Relevant bibliographies by topics / Vortex shedding frequency

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  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Vortex shedding frequency'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Vortex shedding frequency"

1

IMAICHI, Kensaku, and Eiichi TADA. "Determination of vortex shedding frequency and drag for karman vortex street (1st report, Vortex shedding frequency)." Transactions of the Japan Society of Mechanical Engineers Series B 51, no. 471 (1985): 3685–88. http://dx.doi.org/10.1299/kikaib.51.3685.

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Hu, Jian, Zibin Wang, Wang Zhao, Shili Sun, Cong Sun, and Chunyu Guo. "Numerical Simulation on Vortex Shedding from a Hydrofoil in Steady Flow." Journal of Marine Science and Engineering 8, no. 3 (March 12, 2020): 195. http://dx.doi.org/10.3390/jmse8030195.

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This paper presents a numerical modeling procedure for the idealization of vortex shedding effects in the wake flow field of a NACA0009 hydrofoil. During the simulation, the lift and drag acting on the hydrofoil were monitored, and the vortex-shedding frequency of the hydrofoil was analyzed. The effects of inflow velocity, trailing-edge thickness, angle of attack, and maximum hydrofoil thickness on vortex shedding were investigated. The results indicate that an increase in the inflow velocity led to an increase in the vortex-shedding frequency and a negligible change in the Strouhal number. Furthermore, as the thickness of the trailing edge increased, the vortex-shedding frequency decreased gradually, whereas the Strouhal number first increased and then decreased. Vortex shedding and lift curve oscillations ceased altogether after the angle of attack of the hydrofoil increased beyond a certain threshold. When the maximum hydrofoil thickness was increased while keeping the thickness and chord length of the trailing edge constant, the vortex-shedding frequency decreased.
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Zhang, Mingming, and Anping Hou. "Numerical Investigation on Unsteady Separation Flow Control in an Axial Compressor Using Detached-Eddy Simulation." Applied Sciences 9, no. 16 (August 12, 2019): 3298. http://dx.doi.org/10.3390/app9163298.

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Unsteady excitation has proved its effectiveness in separation flow control and has been extensively studied. It is observed that disordered shedding vortices in compressors can be controlled by unsteady excitation, especially when the excitation frequency coincides with the frequency of the shedding vortex. Furthermore, former experimental results indicated that unsteady excitation at other frequencies also had an impact on the structure of shedding vortices. To investigate the impact of excitation frequency on vortex shedding structure, the Detached-Eddy Simulation (DES) method was applied in the simulation of shedding vortex structure under unsteady excitations at different frequencies in an axial compressor. Effectiveness of the DES method was proved by comparison with URANS results. The simulation results showed a good agreement with the former experiment. The numerical results indicated that the separation flow can be partly controlled when the excitation frequency coincided with the unsteady flow inherent frequency. It showed an increase in stage performance under the less-studied separation flow control by excitation at a certain frequency of pressure side shedding vortex. Compared with other frequencies of shedding vortices, the frequency of pressure side shedding vortex was less sensitive to mass-flow variation. Therefore, it has potential for easier application on flow control in industrial compressors.
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Britto, Abraham Benjamin, and Sathesh Mariappan. "Lock-in phenomenon of vortex shedding in oscillatory flows: an analytical investigation pertaining to combustors." Journal of Fluid Mechanics 872 (June 7, 2019): 115–46. http://dx.doi.org/10.1017/jfm.2019.353.

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An analytical investigation is performed to understand the lock-in phenomenon, observed in vortex shedding combustors. Several aeroengine afterburners and ramjets use a bluff body to stabilize the flame. The bluff body sheds vortices. During the occurrence of high-amplitude combustion instability, the frequency of vortex shedding locks in to the frequency of the chamber acoustic field. This phenomenon is termed vortex-acoustic lock-in. In general, there is a two-way coupling between the vortex shedding process and the acoustic field, making analytical investigation difficult. Since the frequency of the latter remains largely unaltered, performing an investigation to study the response of vortex shedding to external excitation not only allows one to gain insights, but also make the problem analytically tractable. We begin with a lower-order model available in the literature to describe the vortex shedding process in non-reacting flows, arising from sharp corners in the presence of upstream velocity excitation. The continuous time domain model is transformed to a discrete map, which connects the time instances of two successive vortex shedding events. The frequency and amplitude of excitation are varied to study the instantaneous vortex shedding time period, as the response of the system. In the absence of forcing, the iterates of the map form a period-1 solution with the frequency equalling the natural vortex shedding frequency. On increasing the amplitude of excitation, quasi-periodic behaviour of the iterates is observed, followed by a period-1 lock-in solution, where vortex shedding occurs at the excitation frequency. On further increasing the amplitude, de-lock-in occurs. From the map, an analytical solution is extracted, which represents the lock-in state. The condition and thereby the region in the frequency–amplitude parameter space where a general$p:1$lock-in occurs is then identified. Several important analytical expressions, such as for (1) critical threshold frequency above which lock-in occurs, (2) boundary of lock-in region in the parameter space, that are of direct importance to the design of quieter combustors are obtained. The study also identifies the transition of higher-order$p:1$to$1:1$lock-in state, through a series of lock-in and de-lock-in steps, whose occurrence could be verified from future experiments.
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Bejan, A. "Predicting the Pool Fire Vortex Shedding Frequency." Journal of Heat Transfer 113, no. 1 (February 1, 1991): 261–63. http://dx.doi.org/10.1115/1.2910540.

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Konstantinidis, E., S. Balabani, and M. Yianneskis. "A Study of Vortex Shedding in a Staggered Tube Array for Steady and Pulsating Cross-Flow." Journal of Fluids Engineering 124, no. 3 (August 19, 2002): 737–46. http://dx.doi.org/10.1115/1.1487359.

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This paper describes an experimental investigation of the vortex shedding phenomena in a staggered tube array with streamwise and transverse spacing to diameter ratios of 2.1 and 3.6, respectively. LDA measurements were employed to monitor the flow fluctuations and a visualization technique was implemented to reveal the underlying flow patterns in the array for steady and pulsating cross-flow. The results obtained in steady flow are in general agreement with results from previous investigations and show that vortex shedding occurs at two distinct frequencies in the front and inner rows. A lower frequency component was detected at the exit of the array, which has not been previously identified. Pulsating flow caused the frequency of vortex shedding to lock-on at the subharmonic of the imposed frequency. In the lock-on range, vortex shedding from all the tubes was synchronized and in-phase and velocity fluctuations at the shedding frequency increased considerably compared to their counterparts in steady flow.
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Xiong, Zhongying, and Xiaomin Liu. "Very Large-Eddy Simulations of the Flow Past an Oscillating Cylinder at a Subcritical Reynolds Number." Applied Sciences 10, no. 5 (March 9, 2020): 1870. http://dx.doi.org/10.3390/app10051870.

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This work focuses on flow past a circular cylinder at a subcritical Reynolds number. Although this classical study has been a concern for many years, it is still a challenging task due to the complexity of flow characteristics. In this paper, a high-efficiency very large-eddy simulation method is adopted and verified in order to handle the oscillating boundary. A series of numerical simulations are conducted to investigate the transient flow around the oscillating cylinder. The results show that the vortex shedding mode varies with an increase in the excitation amplitude and the excitation frequency. Vortex shedding is a lasting process under the condition of a low excitation amplitude that leads to irregular fluctuations of the lift and drag coefficients. For a vortex shedding mode that exhibits a strong vortex pair and a weak vortex pair or a weak single vortex, the temporal evolution of the lift coefficient of the oscillating cylinder shows irregular ”jumping” at a specific time per cycle corresponding to the shedding of the strong vortex pair. The vortex shedding mode and the frequency and time of the vortex shedding co-determine the temporal evolutions of the lift and drag coefficient.
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Leontini, Justin S., David Lo Jacono, and Mark C. Thompson. "A numerical study of an inline oscillating cylinder in a free stream." Journal of Fluid Mechanics 688 (November 3, 2011): 551–68. http://dx.doi.org/10.1017/jfm.2011.403.

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AbstractSimulations of a cylinder undergoing externally controlled sinusoidal oscillations in the free stream direction have been performed. The frequency of oscillation was kept equal to the vortex shedding frequency from a fixed cylinder, while the amplitude of oscillation was varied, and the response of the flow measured. With varying amplitude, a rich series of dynamic responses was recorded. With increasing amplitude, these states included wakes similar to the Kármán vortex street, quasiperiodic oscillations interleaved with regions of synchronized periodicity (periodic on multiple oscillation cycles), a period-doubled state and chaotic oscillations. It is hypothesized that, for low to moderate amplitudes, the wake dynamics are controlled by vortex shedding at a global frequency, modified by the oscillation. This vortex shedding is frequency modulated by the driven oscillation and amplitude modulated by vortex interaction. Data are presented to support this hypothesis.
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Perrot-Minot, Clément, Emmanuel Mignot, Nicolas Riviere, and Richard Perkins. "Predicting the vortex shedding frequency at the interface of the lateral cavities." E3S Web of Conferences 40 (2018): 05011. http://dx.doi.org/10.1051/e3sconf/20184005011.

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The vortex shedding frequency in the mixing layer between a cavity and a main stream has been examined experimentally in absence of large oscillation of the free surface inside the cavity, called seiching. It was observed that the vortex shedding frequency follows a monotonically increasing trends with possible jumps from one to another with increasing Froude number of the main stream. These trends are obtained by solving a model based on the Rossiter approach. This model considers that the vortices shed in the mixing layer create some water depth variation at the impingement corner of the cavity. This water depth variation in turn generate pressure waves that propagates upstream and influence the vortex shedding process. Finally the measured vortex shedding frequencies correspond quite accurately to the frequencies predicted by the model. This highlights the existence of a resonant phenomena between vortices in the mixing layer of a lateral cavity and gravity waves even without any seiching phenomena.
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Okafor, Chinedum Vincent. "Finite Element Analysis of Vortex Induced Responses of Multistory Rectangular Building." European Journal of Engineering Research and Science 3, no. 2 (February 25, 2018): 35. http://dx.doi.org/10.24018/ejers.2018.3.2.612.

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High-rise buildings may experience high levels of vibrations under the actions of wind which cause building motions, adversely affecting serviceability and occupant comfort. The paper analyzed the vortex shedding responses of a multistory building with moment resisting frame. It presents a numerical model based on computational wind engineering technique to simulate the wind action over a typical high-rise building using wind speed data of Lagos state Nigeria. The vortex shedding frequency of the vortices and the natural frequency of vibration of the entire high-rise building structural system were calculated by computing fast Fourier transform algorithm (FFT) of the force coefficient and finite element analysis (FEA) of the structural system respectively. From the result obtained, the vortex shedding frequency of the wind vortices was lower than the fundamental frequency of vibration of the typical high-rise building. Hence, vortex shedding was not responsible for the failure of high-rise buildings in the locality being considered due to the reasons stated in the author’s conclusion.
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Dissertations / Theses on the topic "Vortex shedding frequency"

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Pinhata, Gustavo Marcelo. "Estudo do número de Strouhal em função do número de Reynolds em um anteparo triangular utilizando a técnica da análise tempo-freqüência." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-08112006-164254/.

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Neste trabalho simulou-se o escoamento do fluxo de ar em um tubo, com um anteparo de formato triangular com arestas cortantes, posicionado no centro do tubo. O objetivo do estudo é a análise do comportamento do número de Strouhal em função do número de Reynolds. Para isto, foi utilizada a técnica da análise tempo-freqüência, baseada na transformada de Fourier e na transformada de Gabor. Os ensaios foram realizados com o fluxo com velocidades médias de escoamento de 3 a 10 m/s, sendo utilizado um sensor de pressão tipo piezo-resistivo para a detecção da flutuação de pressão ocasionada pelo desprendimento e formação dos vórtices. Os ensaios foram realizados em cinco etapas com o objetivo de se verificar a influência dos seguintes parâmetros na coleta de sinais e no fenômeno: ruído da rede elétrica; influência do anteparo e do ruído proveniente do escoamento do fluxo de ar; número de pontos da amostragem na coleta dos dados; do comprimento da tubulação; e posicionamento do sensor. Pode-se observar, a sensibilidade do sistema de medição através do ensaio realizado sem o anteparo, sendo verificada a influência do ruído do escoamento de ar pelo tubo; pode-se observar também uma pequena interferência do ruído da rede elétrica predominantemente para velocidades abaixo de 3 m/s. Apesar das influências citadas, e utilizando a transformada de Gabor para análise dos sinais, observou-se um sinal mais intenso na freqüência dos vórtices para as velocidades de escoamento, podendo-se comprovar que o número de Strouhal permanece quase constante e é independente do número de Reynolds, devendo-se ressaltar que esta conclusão é valida para números de Reynolds compreendidos na faixa de 3000 a 100000. No experimento obteve-se um fator de sensibilidade (freqüência vórtices/velocidade média) de 8,2 Hz/m/s, e número de Strouhal médio de 0,196.
This work concerns the simulation of an air flux through a pipe with a triangular bluff body positioned inside it. In order to study the behavior of the Strouhal number in function of the Reynolds number. For this, the time-frequency analysis technique was used, based on Fourier transform and the Gabor transform. The experiments were carried out with an air flux velocity ranging from 3 to 10 m/s and using a piezoresistive pressure sensor to detect pressure fluctuations caused by the shedding and vortex formation. The experimental procedures were divided in five stages to make it possible to verify the influence of the following parameters in the signal data acquisition: electric network noise, the bluff body presence and the noise generated due to its presence, number of sampling data points, tubing length and sensor positioning. The sensitivity of the experiment could be observed testing the air flowing with no bluff body inside the pipe. Thus, it was possible to investigate the influence of the noise generated due to this flux limiting body. It could be also observed, mainly at 3 m/s or less, the noise generated due to the electric network. Despite the listed influences, and with the use of the Gabor transform, a more intense signal on the vortex frequency for the flow velocity was observed, showing that the Strouhal number remains almost constant and is independent of the Reynolds number. It is important to recall that this conclusion is valid for Reynolds numbers between 3000 and 100000. In the experiments the factor of sensitivity (vortex frequency/mean velocity) obtained was 8,2 Hz/m/s and the mean Strouhal number 0,196.
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Barberini, Riccardo. "Wind Tunnel Analysis of an Automotive Wheel and Comparison with Numerical Simulations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19430/.

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The main purpose of this thesis is to find a relation between the results obtained with numerical simulations and the results coming from the experiments in the case of an automotive wheel. Before this study, it was investigated the phenomenon of the vortex shedding of a 2D cylinder. It was proven that the shedding frequency has a linear relation with the free stream velocity and this relation depends on the Strouhal number. The last stage of this acquistion campaign was to compare the calibration of the hot-wire anemometer with the Pitot probe and the calibration exploiting the vortex shedding frequency, obtaining very similar results. The second step of this study was focused on the wake of three different type of wheels (sharp shoulders, 45 degrees shoulders and rounded shoulders) discovering that the sharp one generates a much larger wake than the other two. Also the Cd was evaluated, through the Trefftz plane method, obtaining a value of 0.98 for the rounded shoulders and 1.3 for 45-degrees one. The wake develpoment was very similar between the 45 degrees shoulders and rounded one. It was also studied the effect of some angles (camber and toe) on the rounded shoulders wheel, the camber (with an angle of -3.5°) produces an asymmetry of the wake, while the toe angle (with an angle of -0.5°) does not affect too much the results. The comparison with the CFD was made with the wheel without any angles of toe and camber[1]. Similar results were obtained in the wake shape and in the evaluation of the Strohual number. In particular the wake shape (visualized through the velocity contours) was compared with the solution of the RANS equations with Spalart-Allmaras turbulence model. Furthermore, the spectral analysis was compared with the Detatched-Eddy-Simulation. Both the S-A and the spectral analysis show a good match between numerical results and experimental ones.
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da, Cunha Daise Nunes Queiroz. "Properties of Flow Through the Ascending Aorta in Boxer Dogs with Mild Aortic Stenosis: Momentum, Energy, Reynolds Number, Womersley’s, Unsteadiness Parameter, Vortex Shedding, and Transfer Function of Oscillations from Aorta to Thoracic Wall." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243910694.

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Novotný, Vojtěch. "Vliv zakončení výztužné lopatky u Francisovy turbíny na tvorbu Karmánových vírů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232009.

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In the flow past bluff bodies for a certain range of velocity a periodical vortex shedding emerges which is known as von Kármán vortex street. This phenomenon causes the periodical alteration of pressure field which affects the body. Should the vortex shedding frequency be similar to the body natural frequency, the amplitude of vibration significantly increases which can lead to fatigue cracking. In the case of water turbines, this phenomenon often affects the stay vanes. Both the vortex shedding frequency and the lift force amplitude can be influenced by the modification of the trailing edge geometry. The aim of this thesis is to use CFD computation in order to find the optimal geometry of the stay vane trailing edge for the specific Francis turbine unit.
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Wang, Chin-Tsan, and 王金燦. "INVESTIGATION OF LOW-FREQUENCY VARIATIONS EMBEDDED IN VORTEX SHEDDING PROCESS." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/48134667574804811619.

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博士
國立成功大學
航空太空工程學系
88
Experiments were made to study the flow characteristics in the near wake region of a two-dimensional bluff body, namely a trapezoidal cylinder or a circular cylinder. The instantaneous velocity signals obtained at the inner edge of the separated shear layer and in the neighborhood of the rear end of the vortex formation region show the presence of low-frequency variations at the Reynolds numbers of 104. The low frequency variations noted in the velocity signals measured in the near wake and the instantaneous base pressure measured on the bluff body appear to be well correlated. These experimental observations suggest a physical picture that the variations of vortex formation length and base pressure are closely related in a real time manner. Further experiments were made to perform a quantitative analysis on low-frequency variations embedded in the vortex shedding process behind a trapezoidal cylinder. Firstly, the low-passed base pressure fluctuations were examined with different cut-off frequencies. It is interesting to point out that the normalized integral time scales obtained with respect to the non-dimensional cut-off frequencies are collapsed into a single curve, irrespective of the Reynolds numbers and aspect ratio studied. Further, this curve can be expressed in an exponential form. Secondly, time-lag correlation between the base-pressure fluctuations measured at rear surface of bluff body and the velocity fluctuations detected in the near wake region was performed for the signal traces low-passed at different cut-off frequencies. The optimal cut-off frequency was then determined as the one at which the maximum correlation coefficient was occurred. The optimal cut-off frequencies found vary with Reynolds numbers in a linear fashion roughly, hence can be non-dimensionalized and represented by a single value. Finally, the integral time scales associated with the spanwise velocity fluctuations measured at different streamwise locations in the separated shear layer appear to be very close to the integral time scale of the low frequency variations. This strongly suggests that spanwise unsteady motions of the separated shear layers are closely related to mentioned previously the low frequency variations embedded in the vortex shedding process. Meanwhile, the water-tunnel flow visualization photographs reveal that the three-dimensional pattern of the wake flow varies globally in time. Based on these understanding, a physical picture proposed is that the low frequency variations in the vortex shedding process are associated with the global change of the three-dimensional flow pattern with respect to time.
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Wu, Shiang-Jie, and 伍湘杰. "INSTANTANEOUS PROPERTIES OF LOW-FREQUENCY MODULATIONS AND THREE-DIMENSIONALITY ASSOCIATED WITH VORTEX SHEDDING." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/22292835764323400479.

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博士
國立成功大學
航空太空工程學系碩博士班
91
The characteristic behaviors of low-frequency modulations embedded in the vortex shedding process were studied experimentally with a normal plate situated in a low-speed wind tunnel at Re = 1.8×103 to 2.7×104. Hot-wire signals and smoke-wire visualization images were acquired simultaneously to examine the correlation between low-frequency modulations and the vortex formation length. Wavelet analysis was performed to extract the instantaneous properties from the raw hot-wire signals measured in the region upstream of the normal plate model. Results show that the variations of instantaneous vortex shedding frequency appear to be correlated in a negative manner with the low-frequency modulations, that the cross-correlation coefficient can reach —0.7 in value. This substantiates that the low-frequency modulations observed are linked with the vortex shedding process. Further experiments using three hot-wires situated at different spanwise locations at the edge of separated shear layer were performed to investigate the three-dimensionality of the vortex shedding. Meanwhile, the three-dimensionality was evident by the streamwise vortices and the spanwise incoherence in the separated shear layer as visualized using the smoke-wire technique. It is noted that the phase difference of vortex shedding between the two signals with spanwise separation of two characteristic length may reach as high as 35°, at which the amplitude of vortex shedding sensed by either of the hot-wires appeared to be minimal. More specifically, the correlation coefficient of the spanwise phase differences of vortex shedding and the amplitude of vortex shedding reduced from the hot-wire signals measured amounts to —0.4, signifying that the linkage between the low-frequency modulations and three-dimensionality is noticeable. As a result, it is suggested that the low-frequency unsteadiness and the three-dimensionality of vortex shedding are can be described into two modes; namely, the long formation region mode, called mode L, and the short formation region mode, called mode S. In mode S, the instantaneous vortex shedding frequency appears to be higher, the instantaneous vortex shedding amplitude detected at a point outside the separated shear layer is weaker, and the three-dimensionality appears to be more pronounced. The mode S, corresponding to the events of vortex shedding with the spanwise phase difference larger than 20°, occupies less than 5% of the total time measured. In this study, the mode S is referred as the burst mode in vortex shedding.
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Yang, Yi. "Experimental Investigations of Vortex Induced Vibration of A Flat Plate in Pitch Oscillation." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8984.

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A bluff structure placed in a flowing fluid, may be subjected to vortex-induced vibrations (VIV). For a flat plate with only rotational degree of freedom, the VIV is rotational oscillation. Based on the experimental investigation, vortex-induced oscillation of the plate is studied. The Strouhal number is measured from the stationary plate in a low speed steady wind tunnel. A set of vibration tests are conducted to investigate the relationships between shedding frequency and vibration frequency. “lock-in” phenomena is observed with and without large amplitude. An empiricalanalytical model via introducing a nonlinear van der Pol oscillator is developed. This thesis investigates the “lock-in” phenomena of a flat plate in pitch oscillation. Results from wind tunnel experiments on a flat plate indicate the “lock-in” is frequency “lock-in”, resonance which appears large response amplitude occurs in the “lock-in” regime and may be influenced by “lock-in” phenomena.
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Zhan, Bowen, and 詹博文. "Parametrical Analysis For The Numerical Simulation On Staircase-like Vortex Shedding Frequency Downstream Of A Tapered Cylinder." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/07591078184996597290.

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碩士
義守大學
機械與自動化工程學系
100
In this thesis, we studied numerical parameters on the phenomenon of staircase-like vortex shedding frequency axially behind the vortex generator in a duct. Preprocessor was used for non-structural grid construction for calculation, thereafter the mesh exported to CFD software for flow-field analysis and result discussion. This study has successfully simulated the vortex shedding frequency showing staircase-like phenomenon downstream of the tapered cylinder, and it is consistent with the experimental data. To reduce the discrepancy between numerical results and experimental data, parameters, such as grid number, grid distribution and numbers of computational segment for the tapered cylinder axially have been analyzed and discussed. We found those parameters affect the Srouhal number apparently. In addition, the Reynolds number at the entrance, turbulence intensity and turbulence model also play an important role on the numerical results. The case with simulated conditions by non-structured grids of 0.6 million, the nine segments along the tapered cylinder, the LES turbulence model and turbulence intensity of 0.4% show the most favorable results to the literature experimental data among our parametrical studies.
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"The Effect of a Splitter Plate on the Flow around a Surface-Mounted Finite Circular Cylinder." Thesis, 2011. http://hdl.handle.net/10388/ETD-2011-09-171.

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Splitter plates are passive flow control devices for reducing drag and suppressing vortex shedding from bluff bodies. Most studies of splitter plates involve the flow around an “infinite” circular cylinder, however, in the present study the flow around a surface-mounted finite-height circular cylinder, with a wake-mounted splitter plate, was studied experimentally in a low-speed wind tunnel using a force balance and single-component hot-wire anemometry. Four circular cylinders of aspect ratios AR = 9, 7, 5 and 3 were tested for a Reynolds number range of Re = 1.9×10^4 to 8.2×10^4. The splitter plates had lengths, relative to the cylinder diameter, of L/D = 1, 1.5, 2, 3, 5 and 7, thicknesses ranging from T/D = 0.10 and 0.15, and were the same height as the cylinder being tested. The cylinders were partially immersed in a flat-plate turbulent boundary layer, where the range of boundary layer thickness relative to the cylinder diameter was δ/D = 1.4 to 1.5. Measurements were made of the mean drag force coefficient, the Strouhal number at the mid-height position, and the Strouhal number and power spectra along the cylinder height. For all four finite circular cylinders, the splitter plates were effective at reducing the magnitude of the Strouhal number, and weakening or even suppressing vortex shedding, depending on the specific combination of AR and L/D. Compared to the case of an infinite circular cylinder, the splitter plate is less effective at reducing the mean drag force coefficient of a finite circular cylinder. The largest drag reduction was obtained for the cylinder of AR = 9 and splitter plates of L/D = 1 to 3, while negligible drag reduction occurred for the shorter cylinders.
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Books on the topic "Vortex shedding frequency"

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executive, Health and safety. Evaluation of Vortex Shedding Frequency and Dynamic Span Response (Offshore Technology Information). Health and Safety Executive (HSE), 1993.

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M, O'Farrell J., and George C. Marshall Space Flight Center., eds. High frequency flow/structural interaction in dense subsonic fluids. Marshall Space Flight Center, Ala: National Aeronautics and Space Administration, Marshall Space Flight Center, 1995.

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M, O'Farrell J., and United States. National Aeronautics and Space Administration., eds. High frequency flow/structural interaction in dense subsonic fluids. [Huntsville, Ala.]: Rockwell Aerospace, Space Systems Division, Huntsville Operations, 1994.

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Book chapters on the topic "Vortex shedding frequency"

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Zhou, Yunlong, Wenpeng Hong, Guangpei Wang, Bin Sun, and Wei Liu. "Numerical Simulation of Vortex Shedding Frequency and the Oscillation Lift Based on Gas-liquid Two-phase Flow Around Circular Cylinders in the Vertical Pipeline." In Challenges of Power Engineering and Environment, 1361–66. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-76694-0_256.

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Perrot-Minot, C., E. Mignot, N. Riviere, and D. Lopez. "Predicting the vortex shedding frequency at an open-channel lateral cavity." In River Flow 2020, 68–75. CRC Press, 2020. http://dx.doi.org/10.1201/b22619-13.

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Mori, Masaaki. "Wake-Body Interaction Noise Simulated by the Coupling Method Using CFD and BEM." In Vortex Dynamics Theories and Applications. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92783.

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In many engineering applications, obstacles often appear in the wake of obstacles. Vortices shed from an upstream obstacle interact with downstream obstacle and generate noise, for example blades in a turbomachinery, tubes in a heat exchanger, rotating blades like a helicopter and wind turbine and so on. This phenomenon is called wake-body interaction or body-vortex interaction (BVI). The rod-airfoil and airfoil-airfoil configurations are typical models for the wake-body interaction. A rod and an airfoil are immersed upstream of the airfoil. In this chapter, we review the noise mechanism generated by the wake-body interaction and show the numerical results obtained by the coupling method using commercial CFD and acoustic BEM codes. The results show that depending on the spacing between the rod or airfoil and the airfoil, the flow patterns and noise radiation vary. With small spacing, the vortex shedding from the upstream obstacle is suppressed and it results in the suppression of the sound generation. With large spacing, the shear layer or the vortices shed from the upstream obstacle impinge on the downstream obstacle and it results in the large sound generation. The dominant peak frequency of the generated sound varies with increase in the spacing between the two obstacles.
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Kumar, K. Karthik Selva, and L. A. Kumaraswamidhas. "Wake Interaction Using Lattice Boltzmann Method." In Advances in Computer and Electrical Engineering, 223–61. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-4760-0.ch007.

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In this chapter, a brief discussion about the application of lattice Boltzmann method on complex flow characteristics over circular structures is presented. A two-dimensional computational simulation is performed to study the fluid flow characteristics by employing the lattice Boltzmann method (LBM) with respect to Bhatnagar-Gross-Krook (BGK) collision model to simulate the interaction of fluid flow over the circular cylinders at different spacing conditions. From the results, it is observed that there is no significant interaction between the wakes for the transverse spacing's ratio higher than six times the cylinder diameter. For smaller transverse spacing ratios, the fluid flow regimes were recognized with presence of vortices. Apart from that, the drag coefficient signals are revealed as chaotic, quasi-periodic, and synchronized regimes, which were observed from the results of vortex shedding frequencies and fluid structure interaction frequencies. The strength of the latter frequency depends on spacing between the cylinders; in addition, the frequency observed from the fluid structure interaction is also associated with respect to the change in narrow and wide wakes behind the surface of the cylinder. Further, the St and mean Cd are observed to be increasing with respect to decrease in the transverse spacing ratio.
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Conference papers on the topic "Vortex shedding frequency"

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Meng, Ying, Min Lin, and Yong Mei Huang. "Stochastic Energetic Resonance in Detecting Vortex Shedding Frequency." In 2011 Fourth International Workshop on Chaos-Fractals Theories and Applications (IWCFTA). IEEE, 2011. http://dx.doi.org/10.1109/iwcfta.2011.10.

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Wang, Li, Yuan Wang, and Zhiqiang Li. "A method to estimate vortex shedding frequency in turbulence." In 2010 3rd International Congress on Image and Signal Processing (CISP). IEEE, 2010. http://dx.doi.org/10.1109/cisp.2010.5647360.

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Rangarao, Kaluri V., and Venugopal Arumuru. "gold-Fourier Kaluri method for estimating vortex shedding frequency." In 2016 IEEE Region 10 Symposium (TENSYMP ). IEEE, 2016. http://dx.doi.org/10.1109/tenconspring.2016.7519436.

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Miau, J., J. Wang, J. Chou, J. Miau, J. Wang, and J. Chou. "Characteristics of low-frequency variations embedded in vortex shedding process." In 28th Fluid Dynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1997. http://dx.doi.org/10.2514/6.1997-1921.

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Akresh, M., W. D. Walker, and L. Reindl. "Flow measurement using Kalman filter for smoothing vortex shedding frequency." In 2010 IEEE Instrumentation & Measurement Technology Conference Proceedings. IEEE, 2010. http://dx.doi.org/10.1109/imtc.2010.5488084.

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Sondak, Douglas L., and Daniel J. Dorney. "Simulation of Vortex Shedding in a Turbine Stage." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-242.

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Vortex shedding in a turbomachine blade row is affected by the passing of blades in the adjacent downstream blade row, but these effects have not been examined in the literature. A series of flow simulations has been performed to study vortex shedding in a turbine stage, and to quantify the blade interaction effects on the unsteady pressure response. The numerical issues of spatial order of accuracy and the use of Newton subiterations were first investigated. Second order spatial accuracy was shown to be inadequate to accurately model the shedding frequency response and time-averaged base pressure. For the small time step employed for temporal accuracy, Newton iterations were shown to be unnecessary. The effects of the adjacent blade row were examined by comparing the shedding frequency response for the stage simulations to the response for isolated cascades. The vane shedding was shown to occur exactly on a series of harmonics of the blade passing frequency for the stage case, compared to a single predominant frequency for the isolated cascade. Losses were also examined in the wake region. It was shown that close to the trailing edge, losses were mainly due to wake mixing. Farther downstream of the trailing edge, losses were predominantly due to the trailing edge shock wave.
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Wilkins, Stephen J., James D. Hogan, and Joseph W. Hall. "Vortex Shedding in a Yawed-Tandem Circular Cylinder Arrangement." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30313.

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This investigation examines the flow produced by a tandem cylinder system with the downstream cylinder yawed to the mean flow direction. The yaw angle was varied from α = 90° (two parallel tandem cylinders) to α = 60°; this has the effect of varying the local spacing ratio between the cylinders. Fluctuating pressure and hot-wire measurements were used to determine the vortex-shedding frequencies and flow regimes produced by this previously uninvestigated flow. The results showed that the frequency and magnitude of the vortex-shedding varies along the cylinder span depending on the local spacing ratio between the cylinders. In all cases the vortex-shedding frequency observed on the front cylinder had the same shedding frequency as the rear cylinder. In general, at small local spacing ratios the cylinders behaved as a single large body with the shear layers separating from the upstream cylinder and attaching on the downstream cylinder, this caused a correspondingly large, low frequency wake. At other positions where the local span of the tandem cylinder system was larger, small scale vortices began to form in the gap between the cylinders which in turn increased the vortex-shedding frequency. At the largest spacings, classical vortex-shedding persisted in the gap formed between the cylinders and both cylinders shed vortices as separate bodies with shedding frequencies typical of single cylinders. At certain local spacing ratios two distinct vortex-shedding frequencies occurred indicating that there was some overlap in these flow regimes.
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Valipour, Reza, Abbas Yeganeh Bakhtiary, Abbas Ghaheri, and Mohammad H. Kazeminezhad. "Determination of Vortex Shedding Frequency Around Offshore Pipeline Using Unsteady Drag Force Model." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57262.

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Laying offshore pipelines on the uneven sea floor makes the flow turbulence and instability behind the pipe, which is termed as the vortex shedding. Vortex shedding causes a periodic change in the net hydrodynamic pressure around the pipe which in turn increases significantly the potential of fatigue damage of a pipeline at the free span section. This potential especially will rise when the vortex frequency is synchronized with one of the natural frequency of the pipeline span and/or resonance occurs. Thus, during the design process for avoiding resonance, it is crucially important to estimate the frequency of vortex shedding behind the pipeline to limit the length of pipeline on the free span section to its allowable value. Due to the essential role of obtaining vibration drag forces and as a consequence vortex shedding frequency as well as its induced time dependent pressure and velocity distribution, using numerical simulation model for simulation of hydrodynamic forces acting on the pipe become necessary. In the present study, the vortex shedding frequency around an offshore pipeline is calculated by employing the pattern of unsteady dynamic drag force. The unsteady pattern of dynamic drag force is obtained by the model, which is constructed based on the Reynolds Averaged Navier-Stokes (RANS) equations in conjunction with a standard k-ε turbulence model for turbulence closure. As a results of employing this numerical model, vortex shedding frequency, caused by current, around the offshore pipelines is calculated along with its induced turbulent pressure and velocity field. Finally, the results of estimating vortex shedding frequency behind the pipeline is compared with those of experimental data, for different situations of laying offshore pipeline on the seabed and various environmental conditions. The results reveal that the employed numerical model is capable of evaluating vortex shedding frequency around an offshore pipeline.
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Morton, Chris, and Serhiy Yarusevych. "Vortex Shedding From Low Aspect Ratio Dual Step Cylinders." In ASME 2012 Fluids Engineering Division Summer Meeting collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/fedsm2012-72178.

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A low aspect ratio dual-step cylinder is comprised of two cylinders of different diameters (D and d). The large diameter cylinder (D) with low aspect ratio (L/D) is attached to the mid-span of a small diameter cylinder (d). This geometry is relevant to many engineering applications, e.g., finned-tube heat exchangers, underwater cables, and cylindrical support structures. The present study investigates the effect of Reynolds number (ReD) and L/D on dual step cylinder wake development for 1050 ≤ ReD ≤ 2100, D/d = 2, and 0.2 < L/D ≤ 3. Experiments have been performed in a water flume facility utilizing flow visualization, Laser Doppler Velocimetry (LDV), and Particle Image Velocimetry (PIV). The results show that vortex shedding occurs from the large and small diameter cylinders at distinct frequencies for L/D ≥ 1 & ReD = 2100 and L/D ≥ 2& ReD = 1050. At these higher aspect ratios investigated, large cylinder vortices predominantly form closed vortex loops in the wake and small cylinder vortices form half-loop vortex connections. In contrast, at lower aspect ratios, vortex shedding from the large cylinder ceases, with the dominant frequency centred-activity in the large cylinder wake attributed to the passage of vortex filaments connecting small cylinder vortices. The presence of the large cylinder distorts the vortex filaments causing cyclic vortex dislocations accompanied by the formation of half-loop vortex connections. Increasing L/D decreases the frequency of occurrence of vortex dislocations and increases the dominant frequency in the large cylinder wake. The results also show that the Reynolds number has a substantial effect on wake vortex shedding frequency, which is more profound than that expected for a uniform cylinder.
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Sweeney, C., and C. Meskell. "Numerical Simulation of Vortex Shedding in Tube Arrays." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32788.

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Vortex shedding may occur in tube arrays, resulting in strong excitation forces at discrete frequencies. In the past the Strouhal numbers governing vortex shedding in these systems were determined experimentally. This paper presents a method of numerical simulation for the unsteady flow through a rigid normal triangular tube array and hence provides a method of determining both the frequency of vortex shedding and the magnitude of the fluid forces acting on the tubes. The technique used is based on a discrete vortex method similar to the cloud-in-cell approach which has been applied to flow problems for small numbers of cylinders. However, in the current implementation the flow velocity calculation is carried out on an unstructured grid using a finite element discretization. Thus, the complex geometry associated with a tube array can be easily accomodated. The method, referred to as the “Cloud-in-element” method, is validated for the standard case of flow over a single cylinder and then applied to flow through a normal triangular array with a pitch diameter of 1.6. The Reynolds number is 2200. The Stouhal number obtained from the numerical simulation is 1.27, which is within 6% of the value available in the literature. Qualitatively, the vortex shedding pattern obtained is in agreement with published flow visualization.
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