Journal of Fluids Engineering-Transactions of the Asme最新文献_第9页

Flow Characterization of Bluff Bodies: A Two-Dimensional Transformation From Square to Triangular Cylinder 钝体的流动特性:从正方形到三角形圆柱体的二维变换

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-31 DOI: 10.1115/1.4051310

R. Borah, Siddhant Jain, Dyuman V. Joshi, U. Saha

{"title":"Flow Characterization of Bluff Bodies: A Two-Dimensional Transformation From Square to Triangular Cylinder","authors":"R. Borah, Siddhant Jain, Dyuman V. Joshi, U. Saha","doi":"10.1115/1.4051310","DOIUrl":"https://doi.org/10.1115/1.4051310","url":null,"abstract":"\u0000 In the present study, two-dimensional unsteady, incompressible flow around a square body that is being transformed into a vertex oriented towards the flow configuration of a triangular body is numerically investigated at Re =100 using ANSYS FLUENT 19.0 software. The purpose is to explore the effect of this transformation on the wake characteristics of a square body with l/d = 1 to a triangular body with l/d = 0; where l is the length of lateral and front surface, and d is the body height. The effect on the flow behavior caused by the leading-edge transformation from the prospect of wake width, recirculation length and stagnation pressure difference is discussed. It is seen that as the l/d ratio decreases, the vortex strength increases which is attributed to the higher stagnation pressure difference value resulting in more intense rolling of the shedding vortex and a smaller wake width. For lower l/d, the fluid traverses a longer distance along the lateral surfaces resulting in greater loss of momentum and hence the lower vortex formation length. The mean drag coefficient is found to be minimum for l/d = 0.75 with stagnation pressure difference and recirculation length being the more dominating factor on this variation. The flow in all the cases separates at the rear surface and the general trend of decrease in drag coefficient with decrease in wake width is not followed. However, such modification leads to better aerodynamic outcome by weakening the periodic drag and lift forces.","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":"77723561","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: 1

Vortex Pump as Turbine for Energy Recovery in Viscous Fluid Flows with Reynolds Number Effect 涡流泵作为涡轮用于雷诺数效应下粘性流体流动的能量回收

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-31 DOI: 10.1115/1.4051313

Wenguang Li

{"title":"Vortex Pump as Turbine for Energy Recovery in Viscous Fluid Flows with Reynolds Number Effect","authors":"Wenguang Li","doi":"10.1115/1.4051313","DOIUrl":"https://doi.org/10.1115/1.4051313","url":null,"abstract":"\u0000 A vortex pump with a specific speed of 76 was studied in its turbine mode by using Fluent 6.3 based on the steady, three-dimensional, incompressible, Reynolds time-averaged Navier-Stokes equations, standard k-? turbulence model and non-equilibrium wall function in multiple reference system. The performance and flow structure of six liquids with different densities and viscosities were characterized, and the hydraulic, volumetric, and mechanical losses were discomposed. The correction factors of flow rate, head, shaft-power, efficiency, and disc friction power in turbine mode were correlated with impeller Reynolds number at three operational points. The conversion factors of flow rate, head, efficiency from the pump mode to the turbine mode were expressed with Reynolds number and compared with the counterparts of centrifugal pumps in the literature. It was indicated that the vortex pump can produce power as a turbine but becomes inefficient with increasing viscosity or decreasing impeller Reynolds number, especially as the number is smaller than 104 due to increased hydraulic, volumetric, and mechanical power losses. A vortex structure with radial, axial, and meridian vortices occurs in the impeller at different flow rates and viscosities. The incidence at blade leading edge and deviation angle at blade trailing edge depend largely on flow rate and viscosity. The impeller should be modified to improve its hydraulic performance under highly viscous fluid flow conditions. The entropy generation rate method cannot demonstrate the change in hydraulic loss with viscosity when the Reynolds number is below 104.","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":"84199697","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

Hydrodynamic Optimization of Coaxial Ground Heat Exchanger 同轴地热交换器的水动力优化

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-06 DOI: 10.1115/1.4051080

J. Wojtkowiak

引用次数: 0

Special Issue on the 2020 Fluids Engineering Division Summer Meeting 2020年流体工程部门夏季会议特刊

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-06 DOI: 10.1115/1.4051071

F. Battaglia

引用次数: 0

Experimental Study on Propagation of Particle-Bearing Jets in a Confined Geometry 含粒子射流在受限几何空间内传播的实验研究

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-06 DOI: 10.1115/1.4051076

Mohnish Kapil, S. Balasubramanian

{"title":"Experimental Study on Propagation of Particle-Bearing Jets in a Confined Geometry","authors":"Mohnish Kapil, S. Balasubramanian","doi":"10.1115/1.4051076","DOIUrl":"https://doi.org/10.1115/1.4051076","url":null,"abstract":"\u0000 The spreading characteristics of particle-bearing jets down a gentle slope in a uniform ambient with confined side-walls are reported through a series of laboratory experiments. A round water jet is mixed with solid particles having particle volume fraction ranging between 0% and 0.4%. The jet Reynolds number is varied between Re = 3000 and 8000. We document that the jet front position varies with time t as xf∝t2/3. The jet front propagation in the presence of side-walls is found to be higher than the unconfined case and is attributed to the recirculation due to the confinement that increases the flow inertia and accelerates the flow. The jet propagation is found to be self-similar and is unaffected by the variations in the volume fraction and Re. The sediment pattern near the source, formed by the settling of the particles, exhibits a similar tear-drop shape, which is well-predicted using the unconfined jet theory that assumes a Gaussian velocity profile. The results have implication in engineering and environmental flows, where higher jet propagation rate for confined jets should be modeled accurately without modifying the sedimentation dynamics.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86878948","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

Hybrid RANS–LES Simulation of Turbulent Heat Transfer in a Channel Flow With Imposed Streamwise or Spanwise Mean Temperature Gradient 施加沿流或沿展平均温度梯度的通道流动湍流传热的混合ranss - les模拟

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-06 DOI: 10.1115/1.4051067

Olalekan O. Shobayo, D. K. Walters

{"title":"Hybrid RANS–LES Simulation of Turbulent Heat Transfer in a Channel Flow With Imposed Streamwise or Spanwise Mean Temperature Gradient","authors":"Olalekan O. Shobayo, D. K. Walters","doi":"10.1115/1.4051067","DOIUrl":"https://doi.org/10.1115/1.4051067","url":null,"abstract":"\u0000 Computational fluid dynamics (CFD) results are presented for turbulent flow and heat transfer in a plane channel. This study investigates an idealized fully developed planar channel flow case for which the mean velocity gradient is nonzero only in the wall-normal direction, and the mean temperature gradient is imposed to be uniform and nonzero in the streamwise or spanwise direction. The objective is to evaluate the accuracy of turbulent heat flux predictions using hybrid Reynolds-averaged Navier–Stokes (RANS)–large eddy simulation (LES) models in wall-bounded flows. Results are obtained at Prandtl number of 0.71 and Reynolds number of 180 based on wall friction velocity and channel half-height and are compared to available direct numerical simulation (DNS) data and to a well-validated RANS model (k–ω shear-stress transport (SST)). The specific hybrid RANS–LES (HRL) models investigated include delayed detached eddy simulation (DDES), improved delayed detached eddy simulation (IDDES), and dynamic hybrid RANS–LES (DHRL). The DHRL model includes both the standard formulation that has been previously documented in the literature as well as a modified version specifically developed to improve predictive capability for flows in which the mean velocity and mean temperature gradients are not closely aligned. The modification consists of using separate RANS-to-LES blending parameters in the momentum and energy equations. Results are interrogated to evaluate the performance of the three different model types and specifically to evaluate the performance of the new modified DHRL variant compared with the baseline version.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87129399","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

Assessment of a Homogeneous Model for Simulating a Cavitating Flow in Water Under a Wide Range of Temperatures 大范围温度下模拟水中空化流动的均匀模型的评价

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-06 DOI: 10.1115/1.4051078

A. D. Le, Hoang Phan Thanh

{"title":"Assessment of a Homogeneous Model for Simulating a Cavitating Flow in Water Under a Wide Range of Temperatures","authors":"A. D. Le, Hoang Phan Thanh","doi":"10.1115/1.4051078","DOIUrl":"https://doi.org/10.1115/1.4051078","url":null,"abstract":"\u0000 The cavitating flow on a NACA0015 hydrofoil in water under a wide range of temperatures is simulated with or without noncondensation gas using a homogeneous model. Our simplified thermodynamic model is coupled with governing equations to capture the latent heat transfer in cavitation. A numerical evaluation proves its applicability through a comparison with experimental data. As a result, the numerical evaluation illustrates good agreement with measured data for both simulations with or without noncondensation gas. The expected prediction pressure coefficient is in better agreement with experimental data for high-temperature water compared to the existing numerical data. Although the temperature depression inside the cavity is confirmed numerically, the thermodynamic effect shows a weak impact on the cavitation behavior near the boiling temperature (100 °C). The cavitating flow can therefore be simulated reasonably by an isothermal approach at a reasonable cost. The suppression of the void fraction as the water temperature increases is deduced by the flow behavior rather than the thermodynamic effect. Finally, the impact of a noncondensation gas is closely linked to the thermodynamic properties of the water and the flow behavior. The attached cavity position shifts closer to the hydrofoil leading edge significantly in high-temperature water, while an identical position is reproduced for room temperature conditions in comparison with the simulation without a noncondensation gas.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81534503","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: 8

A Modified Chezy Formula for One-Dimensional Unsteady Frictional Resistance in Open Channel Flow 明渠流动一维非定常摩擦阻力的修正Chezy公式

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-01 DOI: 10.1115/1.4049681

Junwei Zhou, W. Bao, G. Tick, H. Moftakhari, Yu Li, Li Cheng

{"title":"A Modified Chezy Formula for One-Dimensional Unsteady Frictional Resistance in Open Channel Flow","authors":"Junwei Zhou, W. Bao, G. Tick, H. Moftakhari, Yu Li, Li Cheng","doi":"10.1115/1.4049681","DOIUrl":"https://doi.org/10.1115/1.4049681","url":null,"abstract":"\u0000 It has been observed in literature that for unsteady flow conditions the one-to-one relationships between flow depth, cross-sectional averaged velocity, and frictional resistance as determined from steady uniform flow cases may not be appropriate for these more complex flow systems. Thus, a general friction resistance formula needs to be modified through the addition of new descriptive terms to account for flow unsteadiness, in order to eliminate errors due to uniform and steady-flow assumptions. An extended Chezy formula incorporating both time and space partial derivatives of hydraulic parameters was developed using dimensional analysis to investigate the relationship between flow unsteadiness and friction resistance. Results show that the proposed formula performs better than the traditional Chezy formula for simulating real hydrograph cases whereby both formula coefficients are individually identified for each flood event and coefficients are predetermined using other flood events as calibration cases. Although the extended Chezy formula as well as the original Chezy formula perform worse with the increasing degree of flow unsteadiness, its results are less dramatically affected by unsteadiness intensity, thereby improving estimations of flood routing. As a result, it tends to perform much better than traditional Chezy formula for severe flood events. Under more complex conditions whereby peak flooding events may occur predominantly under unsteady flow, the extended Chezy model may provide as a valuable tool for researchers, practitioners, and water managers for assessing and predicting impacts for flooding and for the development of more appropriate mitigation strategies and more accurate risk assessments.","PeriodicalId":54833,"journal":{"name":"Journal of Fluids Engineering-Transactions of the Asme","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79890344","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: 1

Numerical Calibration of Three-Dimensional Printed Five-Hole Probes for the Transonic Flow Regime 三维印刷五孔探头跨声速流态的数值标定

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-01 DOI: 10.1115/1.4049680

Maximilian Passmann, S. Wiesche, F. Joos

引用次数: 1

Propagation of Shock Wave at the Cavitation Bubble Expansion Stage Induced by a Nanosecond Laser Pulse 纳秒激光脉冲诱导空化气泡膨胀阶段激波的传播

IF 2 3区工程技术

Journal of Fluids Engineering-Transactions of the Asme Pub Date : 2021-05-01 DOI: 10.1115/1.4049933

Siyuan Geng, Z. Yao, Q. Zhong, Yuxin Du, R. Xiao, Fujun Wang

引用次数: 10