Volume 1: Fluid Mechanics最新文献_第6页

Vortical Structure Characteristics of Transitional Flow Through Porous Media 多孔介质过渡流的涡旋结构特征

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-5094

R. Ziazi, J. Liburdy

{"title":"Vortical Structure Characteristics of Transitional Flow Through Porous Media","authors":"R. Ziazi, J. Liburdy","doi":"10.1115/ajkfluids2019-5094","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5094","url":null,"abstract":"\u0000 The flow characteristics in the inertial Reynolds number regime are investigated in a mono-dispersed random pack porous media. Time-resolved particle image velocimetry (PIV) is used to visualize the velocity field in a low aspect ratio bed with 15 mm glass beads. An aqueous solution of Ammunium Thiocynante is used as the working fluid to facilitate matching the solid-fluid refractiveindices. In order to illuminate the inertial regime characteristics, two pore Reynolds number of 100 and 270 are examined. Also, due to the random nature of the packing several pore geometries are compared to identify local scaling used to define the inertial regime effects. Discrete vortical flow structures are evaluated using LES (lowpass filtering) decomposition, in conjunction with criticalpoint analysis of the local velocity gradient tensor. The identified scales associated with the vortical elements are compared based on Reynolds number and pore geometry. Implementing circulation as an integral measure of all vortical structures locally at the pore-scale level demonstrated a linear attitude over the range of Reynolds numbers. Evolution of inertial effects within pore-regions are indicated to be the primary driving mechanism for the emergence of swirling structures passing through the PIV field of view at the onset of turbulence.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131046072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Wake Characteristics Comparison Between Isolated and Pair Configurations of Marine Hydrokinetic Crossflow Turbines at Low Reynolds Numbers 低雷诺数下海洋水动力横流涡轮独立与对对结构的尾迹特性比较

Volume 1: Fluid Mechanics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-4741

Ivan H. Alayeto, Minh N. Doan, Kana Kumazawa, S. Obi

{"title":"Wake Characteristics Comparison Between Isolated and Pair Configurations of Marine Hydrokinetic Crossflow Turbines at Low Reynolds Numbers","authors":"Ivan H. Alayeto, Minh N. Doan, Kana Kumazawa, S. Obi","doi":"10.1115/ajkfluids2019-4741","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4741","url":null,"abstract":"\u0000 Wake characteristics and power coefficient of laboratory scaled marine hydrokinetic cross flow turbines were studied both experimentally and numerically. Single and turbine pair configurations were experimentally tested in a 3.5 m long, 0.3 m wide and 0.15 m deep water channel facility. Each turbine was built with three straight NACA0012 blades with chord 2.54 cm and 6.828 cm diameter, corresponding to a solidity of 1.2. The Reynolds number associated with the velocity given by the water pump and blade chord oscillated near 7000. Empirical power measurement was obtained multiplying the average torque by average rotational velocity. These measurements were obtained with a magnetic hysteresis brake utilized as control system and a Hall effect sensor used as speed transducer, respectively. Wake velocity profile was obtained by image processing of Particle Image Velocimetry (PIV) measurements at different positions. The empirical results were contrasted with numerical computational fluid dynamics (CFD) simulations carried out with Salome and OpenFoam. The computational model solved the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations in 2 dimensions using the turbulence models k-ω Shear Stress Transport (SST) and Spallart-Allmaras (SA). The experimental and numerical results show a clear difference of power coefficient and wake shape for both turbine configurations. This influence of two nearby blades on the flow can be exploited to obtain higher ratios of power per land area, leading to an increase of the overall generation of a power plant by a careful arrangement.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"2011 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114867275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Investigation of Turbulent Flow Behavior in a Heated Boundary Layer 热边界层湍流流动特性的研究

Volume 1: Fluid Mechanics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5437

K. Dennis, K. Siddiqui

{"title":"Investigation of Turbulent Flow Behavior in a Heated Boundary Layer","authors":"K. Dennis, K. Siddiqui","doi":"10.1115/ajkfluids2019-5437","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5437","url":null,"abstract":"\u0000 The boundary layers are known to play key roles in many engineering systems. The hydrodynamic boundary layer found in these systems is often turbulent in nature and heat transfer is involved which further increases flow complexity due to the influence of buoyancy. One of the constituent layers of the turbulent boundary layer, the inner layer, has been established as home to key dynamical turbulent phenomena which can be influenced by the buoyant force. In the mixed convection flow regime, flow inertia and buoyant force are on the same order of magnitude. In this regime, buoyant thermals rising from the wall interact with the inertia-driven turbulent flow field resulting in highly complex three-dimensional flow dynamics. Past research studies conducted in this flow regime have been mostly computational in nature with little experimental work. The current knowledge on the impact of the relative contributions by the buoyant force and flow inertia on turbulent phenomena in the mixed convection flow regime is very limited.\u0000 This study reports on an investigation into the turbulent flow phenomena present in mixed convection turbulent boundary layer flow over a heated smooth horizontal flat plate. Experiments were performed in a closed loop wind tunnel where the turbulent boundary layer was heated from below. The multi-plane particle image velocimetry (PIV) technique was used to capture two-dimensional velocity fields over two planes with respect to the flow direction. Experiments were conducted over a range of Richardson numbers (Ri) between 0.0 and 2.0 to control the relative contribution of the buoyant force with respect to flow inertia. The measured velocity fields are used to describe the influence of buoyancy on the three-dimensional turbulent boundary layer flow.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115314081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Wake Flow and Vortex Shedding Patterns Behind Rotating Finite Length Cylinders 有限长旋转圆柱后的尾流和旋涡脱落模式

Volume 1: Fluid Mechanics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5110

Amber Donaldson, J. Vaccaro, D. M. Rooney

{"title":"Wake Flow and Vortex Shedding Patterns Behind Rotating Finite Length Cylinders","authors":"Amber Donaldson, J. Vaccaro, D. M. Rooney","doi":"10.1115/ajkfluids2019-5110","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5110","url":null,"abstract":"\u0000 An experimental wind tunnel study was performed to assess the effect of aspect ratio and rotational speed of circular cylinders of varying diameter on the flow patterns behind the cylinders in the presence of a uniform upstream crossflow. Six circular cylinders of constant length but different diameters, producing aspect ratios 6 ≤ AR ≤ 32 were examined at a single upstream velocity such that the Reynolds number varied between 1920 ≤ Re ≤ 10240. Rotational speeds from stationary up to 3600 rpm were applied to the cylinders, so that the maximum relative velocity α = πfD/U∞ = 0.80. Mean velocity profiles were measured three diameters downstream of the cylinder axis at 6 equidistant locations, and PSD power spectral density were generated for 26 equidistant locations along the cylinder, to create a comprehensive record of spanwise variations under all rotational conditions. For the highest aspect ratio tested, the wake velocity profiles were independent of rotational speed at all spanwise locations, whereas at lower aspect ratios, the maximum velocity defect diminished with increasing rotational speed along most of the span and became asymmetric near the free end. Two distinct shedding cells were found only for a cylinder with an aspect ratio of twelve at three relative spin rates of 0.067, 0.27, and 0.4. In cases where only a single cell existed, increased rotational speed produced a higher vortex shedding frequency on a given aspect ratio cylinder.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123775900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental Study on Abrasion and Cavitation Resistance of Non-Metallic Coating Materials for Pump 泵用非金属涂层材料耐磨性和抗气蚀性试验研究

Volume 1: Fluid Mechanics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5003

Hou-lin Liu, Cao Manhui, Jie Chen, Yong Wang, Cheng-bin Wang

{"title":"Experimental Study on Abrasion and Cavitation Resistance of Non-Metallic Coating Materials for Pump","authors":"Hou-lin Liu, Cao Manhui, Jie Chen, Yong Wang, Cheng-bin Wang","doi":"10.1115/ajkfluids2019-5003","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5003","url":null,"abstract":"\u0000 The protection of the flow-passage components of pump by using coating is an important method to increase wear resistance. This paper aims at examining abrasion resistance and cavitation erosion resistance of three typical non-metallic coating materials for pump including epoxy resin mortar, composite resin mortar and polyurethane. A wear-resistance test bench was built, using ultrasonic vibrating air eroding machine. Meanwhile, the main relative raw materials and formulas were introduced. The results indicate that: (1) The accumulated volume reduction of abrasion of composite resin mortar changes in an oblique waveform, and its abrasion resistance is better than that of epoxy resin mortar in a short period of time. The wear rate of epoxy resin mortar and composite resin mortar is higher than that of polyurethane. The total wear volume of epoxy resin mortar, composite resin mortar and polyurethane is decreased by 8.74%, 9.89% and 0.58% respectively within 30h of anti-wear test time; (2) The accumulated volume reduction of cavitation erosion of epoxy resin mortar is proportional to the time. In anti-cavitation erosion test time of 26 h, the erosion volume of composite resin mortar, polyurethane and epoxy resin mortar cavitation is reduced by 0.44%, 0.29% and 0.35%, respectively. It shows that cavitation erosion resistance of three coating materials is similar, while polyurethane materials have the best abrasion resistance.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125510252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Computational Study of Mach Number Effects on Dynamic Stall 马赫数对动态失速影响的计算研究

Volume 1: Fluid Mechanics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5336

Taesoon Kim, Seungtae Kim, Jiseop Lim, Junkyu Kim, S. Jee

{"title":"Computational Study of Mach Number Effects on Dynamic Stall","authors":"Taesoon Kim, Seungtae Kim, Jiseop Lim, Junkyu Kim, S. Jee","doi":"10.1115/ajkfluids2019-5336","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5336","url":null,"abstract":"\u0000 A rotorcraft main-rotor blade experiences a broad range of the Mach number in high-speed forward flights or rapid maneuvering conditions. Near the boundary of the flight envelope, the rotor blade often encounters severe dynamic stall which limits the overall aerodynamic performance. Of interest here is effects of the Mach number on the dynamic stall. A rotor airfoil, VR-12, is computationally investigated for both static and dynamic stall conditions with varying the Mach number from 0.2 to 0.4. For the small enough Mach number 0.2, both static and dynamic stall are significantly influenced by flow separation due to adverse pressure gradient. For the highest Mach number 0.4, compressibility near the leading edge is no longer negligible, forming a shock there. The shock-induced separation occurs near the leading edge, which dominates both the static and dynamic stall at the high Mach number. At the intermediate Mach number 0.3, it is observed that both adverse pressure gradient and the shock affect the stall. Current computations are conducted with the unsteady Reynolds-averaged Navier Stokes approach with the Spalart-Allmaras model. Numerical results are compared to relevant wind-tunnel test data.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116616855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Some Consideration on the Aerodynamic Design of Blast Wave Simulator Using a Shock Tube System 基于激波管系统的冲击波模拟器气动设计的若干思考

Volume 1: Fluid Mechanics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5133

Suguru Kushida, K. Asada, K. Fujii, T. Tatsukawa, K. Sakamoto

引用次数: 0

Experimental Study and Modelling of the Tip-Leakage Flow for an Isolated Fixed Blade 孤立固定叶片叶尖-泄漏流动的实验研究与建模

Volume 1: Fluid Mechanics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-4710

B. Deveaux, Camille Fournis, V. Brion, J. Marty, A. Dazin

引用次数: 1

Effect of Diameter Size on the Unsteady Characteristics of Pulsatile Flow in Curved Human Blood Vessel 管径大小对弯曲血管内脉动流动不稳定特性的影响

Volume 1: Fluid Mechanics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5227

Ruixuan Tang, Xuanming Zhao, Junshi Wang, J. Hyde, B. Kesser, Haibo Dong

{"title":"Effect of Diameter Size on the Unsteady Characteristics of Pulsatile Flow in Curved Human Blood Vessel","authors":"Ruixuan Tang, Xuanming Zhao, Junshi Wang, J. Hyde, B. Kesser, Haibo Dong","doi":"10.1115/ajkfluids2019-5227","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5227","url":null,"abstract":"\u0000 Pulse-synchronous tinnitus (PST) has been linked to multiple anatomical variants of the venous outflow tract, including transverse sinus (TS) stenosis and sigmoid sinus (SS) dehiscence. It is unknown if the size of diameter in the TS part at the symptomatic side will result in PST. In this study, a combined experimental and computational approach is adopted to study the blood flow during PST. A parametric study is performed on the diameter size of one PST patient at the symptomatic side. A Reynold-averaged-Navier-Stokes (RANS) flow solver is employed in ANSYS Fluent to simulate the symptomatic side at different TS diameter sizes. Results have shown distinct differences in the flow characteristics (including pressure, turbulent kinetic energy (TKE), velocity and shear stress) between the symptomatic side at different TS diameter sizes. The result provides evidence to the hypothesis that anatomic differences can be an important element in affecting blood flow in the venous outflow tract. Resulted findings reveal the strong connection between the flow characteristics of a dehiscent SS and resultant PST. The findings help to understand the flow physics of PST and provide insightful guidance for surgical interventions.","PeriodicalId":314304,"journal":{"name":"Volume 1: Fluid Mechanics","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128990385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dynamic Performance Analysis of Large-Scale Packed Bed Truncated Conical Thermal Energy Storage 大型填料床截锥形蓄热器动态性能分析

Volume 1: Fluid Mechanics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5680

Shobhana Singh, K. Sørensen

引用次数: 0