the energy transformation. It is found out the ninety angle between blades with aspect ratio of 2.5 has the highest energy conversion efficiency.

Thesis (M.A.)--University of Wisconsin--Madison, 1992.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 69-72).

碩士
國立臺灣大學
工程科學及海洋工程學研究所
105
The purpose of this study is to investigate the deployment and recovery operations for Floating Kuroshio Turbine (FKT) in moored conditions, and those in ship towing conditions by applying the simulation software OrcaFlex. The hydrodynamic coefficients of each element of FKT were calculated by CFD tools of ANSYS-FLUENT and WAMIT. Then these results were introduced into OrcaFlex to set-up the numerical model of FKT, and the simulations of the deployment and recovery operations for FKT in moored conditions, and those in ship towing conditions were carried out. In order to improve the accuracy of simulations, the setting data for the rotor blades in OrcaFlex, which simulates blades performance basing on 2D element method, were modified to fit the more accurate blades performance obtained by 3D CFD method. In the present study, based on the FKT numerical model built by the modified 2D blade setting data and under the current speed conditions of 1.1 m/s to 1.5 m/s, we accordingly set up simulation scenarios of employing buoyancy engines to adjust water ballast for controlling the FKT’s ascending and descending for simulating the deployment and recovery operations. As the FKT develops to a certain extent, the towing test by ship in real sea must be first conducted. An analysis method to estimate the FKT’s towing force and submerged depth was proposed in the present study, and considered as the basis for cable length planning. Its validity was confirmed by comparing the estimated results with those obtained by OrcaFlex simulation. The results of simulation based on FKT numerical model with the modified blade performance show that the FKT can achieve the goal depth of the deployment and recovery operation in moored condition under the original capacity of buoyancy engines by adding proper ballast weight for the FKT. Moreover, the simulation results also show that FKT can submerge to proper depth in ship towing condition under the original capacity of buoyancy engines by adding proper ballast weight for the FKT