Journal of Fluids Engineering-Transactions of the Asme最新文献_第8页

Unsteady Hemodynamics in Intracranial Aneurysms With Varying Dome Orientations 颅内不同圆顶动脉瘤的不稳定血流动力学

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4049932

A. Usmani, K. Muralidhar

{"title":"Unsteady Hemodynamics in Intracranial Aneurysms With Varying Dome Orientations","authors":"A. Usmani, K. Muralidhar","doi":"10.1115/1.4049932","DOIUrl":"https://doi.org/10.1115/1.4049932","url":null,"abstract":"\u0000 Fluid loading within an intracranial aneurysm is difficult to measure but can be related to the shape of the flow passage. The outcome of excessive loading is a fatal hemorrhage, making it necessary for early diagnosis. However, arterial diseases are asymptomatic and clinical assessment is a challenge. A realistic approach to examining the severity of wall loading is from the morphology of the aneurysm itself. Accordingly, this study compares pulsatile flow (Reynolds number Re = 426, Womersley number Wo = 4.7) in three different intracranial aneurysm geometries. Specifically, the spatio-temporal movement of vortices is followed in high aspect ratio aneurysm models whose domes are inclined along with angles of 0, 45, and 90 deg relative to the plane of the parent artery. The study is based on finite volume simulation of unsteady three-dimensional flow while a limited set of particle image velocimetry experiments have been carried out. Within a pulsatile cycle, an increase in inclination (0–90 deg) is seen to shift the point of impingement from the distal end toward the aneurysmal apex. This change in flow pattern strengthens helicity, drifts vortex cores, enhances spatial displacement of the vortex, and generates skewed Dean's vortices on transverse planes. Patches of wall shear stress and wall pressure shift spatially from the distal end in models of low inclination (0–45 deg) and circumscribe the aneurysmal wall for an inclination angle of 90 deg. Accordingly, it is concluded that high angles of inclination increase rupture risks while lower inclinations are comparatively safe.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76932379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Enhancing Cryogenic Cavitation Prediction Through Incorporating Modified Cavitation and Turbulence Models 利用改进的空化和湍流模型增强低温空化预测

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4050056

Shanxiu Sun, Jingyuan Sun, Wanyou Sun, Peng Song

{"title":"Enhancing Cryogenic Cavitation Prediction Through Incorporating Modified Cavitation and Turbulence Models","authors":"Shanxiu Sun, Jingyuan Sun, Wanyou Sun, Peng Song","doi":"10.1115/1.4050056","DOIUrl":"https://doi.org/10.1115/1.4050056","url":null,"abstract":"\u0000 Cavitating flow prediction is essential for designing cavitation-resistant hydraulic machines. Despite the advances achieved in normal-temperature cavitation prediction, cryogenic cavitation prediction has remained a challenging task in which thermal effects play a significant role. This study aims to enhance the prediction of cryogenic cavitation, and both the cavitation and turbulence models are improved simultaneously. The original cavitation model embedded in the CFX flow solver is modified by incorporating additional source terms (such as mass and heat transfer rates) for dual evaporation and condensation processes. The renormalization group k–ε turbulence model is modified on the basis of the filter-based turbulence model and density correction method to permit a smooth prediction of turbulence eddy viscosity, which mitigates the overestimation of the turbulence length scale in the cryogenic cavity (which is intrinsic to the original renormalization group k–ε turbulence model). The modified cavitation and turbulence models are implemented through CFX Expression Language (CEL) within the CFX frame. To verify the modified models and the enhancement of cryogenic cavitation prediction, Hord's liquefied nitrogen (LN2) and liquefied hydrogen (LH2) experiments over a hydrofoil and ogive are used, and cavitating flow simulation is conducted for each of the test cases. When using the modified models, the predicted temperature and pressure curves agree well with the measured values, and the predicted cavity lengths are much closer to the measured lengths. It is proven that the cryogenic cavitating flow can be well depicted by the modified models.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86579888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

On the Vortical Characteristics of Horn-Like Vortices in Stator Corner Separation Flow in an Axial Flow Pump 轴流泵定子角分离流中角状涡的垂直特性研究

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4049687

Chaoyue Wang, Fujun Wang, Xie Lihua, Benhong Wang, Z. Yao, R. Xiao

{"title":"On the Vortical Characteristics of Horn-Like Vortices in Stator Corner Separation Flow in an Axial Flow Pump","authors":"Chaoyue Wang, Fujun Wang, Xie Lihua, Benhong Wang, Z. Yao, R. Xiao","doi":"10.1115/1.4049687","DOIUrl":"https://doi.org/10.1115/1.4049687","url":null,"abstract":"\u0000 The phenomenon of horn-like vortex in stator corner separation flow in an axial flow pump was first reported by Wang et al. (2020, “Investigation on the Horn-Like Vortices in Stator Corner Separation Flow in an Axial Flow Pump,” ASME J. Fluids Eng., 142(7), p. 071208), and the associated external features were preliminarily presented. However, internal vortical characteristics of horn-like vortices, including the distributions of swirling strength, the deformation mechanism of vortex tube and the correlation with pressure fluctuation surge, are not revealed. In this paper, the newly developed vorticity decomposition approach is introduced, and thus more novel quantitative results are provided for the physics of horn-like vortex evolution in an axial flow pump. First, the distributions of absolute swirling strength, relative swirling strength and Liutex spectrum are presented to outline the vortical features of the horn-like vortex fields. Second, the deformation mechanism of the horn-like vortex tube is revealed. It is found that the horn-like vortex spatial evolution can be described by the deformation terms (Liutex stretching term, Liutex dilatation term, and curl term of the pseudo-Lamb vector) controlling the Liutex transport process. These terms constantly act on the horn-like vortex tube in an almost independent way, causing its continuous deformations in the transit process. Third, the quantitative correlation between horn-like vortex transit and pressure fluctuation surge is given. It is proved that periodic vortex transit can cause severe pressure fluctuation that is much larger than that induced by rotor–stator interaction. From multiple perspectives, a clearer evolution process of the horn-like vortex is outlined, which is conducive to controlling the corner separation flows and improving the stability of large-capacity and low-head pumping stations.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74937631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

Two-Dimensional Numerical Analysis of Non-Darcy Flow Using the Lattice Boltzmann Method: Pore-Scale Heterogeneous Effects 格子玻尔兹曼法非达西流动的二维数值分析:孔隙尺度非均质效应

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4049689

Y. Takeuchi, Junichiro Takeuchi, T. Izumi, M. Fujihara

{"title":"Two-Dimensional Numerical Analysis of Non-Darcy Flow Using the Lattice Boltzmann Method: Pore-Scale Heterogeneous Effects","authors":"Y. Takeuchi, Junichiro Takeuchi, T. Izumi, M. Fujihara","doi":"10.1115/1.4049689","DOIUrl":"https://doi.org/10.1115/1.4049689","url":null,"abstract":"\u0000 This study simulates pore-scale two-dimensional flows through porous media composed of circular grains with varied pore-scale heterogeneity to analyze non-Darcy flow effects on different types of porous media using the lattice Boltzmann method. The magnitude of non-Darcy coefficients and the critical Reynolds number of non-Darcy flow were computed from the simulation results using the Forchheimer equation. Although the simulated porous materials have similar porosity and representative grain diameters, larger non-Darcy coefficients and an earlier onset of non-Darcy flow were observed for more heterogeneous porous media. The simulation results were compared with existing correlations to predict non-Darcy coefficients, and the large sensitivity of non-Darcy coefficients to pore-scale heterogeneity was identified. The pore-scale heterogeneity and resulting flow fields were evaluated using the participation number. From the computed participation numbers and visualized flow fields, a significant channeling effect for heterogeneous media in the Darcy flow regime was confirmed compared with that for homogeneous media. However, when non-Darcy flow occurs, this channeling effect was alleviated. This study characterizes non-Darcy effect with alleviation of the channeling effect quantified with an increase in participation number. Our findings indicate a strong sensitivity of magnitude and onset of non-Darcy effect to pore-scale heterogeneity and imply the possibility of evaluating non-Darcy effect through numerical analysis of the channeling effect.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82522970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Investigation of Flow Separation Characteristics in a Pump as Turbines Impeller Under the Best Efficiency Point Condition 最佳效率点工况下泵作为涡轮叶轮的流动分离特性研究

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4049816

Tong Lin, Xiaojun Li, Zuchao Zhu, R. Xie, Yan-Jhang Lin

{"title":"Investigation of Flow Separation Characteristics in a Pump as Turbines Impeller Under the Best Efficiency Point Condition","authors":"Tong Lin, Xiaojun Li, Zuchao Zhu, R. Xie, Yan-Jhang Lin","doi":"10.1115/1.4049816","DOIUrl":"https://doi.org/10.1115/1.4049816","url":null,"abstract":"\u0000 The impeller, which is the main energy conversion component of a pump as turbine (PAT), is designed for pumping mode, and its internal flow characteristics are quite complicated even at the best efficiency point (BEP) of the turbine mode. This study aims to investigate the flow separation characteristics in a PAT impeller under the BEP condition by numerical method. The hydraulic performance and transient pressure characteristics of PAT predicted numerically were verified through experimentation. The surface friction lines and flow topological structure were applied to diagnose the flow separation at the surface of the blade. The relationship between flow topological structure and vortex in the impeller and static pressure at the blade were analyzed. Analysis results show that the backflow and open flow separation are observed significantly in the leading region and near the shroud of the trailing region of suction side. The passage vortex always appears near the spiral node. The saddle point and spiral node correspond to the peak position of adverse pressure and the lowest position between two peak values of the static pressure of the blade, respectively. The inflow conditions of blade and shape of the trailing edge significantly influence the flow separations in the impeller.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84796033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 11

On the Pressure Losses Through Multistage Perforated Plates 关于多级穿孔板的压力损失

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4049937

David Rosa, M. Rossi, G. Ferrarese, S. Malavasi

{"title":"On the Pressure Losses Through Multistage Perforated Plates","authors":"David Rosa, M. Rossi, G. Ferrarese, S. Malavasi","doi":"10.1115/1.4049937","DOIUrl":"https://doi.org/10.1115/1.4049937","url":null,"abstract":"\u0000 Perforated plates are commonly used for flow control in pressurized systems. In different industrial applications, these devices are also used in series (multistage perforated plates) to manage high pressure drop or reduce cavitation occurrence in industrial pipes and enhance efficiency of gas turbines in power plants. Based on analysis of literature and modeling considerations, a functional relationship that describes the dimensionless pressure loss for multistage perforated plates is proposed in this paper. Moreover, numerical investigation of the influence of the spacing between perforated plates for two identical-stage plates with aligned and misaligned holes is carried out by simulating a wide range of Reynolds number in turbulent flow regime. The obtained results include the trend of the pressure loss coefficient as the spacing between the two perforated plates varies for both cases of aligned and misaligned holes. The numerical achievements also show that for small spacing, the pressure loss coefficient is very different from that caused by two independent plates and is strongly influenced by the alignment between the holes of the two plates. By increasing the spacing, the behavior of the losses caused by the two-stage plates tends to that of two independent plates. A critical spacing between the plates has also been defined, beyond which the pressure losses are independent from the alignment of the holes.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80975461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Experimental Measurements of the Wake of a Sphere at Subcritical Reynolds Numbers 亚临界雷诺数下球面尾迹的实验测量

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4049936

R. Muyshondt, Thien Nguyen, Y. Hassan, N. Anand

{"title":"Experimental Measurements of the Wake of a Sphere at Subcritical Reynolds Numbers","authors":"R. Muyshondt, Thien Nguyen, Y. Hassan, N. Anand","doi":"10.1115/1.4049936","DOIUrl":"https://doi.org/10.1115/1.4049936","url":null,"abstract":"\u0000 This work experimentally investigated the flow phenomena and vortex structures in the wake of a sphere located in a water loop at Reynolds numbers of Re = 850, 1,250, and 1,700. Velocity fields in the wake region were obtained by applying the time-resolved stereoscopic particle image velocimetry (TR-SPIV) technique. From the acquired TR-SPIV velocity vector fields, the statistical values of mean and fluctuating velocities were computed. Spectral analysis, two-point velocity–velocity cross-correlation, proper orthogonal decomposition (POD) and vortex identification analyses were also performed. The velocity fields show a recirculation region that decreases in length with an increase of Reynolds numbers. The power spectra from the spectral analysis had peaks corresponding to a Strouhal number of St = 0.2, which is a value commonly found in the literature studies of flow over a sphere. The two-point cross-correlation analysis revealed elliptical structures in the wake, with estimated integral length scales ranging between 12% and 63% of the sphere diameter. The POD analysis revealed the statistically dominant flow structures that captured the most flow kinetic energy. It is seen that the flow kinetic energy captured in the smaller scale flow structures increased as Reynolds number increased. The POD modes contained smaller structure as the Reynolds number increased and as mode order increased. In addition, spectral analysis performed on the POD temporal coefficients revealed peaks corresponding to St = 0.2, similar to the spectral analysis on the fluctuating velocity. The ability of POD to produce low-order reconstructions of the flow was also utilized to facilitate vortex identification analysis, which identified average vortex sizes of 0.41D for Re1, 0.33D for Re2, and 0.32D for Re3.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90018063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Analysis on the Inception of the Magnetohydrodynamic Flow Instability in the Annular Linear Induction Pump Channel 环形直线感应泵通道内磁流体动力流动不稳定性的起源分析

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4050008

Zhao Ruijie, D. Xiaohui, Pan Qiang, Zhang Desheng, B. Esch

{"title":"Analysis on the Inception of the Magnetohydrodynamic Flow Instability in the Annular Linear Induction Pump Channel","authors":"Zhao Ruijie, D. Xiaohui, Pan Qiang, Zhang Desheng, B. Esch","doi":"10.1115/1.4050008","DOIUrl":"https://doi.org/10.1115/1.4050008","url":null,"abstract":"\u0000 Flow instability is the intricate phenomenon in the annular linear induction pump (ALIP) when the pump runs at off-design working condition. A three-dimensional (3D) numerical model is built to simulate the flow in the pump channel. The pump heads at different flow rates are accurately predicted by comparing with experiment. The simulation results show the fluid velocity is circumferentially nonuniform in the pump channel even at the nominal flow rate. The flow in the middle sector continuously decelerates to nearly zero with the reducing flow rate. Reversed flow occurs in the azimuthal plane, followed by vortex flow. The reason for the heterogeneous velocity field is attributed to the mismatch between nonuniform Lorentz force and relatively even pressure gradient. It is seen that the flow in the region of small Lorentz force has to sacrifice its velocity to match with the pressure gradient. An analytic expression of the axial Lorentz force is then developed and it is clearly demonstrated the Lorentz force could be influenced by the profiles of velocity and radial magnetic flux density. The coupling between velocity and magnetic field is studied by analyzing the magnitudes of different terms in the dimensionless magnetic induction equation. It is found the dissipation term is determined by not only the magnetic Reynolds number but also the square of wave number of the disturbance in each direction. The smaller disturbing wave number weakens the dissipating effect, resulting in the larger nonuniform magnetic field and axial Lorentz force.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74461997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Impact of Rotational Speed on Turbocharger Compressor Surge Through Particle Image Velocimetry1 利用粒子图像测速技术研究转速对涡轮增压器压气机喘振的影响

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-06-01 DOI: 10.1115/1.4049838

D. Banerjee, R. Dehner, A. Selamet, Keith Miazgowicz

{"title":"Impact of Rotational Speed on Turbocharger Compressor Surge Through Particle Image Velocimetry1","authors":"D. Banerjee, R. Dehner, A. Selamet, Keith Miazgowicz","doi":"10.1115/1.4049838","DOIUrl":"https://doi.org/10.1115/1.4049838","url":null,"abstract":"\u0000 Stereoscopic particle image velocimetry is used to characterize the variation of the turbocharger compressor inlet velocity field as a function of rotational speed, with an emphasis on surge. While the velocity magnitudes at choke or mild surge increased with rotational speed, the velocity profiles remained qualitatively similar. The variation in deep surge flow field with shaft speed, however, was more substantial. At 80 krpm, the overall flow field was comparable at different time instances (at different points on the surge cycle): the core flow near the duct center was always directed into the impeller, whereas reversed flow occupied an annular region near the periphery in nearly all time instances. However, at 140 krpm, while the negative flow rate (cross-sectional average flow is directed out of the inducer back into the inlet duct) portion of the surge cycle was still similar to the overall surge flow field at 80 krpm, over a substantial part of the positive flow rate (cross-sectional average flow is directed into the impeller) portion of the surge cycle, there was no sign of reversed flow within the visualization domain. As the rotational speed was increased, the surge loop (obtained by combining the particle image velocimetry (PIV) and pressure transducer data) extended over a wider portion of the compressor map with higher maximum (positive) and minimum (negative) flow rates, along with higher amplitude pressure fluctuations. The mean amplitude of mass flow rate and pressure ratio fluctuations at deep surge increased in nearly a quadratic fashion with rotational speed.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77452731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fluid Dynamics Behind a Circular Cylinder Embedded with an Active Flapping Jet Actuator 嵌入主动扑动射流作动器的圆柱后流体动力学

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-31 DOI: 10.1115/1.4051312

D. Gao, X. Chang, Guanbin Chen, Wenli Chen

{"title":"Fluid Dynamics Behind a Circular Cylinder Embedded with an Active Flapping Jet Actuator","authors":"D. Gao, X. Chang, Guanbin Chen, Wenli Chen","doi":"10.1115/1.4051312","DOIUrl":"https://doi.org/10.1115/1.4051312","url":null,"abstract":"\u0000 The effects of an active flapping jet actuator on the wake flow dynamics behind a circular cylinder in wind tunnel tests were investigated. An active flapping jet actuator was embedded in the cylinder in advance to invoke a spontaneous flapping jet into the cylinder's wake. The experiment, which was performed in a wind tunnel with a Reynolds number of Re = 1.99 × 104, was based on the oncoming wind speed, cylinder diameter, and kinematic viscosity of the air at the laboratory's temperature. The flow field structures behind the cylinder model with different dimensionless jet momentum coefficients, Cu, were obtained using the high-speed particle image velocimetry technique. The proper orthogonal decomposition (POD) method was used to represent the variation of the POD mode energy, mode coefficients, and the reconstructed spreading vorticity. The dynamic temporal evolution and time-averaged results in the near wake region of the cylinder with and without active flapping-jet control were calculated and analyzed to illustrate the rich phenomena produced by, and the control effect of, the flapping jet. For Cu values up to 0.0554, the periodic vortex shedding was pushed to farther wakes. Meanwhile, the time-averaged wake changed considerably, and the distributions of the turbulent kinetic energy and Reynolds shear stress decreased significantly. A data-driven dynamic mode decomposition method was used to extract the coherent structure of the wake of the cylinder embedded with the flapping jet actuator. The Strouhal number of the main mode of the Cu = 0.0865 case was different from the natural case.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76967625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5