Cavity flows studied over the past few decades have led to an increased understanding of the flow physics and instability modes in a range of configurations. While a large number of these studies focus on two-dimensional and three-dimensional rectangular cavities, significant variations are seen with three-dimensional cylindrical cavities with a top bounding wall. The present work details the flow physics of such cavities with a compressible (air) flow past the cavity at two pressure drops of 3850 Pa and 2000 Pa. Results from Detached Eddy Simulations (DES) reveal the presence of the wake mode and shear layer instabilities respectively, with modified dynamics and oscillatory modes owing to the top wall. In the interest of preventing mode switching with changes in operating conditions, which could lead to large-scale flow disruptions, a passive flow control technique is tested. The modified cavity (with a downstream ramp scaled by the size of shed structures) is seen to maintain the same mode throughout the range of operation offering valuable insights into design modifications for such cavities in practical settings.
过去几十年来对空腔流的研究加深了人们对各种构造中的流动物理和不稳定模式的理解。虽然大量研究都集中在二维和三维矩形空腔上，但带有顶壁的三维圆柱形空腔也有很大的不同。本研究详细介绍了在 3850 Pa 和 2000 Pa 两种压降条件下，可压缩（空气）流过空腔的流动物理原理。离散涡流模拟（DES）的结果表明，由于顶壁的存在，分别存在唤醒模式和剪切层不稳定性，以及修正的动力学和振荡模式。为了防止在工作条件发生变化时出现模式切换，从而导致大规模流动中断，我们对一种被动流动控制技术进行了测试。结果表明，改进后的空腔（下游斜坡按棚状结构的尺寸缩放）在整个运行范围内都能保持相同的模式，这为在实际环境中改进此类空腔的设计提供了宝贵的启示。
{"title":"Flow Instabilities and Control Mechanisms in Cylindrical Cavities with Top Bounding Walls","authors":"Aarthi Sekaran","doi":"10.1115/1.4064759","DOIUrl":"https://doi.org/10.1115/1.4064759","url":null,"abstract":"\u0000 Cavity flows studied over the past few decades have led to an increased understanding of the flow physics and instability modes in a range of configurations. While a large number of these studies focus on two-dimensional and three-dimensional rectangular cavities, significant variations are seen with three-dimensional cylindrical cavities with a top bounding wall. The present work details the flow physics of such cavities with a compressible (air) flow past the cavity at two pressure drops of 3850 Pa and 2000 Pa. Results from Detached Eddy Simulations (DES) reveal the presence of the wake mode and shear layer instabilities respectively, with modified dynamics and oscillatory modes owing to the top wall. In the interest of preventing mode switching with changes in operating conditions, which could lead to large-scale flow disruptions, a passive flow control technique is tested. The modified cavity (with a downstream ramp scaled by the size of shed structures) is seen to maintain the same mode throughout the range of operation offering valuable insights into design modifications for such cavities in practical settings.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"478 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139839093","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}
Cavity flows studied over the past few decades have led to an increased understanding of the flow physics and instability modes in a range of configurations. While a large number of these studies focus on two-dimensional and three-dimensional rectangular cavities, significant variations are seen with three-dimensional cylindrical cavities with a top bounding wall. The present work details the flow physics of such cavities with a compressible (air) flow past the cavity at two pressure drops of 3850 Pa and 2000 Pa. Results from Detached Eddy Simulations (DES) reveal the presence of the wake mode and shear layer instabilities respectively, with modified dynamics and oscillatory modes owing to the top wall. In the interest of preventing mode switching with changes in operating conditions, which could lead to large-scale flow disruptions, a passive flow control technique is tested. The modified cavity (with a downstream ramp scaled by the size of shed structures) is seen to maintain the same mode throughout the range of operation offering valuable insights into design modifications for such cavities in practical settings.
过去几十年来对空腔流的研究加深了人们对各种构造中的流动物理和不稳定模式的理解。虽然大量研究都集中在二维和三维矩形空腔上，但带有顶壁的三维圆柱形空腔也有很大的不同。本研究详细介绍了在 3850 Pa 和 2000 Pa 两种压降条件下，可压缩（空气）流过空腔的流动物理原理。离散涡流模拟（DES）的结果表明，由于顶壁的存在，分别存在唤醒模式和剪切层不稳定性，以及修正的动力学和振荡模式。为了防止在工作条件发生变化时出现模式切换，从而导致大规模流动中断，我们对一种被动流动控制技术进行了测试。结果表明，改进后的空腔（下游斜坡按棚状结构的尺寸缩放）在整个运行范围内都能保持相同的模式，这为在实际环境中改进此类空腔的设计提供了宝贵的启示。
{"title":"Flow Instabilities and Control Mechanisms in Cylindrical Cavities with Top Bounding Walls","authors":"Aarthi Sekaran","doi":"10.1115/1.4064759","DOIUrl":"https://doi.org/10.1115/1.4064759","url":null,"abstract":"\u0000 Cavity flows studied over the past few decades have led to an increased understanding of the flow physics and instability modes in a range of configurations. While a large number of these studies focus on two-dimensional and three-dimensional rectangular cavities, significant variations are seen with three-dimensional cylindrical cavities with a top bounding wall. The present work details the flow physics of such cavities with a compressible (air) flow past the cavity at two pressure drops of 3850 Pa and 2000 Pa. Results from Detached Eddy Simulations (DES) reveal the presence of the wake mode and shear layer instabilities respectively, with modified dynamics and oscillatory modes owing to the top wall. In the interest of preventing mode switching with changes in operating conditions, which could lead to large-scale flow disruptions, a passive flow control technique is tested. The modified cavity (with a downstream ramp scaled by the size of shed structures) is seen to maintain the same mode throughout the range of operation offering valuable insights into design modifications for such cavities in practical settings.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"84 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139779420","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}
The objective of the study is to thoroughly analyze the flow and heat transfer of Bingham plastic fluids through an array of uniformly gapped rough surface cylinders embedded between two confined boundaries. Radial notches are used as the surface roughness in the model, evenly distributed. Due to the formation of front vortices in uniformly gapped cylinders, a negative pressure gradient is developed. The results of the numerical simulation analysis have shown that, when compared to the averaged Nusselt number, roughness has a minimal effect on the drag coefficient and pressure drop. As the degree of roughness increases, the size of the vortices decreases, resulting in a drop in heat transfer. Moreover, the analysis of each column shows that the first column array of cylinders has a higher total drag coefficient and average Nusselt number.
{"title":"Numerical Study of the Fluid Flow Over the Array of Rough Cylindrical Particles: An Analysis of Porous Media Flow","authors":"Pooja Thakur, Shruti Gautam, Aruna Thakur","doi":"10.1115/1.4064762","DOIUrl":"https://doi.org/10.1115/1.4064762","url":null,"abstract":"\u0000 The objective of the study is to thoroughly analyze the flow and heat transfer of Bingham plastic fluids through an array of uniformly gapped rough surface cylinders embedded between two confined boundaries. Radial notches are used as the surface roughness in the model, evenly distributed. Due to the formation of front vortices in uniformly gapped cylinders, a negative pressure gradient is developed. The results of the numerical simulation analysis have shown that, when compared to the averaged Nusselt number, roughness has a minimal effect on the drag coefficient and pressure drop. As the degree of roughness increases, the size of the vortices decreases, resulting in a drop in heat transfer. Moreover, the analysis of each column shows that the first column array of cylinders has a higher total drag coefficient and average Nusselt number.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"50 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139777355","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}
Sen Li, Juan Liao, Chuangxin He, Chunjing Song, Yingzheng Liu, Yun Zhong
In this work, a large-scale mock-up of a compact complex system integrating a steam generator (SG) and a reactor coolant pump (RCP) is considered. The three-dimensional turbulent flow in the steam generator channel head (SGCH) is measured in detail. Dual-orthogonal-plane particle image velocimetry (PIV) is employed to extract high-resolution flow information in two orthogonal planes. Two separate measurements are first made to see the three-dimensional time-mean flow dynamics and the statistical quantities in the two planes. These measurements highlight two distinct flow phenomena: jet arrays and massive turbulent separation bubbles (TSBs). These patterns are attributed to mass flow redistribution in the U-shaped tubes. Proper orthogonal decomposition (POD) identifies the first POD mode as corresponding to the TSB breathing-like motion, which significantly intensifies the side view streamwise velocity fluctuations, leading to them reaching 370% of the local mean velocity. To examine the unsteady behavior of massively separated regions, the dual-orthogonal-plane PIV system is then synchronized to simultaneously measure variations in the flow fields, and the missing data due to illumination interference is reconstructed using gappy POD. The synchronized analysis reveals a direct relationship between the low-frequency fluctuations in the side and front views. These fluctuations are in phase across both views, indicating a synchronized behavior that spans the entire field. This large-scale low-frequency breathing motion has critical implications for numerical simulations and sheds light on the unsteady behavior of the RCP system within the SGCH.
在这项工作中，考虑了一个集成了蒸汽发生器（SG）和反应堆冷却剂泵（RCP）的紧凑型复杂系统的大型模型。详细测量了蒸汽发生器通道头（SGCH）中的三维湍流。采用双正交平面粒子图像测速仪（PIV）提取两个正交平面的高分辨率流动信息。首先进行两次单独测量，以观察两个平面上的三维时均流动动态和统计量。这些测量结果突出显示了两种截然不同的流动现象：喷流阵列和大量湍流分离气泡（TSBs）。这些模式归因于 U 形管中的质量流再分布。适当正交分解（POD）确定了第一种 POD 模式与 TSB 呼吸运动相对应，它显著增强了侧视流向速度波动，使其达到局部平均速度的 370%。为了研究大规模分离区域的非稳态行为，双正交平面 PIV 系统被同步化，以同时测量流场的变化，并使用 gappy POD 重构由于光照干扰而缺失的数据。同步分析显示，侧视图和正视图中的低频波动之间存在直接关系。这些波动在两个视图中的相位是一致的，这表明在整个视野中存在同步行为。这种大规模的低频呼吸运动对数值模拟具有重要意义，并揭示了 SGCH 内 RCP 系统的不稳定行为。
{"title":"Dual-Orthogonal-Plane Particle Image Velocimetry Measurement of the Turbulent Flow in the Channel Head of a Large-Scale Steam Generator Mock-Up","authors":"Sen Li, Juan Liao, Chuangxin He, Chunjing Song, Yingzheng Liu, Yun Zhong","doi":"10.1115/1.4064754","DOIUrl":"https://doi.org/10.1115/1.4064754","url":null,"abstract":"\u0000 In this work, a large-scale mock-up of a compact complex system integrating a steam generator (SG) and a reactor coolant pump (RCP) is considered. The three-dimensional turbulent flow in the steam generator channel head (SGCH) is measured in detail. Dual-orthogonal-plane particle image velocimetry (PIV) is employed to extract high-resolution flow information in two orthogonal planes. Two separate measurements are first made to see the three-dimensional time-mean flow dynamics and the statistical quantities in the two planes. These measurements highlight two distinct flow phenomena: jet arrays and massive turbulent separation bubbles (TSBs). These patterns are attributed to mass flow redistribution in the U-shaped tubes. Proper orthogonal decomposition (POD) identifies the first POD mode as corresponding to the TSB breathing-like motion, which significantly intensifies the side view streamwise velocity fluctuations, leading to them reaching 370% of the local mean velocity. To examine the unsteady behavior of massively separated regions, the dual-orthogonal-plane PIV system is then synchronized to simultaneously measure variations in the flow fields, and the missing data due to illumination interference is reconstructed using gappy POD. The synchronized analysis reveals a direct relationship between the low-frequency fluctuations in the side and front views. These fluctuations are in phase across both views, indicating a synchronized behavior that spans the entire field. This large-scale low-frequency breathing motion has critical implications for numerical simulations and sheds light on the unsteady behavior of the RCP system within the SGCH.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"24 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139784967","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}
An open valveless micropump pumped by a disc-shaped piezoelectric actuator was developed, and its working principles were investigated. The electrode of the pump buzzer was divided into two semicircles as piezoelectric actuators, and single-phase or dual-phase AC driving potential was applied. The flow rate of the pump was analyzed when actuated in basic symmetric (W00) and anti-symmetric (W01) modes. The finite element package software ANSYS was used to analyze the resonant frequency and mode of the buzzer under fluid loading, and the vibration displacement generated by the single-phase and dual-phase time-harmonic actuation was both simulated by using an additional mass method and experimentally investigated. The experimental results show that the resonant frequency of the disc-shaped actuator decreased due to the fluid loading effect and as the gap distance between the conduit and the actuator decreased. The maximum flow rates of the W00 and W01 mode actuated pumps were 133.13 and 9.63 mL/min, respectively. The driving frequency with the highest pump efficiency was slightly lower than the resonance frequency of the fluid-loaded buzzer. Applying a hydrophobic treatment to the back of the buzzer decreased the resonance frequency under fluid loading. The results show that simulating the structural resonance frequency for various fluid loads by the additional mass method is feasible. The flow direction could be controlled by activating the W01 mode.
{"title":"Design of a Simple Valveless Micropump Using Piezoelectric Actuators","authors":"Tai-Ho Yu, Chun-Hung Lai, Yuan-Hsin Chen","doi":"10.1115/1.4064755","DOIUrl":"https://doi.org/10.1115/1.4064755","url":null,"abstract":"\u0000 An open valveless micropump pumped by a disc-shaped piezoelectric actuator was developed, and its working principles were investigated. The electrode of the pump buzzer was divided into two semicircles as piezoelectric actuators, and single-phase or dual-phase AC driving potential was applied. The flow rate of the pump was analyzed when actuated in basic symmetric (W00) and anti-symmetric (W01) modes. The finite element package software ANSYS was used to analyze the resonant frequency and mode of the buzzer under fluid loading, and the vibration displacement generated by the single-phase and dual-phase time-harmonic actuation was both simulated by using an additional mass method and experimentally investigated. The experimental results show that the resonant frequency of the disc-shaped actuator decreased due to the fluid loading effect and as the gap distance between the conduit and the actuator decreased. The maximum flow rates of the W00 and W01 mode actuated pumps were 133.13 and 9.63 mL/min, respectively. The driving frequency with the highest pump efficiency was slightly lower than the resonance frequency of the fluid-loaded buzzer. Applying a hydrophobic treatment to the back of the buzzer decreased the resonance frequency under fluid loading. The results show that simulating the structural resonance frequency for various fluid loads by the additional mass method is feasible. The flow direction could be controlled by activating the W01 mode.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"78 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139783559","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}
Yan Li, Guoqing Su, Qianlin Wang, Zhansheng Tao, Jianwen Zhang
In the petroleum and petrochemical industries, oil-water flow is widespread inside the pipes. The existence of water often results in internal corrosion in the horizontal-vertical downward pipe when water contacts the pipe wall. Surface wetting behavior and wall shear stress are two important factors affecting corrosion procedure, which are governed by the flow patterns. With the propose to mitigate corrosion, focus shall be concentrated on the impact of flow pattern towards corrosion. In this work, the flow regime with oil-water flow in the horizontal-vertical pipe are investigated by computational fluid dynamics simulations. The cases with different mixture velocity (0.1m/s-2.2m/s) and different water cut (3%-40%) are investigated. The key discovery in this paper is that five types of flow patterns can be identified based on the multiphase flow in the horizontal-vertical pipe, which is rarely reported in recent work. According to the results of the surface wetting status and wall shear stress distribution, the severe corrosion area is predicted and classified into five types. The inside wall of elbows and the outside wall of vertical pipes are the areas most susceptible to corrosion, and the results are well in line with the on-site data.
{"title":"Investigation of the Influence of Flow Pattern On the Internal Corrosion in Horizontal-Vertical Downward Pipe with Oil-Water Flow","authors":"Yan Li, Guoqing Su, Qianlin Wang, Zhansheng Tao, Jianwen Zhang","doi":"10.1115/1.4064756","DOIUrl":"https://doi.org/10.1115/1.4064756","url":null,"abstract":"\u0000 In the petroleum and petrochemical industries, oil-water flow is widespread inside the pipes. The existence of water often results in internal corrosion in the horizontal-vertical downward pipe when water contacts the pipe wall. Surface wetting behavior and wall shear stress are two important factors affecting corrosion procedure, which are governed by the flow patterns. With the propose to mitigate corrosion, focus shall be concentrated on the impact of flow pattern towards corrosion. In this work, the flow regime with oil-water flow in the horizontal-vertical pipe are investigated by computational fluid dynamics simulations. The cases with different mixture velocity (0.1m/s-2.2m/s) and different water cut (3%-40%) are investigated. The key discovery in this paper is that five types of flow patterns can be identified based on the multiphase flow in the horizontal-vertical pipe, which is rarely reported in recent work. According to the results of the surface wetting status and wall shear stress distribution, the severe corrosion area is predicted and classified into five types. The inside wall of elbows and the outside wall of vertical pipes are the areas most susceptible to corrosion, and the results are well in line with the on-site data.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"36 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139784832","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}
With the increasing popularity of vertical axis turbines (VATs), researchers are now focussing on their performance improvement. Instead of adopting conventional means of performance improvements such as augmentation techniques and exhaustive parametric design optimization, the bioinspired turbine designs have become a centre of attraction, especially during the last decade. This review article attempts to compile the bioinspired designs belonging to the VATs. Bioinspired designs implemented in Savonius and Darrieus turbines are elaborated besides giving a detailed explanation of the corresponding bio-organism and natural phenomenon. How are the working principles of bio-organisms emulated in the form of fluid dynamic design is explained thoroughly in this paper. The bioinspired designs for VATs are classified pragmatically for the future designs. Research gaps are highlighted for the aspiring researchers, and this is followed by the important strategies and allied challenges.
{"title":"Bioinspired Fluid Dynamic Designs of Vertical-Axis Turbines: State-of-the-Art Review and the Way Forward","authors":"Umang H. Rathod, U. Saha, V. Kulkarni","doi":"10.1115/1.4064753","DOIUrl":"https://doi.org/10.1115/1.4064753","url":null,"abstract":"\u0000 With the increasing popularity of vertical axis turbines (VATs), researchers are now focussing on their performance improvement. Instead of adopting conventional means of performance improvements such as augmentation techniques and exhaustive parametric design optimization, the bioinspired turbine designs have become a centre of attraction, especially during the last decade. This review article attempts to compile the bioinspired designs belonging to the VATs. Bioinspired designs implemented in Savonius and Darrieus turbines are elaborated besides giving a detailed explanation of the corresponding bio-organism and natural phenomenon. How are the working principles of bio-organisms emulated in the form of fluid dynamic design is explained thoroughly in this paper. The bioinspired designs for VATs are classified pragmatically for the future designs. Research gaps are highlighted for the aspiring researchers, and this is followed by the important strategies and allied challenges.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"61 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139844467","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}
Yan Li, Guoqing Su, Qianlin Wang, Zhansheng Tao, Jianwen Zhang
In the petroleum and petrochemical industries, oil-water flow is widespread inside the pipes. The existence of water often results in internal corrosion in the horizontal-vertical downward pipe when water contacts the pipe wall. Surface wetting behavior and wall shear stress are two important factors affecting corrosion procedure, which are governed by the flow patterns. With the propose to mitigate corrosion, focus shall be concentrated on the impact of flow pattern towards corrosion. In this work, the flow regime with oil-water flow in the horizontal-vertical pipe are investigated by computational fluid dynamics simulations. The cases with different mixture velocity (0.1m/s-2.2m/s) and different water cut (3%-40%) are investigated. The key discovery in this paper is that five types of flow patterns can be identified based on the multiphase flow in the horizontal-vertical pipe, which is rarely reported in recent work. According to the results of the surface wetting status and wall shear stress distribution, the severe corrosion area is predicted and classified into five types. The inside wall of elbows and the outside wall of vertical pipes are the areas most susceptible to corrosion, and the results are well in line with the on-site data.
{"title":"Investigation of the Influence of Flow Pattern On the Internal Corrosion in Horizontal-Vertical Downward Pipe with Oil-Water Flow","authors":"Yan Li, Guoqing Su, Qianlin Wang, Zhansheng Tao, Jianwen Zhang","doi":"10.1115/1.4064756","DOIUrl":"https://doi.org/10.1115/1.4064756","url":null,"abstract":"\u0000 In the petroleum and petrochemical industries, oil-water flow is widespread inside the pipes. The existence of water often results in internal corrosion in the horizontal-vertical downward pipe when water contacts the pipe wall. Surface wetting behavior and wall shear stress are two important factors affecting corrosion procedure, which are governed by the flow patterns. With the propose to mitigate corrosion, focus shall be concentrated on the impact of flow pattern towards corrosion. In this work, the flow regime with oil-water flow in the horizontal-vertical pipe are investigated by computational fluid dynamics simulations. The cases with different mixture velocity (0.1m/s-2.2m/s) and different water cut (3%-40%) are investigated. The key discovery in this paper is that five types of flow patterns can be identified based on the multiphase flow in the horizontal-vertical pipe, which is rarely reported in recent work. According to the results of the surface wetting status and wall shear stress distribution, the severe corrosion area is predicted and classified into five types. The inside wall of elbows and the outside wall of vertical pipes are the areas most susceptible to corrosion, and the results are well in line with the on-site data.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"57 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139844685","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}
An open valveless micropump pumped by a disc-shaped piezoelectric actuator was developed, and its working principles were investigated. The electrode of the pump buzzer was divided into two semicircles as piezoelectric actuators, and single-phase or dual-phase AC driving potential was applied. The flow rate of the pump was analyzed when actuated in basic symmetric (W00) and anti-symmetric (W01) modes. The finite element package software ANSYS was used to analyze the resonant frequency and mode of the buzzer under fluid loading, and the vibration displacement generated by the single-phase and dual-phase time-harmonic actuation was both simulated by using an additional mass method and experimentally investigated. The experimental results show that the resonant frequency of the disc-shaped actuator decreased due to the fluid loading effect and as the gap distance between the conduit and the actuator decreased. The maximum flow rates of the W00 and W01 mode actuated pumps were 133.13 and 9.63 mL/min, respectively. The driving frequency with the highest pump efficiency was slightly lower than the resonance frequency of the fluid-loaded buzzer. Applying a hydrophobic treatment to the back of the buzzer decreased the resonance frequency under fluid loading. The results show that simulating the structural resonance frequency for various fluid loads by the additional mass method is feasible. The flow direction could be controlled by activating the W01 mode.
{"title":"Design of a Simple Valveless Micropump Using Piezoelectric Actuators","authors":"Tai-Ho Yu, Chun-Hung Lai, Yuan-Hsin Chen","doi":"10.1115/1.4064755","DOIUrl":"https://doi.org/10.1115/1.4064755","url":null,"abstract":"\u0000 An open valveless micropump pumped by a disc-shaped piezoelectric actuator was developed, and its working principles were investigated. The electrode of the pump buzzer was divided into two semicircles as piezoelectric actuators, and single-phase or dual-phase AC driving potential was applied. The flow rate of the pump was analyzed when actuated in basic symmetric (W00) and anti-symmetric (W01) modes. The finite element package software ANSYS was used to analyze the resonant frequency and mode of the buzzer under fluid loading, and the vibration displacement generated by the single-phase and dual-phase time-harmonic actuation was both simulated by using an additional mass method and experimentally investigated. The experimental results show that the resonant frequency of the disc-shaped actuator decreased due to the fluid loading effect and as the gap distance between the conduit and the actuator decreased. The maximum flow rates of the W00 and W01 mode actuated pumps were 133.13 and 9.63 mL/min, respectively. The driving frequency with the highest pump efficiency was slightly lower than the resonance frequency of the fluid-loaded buzzer. Applying a hydrophobic treatment to the back of the buzzer decreased the resonance frequency under fluid loading. The results show that simulating the structural resonance frequency for various fluid loads by the additional mass method is feasible. The flow direction could be controlled by activating the W01 mode.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"66 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139843605","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}
With the increasing popularity of vertical axis turbines (VATs), researchers are now focussing on their performance improvement. Instead of adopting conventional means of performance improvements such as augmentation techniques and exhaustive parametric design optimization, the bioinspired turbine designs have become a centre of attraction, especially during the last decade. This review article attempts to compile the bioinspired designs belonging to the VATs. Bioinspired designs implemented in Savonius and Darrieus turbines are elaborated besides giving a detailed explanation of the corresponding bio-organism and natural phenomenon. How are the working principles of bio-organisms emulated in the form of fluid dynamic design is explained thoroughly in this paper. The bioinspired designs for VATs are classified pragmatically for the future designs. Research gaps are highlighted for the aspiring researchers, and this is followed by the important strategies and allied challenges.
{"title":"Bioinspired Fluid Dynamic Designs of Vertical-Axis Turbines: State-of-the-Art Review and the Way Forward","authors":"Umang H. Rathod, U. Saha, V. Kulkarni","doi":"10.1115/1.4064753","DOIUrl":"https://doi.org/10.1115/1.4064753","url":null,"abstract":"\u0000 With the increasing popularity of vertical axis turbines (VATs), researchers are now focussing on their performance improvement. Instead of adopting conventional means of performance improvements such as augmentation techniques and exhaustive parametric design optimization, the bioinspired turbine designs have become a centre of attraction, especially during the last decade. This review article attempts to compile the bioinspired designs belonging to the VATs. Bioinspired designs implemented in Savonius and Darrieus turbines are elaborated besides giving a detailed explanation of the corresponding bio-organism and natural phenomenon. How are the working principles of bio-organisms emulated in the form of fluid dynamic design is explained thoroughly in this paper. The bioinspired designs for VATs are classified pragmatically for the future designs. Research gaps are highlighted for the aspiring researchers, and this is followed by the important strategies and allied challenges.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139784796","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}
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