Structures with a partially overlapped status in water can be seen in some engineering applications, and the fluid-structure coupling vibration behavior of two partially overlapped identical plates has been studied previously through the experimental method. In this study, the added damping of the T(0,1) modes of two submerged partially overlapped plates is numerically investigated through the one-way fluid-structure interaction (FSI) method. The relevant numerical settings, like the mesh size, calculated periods, time step size, and vibration amplitude, were tested first. Then, the numerical results were compared with experimental results, and good agreements were found. Finally, numerical results were analyzed. The vibration status of two plates in the joint abutting area or the overlapped area has an important influence on the added mass variation. When the added mass is higher, the phase difference between modal force and vibration displacement is also greater, which is the main reason for the higher added damping. The relationship between the phase difference and the frequency in water can be approximately fitted to a straight line, which can probably be used to predict the added damping variations caused by fluid boundary changes of submerged structures.
{"title":"One-way FSI Simulation of the Added Damping of T(0,1) Modes of Two Partially Overlapped Identical Plates in Still Water","authors":"Ming Zhang, Qing-guang Chen, Jun Li","doi":"10.1115/1.4065151","DOIUrl":"https://doi.org/10.1115/1.4065151","url":null,"abstract":"\u0000 Structures with a partially overlapped status in water can be seen in some engineering applications, and the fluid-structure coupling vibration behavior of two partially overlapped identical plates has been studied previously through the experimental method. In this study, the added damping of the T(0,1) modes of two submerged partially overlapped plates is numerically investigated through the one-way fluid-structure interaction (FSI) method. The relevant numerical settings, like the mesh size, calculated periods, time step size, and vibration amplitude, were tested first. Then, the numerical results were compared with experimental results, and good agreements were found. Finally, numerical results were analyzed. The vibration status of two plates in the joint abutting area or the overlapped area has an important influence on the added mass variation. When the added mass is higher, the phase difference between modal force and vibration displacement is also greater, which is the main reason for the higher added damping. The relationship between the phase difference and the frequency in water can be approximately fitted to a straight line, which can probably be used to predict the added damping variations caused by fluid boundary changes of submerged structures.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":" 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140387451","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}
Anshul S. Tomar, A. Hellum, Kristina M. Kamensky, Ranjan Mukherjee
Bernoulli pads are traditionally used for non-contact pick-and-place operations in industry. The normal force produced by a Bernoulli pad allows it to adhere to an object or workpiece. In addition to the normal force, the pad produces shear forces, which allows it to clean a workpiece without contact. A direct relationship between the inlet fluid power and the shear losses motivates us to explore other methods of providing power to the system with the objective of increase shear forces and thereby improve cleaning efficacy. Here we numerically investigate a system in which additional mechanical power is added by rotating the Bernoulli pad. The rotating system provides additional fluid forces (normal and shear) for the same inlet fluid power. For a specific pad that we investigated, the maximum wall shear stress increased by ≈ 15 % and the normal force changed from +1.4 N (repulsive) to -6.6 N (attractive) for change in the rotational speed by 60 rad/s. Also, for a given normal attractive force, a stable equilibrium configuration can exist for two mass flow rates, with the higher mass flow rate resulting in a higher stiffness of the flow field.
{"title":"Flow Physics of a Rotating Bernoulli Pad: A Numerical Study","authors":"Anshul S. Tomar, A. Hellum, Kristina M. Kamensky, Ranjan Mukherjee","doi":"10.1115/1.4065148","DOIUrl":"https://doi.org/10.1115/1.4065148","url":null,"abstract":"\u0000 Bernoulli pads are traditionally used for non-contact pick-and-place operations in industry. The normal force produced by a Bernoulli pad allows it to adhere to an object or workpiece. In addition to the normal force, the pad produces shear forces, which allows it to clean a workpiece without contact. A direct relationship between the inlet fluid power and the shear losses motivates us to explore other methods of providing power to the system with the objective of increase shear forces and thereby improve cleaning efficacy. Here we numerically investigate a system in which additional mechanical power is added by rotating the Bernoulli pad. The rotating system provides additional fluid forces (normal and shear) for the same inlet fluid power. For a specific pad that we investigated, the maximum wall shear stress increased by ≈ 15 % and the normal force changed from +1.4 N (repulsive) to -6.6 N (attractive) for change in the rotational speed by 60 rad/s. Also, for a given normal attractive force, a stable equilibrium configuration can exist for two mass flow rates, with the higher mass flow rate resulting in a higher stiffness of the flow field.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":" 30","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140214019","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}
Mitigation of gust-induced separation and aerodynamic loads using a high-frequency blowing/suction slot, previously shown to be effective at alleviating dynamic stall on pitching wings, is demonstrated using high-order implicit large-eddy simulation. A NACA0012 wing section at a transitional chord-based Reynolds number of Re = 500,000 and subsonic freestream Mach number of M = 0.1 at angles of attack of 4 deg and 12 deg is subjected to various discrete 1-cos transverse gusts. Gust-induced stall is demonstrated and then active flow control is applied to cases vulnerable to gust-induced stall. The flow control strategy is shown to be effective at stall suppression during gust encounter thereby providing partial alleviation of gust induced loads and is most effective at attenuating pitching moment increment.
利用高阶隐式大涡流仿真演示了使用高频吹气/吸气槽减轻阵风引起的分离和气动载荷的方法，该方法以前曾被证明能有效减轻俯仰翼的动态失速。在攻角分别为 4 度和 12 度的情况下，对过渡弦雷诺数 Re = 500,000 和亚音速自由流马赫数 M = 0.1 的 NACA0012 翼段进行各种离散 1-cos 横向阵风试验。演示了阵风诱发的失速，然后对易受阵风诱发失速影响的情况进行了主动流量控制。结果表明，在遇到阵风时，流量控制策略可有效抑制失速，从而部分减轻阵风引起的载荷，并且在减小俯仰力矩增量方面最为有效。
{"title":"Exploration of High-Frequency Actuation On Gust Response Using Large-Eddy Simulation","authors":"Caleb Barnes","doi":"10.1115/1.4065149","DOIUrl":"https://doi.org/10.1115/1.4065149","url":null,"abstract":"\u0000 Mitigation of gust-induced separation and aerodynamic loads using a high-frequency blowing/suction slot, previously shown to be effective at alleviating dynamic stall on pitching wings, is demonstrated using high-order implicit large-eddy simulation. A NACA0012 wing section at a transitional chord-based Reynolds number of Re = 500,000 and subsonic freestream Mach number of M = 0.1 at angles of attack of 4 deg and 12 deg is subjected to various discrete 1-cos transverse gusts. Gust-induced stall is demonstrated and then active flow control is applied to cases vulnerable to gust-induced stall. The flow control strategy is shown to be effective at stall suppression during gust encounter thereby providing partial alleviation of gust induced loads and is most effective at attenuating pitching moment increment.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":" 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140220110","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}
This paper presents a multidisciplinary design methodology for a single-stage radial compressor of a small-scale gas turbine jet engine. The entire engine, producing more than 600N thrust with an engine diameter of less than 30 cm will be manufactured by the AM in a single piece. Therefore, it is crucial to pinpoint the design limitations that may arise due to the AM methods. The preliminary design calculations are carried out in the VKI's in-house Centrifugal Compressor Off-Design (CCOD) code. The detailed design and optimization studies coupled with CFD simulations are performed to improve the aerodynamic performance of the radial compressor by using the Sequential Quadratic Programming (SQP) method with an Adjoint solver in the VKI's in-house Computer Aided Design and Optimization (CADO) tool. In the final design, a large increase in thrust is obtained and the manufacturing constraints are satisfied.
本文介绍了小型燃气涡轮喷气发动机单级径向压气机的多学科设计方法。整个发动机的推力超过 600N，直径小于 30 厘米，将由 AM 单件制造。因此，找出因 AM 方法而可能产生的设计限制至关重要。初步设计计算在 VKI 内部的离心压缩机非设计（CCOD）代码中进行。详细的设计和优化研究与 CFD 模拟相结合，通过使用顺序二次编程 (SQP) 方法和 VKI 内部计算机辅助设计和优化 (CADO) 工具中的交点求解器来改善径向压缩机的气动性能。在最终设计中，推力得到大幅增加，并满足了制造约束条件。
{"title":"The Design and Optimization of Additively Manufactured Radial Compressor of a Miniature Gas Turbine Engine","authors":"C. C. Ergin, T. Verstraete, B. Saracoglu","doi":"10.1115/1.4065098","DOIUrl":"https://doi.org/10.1115/1.4065098","url":null,"abstract":"\u0000 This paper presents a multidisciplinary design methodology for a single-stage radial compressor of a small-scale gas turbine jet engine. The entire engine, producing more than 600N thrust with an engine diameter of less than 30 cm will be manufactured by the AM in a single piece. Therefore, it is crucial to pinpoint the design limitations that may arise due to the AM methods. The preliminary design calculations are carried out in the VKI's in-house Centrifugal Compressor Off-Design (CCOD) code. The detailed design and optimization studies coupled with CFD simulations are performed to improve the aerodynamic performance of the radial compressor by using the Sequential Quadratic Programming (SQP) method with an Adjoint solver in the VKI's in-house Computer Aided Design and Optimization (CADO) tool. In the final design, a large increase in thrust is obtained and the manufacturing constraints are satisfied.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"60 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140230523","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}
A method for the evaluation of time-resolved entropy production in isothermal and incompressible flow is presented. It is applied as a post-processing of the three-dimensional flow field obtained by time-resolved computational fluid dynamics with scale adaptive turbulence modeling. Wall functions for direct and turbulent entropy production are presented for a cell-centered finite volume method, implemented in the open source software OpenFOAM and validated on channel, asymmetric diffuser and periodic hill flow. Single- and two-blade centrifugal pump flow is considered for a wide range of load conditions. Results are compared to experimental data. Time-averaged analysis shows essentially the same loss density distribution among pump components for both pumps, with the impeller and volute region contributing the most, especially in off-design conditions. For both pumps, the losses exhibit significant fluctuations due to impeller-volute interactions. The fluctuation magnitude of loss density is in the same range as flow rate fluctuations and much smaller than pressure fluctuation magnitude. For the two-blade pump, loss fluctuation magnitude is smaller than for the single-blade pump. Distinct loss mechanisms are identified for different load conditions. Upon blade passage, a promoted or attenuated volute tongue separation is imposed at part or overload, respectively. In between blade passages, a direct connection from pump inlet to the discharge leads to enhanced flow rate and loss density fluctuations. Future work aims at extending this analysis to stronger off-design conditions in multi-blade pumps, where stochastic cycle fluctuations occur.
{"title":"Time-Resolved Local Loss Analysis of Single- and Two-Blade Pump Flow","authors":"A. Pesch, R. Skoda","doi":"10.1115/1.4065099","DOIUrl":"https://doi.org/10.1115/1.4065099","url":null,"abstract":"\u0000 A method for the evaluation of time-resolved entropy production in isothermal and incompressible flow is presented. It is applied as a post-processing of the three-dimensional flow field obtained by time-resolved computational fluid dynamics with scale adaptive turbulence modeling. Wall functions for direct and turbulent entropy production are presented for a cell-centered finite volume method, implemented in the open source software OpenFOAM and validated on channel, asymmetric diffuser and periodic hill flow. Single- and two-blade centrifugal pump flow is considered for a wide range of load conditions. Results are compared to experimental data. Time-averaged analysis shows essentially the same loss density distribution among pump components for both pumps, with the impeller and volute region contributing the most, especially in off-design conditions. For both pumps, the losses exhibit significant fluctuations due to impeller-volute interactions. The fluctuation magnitude of loss density is in the same range as flow rate fluctuations and much smaller than pressure fluctuation magnitude. For the two-blade pump, loss fluctuation magnitude is smaller than for the single-blade pump. Distinct loss mechanisms are identified for different load conditions. Upon blade passage, a promoted or attenuated volute tongue separation is imposed at part or overload, respectively. In between blade passages, a direct connection from pump inlet to the discharge leads to enhanced flow rate and loss density fluctuations. Future work aims at extending this analysis to stronger off-design conditions in multi-blade pumps, where stochastic cycle fluctuations occur.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140229347","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}
Electrical submersible pump (ESP) is extensively utilized in industrial sectors such as petroleum, chemical, and nuclear energy. However, ESPs will experience pressurization deterioration due to the high gas volume fraction (GVF), resulting in the pressurization failure. In this paper, a three-stage mixed-flow ESP with closed impeller structure is designed and developed. The interstage hydraulic characteristics and pressurization deterioration mechanism of the mixed-flow ESP are investigated at various rotational speeds and inlet conditions by combining experimental and simulation. The Population Balance Model (PBM) and RNG k-e model are employed. As the liquid flow rate increases, the ESP experiences a ‘three-stage’ downward trend in pressurization. It is discovered that the first booster stage has a lower inflow velocity and flow separation degree compared to the subsequent booster stages, resulting in a greater liquid-phase pressurization capacity. The gas-liquid pressurization exhibits a wave-shaped downward trend due to significant deterioration in stage-wise pressurization when the liquid flow rate is low. Once the Inlet Gas Volume Fraction (IGVF) reaches the first critical GVF, the gas aggregates on the impeller's suction surface is removed at the impeller outlet, creating an annular air mass which creating a chaotic vortex absorbing the fluids’ kinetic energy. As a result, the first booster stage experiences a significant reduction in its pressurization ability, causing an abrupt decrease in the pressurization curve.
{"title":"Experimental and Numerical Study of Hydraulic Characteristics and Pressurization Deterioration Mechanism of a Three-Stage Mixed-Flow Electrical Submersible Pump Under Gas-Liquid Condition","authors":"Xiaoyu Dai, Qiang Xu, Chenyu Yang, Xiaobin Su, Liang Chang, Liejin Guo","doi":"10.1115/1.4065100","DOIUrl":"https://doi.org/10.1115/1.4065100","url":null,"abstract":"\u0000 Electrical submersible pump (ESP) is extensively utilized in industrial sectors such as petroleum, chemical, and nuclear energy. However, ESPs will experience pressurization deterioration due to the high gas volume fraction (GVF), resulting in the pressurization failure. In this paper, a three-stage mixed-flow ESP with closed impeller structure is designed and developed. The interstage hydraulic characteristics and pressurization deterioration mechanism of the mixed-flow ESP are investigated at various rotational speeds and inlet conditions by combining experimental and simulation. The Population Balance Model (PBM) and RNG k-e model are employed. As the liquid flow rate increases, the ESP experiences a ‘three-stage’ downward trend in pressurization. It is discovered that the first booster stage has a lower inflow velocity and flow separation degree compared to the subsequent booster stages, resulting in a greater liquid-phase pressurization capacity. The gas-liquid pressurization exhibits a wave-shaped downward trend due to significant deterioration in stage-wise pressurization when the liquid flow rate is low. Once the Inlet Gas Volume Fraction (IGVF) reaches the first critical GVF, the gas aggregates on the impeller's suction surface is removed at the impeller outlet, creating an annular air mass which creating a chaotic vortex absorbing the fluids’ kinetic energy. As a result, the first booster stage experiences a significant reduction in its pressurization ability, causing an abrupt decrease in the pressurization curve.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"73 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140237123","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}
In this paper, analyze the influence of the stepped planing structure on the drag performance by observing waveform diagrams at the stern of the double M-ship and water-air and pressure distribution diagrams at the bottom of the ship. This study the combined stepped planing-air drag reduction technology to improve the sailing characteristics of the double M-ship. Research findings: The stepped planing contributes to a reduction in bottom pressure, enhances water-air distribution, and augments the amplitude of hull movement. Within the design speed range, the maximum drag reduction rate achieved by the stepped planing is 7.574%. However, this enhancement comes at the expense of increased viscous pressure resistance, which becomes the predominant resistance when sailing at full speed; Injecting air at the stepped planing can effectively reduce the viscous pressure resistance increased by the stepped planing. The combined drag reduction technology of stepped planing and air successfully realizes the total drag reduction at the double-M ship's high speed. The total resistance experienced when air is injected at the stepped planing is reduced by up to 20.981% compared to the original hull.
本文通过观察双 M 型船船尾波形图和船底水气、水压分布图，分析阶梯式刨削结构对阻力性能的影响。研究了阶梯刨削-空气减阻组合技术，以改善双 M 型船的航行特性。研究结果：阶梯式刨削有助于降低船底压力，改善水气分布，提高船体运动幅度。在设计速度范围内，阶梯式刨削实现的最大阻力降低率为 7.574%。然而，这种增强是以粘性压力阻力的增加为代价的，当全速航行时，粘性压力阻力成为主要阻力；在阶梯刨削处注入空气可有效减少阶梯刨削所增加的粘性压力阻力。阶梯刨削和空气联合减阻技术成功实现了双 M 型船高速行驶时的总阻力减小。与原来的船体相比，在阶梯刨削处注入空气时所产生的总阻力最多可减少 20.981%。
{"title":"Numerical Analysis of The Drag Reduction Performance of a Double M-Ship Boat With Stepped Planing-Air Coupling","authors":"Yu Ya, Ziji Zhang, Shuai Wang, Shujiang Li","doi":"10.1115/1.4065097","DOIUrl":"https://doi.org/10.1115/1.4065097","url":null,"abstract":"\u0000 In this paper, analyze the influence of the stepped planing structure on the drag performance by observing waveform diagrams at the stern of the double M-ship and water-air and pressure distribution diagrams at the bottom of the ship. This study the combined stepped planing-air drag reduction technology to improve the sailing characteristics of the double M-ship. Research findings: The stepped planing contributes to a reduction in bottom pressure, enhances water-air distribution, and augments the amplitude of hull movement. Within the design speed range, the maximum drag reduction rate achieved by the stepped planing is 7.574%. However, this enhancement comes at the expense of increased viscous pressure resistance, which becomes the predominant resistance when sailing at full speed; Injecting air at the stepped planing can effectively reduce the viscous pressure resistance increased by the stepped planing. The combined drag reduction technology of stepped planing and air successfully realizes the total drag reduction at the double-M ship's high speed. The total resistance experienced when air is injected at the stepped planing is reduced by up to 20.981% compared to the original hull.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"124 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140235680","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}
Behzad Parsi, Jason B Metten, Clinton Waite, Daniel Maynes, Nathan B. Crane
Microfluidic-based techniques have been shown to address limitations of reconfigurable radio frequency (RF) antennas and filters in efficiency, power handling capability, cost, and frequency tuning. However, the current devices suffer from significant integration challenges associated with packaging, actuation, and control. Recent advances in reconfigurable microfluidics that utilize the motion of a selectively metalized plate (SMP) for RF tuning have demonstrated promising RF capabilities but have exposed a need for an accurate fluid actuation model. This research presents a model for the mechanical motion of a moving plate in a channel to relate the SMP size, microfluidic channel size, velocity, and inlet pressure. This model facilitates understanding of the actuation response of an RF tuning system based on a moving plate independent of the actuation method. This model is validated using a millimeter-scale plate driven by a gravitational pressure head as a quasi-static pressure source. Measurements of the prototyped device show excellent agreement with the analytical model; thus, the designer can utilize the presented model for designing and optimizing a microfluidic-based reconfigurable RF device and selecting actuation methods to meet desired outcomes. To examine model accuracy at device scale, recent papers in the microfluidics reconfigurable RF area have been studied, and excellent agreement between our proposed model and the literature data is observed.
{"title":"Actuation Modeling of a Microfluidically Reconfigurable Radiofrequency Device","authors":"Behzad Parsi, Jason B Metten, Clinton Waite, Daniel Maynes, Nathan B. Crane","doi":"10.1115/1.4065046","DOIUrl":"https://doi.org/10.1115/1.4065046","url":null,"abstract":"\u0000 Microfluidic-based techniques have been shown to address limitations of reconfigurable radio frequency (RF) antennas and filters in efficiency, power handling capability, cost, and frequency tuning. However, the current devices suffer from significant integration challenges associated with packaging, actuation, and control. Recent advances in reconfigurable microfluidics that utilize the motion of a selectively metalized plate (SMP) for RF tuning have demonstrated promising RF capabilities but have exposed a need for an accurate fluid actuation model. This research presents a model for the mechanical motion of a moving plate in a channel to relate the SMP size, microfluidic channel size, velocity, and inlet pressure. This model facilitates understanding of the actuation response of an RF tuning system based on a moving plate independent of the actuation method. This model is validated using a millimeter-scale plate driven by a gravitational pressure head as a quasi-static pressure source. Measurements of the prototyped device show excellent agreement with the analytical model; thus, the designer can utilize the presented model for designing and optimizing a microfluidic-based reconfigurable RF device and selecting actuation methods to meet desired outcomes. To examine model accuracy at device scale, recent papers in the microfluidics reconfigurable RF area have been studied, and excellent agreement between our proposed model and the literature data is observed.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"152 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140249658","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}
It is well known that the ratio of disk friction loss of low specific speed pumps is large. When the specific speed is 100min-1, m3/min, m or less, the disk friction loss increases remarkably. In this study, focusing on the clearance flow from the diffuser outlet to the impeller outlet (This is called the outward flow) behind the centrifugal pump, a fin was installed on outer diameter side of the rotating wall on the back side of a centrifugal pump as a countermeasure, and the influence of changes in velocity distribution near the wall on disk friction loss was investigated by torque measurements, velocity measurement, and CFD analysis. As a result, it was clarified that disk friction loss is decreasing by installing the fin in both torque measurements and CFD results, because the clearance flow is separated by fin and circumferential velocity is increased in the wake region of the fin in both measurements and CFD. In addition, it was clarified that disk friction coefficient (normalized torque) can be expressed as a function of the inlet swirl ratio and Reynolds number. Also, prediction equation is derived for each shape (with and without fin). According to the equation, it was found that disk friction loss reduction effect by installing a fin becomes larger when Reynolds number and the inlet swirl ratio are small.
{"title":"Reduction of Disk Friction Loss by Applying a Fin to the Back of a Centrifugal Impeller","authors":"Satoshi Maeda, Takeshi Sano, Kazuyoshi Miyagawa, Kento Sakai","doi":"10.1115/1.4065047","DOIUrl":"https://doi.org/10.1115/1.4065047","url":null,"abstract":"\u0000 It is well known that the ratio of disk friction loss of low specific speed pumps is large. When the specific speed is 100min-1, m3/min, m or less, the disk friction loss increases remarkably. In this study, focusing on the clearance flow from the diffuser outlet to the impeller outlet (This is called the outward flow) behind the centrifugal pump, a fin was installed on outer diameter side of the rotating wall on the back side of a centrifugal pump as a countermeasure, and the influence of changes in velocity distribution near the wall on disk friction loss was investigated by torque measurements, velocity measurement, and CFD analysis. As a result, it was clarified that disk friction loss is decreasing by installing the fin in both torque measurements and CFD results, because the clearance flow is separated by fin and circumferential velocity is increased in the wake region of the fin in both measurements and CFD. In addition, it was clarified that disk friction coefficient (normalized torque) can be expressed as a function of the inlet swirl ratio and Reynolds number. Also, prediction equation is derived for each shape (with and without fin). According to the equation, it was found that disk friction loss reduction effect by installing a fin becomes larger when Reynolds number and the inlet swirl ratio are small.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"114 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140250818","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}
Submerged annular viscoplastic jet flows were studied numerically within the steady laminar flow regime. The impacts of inner-to-outer annular nozzle diameter ratio, and yield number, for uniform and fully-developed inflow conditions, were investigated. The extent of the outer recirculation region and recirculation intensities of both the central and outer regions were found to substantially diminish with the yield number, resulting in the elimination of recirculation throughout the whole flow field at high yield numbers. The axial penetration of the jet decreases with both the yield number and the annular diameter ratio. The impact of inflow conditions on the flow structure and decay characteristics of the jet is more pronounced at low yield numbers.
{"title":"Inflow Conditions and the Flow Behavior of Submerged Annular Viscoplastic Non-newtonian Jets","authors":"K. Hammad","doi":"10.1115/1.4065052","DOIUrl":"https://doi.org/10.1115/1.4065052","url":null,"abstract":"\u0000 Submerged annular viscoplastic jet flows were studied numerically within the steady laminar flow regime. The impacts of inner-to-outer annular nozzle diameter ratio, and yield number, for uniform and fully-developed inflow conditions, were investigated. The extent of the outer recirculation region and recirculation intensities of both the central and outer regions were found to substantially diminish with the yield number, resulting in the elimination of recirculation throughout the whole flow field at high yield numbers. The axial penetration of the jet decreases with both the yield number and the annular diameter ratio. The impact of inflow conditions on the flow structure and decay characteristics of the jet is more pronounced at low yield numbers.","PeriodicalId":504378,"journal":{"name":"Journal of Fluids Engineering","volume":"28 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140250384","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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