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1
Osgood, David B. "Oscillating flow about perforated cylinders." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA381845.
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Thesis (M.S. in Mechanical Engineering) Naval Postgraduate School, Sept. 2000.Thesis advisor(s): Sarpkaya, T. Sarpkaya. "September 2000." Includes bibliographical references (p. 17). Also available in print.
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Hayder, Mir Mohammad Abu 1976. "Cross-flow past oscillating circular cylinders." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115685.
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The cross-flow past a pair of equal-diameter circular cylinders, arranged in a staggered configuration, was investigated experimentally in a closed-circuit water tunnel at Reynolds numbers, based on the mean-flow velocity and the cylinder diameter, within the lower subcritical range. The wake formation process was studied employing dye-injection flow visualization and hot-film measurements. The main emphasis was placed on acquiring a physical understanding of the mechanisms leading to vortex shedding, and particularly on the effect of a forced oscillation transverse to the flow direction of either of the two cylinders. For comparison purposes, investigations were also carried out with both cylinders stationary.Experimental results showed that, for a reasonably large angle of incidence, the flow in the wake of a stationary cylinder pair could be characterized by two distinct periodicities, each of which was dominant on one side of the wake. Furthermore, for lower Reynolds numbers (Re < 1.0x10 4), there was an integral relationship between the two Strouhal numbers, but this integral relationship was no longer maintained for Re > 1.0x10 4. On the other hand, the flow around stationary cylinders for a small angle of incidence was characterized by a single Strouhal number, which remained approximately constant over the entire Reynolds number range.
For all the cylinder configurations investigated the wake flow patterns remained essentially the same as those of the corresponding static cases, when either of the two cylinders was forced to oscillate with a nondimensional forcing frequency less than approximately 0.10. However, beyond this value, the wake underwent considerable modification vis-a-vis when the cylinders were stationary, and the flow pattern within the wake was strongly dependent on the value of the forcing frequency. In particular, there were distinct regions of synchronization between the dominant wake periodicities and the cylinder oscillation; these synchronization regions involved sub- and superharmonics as well as fundamental synchronizations. With either upstream or downstream cylinder oscillation, the wake on the mean-flow side of the downstream cylinder synchronized with the shear layers separated from its outer surface, whereas synchronizations on the mean-flow side of the upstream cylinder were caused by the periodicities formed from the interaction of the other three shear layers.
The flow phenomena associated with the synchronizations were described in detail via flow visualization. The organization of the wake was strongly dependent on whether it was the upstream or downstream cylinder which was oscillating. The synchronized wake on the mean-flow side of the downstream cylinder at both lower and higher oscillation frequencies for upstream cylinder oscillation was observed to form either by the shedding of independent vortices or by the coalescence of two or more vortices. However, for downstream cylinder oscillation, although the synchronizations on this side of the wake at lower oscillation frequencies were caused by the shedding of independent vortices or by the coalescence of vortices, those at higher oscillation frequencies were the consequence of the coalescence of vortices only. For large incidence angles, the number of shear layers separated from the downstream cylinder which interacted with those separated from the upstream cylinder was critical in causing the synchronizations on the mean-flow side of the upstream cylinder.
In most cases, the flow for all the cylinder configurations traversed between the same patterns as those obtained when the cylinders were placed stationary at their minimum and maximum transverse spacings; but there were also some situations where the oscillation of either cylinder pushed the flow outside the regimes associated with the stationary configurations. The synchronization ranges obtained when the upstream or downstream cylinder was oscillating were different from each other, and these ranges were much wider than the corresponding synchronization ranges for a single oscillating cylinder. For two cylinders, an analysis of the fundamental synchronization showed that the frequency range over which this occurred was much broader for upstream cylinder oscillation than for downstream cylinder oscillation. Also, the fundamental synchronization ranges for downstream cylinder oscillation were closer to those for single cylinder oscillation in comparison to those for upstream cylinder oscillation.
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Alexandris, Georgios. "Supersonic flow past two oscillating airfoils." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA350226.
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Thesis (M.S. in Applied Physics) Naval Postgraduate School, June 1998."June 1998." Thesis advisor(s): Max F. Platzer, James H. Luscombe, S. Weber. Includes bibliographical references (p. 71-72). Also available online.
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Yan, Baoshe. "Fluid flow induced by oscillating bodies and flows in cyclones." Thesis, University of Leeds, 1991. http://etheses.whiterose.ac.uk/435/.
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In this thesis the following aspects have been investigated: (i) the numerical solutions for unsteady 2-dimensional, incompressible viscous fluid flows induced by a harmonically oscillating cascade, and (ii) the fluid flows in industrial cyclones and their separation efficiencies. In the first part of the thesis we deal with fluid flows induced by harmonically oscillating cascades of cylinders with different cross sectional shapes. Numerical solutions for large amplitude oscillations of a cascade of normal flat plates are obtained by using a finite-difference method and it is found that solutions are in good agreement with some related experimental results. For small amplitude oscillations a perturbation method, series truncation technique and finite-difference methods are used to obtain solutions for cascades of normal flat plates and square cylinders. By assuming that the streaming Reynolds number is 0(1) then the outer streaming flows for cascades of square cylinders, normal flat plates and circular cylinders are investigated numerically for the streaming Reynolds number Rs up to 70. Conformal mapping, grid generation and boundary element methods are used to deal with the different geometries in order to determine the outer potential flows. For small values of the streaming Reynolds number it is found experimentally that the flow remains symmetrical and the numerically predicted fluid flow is in good agreement with the experimental results. As the value of the streaming Reynolds number increases then it is found experimentally that the flow develops asymmetries and this occurs when 8
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Gordon, David R. "Computational unsteady flow dynamics : oscillating flow about a circular cylinder." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28053.
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Pachalla, Seshadri Rajagopal. "Analysis of oscillating flow cooled SMA actuator." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2669.
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Shape Memory Alloys (SMA) are a group of metallic alloys that have the ability to return to some previously defined shape or size when subjected to an appropriate thermal cycling procedure. In recent years there has been a lot of research on the development of small, light and, yet, powerful actuators for use in areas like robotics, prosthetics, biomimetics, shape control and grippers. Many of the miniaturized conventional actuators do not have sufficient power output to be useful and SMAs can be used advantageously here.
The widespread use of SMAs in actuators is limited by their low bandwidth. Use of SMAs in two-way actuators requires that they undergo thermal cycling (heating and cooling). While SMAs can be heated quickly by resistive heating, conventional convection cooling mechanisms are much slower as the exothermic austenitic to martensitic phase transformation is accompanied by the release of significant amount of latent heat.
While a number of cooling mechanisms have been studied in SMA actuator literature, most of the cooling mechanisms involve unidirectional forced convection. This may not be the most effective method. Oscillating flow in a channel can sometimes enhance heat transfer over a unidirectional flow. One possible explanation for this heat transfer enhancement is that the oscillatory flow creates a very thin Stokes viscous boundary-layer and hence a large time-dependent transverse temperature gradient at the heated wall. Therefore heat transfer takes place at a large temperature difference, thereby enhancing the heat transfer.
In this work, the heat transfer from an SMA actuator under an oscillating channel is investigated and is compared to steady, unidirectional flow heat transfer.
Oscillating flow is simulated using a finite volume based method. The resulting velocity field is made use of in solving the heat transfer problem using a finite difference scheme. A parametric study is undertaken to identify the optimal flow conditions required to produce the maximum output for a given geometry of the SMA actuator. The latent heat of transformation of the SMA is accounted for by means of a temperature dependent specific heat.
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Jayaprakash, Arvind Prakash. "Cavitating Flow over Stationary and Oscillating Hydrofoils." Cincinnati, Ohio : University of Cincinnati, 2008. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1205164937.
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Thesis (M.S.)--University of Cincinnati, 2008.Committee/Advisors: Urmila Ghia PhD (Committee Chair), Kirti Ghia PhD (Committee Co-Chair), Milind Jog PhD (Committee Member). Title from electronic thesis title page (viewed Sep.3, 2008). Includes abstract. Keywords: Cavitation; Stationary; Oscillating; Hydrofoils. Includes bibliographical references.
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Yang, Hui. "3D unsteady flow in oscillating compressor cascade." Thesis, Durham University, 2004. http://etheses.dur.ac.uk/2835/.
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An experimental and computational study has been carried out to enhance current understanding of three dimensional (3D) cascade aeroelastic mechanisms. 3D unsteady pressure data produced during executing this project is the first-of-its-kind, which can be directly used for validation of advanced 3D numerical methods for the prediction of aeroelastic problems in turbomachines. A new, low speed flutter test rig with a linear compressor cascade consisting of seven Controlled-Diffusion Blades has been commissioned. The unsteady aerodynamics of the oscillating cascade is investigated using the Influence Coefficient Method, by which the middle blade is mechanically driven to oscillate in a 3D bending mode. Off-board pressure transducers are utilized to allow detailed measurement of the unsteady blade surface pressures in conjunction with a Tubing Transfer Function (TTF) method to correct tubing distortion errors. The linearity of the unsteady aerodynamic response is confirmed by tests with different oscillation amplitudes, which enables unsteady results of a tuned cascade to be constructed by using the Influence Coefficient Method at various inter-blade phase angles. An examination of the techniques adopted and experimental errors indicates a good level of accuracy and repeatability to be attained in the measurement of unsteady pressure. A detailed set of steady flow is obtained from the middle three blades, which demonstrates a reasonable blade-to-blade periodicity. At a nominal steady flow condition unsteady pressure measurements were performed at six spanwise sections between 20% and 98% span for three different reduced frequencies. The 2D laminar bubble-type separation around middle chord on the suction surface is identified to have a local effect on the unsteady flow. The measured results illustrate the fully 3D unsteady flow
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Semler, Cogan S. "Experimental investigation of an oscillating flow generator." Thesis, Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/theses/2010/Mar/10Mar%5FSemler.pdf.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, March 2010.Thesis Advisor(s): Platzer, Max. Second Reader: Hobson, Garth. "March 2010." Description based on title screen as viewed on April 23, 2010. Author(s) subject terms: Oscillating Wing, Tidal Power Production, Flutter, Renewable Energy, Flat Plate Lift Generation. Includes bibliographical references (p. 45). Also available in print.
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JAYAPRAKASH, ARVIND PRAKASH. "Cavitating Flow over Stationary and Oscillating Hydrofoils." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1205164937.
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Hanson, Craig D. "Numerical Analysis of Oscillating Flow about a Circular Cylinder." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA305867.
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Gerontakos, Panayiote. "An experimental investigation of flow over an oscillating airfoil /." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80014.
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The detailed behaviour of the unsteady boundary layer and stall events occurred on a sinusoidally oscillating NACA 0012 airfoil at Re = 1.35 x 105 was investigated experimentally by using closely-spaced multiple hot-film sensor arrays. The hot-film measurements were supplemented by surface pressure measurements, hot-wire wake velocity surveys and smoke-flow visualizations. Three typical oscillation parameters: attached flow, light stall, and deep stall were tested. Special attention was focused on the non-intrusive identification of the spatial-temporal progression of the locations of the boundary-layer transition and separation and reattachment points for a range of oscillation frequencies and amplitudes both prior to, during, and post the stall. The results show that for an unsteady airfoil, the reduced frequency of the oscillation was found to be highly significant and only small values of reduced frequency were required to delay the onset of the various boundary-layer events, and to produce significant variations and hysteresis in the peak values of lift and drag forces and the pitching moments, which are fundamentally different from their static counterparts. Lift stall was observed to occur when the leading-edge vortex reached 90% of the chord, while moment stall occurred at the end of the upward spread of the trailing-edge flow reversal. The convection speed of the leading-edge and the secondary vortices were also reported. Dynamic stall was found to be caused by an abrupt turbulent separation near the leading-edge region and not with the bursting of the laminar separation bubble, as is commonly observed for a static NACA 0012 airfoil; the result being the initiation, growth and convection of an energetic leading-edge vortex. Moreover, the detection of the sudden turbulent breakdown could serve as an indicator for dynamic stall detection and control. The results reported on here provide a deepened insight into the detailed nature of
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Huang, Xiuquan. "Three-dimensional unsteady flow in oscillating turbine blade row." Thesis, Durham University, 2006. http://etheses.dur.ac.uk/2328/.
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This thesis documents an experimental and computational study of the unsteady flow around oscillating blades in low-pressure turbines, with emphasis on the three- dimensional flow behaviour, intra-row interaction effects, tip clearance flow and part- span shroud influence. The research vehicles were a linear low speed oscillating turbine test cascade and a realistic low-pressure steam turbine rotor/stage. Systematic experimental measurements were conducted on the linear turbine cascade, which consists of seven, large scale, prismatic blades with the middle blade being driven to oscillate in a three-dimensional bending/flapping mode. Blades were instrumented with pressure tappings at six span-wise sections between 10% and 95% span to facilitate detailed three-dimensional steady and unsteady pressure measurements on the blade surface. Steady flow pressure was measured by using an inclined manometer bank, whilst the unsteady pressure measurements were obtained through off-board pressure transducers. The measured unsteady pressure was superposed to construct tuned cascade flutter data using a technique named the influence coefficient method. This study produced the first known set of 3D flutter data for tuned turbine cascade. On the computational side, a state-of-the-art, single-passage, three-dimensional, time- marching, Navier-Stokes flow solver has been adopted. The computational solutions of the linear cascade flow exhibits a consistently high level of agreement with the experimental data, which corroborates the experimental findings on the one hand and acts to validate the present flow solver on the other hand. The results, from several aspects, suggest a strong three-dimensional nature of the unsteady aerodynamic response to the blade first-bending/flapping and clearly demonstrate the inadequacies of the currently widely used two-dimensional and quasi-three-dimensional methods. turbine configurations. It was found that accurate flutter predictions require three- dimensional, multi-row flow solvers including tip clearance modelling.
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Thon, Bjørn Olav. "Friction Models for Oscillating Flow in a U-tube." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-24656.
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The basic theory of friction in pipe flow was reviewed in the first part of this thesis. Using the results from this review, steady state friction relations were derived for laminar and turbulent pipe flow.Steady state turbulent friction relations were tested in 1D simulations of oscillating flow in a U-tube with a constant inner diameter. The results show that steady friction relations do not provide sufficient damping compared to experimental data. In order to improve the simulation results, systematic tests of some common dynamic friction relations were conducted. The concluding solution to the friction issue is a combination of laminar and turbulent friction relations, with a dynamic correction. The new friction relation was tested in 1D simulations of oscillating flow in a U-tube with a constant inner diameter. Results show that there is very good accordance between simulations and experimental data. The computational results were validated by experimental data from flow cases of varying Reynolds numbers and three different liquids.In the second part of this thesis, experimental work was conducted on a U-tube with an inner diameter change at the bottom of the bend. The damping of the oscillations was observed to be much greater than in the U-tube with a constant inner diameter. A computer program for image analysis was developed to allow for continuous measurements of the liquid interface level in the U-tube experiments. The program returned satisfying results, both with respect to accuracy and reliability. However, it was concluded that the results from the program could have been better if the U-tube had been made from another material.Simulations of oscillating flow in the U-tube with an inner diameter change were done in order to further investigate the new dynamic friction relation. Comparisons of simulated and experimental results indicated that the friction loss in the diameter change coupling caused inaccuracies in the simulations.
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Lotshaw, John E. "Numerical analysis of oscillating flow about a circular cylinder." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23993.
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Brydges, Bruce E. "Flow visualization of dynamic stall on an oscillating airfoil." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/27060.
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Bell, David Lloyd. "Three dimensional unsteady flow for an oscillating turbine blade." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4794/.
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An experimental and computational study, motivated by the need to improve current understanding of blade flutter in turbomachinery and provide 3D test data for the validation of advanced computational methods for the prediction of this aeroelastic phenomenon, is presented. A new, low speed flutter test facility has been developed to facilitate a detailed investigation into the unsteady aerodynamic response of a turbine blade oscillating in a three dimensional bending mode. The facility employs an unusual configuration in which a single turbine blade is mounted in a profiled duct and harmonically driven. At some cost in terms of modelling a realistic turbomachinery configuration, this offers an important benefit of clearly defined boundary conditions, which has proved troublesome in previous work performed in oscillating cascade experiments. Detailed measurement of the unsteady blade surface pressure response is enabled through the use of externally mounted pressure transducers, and an examination of the techniques adopted and experimental error indicate a good level of accuracy and repeatability to be attained in the measurement of unsteady pressure. A detailed set of steady flow and unsteady pressure measurements, obtained from five spanwise sections of tappings between 10% and 90% span, are presented for a range of reduced frequency. The steady flow measurements demonstrate a predominant two-dimensional steady flow, whilst the blade surface unsteady pressure measurements reveal a consistent three dimensional behaviour of the unsteady aerodynamics. This is most especially evident in the measured amplitude of blade surface unsteady pressure which is largely insensitive to the local bending amplitude. An experimental assessment of linearity also indicates a linear behaviour of the unsteady aerodynamic response of the oscillating turbine blade. These measurements provide the first three dimensional test data of their kind, which may be exploited towards the validation of advanced flutter prediction methods. A three dimensional time-marching Euler method for the prediction of unsteady flows around oscillating turbomachinery blades is described along with the modifications required for simulation of the experimental test configuration. Computationalsolutions obtained from this method, which are the first to be supported by 3D test data, are observed to exhibit a consistently high level of agreement with the experimental test data. This clearly demonstrates the ability of the computational method to predict the relevant unsteady aerodynamic phenomenon and indicates the unsteady aerodynamic response to be largely governed by inviscid flow mechanisms. Additional solutions, obtained from a quasi-3D version of the computational method, highlight the strong three dimensional behaviour of the unsteady aerodynamics and demonstrate the apparent inadequacies of the conventional quasi-3D strip methodology. A further experimental investigation was performed in order to make a preliminary assessment of the previously unknown influence of tip leakage flow on the unsteady aerodynamic response of oscillating turbomachinery blades. This was achievedthrough the acquisition of a comprehensive set of steady flow and unsteady pressure measurements at three different settings of tip clearance. The steady flow measurements indicate a characteristic behaviour of the tip leakage flow throughout the range of tip clearance examined, thereby demonstrating that despite the unusual configuration, the test facility provides a suitable vehicle for the investigation undertaken. The unsteady pressure data show the blade surface unsteady pressure response between 10% and 90% span to be largely unaffected by the variation in tip clearance. Although close examination of the unsteady pressure measurements reveal subtle trends in the first harmonic pressure response at 90% span, which are observed to coincide with localised regions where the tip leakage flow has a discernible impact on the steady flow blade loading characteristic. Finally, some recommendations for further work are proposed
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Liang, Shibin. "Theoretical and experimental investigation of oscillating heat pipes." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4560.
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Thesis (M.S.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 17, 2009) Includes bibliographical references.
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Haslam, Michael C. "Mechanics of oscillating flow in tubes of elliptic cross-section." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq21043.pdf.
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Chamberlain, George A. "Aerodynamic coefficients of a symmetrical airfoil in an oscillating flow." Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241073.
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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, September 1990.Thesis Advisor(s): Miller, James A. Second Reader: Schmidt, Louis V. "September 1990." Description based on title screen viewed on December 17, 2009. DTIC Descriptor(s): Velocity, angles, air flow, angle of attack, airfoils, cycles, time, surfaces, three dimensional, flow rate, coefficients, symmetry, pressure, axes, aerodynamic characteristics, value, unsteady flow, drag, oscillation, free stream, static pressure, pressure distribution, plotting, steady flow, control. DTIC Identifier(s): Airfoils, oscillating flow, pressure measurement, turbulence, moments, aerodynamic lift, aerodynamic drag, aerodynamic coefficients, wind tunnel tests, rotor blades(rotary wings), random variables, symmetrical airfoils, theses. Author(s) subject terms: Oscillating flow, aerodynamic coefficients, symmetrical airfoil. Includes bibliographical references (p. 94). Also available in print.
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Castañeda, Vergara David Armando. "Active Control of Flow over an Oscillating NACA 0012 Airfoil." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587420875168203.
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Katam, Vamsidhar. "SIMULATION OF LOW-RE FLOW OVER A MODIFIED NACA 4415 AIRFOIL WITH OSCILLATING CAMBER." UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_theses/339.
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Recent interest in Micro Aerial Vehicles (MAVs) and Unmanned Aerial Vehicles (UAVs) have revived research on the performance of airfoils at relatively low Reynolds numbers. A common problem with low Reynolds number flow is that separation is almost inevitable without the application of some means of flow control, but understanding the nature of the separated flow is critical to designing an optimal flow control system. The current research presents results from a joint effort coupling numerical simulation and wind tunnel testing to investigate this flow regime. The primary airfoil for these studies is a modified 4415 with an adaptive actuator mounted internally such that the camber of the airfoil may be changed in a static or oscillatory fashion. A series of simulations are performed in static mode for Reynolds numbers of 25,000 to 100,000 and over a range of angles of attack to predict the characteristics of the flow separation and the coefficients of lift, drag, and moment. Preliminary simulations were performed for dynamic mode and it demonstrates a definitive ability to control separation across the range of Re and AoA. The earlier experimental work showed that separation reduction is gradual until a critical oscillation frequency is reached, after which increases in frequency have little additional impact on the flow. Present numerical simulation results were compared with the previous experiments results which were performed on the airfoil in like flow conditions and these comparisons allow the accuracy of both systems to be determined.
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湯健東 and Kin-tung Dick Thung. "Digital PIV techniques for studies of circular cylinder under oscillating flow." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31223473.
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Christopoulos, George P. "Oscillating-flow wind tunnel studies for a circulation control circular cylinder." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28435.
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Thung, Kin-tung Dick. "Digital PIV techniques for studies of circular cylinder under oscillating flow /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22029783.
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Cheng, Peter D. L. (Peter Dien Leung). "Experiments in heat transfer under conditions of oscillating pressure and flow." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/35458.
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Szarko, David James. "Smoke-wire visualization of an oscillating flow in a gas spring." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/38727.
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Grassmyer, William Alan. "Experiments in heat transfer under conditions of oscillating pressure and flow." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35981.
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MAHALATKAR, KARTIKEYA. "CAVITATING FLOW OVER OSCILLATING HYDROFOILS AND HYDROFOIL-BASED SHIP STABILIZATION SYSTEM." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1154301156.
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Körbächer, Heiko. "Experimental investigation of the unsteady flow in an oscillating annular compressor cascade /." Lausanne : EPFL, 1996. http://library.epfl.ch/theses/?nr=1512.
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Stinson, Margaret Beverley. "An investigation into turbulence and the onset of separation in oscillating flow." Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296821.
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Wo, Andrew Man-Chung. "Characteristics of airfoils in an oscillating external flow at low Reynolds numbers." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/42212.
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Wood, Charles Wade. "Oscillating shock impingement on low-angle gas injection into a supersonic flow." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39856.
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Yoon, Il. "Two-phase flow dynamics by real-time neutron imaging in oscillating heat pipe." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5694.
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Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 19, 2009) Includes bibliographical references.
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Ortiz, Miguel A. "Numerical simulation of the flow field about a multi-element airfoil with oscillating flap." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA311471.
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Thesis (M.S. in Aeronautical Engineering) Naval Postgraduate School, March 1996.Thesis advisor(s): Max F. Platzer, Ismail H. Tuncer. "March 1996." Includes bibliographical references. Also available online.
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Hillenherms, Cornelia [Verfasser]. "Experimental Investigation of a Supercritical Airfoil Oscillating in Pitch at Transonic Flow / Cornelia Hillenherms." Aachen : Shaker, 2003. http://d-nb.info/1170540740/34.
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King, Cameron V. "Time-Resolved PIV And Pressure Measurements Of Oscillating And Pulsating Flow In A Diffuser." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/106.
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Separating oscillating and pulsating flows in an internal adverse pressure gradient geometry are studied experimentally. Simultaneous velocity-pressure measurements demonstrate that the minor losses associated with oscillating flow in an adverse pressure gradient geometry can be smaller or larger than for steady flow. Separation is found to begin high in the diffuser and propagate downward. Flows are able to remain attached further into the diffuser with larger Reynolds numbers, larger stroke lengths, and smaller diffuser angles. The extent of separation grows with Lo/h. The minor losses grow with increasing displacement amplitude in the range 10 < Lo/h < 40. Losses decrease with Re in the range of 380
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Gao, Congwei. "Numerical study of mass and momentum exchanges between side asin and forced oscillating main flow." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123274.
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The exchanges of mass and momentum between coastal current and its embayment influence the transport and distribution of pollutant and sediment in the current. In this study, a numerical model of forced oscillating flow was developed to study the exchange between the recirculating flow in a side basin and the main-channel flow. The numerical simulations were carried out based on the shallow water equations, using a staggered grid for minimal intervention. Time integration of the shallow water equations was accomplished using the fourth-order Runge-Kutta scheme. A fifth-order finite volume approximation known as weighted essentially non-oscillatory (WENO) scheme was employed for the spatial interpolation. To visualize the mass exchanges and determine the mass exchange coefficient, tracer mass were introduced into the square basin. The flow in the main channel is forced to oscillate. The mass exchange rate as a fraction of the total mass within the basin is shown to be a first-order reaction process. A mass exchange coefficient is then determined for the first-order process. The momentum exchange as a resistance to the main flow is obtained by integrating the momentum flux at the interface along the opening of the side basin to the main flow.Different flow patterns in the basin are identified relating to the amplitude and the period of the forced oscillations. The regular recirculating flow are dependent on the oscillation amplitude but not on the forcing period. At selected periods of forcing however, the flow is excited leading to self-sustained oscillations in the basin. Two kinds of excitations of different feedback mechanism have been identified. The excitation of the first kind occurs when the forced oscillation frequency matches the fundamental and harmonic mode frequencies of the gravity free-surface waves in the basin. The excitation of the second kind is due to vorticity-wave synchronization with the forced oscillation frequency. The excitation of the free-surface waves in the basin does not promote the mass exchange. On the contrary and in contradiction to intuition, it suppresses the circulation inside the basin and thereby leading to a substantial decrease in mass exchange rate between the basin and the main flow. The momentum exchange on the other hand is enormously enhanced by the excitation of the free-surface waves in the basin.Le processus d'échange de masse et la quantité de mouvement entre le courant côtier et son embouchure influence le transport et la distribution de polluants et de de sédiments dans le courant. Dans cette étude, un modèle numérique de flux principal oscillant force a été développé pour étudier l'échange entre le flux de recirculation dans un sous-bassin d'extrémité et son flux principal. Les simulations numériques ont été élaborées basées sur les équations de flux en eau peu profonde dans un repère orthonormé. L'intégration du temps des équations de flux en eau peu profonde a été accomplie en utilisant la programmation du quatrième degré de Runge-Kutta. Un volume d'éléments finis de cinquième degré connu sous le nom de régime pondéré essentiellement non oscillatoire (en anglais WENO) a été utilisé pour l'interpolation spatiale.Pour visualiser les échanges de masse et déterminer le coefficient d'échange de masse, un traceur a été introduit dans le bassin de forme carré. L'écoulement dans le flux principal est forcé d'osciller. Le taux d'échange de masse en fonction de la masse totale dans le bassin est présenté en tant que procédé de réaction de premier ordre. Un coefficient d'échange de masse est ensuite déterminé pour ce procédé de premier ordre. L'échange de moment en tant que résistance au flux principal est obtenu par intégration du flux de la quantité de mouvement au niveau de l'interface sur l'ouverture du sous-bassin d'extrémité.Différents caractéristiques d'écoulement dans le bassin sont identifiés étant reliés à l'amplitude et à la période de forces oscillatoires. Les flux de recirculation réguliers sont dépendants de la force d'amplitude mais non à la période de la force oscillatoire. Cependant, au niveau de certaines périodes de force sélectionnées, l'écoulement est excité afin d'aboutir à des oscillations durables dans le bassin. Deux types d'excitation de différents mécanismes de feed-backs ont été identifiés. L'excitation du premier type survient quand la fréquence de l'oscillation forcée égale les fréquences des modes fondamental et harmonique associés à la force oscillatoire. L'excitation du second type est due à la synchronisation du tourbillon d'onde avec la fréquence de l'onde oscillatoire. L'excitation des ondes à surface libre dans le bassin ne garantit pas l'échange de masse. Dans le cas contraire et dans la contradiction par rapport à l'intuition, ceci supprime la circulation dans la le bassin et ainsi conduit à une diminution importante dans le taux d'échange de masse entre le bassin et l'écoulement principal. De l'autre côté, l'échange de la quantité de mouvement est énormément amélioré par l'excitation des ondes à surface libre dans le bassin.
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Vu, Huy. "A Machine Learning Assessment to Predict the Sediment Transport Rate Under Oscillating Sheet Flow Conditions." ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/honors_theses/135.
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The two-phase flow approach has been the conventional method designed to study the sediment transport rate. Due to the complexity of sediment transport, the precisely numerical models computed from that approach require initial assumptions and, as a result, may not yield accurate output for all conditions. This research work proposes that Machine Learning algorithms can be an alternative way to predict the processes of sediment transport in two-dimensional directions under oscillating sheet flow conditions, by utilizing the available dataset of the SedFoam multidimensional two-phase model. The assessment utilized linear regression and gradient boosting algorithm to analyze the lowest average mean squared error in each case and search for the best partition method based on the domain height of the simulation setup.
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Kooverji, Bavesh. "Pneumatic power measurement of an oscillating water column converter." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86662.
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Thesis (MScEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: A measurement device was developed to accurately determine the pneumatic power performance of an Oscillating Water Column (OWC) model in a wave flume. The analysis of the pneumatic power is significant due to the wave-topneumatic energy being the primary energy conversion process and where the most energy losses can be expected. The aim of the research study is to address the accurate pneumatic power measurement of unsteady and bidirectional airflow in OWC model experiments. The two fundamental measurements required for the pneumatic power measurement are the pressure difference over an orifice on the OWC model and the volumetric flow rate of air through the outlet. The designed, constructed and assembled measurement device comprised of a venturi flow meter, containing a hot-film anemometer, which could measure the pressure drop and the volumetric flow rate in one device. The assembled pneumatic power measurement device was calibrated in a vertical wind tunnel at steady state. The results from the calibration tests showed that the volumetric flow rate measurements from the pneumatic power measurement device was accurate to within 3 % of the wind tunnel’s readings. The pneumatic power measurement device was incorporated onto a constructed Perspex physical model of a simple OWC device. This assembled system was used as the test unit in the wave flume at Stellenbosch University (SUN). The results from the experimental tests underwent comparative analysis with three analytical OWC air-flow models which were simulated as three scenarios using Matlab Simulink. These results showed that the measurement device has the ability to measure the pneumatic power but there is difficulty in modelling the complex air-flow system of the OWC device. This results in varying levels of agreement between the experimental and simulated pneumatic power results. The research study has revealed that there is difficulty in designing an accurate device for a wide range of test parameters due to the variance in output values. The unsteady and bidirectional nature of the air flow is also difficult to accurately simulate using a one-dimensional analytical model. Recommendations for further investigation are for CFD systems to be used for the analysis of the air-flow in an OWC system and to be used to validate future pneumatic power measurement devices.
AFRIKAANSE OPSOMMING: ‘n Meetinstrument was ontwikkel om die pneumatiese kraglewering van ‘n model van die Ossillerende Water Kolom (OWK) golfenergie omsetter in ‘n golf tenk akkuraat te meet. Dit is belangrik om die omskakeling van golf na pneumatiese energie te analiseer siende dat die grootste energieverlies in dié proses plaasvind. Die doel van hierdie navorsingsprojek was om die akkurate pneumatiese kragmeting van variërende en twee-rigting vloei van lug in ‘n OWK model na te vors. Die twee fundamentele metings wat benodig word vir die pneumatiese kragbepaling is die drukverskil oor die vloei vernouing en die volumetriese vloeitempo van lug deur die uitlaat van die toetstoestel. Die spesiaal ontwerpte meettoestel wat gebruik is in die eksperiment het bestaan uit ‘n venturi vloeimeter wat ‘n verhitte-film anemometer bevat het wat die drukverandering en die volumetriese vloeitempo kan meet in ‘n enkele instrument. Die pneumatiese kragmeting was gekalibreer in ‘n vertikale windtonnel waarin ‘n konstante vloei tempo geïnduseer was. Die kalibrasieproses het bevestig dat die meettoestel metings lewer met ‘n fout van minder as 3 % wanneer dit vergelyk word met die bekende konstante vloei tempo soos bepaal in die windtonnel. ‘n Fisiese model van ‘n vereenvoudigde OWK golfenergie omsetter was ontwerp en gebou uit Perspex om as toetstoestel te gebruik vir die evaluering van die ontwerpte pneumatiese kraglewering meettoestel. Die toetse was uitgevoer in ‘n golftenk by die Universiteit Stellenbosch (SUN). The toetsresultate was vergelyk met drie ander OWK lugvloei modelle wat gesimuleer was deur om die analitiese modelle op te stel en te simuleer in Matlab Simulink. Die vergelyking van modellering resultate het gewys dat die meettoestel die vermoë het om pneumatiese krag te meet. Daar was wel komplikasies met die modellering van die komplekse lugvloei in die OWK toestel, die resultate het geen definitiewe ooreenstemming gewys tussen die eksperimentele en gesimuleerde pneumatiese krag resultate nie. Die navorsingsprojek het gewys dat daar komplikasies is om ‘n enkel toestel te ontwerp wat oor ‘n wye bereik kan meet weens die variasie van die verskillende parameters. Die variërende en twee-rigting lugvloei is ook moeilik om akkuraat te simuleer met ‘n een-dimensionele analitiese simulasie model. Aanbevelings vir verdere navorsing sluit in om die lugvloei in die OWK stelsel te modelleer en te analiseer in ‘n drie-dimensionele model om die lesings van ‘n pneumatiese krag meettoestel te bevestig.
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Angelopoulos, Konstantinos. "The forced vibrations of a cylinder at low Reynolds number flow : an investigation of the non-lock-in and lock-in regions." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/16224.
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The present thesis is examining the forced vibrations of a circular cylinder in the low Reynolds number flow of 200. A numerical study is performed that employs an already existing algorithm developed by (Breuer 1998) and enhanced with the characteristic of the cylinder's motion by (MadaniKermani 2014) who employed the moving frame of reference method of (L. Li, Sherwin et al. 2002). The algorithm was extensively assessed for the benchmark studies of flow around a stationary circular cylinder. A new observation was made on the effect of the aspect ratio of the computational cells in the mid region of the wake. The studies so far are emphasizing on the characteristic of a dense mesh, with a small aspect ratio, in the high divergence areas in the near region of the cylinder surface, neglecting the effect of the regions away from the surface. The present study on a stationary circular cylinder flow, proved that the aspect ratio of the distant cells has a significant effect on the St number and the force coefficients. The main study of the thesis emphasizes on the lock-in region where the wake oscillates in unison with the harmonic motion of the cylinder. The study makes a new observation on the qualitative and quantitative description of the lock-in conditions. In particular, it reveals two regions of resonance and non-resonance lock-in. Despite the fact that the lock-in is achieved, when the frequency ratio is in the first part of the region away from the unity ratio, the forces are not greatly magnified. As the ratio approaches the unity the forces experience a resonance that reaches the highest value after the unity. Furthermore, the adaptation time of the flow to the motion of the cylinder is examined and extends the results of (Anagnostopoulos 2000) to the full extent of the lock-in and the non-lock-in regions. More precisely the flow strives to reach a steady state when it is in the lock-in region rather in the non-lock in cases it reaches the steady state faster. It is postulated that the adaptation time depends on both the numerical and the physical adaptation. Moreover, the force coefficients characteristic of sinusoidal behaviour in the lock-in region is attempted to be approximated by a Newton polynomial that is built by making use of the divided differences method. The amplitude of the forces is approximated by a third degree Netwon polynomial built from the results of the present thesis simulations. The use of an approximation is providing faster results ignoring the need for a full resolution of the Navier-Stokes equation.
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Hind, Michael D. "Quantification of flow structures generated by an oscillating fence actuator in a flat plate laminar boundary layer." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1798480911&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Weinstein, Joel Aaron. "The motion of bubbles and particles in oscillating liquids with applications to multiphase flow in Coriolis meters." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3315790.
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CHIAO, CHIH-YANG, and 楊智喬. "Flow Visualization of the Flow Field with Oscillating Foils." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/wpvag2.
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碩士臺北城市科技大學
機電整合研究所
107
This research experimentally investigates the flow structures and the velocity of air in a rectangular duct with dual oscillating foils. The foils were arranged in tandem and the oscillation was performed through interaction between elec-tromagnetic field and magnets which adhered to the foils. The alternative at-tracting and repelling forces caused the oscillation of the foils. The foil oscilla-tions were conducted in in-phase and counter phase patterns. In the research, the effects of the frequency on the flow structures and the velocity were studied. The structures were observed with laser sheet and smoke. The velocity was measured with hoy wire. The frequency for velocity measurement was between 10.0 Hz and 17.0 Hz. The counter-phase oscillation showed more significant relation with frequency and presented higher optimal velocity than the in-phase oscillation.
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Hou, Cheng-Yu, and 侯承佑. "Flow Past a Rotationally Oscillating Cylinder." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/98395459553143013643.
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碩士逢甲大學
水利工程所
94
Cross flow past a rotationally oscillating circular cylinder is studied by numerical modeling of the two-dimensional incompressible Navier-Stokes equations using primitive variables. The main non-dimensional parameters are Reynolds number, rotational amplitude, and rotational frequency. This model was verified by comparing with Mahfouz’s results. The domain of the rotational frequency were reasonably divided into lock-on, buffer, and non-lock-on regions according to the energy of the lift force at different rotational frequency. The extent of the lock-on region increased with the Reynolds number and the rotational amplitude. The effect of rotational amplitude was much larger than the Reynolds number. The peaks of lift and drag both appeared in lock-on region. A local minimum showed up at both low and high buffer regions. Other flow characteristics at different value of the non-dimensional parameter were also discussed.
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Li, Cheng-jin, and 李忠錦. "Flow Past a Transversely Oscillating Cylinder." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20064841872952761349.
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碩士逢甲大學
水利工程所
94
This study set up a numerical simulation that used to discuss the effect of the flow field of a transversely oscillating cylinder. There are three non-dimensional parameters, i.e. the Reynolds number, the oscillating frequency of the cylinder, and the oscillating amplitude of the cylinder. There have been few cases in numerical simulation, and for the buffer region (between lock-on and unlock-on). So this study use a large number of cases to describe the influence of a oscillating cylinder, especially the influence of the time series of the drag and the lift, and the influence of the buffering region, in addition to the influences of Reynolds number and the oscillating amplitude of the cylinder. The characteristic of flow field includes vortex shedding frequency, effect of lock-on, time-average of the drag coefficient, root mean square of the lift coefficient, and so on. Energy spectrum analysis was used to study the time series of the drag and the lift. Then, the frequency and energy of vortex shedding could be found. The lowest lift and drag, which can be found in the buffer region, were decreasing with increasing Reynolds number. In lock-on region, the lift and drag increased with increasing amplitude of cylinder vibration.
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Liang, Chun-En, and 梁淳恩. "Numerical Study of Oscillating-flow Heat Pipe." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/95856663167065460979.
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碩士淡江大學
航空太空工程學系碩士班
101
This paper discusses numerical studies of the heat transfer characteristics at vertical heating state of a 3-D closed loop oscillating heat pipe(CLOHP), the parameters studied were working fluid filling ratio ,and inclination angle. A set of copper-tube CLOHP with internal diameter of 1.3mm,consisting of 4meandering turns and characteristic heat transfer length of 100mm was used in this study. The CLOHP condenser ,and evaporator section length both are 20mm,working fluid in this study was used water with filling ratio is 50% of total volume of the tube. The result shows that in this study the model ,numerical method which we chose can predict heat transfer mechanism of 3-D CLOHP, and with different filling ratios ,and inclination angles .Verticl heating modle and filling ratio is 50% compare with others inclination angles ,and filling ratio ,it heat resistance is the optimum.
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Lee, Soon-Kong. "Study of a naturally oscillating triangular-jet flow." 2009. http://hdl.handle.net/2440/58581.
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This thesis reports on the structure of the flow inside a nozzle which produces a naturally oscillating jet flow. The nozzle consists of a short cylindrical chamber with a concentric triangular-inlet orifice at one end and a circular exit lip at the other end. This triangular-jet nozzle was developed from the “fluidic-precessing-jet” (FPJ) nozzle, which has a similar arrangement of components, but has a circular rather than a triangular inlet. For reliably oscillating flow, the FPJ nozzle should have an inlet-to-chamber expansion ratio of at least 5.0, a chamber lengthto- diameter ratio between 2.6 and 2.8, and an exit-lip height of about 0.1 chamber diameters. The triangular-jet nozzle produces a continuously and aperiodically oscillating jet flow which is different from the FPJ flow. The oscillation occurs at smaller inlet-to-chamber expansion ratios (2.1 ≲ D /de₁ ≲ 3.5) and over a wider range of chamber lengths (2.0 ≲ L /D ≲ 2.5). The initial spreading angle of the jet flow is smaller, but is still much larger than that of non-oscillating, axisymmetric turbulent-jet flows. In addition, the external “oscillating-triangular-jet” (OTJ) flow has preferred azimuthal directions which are aligned with the three corners of the orifice. The kinetic-energy-loss coefficient of the OTJ nozzle is much smaller than that of the FPJ nozzle because oscillation occurs at much smaller inlet-to-chamber expansion ratios. For a narrow range of length-to-diameter ratios (1.00 ≲ L/D ≲ 1.25), the triangular-inlet nozzle can also produce a non-oscillating or “stationary deflected triangular jet” (SDTJ) which reattaches asymmetrically to the inside surface of the cylindrical chamber. The SDTJ has a weak tendency to oscillate, which suggests that flow patterns required for self-excited oscillation are already present in the SDTJ flow. Surface-flow visualisation and surface-pressure measurements in the SDTJ nozzle have provided the location of critical points and bifurcation lines on the chamber wall, and from this the topology of the SDTJ flow is deduced. Some details of the flow such as a jet-reattachment node near the chamber exit and a strong swirl adjacent to the inlet orifice are known from previous studies of the FPJ flow, but there are many newly observed features. The most easily identified of these are two sink-focus separation points, one on each side of the reattachment node but closer to the inlet plane. The foci counter rotate and are of unequal size. Reverse flow through the exit plane of the chamber is attracted to the larger focus. The vortex core rising from each focus is entrained by the reattaching-jet (SDTJ) flow and is drawn out of the chamber. A backward-facing pressure probe placed in the OTJ “reattaching-flow” region of chamber wall can be used as a reliable detector of jet-flow oscillation. Cross-correlating the signal from this detector probe with simultaneous static-pressure measurements elsewhere on the chamber wall gives a conditionally-averaged pressure on the wall of the OTJ chamber. The OTJ wall-pressure distribution has the same features as the SDTJ surface-pressure distribution, but it has greater asymmetry about a mirror plane drawn through the chamber axis and the detector probe. An array of three backward-facing pressure probes has been used as an “event detector” for conditionally-sampled (PIV) measurements of non-axial velocity components in cross-sections of the OTJ nozzle. The event-detection scheme responds only to a preselected (counter-clockwise) direction of motion of the oscillating-jet flow. The streamline patterns constructed from the conditionally-sampled measurements confirm the presence of the jet-reattachment node, the swirl and the sink foci identified from the SDTJ surface-flow visualisation. The shear-layer interaction between the jet from the triangular orifice and the swirl (adjacent to the inlet plane) produces strong longitudinal vortices in the ensemble-averaged flow. The jet flow distributes these vortices through the length of the chamber. Vortex cores representing the vortices are reconstructed by tracking streamline foci from one PIV cross-section plane to another. The tracking process includes the connection and termination of vortex cores in a manner which is consistent with the Helmholtz vortex law. In this flow field, the vortex core produced by the swirl and the vortex core rising from the larger sink-focus vortex on the chamber wall are connected to form a loop. The extent to which this vortex loop is contained within the chamber determines whether or not the flow is oscillating. If only a small fraction (e.g. 8%) of the vortex circulation passes through the exit plane of the nozzle, the loop is trapped inside the chamber and the deflected jet oscillates. If the length of the chamber is halved, about 35% of vortex circulation escapes from the nozzle and the oscillation stops.http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1353005
Thesis (Ph.D.) - University of Adelaide, School of Mechanical Engineering, 2009
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McCoy, William T. "Stability of the vortex motion in oscillating flow." Thesis, 1986. http://hdl.handle.net/10945/22118.
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Xu, Yong-Zhang, and 許永璋. "Numerical simulation of flow over an oscillating plate." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/14117733755647301818.
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碩士國立中興大學
機械工程研究所
81
The flow filed of flow over an oscillating plate was numerically in the present study. The discrete vortex method wasmployed to carry out the numerical study. The flat plate was initiallyrmal to free stream and then oscillated between 60 .degree. and 120gree. with various angular velocities. Both the global and detailres of the oscillating plate flow field are examined. Due to lack ofrimental and numerical data available from previous investigations,thelts of the flow over a fixed normal flat plate were served as an basis in the present study. From the simulated results,it was foundthe wake behind the oscillated plate can be sweeping up or sweeping downcording to the status of rotation. The vorticity shedding frequency, ie,he Strouhal number,averaged drag and lift coefficients,shear layerelocities and rate of vorticty shedding were also computed.Generally, thetrouhal number,drag, and lift coefficients were found to be larger thanose of fixed normal flat plate flow field, while the shear layeres and rate of vorticity shedding were found to have smaller valuesaring with those of fixed normal flat plate case. These differencesprimarily due to rotation effects.Besides the above mentioned globals of flow field behind the oscillating plate , the detail features in thear wake region behind the oscillated plate were also investigated. Therage velocity , turbulence intensities, and Reynolds stress wereed at several locations in the down stream of wake. In general , thends of variations of these quantities were similar to those of fixedal plate except that rotation clearly enhence these profiles.