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Journal Articles
Journal:
Journal of Fluids Engineering
Article Type: Research-Article
J. Fluids Eng. February 2022, 144(2): 021206.
Paper No: FE-20-1753
Published Online: August 27, 2021
Abstract
The steam trap valve is used in thermal power systems to pour out condensate water and keep steam inside. While flowing through steam trap valves, the condensate water can easily reach cavitation, which may cause serious damage to the piping system. In this paper, in order to control cavitation inside steam trap valves, effects of sleeve parameters, including orifice diameter, installation angle and thickness, are investigated using a cavitation model. The pressure, velocity, and vapor distribution inside valves are analyzed and compared for different sleeve geometrical parameters. The total vapor volumes are also predicted and compared. The results show that the sleeve parameters have a significant influence on the cavitation intensity and cavitation vapor distributions. Specifically, the orifice diameter of the sleeve has much larger effect on each aspect than that of other two geometrical parameters of the sleeve. The improved geometrical parameters of the sleeve are determined to suppress the cavitation inside the valve. The sleeve with smaller diameter orifices, higher installation angle (maximum 80 deg), and higher thickness is recommended in practice for better anticavitation performance. The work is of significance for cavitation control and the optimization design of steam trap valves.
Proceedings Papers
Proc. ASME. VVS2020, ASME 2020 Verification and Validation Symposium, V001T09A001, May 20–22, 2020
Paper No: VVS2020-8808
Abstract
Intervertebral disc (IVD) degeneration may cause low back pain which has a tremendous impact on the society and economy in the United States. It is important to quantitatively and qualitatively evaluate its pathophysiology in order to diagnose and treat disc degeneration. Recently, we have developed a multiphasic computational model for investigating cell mediated disc degeneration as well as exploring new strategies for disc therapies. The objective of this study was to verify this new computational model according to the guidelines of ASME V&V40. The model was discretized with finite element method and implemented in COMSOL Multiphysics. Several benchmark problems and method of manufactured solutions (MMS) were used to verify the numerical implementation. For all the benchmark problems tested, the numerical results were in excellent agreement with those analytical solutions or other numerical solutions. In addition, the observed convergence rates of primary unknowns obtained with MMS were in excellent agreement with theoretical convergence rates. This study showed that our model has been verified and found no evidence of coding errors.
Journal Articles
Journal:
Journal of Fluids Engineering
Article Type: Research-Article
J. Fluids Eng. October 2020, 142(10): 101210.
Paper No: FE-20-1152
Published Online: July 13, 2020
Abstract
Compared to conventional globe valves, the pilot-control globe valve (PCGV) possesses advantages of lower energy consumption and higher space utilization. In order to analyze the effects of pilot pipe and damping orifice arrangements, this work proposes four PCGVs and conducts simulations to compare their overall performances, overall flow characteristics, and local flow characteristics around the valve core. In general, the arrangement of the pilot pipe has larger effects on the hydroperformances of PCGVs than the arrangement of the damping orifice. The pipe-parallel-mounted type PCGV performs better in hydroperformance than the pipe-perpendicular-mounted type PCGV, and thus is recommended in practice. As the specified valve core travel increases, the flow resistance of PCGVs decreases and the flow capacity of PCGVs increases. However, overlarge specified valve core travel has little effects on the flow resistance and flow capacity of PCGVs. Besides, the increased specified valve core travel could effectively reduce the wear induced by the uneven pressure distribution on the external lateral face of valve core, but it has little effect on the wear induced by the uneven pressure distribution on the bottom face. For all pipe-perpendicular-mounted type PCGVs, the variation of axial force imposed on the valve core relative to the specific valve core travel presents similar tendencies under different incoming flow velocity within the scope of the investigation, which could be concluded into a fitting equation. This work could be referred for the optimization of PCGVs and other similar valves.
Journal Articles
Article Type: Research Papers
J. Electrochem. En. Conv. Stor. February 2020, 17(1): 011006.
Paper No: JEECS-19-1023
Published Online: September 10, 2019
Abstract
In a previous numerical study on heat and mass transfer in air-cooled proton exchange membrane fuel cells, it was found that the performance is limited by heat transfer to the cathode side air stream that serves as a coolant, and it was proposed to place a turbulence grid before the cathode inlet in order to induce a mixing effect to the air and thereby improve the heat transfer and ultimately increase the limiting current and maximum power density. The current work summarizes experiments with different turbulence grids which varied in terms of their pore size, grid thickness, rib width, angle of the pores, and the distance between the grid and the cathode inlet. For all grids tested in this study, the limiting current density of a Ballard Mark 1020 ACS stack was increased by 20%. The single most important parameter was the distance between the turbulence grid and the cathode inlet, and it should be within 5 mm. For the best grid tested, the fuel cell stack voltage and thus the efficiency were increased by up to 20%. The power density was increased by more than 30% and further improvements are believed to be possible.
eBook Chapter
Series: ASME Press Select Proceedings
Publisher: ASME Press
Published: 2018
ISBN: 9780791861851
Abstract
Cavitation can be useful in many occasions, for example, it can be adopted to improve the mass and heat transfer of the solution and it can also be used during the wastewater treatment. Among the ways to generate cavitation in hydrodynamic devices, the sharp-edged orifice is often used because it has a simple structure and the tube that has multi-holes orifice plate is more likely to generate cavitation. In this paper, experiment and computational fluid dynamic (CFD) method are carried out, the flux of the test tube is recorded during the experimental process, and the cavitation model used in the numerical study is validated by comparing the simulated results with the experimental results, then triangular, rectangular, and circular shape of holes and different kinds of distributions of holes such as circular and rectangular distributions are numerically studied. The vapor volume fraction is visualized to find out the effects of holes shape and arrangement on cavitation intensity. Besides, study focusing on the inlet pressure is achieved using CFD simulations, and the cavitation number is calculated under different cases to find out their effects on cavitation intensity. It can be concluded from the obtained results that cavitation number decreases with the increase of pressure drop, and under a certain value of pressure drop, the orifice plates with circular holes have the minimal cavitation number and maximal cavitation intensity. When the holes are circular arrangement, the orifice plates with circular and triangular holes has higher cavitation intensity, and when inlet pressure is large enough, different arrangement and shape of holes barely affect the cavitation intensity.
Topics:
Cavitation
Proceedings Papers
Proc. ASME. FEDSM2018, Volume 2: Development and Applications in Computational Fluid Dynamics; Industrial and Environmental Applications of Fluid Mechanics; Fluid Measurement and Instrumentation; Cavitation and Phase Change, V002T11A005, July 15–20, 2018
Paper No: FEDSM2018-83159
Abstract
Hydropower stations play an important role in discharging the flood. Especially in wet seasons, the river water always contains several percentages of sediment, and the velocity of the water flowing through the flood discharging tunnel is very high. Arranging some energy dissipation orifice plates in the flood discharging tunnel, cannot only reduce the pressure and flow velocity, but also deposit sediment and reduce the sediment content. However, fouling on energy dissipation orifice plates can initiate material corrosion of perforated plates, even weaken the energy dissipation performance. In this paper, the fouling performance on energy dissipation orifice plates with sediment contained water flow is investigated. To begin with, the pressure along the path is used to compare with a reported experiment to verify the reliability of the numerical method. Then, effects of the solid particle diameter, the sediment volume concentration and the inlet flow velocity on the particle distribution are observed. The results show that with the increase of the Reynolds number, the sediment volume fraction and the sediment particle diameter, more sediments accumulate at both surfaces of the orifice plate. The Reynolds number and the sediment volume fraction affect the upstream surface more significantly, while the effect of sediment particle diameter is more notable on the downstream surface. Additionally, the energy dissipation coefficient of the orifice plate is mainly dominated by the Reynolds number. This work is of significance for further analysis of fouling problems in energy dissipation orifice plates or similar fluid machinery.
Proceedings Papers
Proc. ASME. FEDSM2018, Volume 3: Fluid Machinery; Erosion, Slurry, Sedimentation; Experimental, Multiscale, and Numerical Methods for Multiphase Flows; Gas-Liquid, Gas-Solid, and Liquid-Solid Flows; Performance of Multiphase Flow Systems; Micro/Nano-Fluidics, V003T12A015, July 15–20, 2018
Paper No: FEDSM2018-83156
Abstract
In a piping system, due to the sudden opening or closing of valves and pumps etc., pressure inside can be changed both rapidly and suddenly, which may cause water hammer, noise, vibration, and even damage the whole piping system seriously. Thus, to stabilize pressure in piping system under a target value is very important. In this paper, a novel pressure regulation component, two-stage spring linked perforated plate (TSP), is proposed, which is mainly made up of a fixed perforated plate, a mobile perforated plate and a spring to link them. To begin with, a transient numerical model of a TSP is established and the simulation results are compared with the theoretical formula for the purpose of validation. Then, its dynamic flow and pressure characteristics are investigated under typical inlet pressure and outlet pressure to present its advantage on pressure stabilization. Meanwhile, different pressure ratios from 1 to 2 are all investigated on dynamic motion of mobile perforated plate. Under different working conditions, the displacement during the dynamic motion at different flow time, the response time to reach the final stabilization, and pressure characteristics are all figured out. This work can be useful for the further design work on two-stage spring linked perforated plates and similar pressure regulation components.
Journal Articles
Journal:
Journal of Fluids Engineering
Article Type: Research-Article
J. Fluids Eng. November 2018, 140(11): 111103.
Paper No: FE-18-1033
Published Online: May 18, 2018
Abstract
Globe valve is widely used in numerous industries, and its driving energy consumption accounts for high percentages of the whole piping system. In order to figure out novel globe valves with low energy consumption, the pilot control globe valve (PCGV) is proposed, which is made up of a main valve and a pilot valve. By the pressure difference of fluid itself, the opened/closed status of the main valve can be controlled by the pilot valve, which can save driving energy and shorten the response time. In order to fit PCGV in an angle displaced piping system, the pilot control angle globe valve (PCAGV) is developed. In this paper, with validated numerical methods, both steady and transient simulations focusing on the valve core diameter, the single/multi orifices, orifice diameters and their arrangements located on the valve core bottom are presented. The results show that the pressure difference increases with the increase of the valve core diameter and the decrease of the orifice diameter, and large orifice diameters (d > 12 mm) should be avoided in case the valve cannot be opened. As for the multi orifices, it can be treated as a single orifice which having similar cross-sectional area. Meanwhile, the opening time of the main valve also increases with the increase of the valve core diameter correspondingly. Besides, a fitting formula of pressure difference calculation depending on the inlet velocity and the valve core diameter is obtained, which is a power–law relationship.
Journal Articles
Journal:
Journal of Fluids Engineering
Article Type: Research-Article
J. Fluids Eng. March 2018, 140(3): 031208.
Paper No: FE-17-1278
Published Online: October 31, 2017
Abstract
Hydrodynamic cavitation that occurs inside valves not only increases the energy consumption burden of the whole piping system but also leads to severe damages to the valve body and the piping system with a large economic loss. In this paper, in order to reduce the hydrodynamic cavitation inside globe valves, effects of valve body geometrical parameters including bending radius, deviation distance, and arc curvature linked to in/export parts on hydrodynamic cavitation are investigated by using a cavitation model. To begin with, the numerical model is compared with similar works to check its accuracy. Then, the cavitation index and the total vapor volume are predicted. The results show that vapor primarily appears around the valve seat and connecting downstream pipes. The hydrodynamic cavitation does not occur under a small inlet velocity, a large bending radius, and a large deviation distance. Cavitation intensity decreases with the increase of the bending radius, the deviation distance, and the arc curvature linked to in/export parts. This indicates that valve geometrical parameters should be chosen as large as possible, while the maximal fluid velocity should be limited. This work is of significance for hydrodynamic cavitation or globe valve design.
Proceedings Papers
Proc. ASME. FEDSM2017, Volume 1A, Symposia: Keynotes; Advances in Numerical Modeling for Turbomachinery Flow Optimization; Fluid Machinery; Industrial and Environmental Applications of Fluid Mechanics; Pumping Machinery, V01AT03A013, July 30–August 3, 2017
Paper No: FEDSM2017-69210
Abstract
In this paper, a new high multi-stage pressure reducing valve (HMSPRV) is proposed. The main advantages include reducing noise and vibration, reducing energy consumption and dealing with complex conditions. As a new high pressure reducing valve, its flow characteristics need to be investigated. For that the valve opening has a great effect on steam flow, pressure reduction and energy consumption, thus different valve openings are taken as the research points to investigate the flow characteristics. The analysis is conducted from four aspects: pressure, velocity, temperature fields and energy consumption. The results show that valve opening has a great effect on flow characteristics. No matter for pressure, velocity or temperature field, the changing gradient mainly reflects at those throttling components for all valve openings. For energy consumption, in the study of turbulent dissipation rate, it can be found that the larger of valve opening, the larger of energy consumption. It can be concluded that the new high multi-stage pressure reducing valve works well under complex conditions. This study can provide technological support for achieving pressure regulation, and benefit the further research work on energy saving and multi-stage design of pressure reducing devices.
Proceedings Papers
Proc. ASME. FEDSM2017, Volume 1B, Symposia: Fluid Measurement and Instrumentation; Fluid Dynamics of Wind Energy; Renewable and Sustainable Energy Conversion; Energy and Process Engineering; Microfluidics and Nanofluidics; Development and Applications in Computational Fluid Dynamics; DNS/LES and Hybrid RANS/LES Methods, V01BT11A007, July 30–August 3, 2017
Paper No: FEDSM2017-69137
Abstract
Vertical pilot-control globe valve (VPCGV) is a novel globe valve that costs little driving energy and responds quickly. In VPCGV, the opening and closing forces are related to the pressure difference before and after the valve core. In this paper, parameters that have influences on pressure difference such as orifice diameter, valve core displacement, and inlet velocity are thoroughly investigated by computational fluid dynamics (CFD) method. It is found that pressure difference increases with the raising of inlet velocity and the diminishing of valve core displacement, and middle-sized orifice diameter is the best in VPCGV. Furthermore, the correlation between pressure difference and inlet velocity is obtained, which can be beneficial for the selection of VPCGV under certain conditions.
Journal Articles
Journal:
Journal of Fluids Engineering
Article Type: Research-Article
J. Fluids Eng. September 2017, 139(9): 091102.
Paper No: FE-17-1029
Published Online: June 7, 2017
Abstract
Pilot-control globe valve (PCGV) can use the pressure drop caused by fluid flowing through the orifice located at valve core bottom to open or close the main valve using a small pilot valve. In this paper, computational fluid dynamics (CFD) method is adopted to analyze the pressure drop before and after valve core of PCGV and minor loss of orifice under different structural parameters and inlet velocities, and the simulation results show a good agreement with the experimental results. It turns out that the valve diameters, orifice diameters, and pilot pipe diameters have great influences on the pressure drop and the loss coefficient. Moreover, an expression is proposed which can be used to calculate minor loss coefficient, then to estimate the pressure drop and driving force of a PCGV within limited conditions. This paper can be referenced as guidance for deciding the dimension of structural parameters and spring stiffness during design process of a PCGV.
Journal Articles
Journal:
Journal of Applied Mechanics
Article Type: Research-Article
J. Appl. Mech. February 2016, 83(2): 021011.
Paper No: JAM-15-1461
Published Online: November 9, 2015
Abstract
Intervertebral disk (IVD) is the largest avascular structure in human body, consisting of three types of charged hydrated soft tissues. Its mechanical behavior is nonlinear and anisotropic, due mainly to nonlinear interactions among different constituents within tissues. In this study, a more realistic anisotropic multiphysics model was developed based on the continuum mixture theory and employed to characterize the couplings of multiple physical fields in the IVD. Numerical simulations demonstrate that this model is capable of systematically predicting the mechanical and electrochemical signals within the disk under various loading conditions, which is essential in understanding the mechanobiology of IVD.
Proceedings Papers
Proc. ASME. SBC2013, Volume 1A: Abdominal Aortic Aneurysms; Active and Reactive Soft Matter; Atherosclerosis; BioFluid Mechanics; Education; Biotransport Phenomena; Bone, Joint and Spine Mechanics; Brain Injury; Cardiac Mechanics; Cardiovascular Devices, Fluids and Imaging; Cartilage and Disc Mechanics; Cell and Tissue Engineering; Cerebral Aneurysms; Computational Biofluid Dynamics; Device Design, Human Dynamics, and Rehabilitation; Drug Delivery and Disease Treatment; Engineered Cellular Environments, V01AT16A006, June 26–29, 2013
Paper No: SBC2013-14645
Abstract
Proteoglycans (PGs) are one of the major components in the extracellular matrix (ECM) of cartilage, and are negatively charged due to the charged groups attached to their backbone (i.e., fixed charge groups). PGs play substantial roles in the mechanical, biotransport and electrical events within the tissue. 3,7 More specifically, swelling pressure generated by the interaction between fixed charge groups and ionic interstitial fluid enhances cartilage’s capacity of load-bearing. In addition, biotransport properties (e.g., hydraulic permeability) and electrical properties (e.g., electrical conductivity) have been shown to be affected by water content (i.e., porosity) and fixed charge density (FCD). 2–4 The alteration of proteoglycan content will affect the tissue FCD and water content, which could cause the changes in biomechanical, biotransport and electrical properties of the cartilage. The relationship between the PG content and biomechanical properties has been widely studied, 6,8 but the knowledge on the effects of PG content on biotransport and electrical properties is limited. 1 It is not clear whether the dependences of biotransport and electrical properties on PG content are mainly due to electric effects through the FCD associated with PGs or due to hindrance effects related to the effective pore size (i.e., water content) of the tissue. Therefore, the objectives of this study were (1) to investigate the effects of PG content on cartilage biotransport and electrical properties, (2) to analyze whether these effects are caused by changes of water content or FCD.
Journal Articles
Article Type: Research Papers
J. Pressure Vessel Technol. June 2010, 132(3): 031202.
Published Online: May 4, 2010
Abstract
This paper presents a new analytical method that can calculate the load distribution on the thread teeth in cylindrical pipe threaded connection. The new method was developed by analyzing each male and female thread tooth from the connection on the basis of elastic mechanics. By using this method, the load distribution on each thread tooth can be calculated with the tightening torque and thread numbers. By applying the new method on the sample of API 88.9 mm round threaded connection, the obtained results show that the load on thread tooth mainly concentrates on the last four or five threads engaged. By using the finite element analysis method to the same sample validates the new method. The new method proposed in this paper is practical and convenient because it can be applied to calculate the load and deformation on each thread tooth just with tightening torque and thread numbers, which is easier to implement in practice.
