Valve Disc Research Articles

Internal flow and vibration characteristics of axial flow check valves based on fluid-structure interaction analysis

Axial flow check valves are primarily employed to regulate the unidirectional flow of fluids within pipelines, preventing backflow or reverse flow. The design of this type of check valve ensures its opening in the direction of fluid flow and closing in the case of reverse flow, thereby ensuring that fluid within the pipeline system can only move in the predetermined direction. This paper establishes a three-dimensional physical model of the axial flow check valve with the length of 2050 mm, the height of 2200 mm and the inlet/outlet diameter of 1716 mm. Dynamic characteristics of the flow field during the closing process of axial flow check valve under different pressure difference were studied using dynamic mesh technology and User Defined Function. The vibration of the valve stem of the axial flow check valve was predicted and analyzed through fluid-structure coupling. Additionally, a fluid-structure coupled approach is employed to predict and analyze the vibration of the valve stem in axial flow check valves. The results indicate that with an increase in the pressure difference at the inlet and outlet, the time required for the check valve to close decreases, leading to an acceleration in the valve disc’s velocity. Simultaneously, the fluid forces exerted by the flow field on the valve stem the increase, resulting in more significant vibrations. Among these vibrations, the first three natural modes have the most substantial impact on the valve stem. To prevent damage to the valve stem, efforts should be made to minimize the influence of these first three modes on axial flow check valves. This study provides valuable recommendations and support for preventing damage to the valve stem in operational scenarios involving axial flow check valves.

PDMS micro check valve with 3D valve disk for reducing fluid resistance

Check valves are essential components in various biomedical, chemical, medical diagnostic, and process applications, as they allow fluid flow in the forward direction while blocking the reverse flow. This paper presents a method to enhance the performance of unibody micro check valves composed of polydimethylsiloxane using 3D design and printing technologies. Passive micro check valves, which are known for their structural simplicity, miniaturization, and light weight, have shown improved performance with the application of 3D valve disks formed via 3D printing technology. The performance of various valve disk designs was evaluated using simulations and experiments, which revealed that cone-shaped 3D valve disks offer a 58.33% improvement in blocking pressure performance compared to traditional two-dimensional designs. This underscores the potential for efficient fluid control in micro check valves using 3D structures while highlighting the importance of 3D printing technology in the design and manufacturing processes of microfluidic devices.

Butterfly valve erosion prediction based on LSTM network

When valves and pipelines are used, erosion wear is a major concern. Erosion wear can lead to equipment downtime, material replacement, and other issues, as well as seal surface failure. The research delves into the phenomenon of erosion in butterfly valves, crucial components utilized across diverse industrial sectors. Erosion primarily affects the valve's disc and seat regions, leading to premature wear and compromised performance. To address this issue, the research employs computational fluid dynamics (CFD) and machine learning techniques, including long short-term memory (LSTM) and BP neural networks, to predict erosion rates under various conditions (different valve openings and particle diameters). Results indicate that erosion escalates with time and larger valve openings, highlighting the need for proactive maintenance strategies. The LSTM model demonstrates superior predictive capabilities compared to the BP neural network, offering valuable insights for improving butterfly valve design and operational efficiency in industrial settings. Furthermore, to seek a more efficient network configuration, the intelligent search capabilities of the particle swarm optimization (PSO) algorithm have been utilized to systematically explore the optimal network structure parameters. The prediction results highlight the advantages of LSTM in handling time series data, particularly in predicting erosion rates with complex dynamic characteristics.

Integrated High-Throughput Centrifugal Microfluidic Chip Device for Pathogen Detection On-Site.

An integrated and high-throughput device for pathogen detection is crucial in point-of-care testing (POCT), especially for early diagnosis of infectious diseases and preventing the spread of infection. We developed an on-site testing platform that utilizes a centrifugal microfluidic chip and automated device to achieve high-throughput detection. The low-power (<32 W), portable (220 mm × 220 mm × 170 mm, 4 kg) device can complete bacterial lysis, nucleic acid extraction and purification, loop-mediated isothermal amplification (LAMP) reaction, and real-time fluorescence detection. Magnetic beads for nucleic acid adsorption can be mixed by applying electromagnetic fields and centrifugal forces, and the efficiency of nucleic acid extraction is improved by 60% compared to the no-mixing group. The automated nucleic acid extraction process achieves equivalent nucleic acid extraction efficiency in only 40% of the time consumed using the kit protocol. By designing the valve system and disc layout, the maximum speed required for the centrifugal microfluidic chip is reduced to 1500 rpm, greatly reducing the equipment power consumption and size. In detecting E. coli, our platform achieves a limit of detection (LOD) of 102 CFU/mL in 60 min. In summary, our active centrifugal microfluidic platform provides a solution for the integration of complex biological assays on turntables, with great potential in the application of point-of-care diagnosis.

PLUG KNOT PROCESSING OF GLOBE VALVE

Globe valves are essential components in fluid control systems, widely used in various industries for regulating flow. This paper provides an overview of globe valves, focusing on their design, operation, and applications. The distinctive spherical body shape of globe valves allows for precise control of fluid flow through the system. The paper discusses the internal components of globe valves, including the valve stem, disk, seat, and bonnet, highlighting their roles in the valve's functionality. Furthermore, it examines different types of globe valves, such as straight pattern, angle pattern, and Y-pattern valves, along with their specific applications and advantages. Additionally, the paper addresses common materials used in globe valve construction, emphasizing the importance of selecting materials suitable for the operating conditions and the fluid being controlled. Lastly, maintenance and troubleshooting tips are provided to ensure optimal performance and longevity of globe valves in industrial settings. Emphasis is placed on their operational mechanisms, wherein the movement of the plug, controlled by the stem, modulates flow rates precisely. Overall, this paper serves as a comprehensive guide to understanding globe valves and their significance in fluid control systems Keywords: Globe vаlve (type) , valve body, bonnet, plug , disk ,valve seat, stem.

Liquid hydrogen cavitation analysis inside an oblique globe valve

Liquid hydrogen is widely used in the rocket engine test system as a fuel, and the fueling process of liquid hydrogen is controlled by the oblique globe valve installed in the liquid hydrogen main pipeline. As LH2 is transported through the oblique globe valve, cavitation has the tendency to occur near the throttling region where fluid flow causes the local static pressure to be lower than the saturated vapor pressure, especially during opening and closing process. In this paper, the cavitation dynamic evolution and axial force for the whole valve disc during opening and closing process of an oblique globe valve are investigated by the dynamic mesh and UDF technology. The results reveal that the cavitation evolution during opening process is divided into three stages including cavitation inception, cavitation development and cavitation full development. The axial force for the whole valve disc during the cavitation evolution process is increased first and then decreased as the time goes on. The unbalanced pressure distribution on the bottom of valve disc is harmful to the response of the valve disc at its maximum displacement. This work is of significance for the cavitation control and structural design of liquid hydrogen oblique globe valves.

Research and development of innovative bidirectional control plate valve for reciprocating compressor

Currently, the reciprocating compressor valve operates on a single working principle, where the valve structure relies on the combined force of its own elasticity and gas thrust to drive the movement of the valve disc, and continues to open and close in the way of impact. Due to the defects of the conventional plate valve, such as delayed opening, premature closing, and insufficient full opening time, in combination with the self-acting valve structure and constant volume cylinder where artificial adjustment of compressed air volume is not feasible. Therefore an innovative bidirectional control plate valve has been developed in this study, which employs a linear motor to regulate the valve disc and eliminates structural components such as springs, buffer discs, and valve lift guard. Throughout the entire opening and closing cycle, precise control of the valve disc enables swift operation with prolonged full open state, minimal resistance loss, and absence of impact, vibration or rebound. Its ideal movement mode can directly and accurately achieve stepless capacity regulation. The primary suction valve of the industrial 3LW-5-8 reciprocating compressor is taken as the research subject in this paper. Fluent software is utilized to design the structural parameters of an innovative plate valve, and its feasibility and effectiveness are validated through tests conducted on an automated multi-functional experiment table and an L-type reciprocating compressor. The results demonstrate that the new valve exhibits a 21.52% increase in effective flow area compared to the conventional plate valve, along with a 3.02% increase in exhaust volume and a potential reduction of 2.32% in power consumption when replaced one of the four. Moreover, the innovative bidirectional control plate valve demonstrates precise control over high-frequency motion of the valve disc, effectively addressing inherent limitations of traditional plate valves and exhibiting promising application prospects.

Reliability analysis of respirators based on the analytic hierarchy process and multicriteria decision-making

This study examined the reliability of respirators using hierarchical analysis and multicriteria decision-making. The hierarchical structure, which consists of three assessment criteria and six product assemblies as decision possibilities, reveals that the priority of evaluation criteria follows the trend of cost, complexity and technology. Face-piece, triple-piece and visor assemblies have the highest failure rate, according to an analysis of product reliability at the assembly level. However, according to the analysis at the parts level, the most likely failures are found in the face-piece, upper and lower visor frames, visor, head-harness, exhalation valve disc and exhalation valve seat. In addition, the Weibull distribution function (with a shape parameter >1) can be utilized to predict product reliability. Among the six defined product assemblies, according to the sensitivity analysis, the overall weight of the triple-piece assembly and the visor assembly has the most sensitivity to changes in the priority of evaluation criteria.

Analysis of disc movement during the closing process of axial flow check valves

In a long-distance pipeline system, when the pump is stopped, the axial flow check valve will suddenly close under the pressure difference force of the medium, and the instantaneous valve disc will collide and impact the valve seat at a certain speed, which will have a certain impact on the structural strength and service life of the check valve. This article uses explicit dynamics to simulate the movement process of the instantaneous valve disc when it is completely closed and analyzes the velocity of the valve disc after the collision. Based on the spring damping model theory, the velocity of the valve disc after collision is derived. After error analysis, the reliability of numerical simulation has been verified, which has a certain guiding significance for the practical application and design improvement of axial flow check valves.

Nondestructive evaluation of mechanical heart valve disc thickness degradation due to accelerated durability test using THz-TDS measurements

ABSTRACT Quality assurance and control during the mechanical heart valve components’ production process is paramount to mitigate most of the valve-related complications arising from valve replacement. Nondestructive evaluation of heart valve implants with complex profiles during production is challenging due to the biocompatibility requirements and clean room assembly conditions. This study first tested the UHMWPE disc of TTK Chitra mechanical heart valve models TC1 and TC2 using Terahertz imaging in reflection mode. The UHMWPE discs were raster scanned in X-Y directions to obtain a Terahertz-C scan to locate the macro defects due to wear out, and to distinguish between the true positive and true negative samples. The results were verified with digital microscope studies. Second, this study investigates a unique relationship between Terahertz imaging in reflection mode and heart valve disc degradation due to accelerated durability study. Third, the variation of disc surface roughness due to accelerated durability test was studied by Gaussian curve fitting analysis of fast Fourier transform of the Terahertz reflections. Finally, a comparison between the TC1 and TC2 heart valve model’s wear-out foot print was carried out using Terahertz C-scan. Our results imply that Terahertz time-domain spectroscopy has promising applications in NDE measurements of biocompatible implants.

Acoustic Emission Valve Disc Slight Opening Recognition Technology

Currently, there is no universally recognized valve disc slight opening identification technology for online verification in safety valves. For spring-loaded safety valves, there is no online verification method available when the mid-range value is unknown. Particularly in the online verification of spring-loaded safety valves, the existing methods generally suffer from the drawback of poor verification accuracy. This paper proposes a novel approach, centered around a computer system, comprising an acoustic emission sensor, a signal amplifier, a valve stem lifting device, and an additional acoustic emission sensor. The signals indicating the slight opening of the safety valve disc are collected by the acoustic emission sensors, and the extracted features of these signals are subsequently analyzed for identification purposes. This method exhibits high accuracy and generalizability, thereby enhancing the accuracy of online verification results for safety valve disc slight opening. The experimental setup complies with the "TSG-ZF001-2006" (Regulations for Safety Technical Supervision of Safety Valves), and the experimental apparatus demonstrates an error rate below 2% compared to the offline calibration bench, outperforming other methods with 5%-10% higher accuracy than safety valve online verification devices. This approach holds significant potential for widespread adoption within the industry, aligning with SCI (Science Citation Index) standards.

CFD investigation of flow forces on a safety valve

In this article, authors investigated a DN50/80 size safety valve with computer fluid dynamics (CFD) simulation to determine the lift forces and mass flows acting on the valve disc at 3.5 to 5.5 barg inlet pressures and to observe the evolution of turbulent streamlines in the outlet side of the valve, with static disc position. The simulation results were compared with measured data. Authors studied the inner flow field of the valve with fixed 5 mm disc elevation. Lift force acting the disc and overall stream pattern were investigated with the gas vale. To eliminate backflow, authors applied a virtual streamtube on the outlet nozzle with various lengths. Differences between data of the valve measured and simulated results were investigated besides changing the length (50, 150, 250, 350 and 400 mm) of the applied tube.

Automated multi-functional system for the characterization of plate valves in reciprocating compressors

At present, there are two independent technologies and equipment for the test of the reciprocating compressor plate valve: the sealing test and blowing test. This method has single function and complicated test operation and may rely on theoretical calculations, which reduces the reliability of the test conclusion because the motion law of valve disk during opening and closing is extremely complicated. The existing test methods cannot meet the needs of more in-depth and accurate research, development and improvement of the plate valve. This study proposes a test device and method that can not only quantitatively test the performance of the plate valve but also qualitatively test the dynamic process of the suction valve plate, which can greatly reduce the testing time provide more intuitive and accurate valve plate motion tracks and valve paths. This paper takes the primary plate suction valve as the test object and adopts the automated multi-functional system to accurately obtain the valve’s sealing property, effective flow area, thrust coefficient, flow coefficient, drag drop, valve gap Mach number, initial opening pressure difference, maximum opening, and residence time of the valve plate on the valve lift guard to provide necessary data for valve design and performance evaluation. The test results of valve opening time are verified by industrial reciprocating compressor, which proves the accuracy and practicability of the system.

Flow accelerated corrosion and thinning mechanism of the pipeline after the butterfly valve based on CFD

Severe thinning was found on the pipeline after the butterfly valve of a hydrogenation unit, gravely threatening the safety and reliability of the unit. The mechanism of pipeline thinning was fully investigated in this work. The results of microstructure analysis showed that the corrosion products of thinned pipeline were mainly FeS2. The CFD results showed that flow accelerated corrosion was the main cause of pipeline thinning. The fluid behind the valve was violently disturbed due to the flow restriction of the valve disc. As a result, the pipeline suffered from erosive effect from high velocity flow with a very large wall shear stress. The region of high velocity and high wall shear stress was basically the same as the actual thinning region. The thinning mechanism of the pipeline was systematically dissected and described.

Fluid Flow and Effect of Turbulence Model on Large-Sized Triple-Offset Butterfly Valve

The performance a valve has been frequently estimated with numerical methods owing to limitations such as cost and place. In this study, for the triple-offset butterfly valves, the different sizes in various disc-opening cases was numerically conducted using different turbulence models of the two-equation turbulence models of k–ε, k-ω, and Reynolds stress model. The numerical calculations were validated against experimentally obtained valve flow test results. The numerical effect with the different turbulence models were analyzed with respect to the disc-opening cases. From the numerical analysis, the Reynolds stress model exhibits the most pronounced turbulence effects among the various turbulence models showing higher value of Reynolds normal stress near the valve disc region. The sensitivity of the turbulence model constants was examined using the 300 mm valve to observe the sensitivity of the turbulence model parameters in the two-equation turbulence models.

Numerical analysis of fluid force on orifice structure of valve disc for nuclear globe valve

The globe valve fails to open completely sometimes due to insufficient lifting of the valve disc during the operation of the nuclear power plant. The main reason is the inadequate understanding of changes in fluid force. Therefore, conducting research on the fluid force of the globe valve is crucial. In this study, we establish a high-fidelity computational fluid dynamics (CFD) numerical model to investigate the flow characteristics of a novel balanced globe valve. Based on the analysis results, we concluded that the size of the throttle orifice is an essential factor affecting fluid force. Therefore, the impact of the throttle orifice sizes on the fluid force is studied. Meanwhile, the coupling influence of different valve disc displacements and inlet pressures on fluid force is quantitatively analyzed. This study provides a basis for the design of globe valves and has potential value for the dynamic control and energy utilization.

Experimental and numerical investigation on dynamic characteristic of nozzle check valve and fluid-valve transient interaction

Check valves play an important role in multiple systems within nuclear power plants. This study focuses on the valve closing process and investigates the dynamic characteristics, valve disc motion, and flow field of a nozzle check valve under different spring stiffness and fluid deceleration rates using experimental and numerical simulation methods. Experimental tests were conducted on a DN300 annular disc-type nozzle check valve with a spring stiffness of 3000 N/m, and the dynamic characteristic curve of the check valve was obtained. The curve exhibits a small maximum slope (0.0454), indicating good dynamic performance of the check valve. Numerical simulations were performed using the dynamic mesh method and RNG k-ε turbulence model to study the effects of different spring stiffness and fluid deceleration rates on the maximum reverse flow velocity, disc motion process, disc impact velocity, and internal flow field of the valve. The maximum reverse flow velocity was also corrected, and the resulting dynamic characteristic curve agrees well with experimental values. This study analyzes the influence of spring stiffness and fluid deceleration rate on various parameters during the dynamic closing process of the check valve. This study contributes to the optimization design of check valves and provides guidance for more accurate calculation of the dynamic characteristic curve of check valves through numerical simulations.

Numerical simulation of liquid–solid two-phase flow and erosion of Y-type slurry valve with different openings

Most conveyed industrial slurries contain hard particles, and the Y-type slurry valve is eroded after the long-term operation, causing economic losses. In this study, the liquid–solid two-phase flow and erosion characteristics of the Y-type slurry valve were studied. The distribution positions of particles with different sizes were determined, and large particles showed a deposition phenomenon. The particle distributions were more dispersed. At smaller valve opening degrees and the average velocity of solid particles decreased with the increase in valve opening degree. The main erosion area of the valve was concentrated on the ring area around the valve body connecting the downstream pipeline, and the valve disc. The relationship between the particle size and the erosion rate was analyzed, and the distribution of the main erosion area was obtained.

Comparative Analysis of the Performance Characteristics of Butterfly and Pinch Valves

Valves are important components in controlling the amount of fluid going to devices. One of these types is the butterfly valve (BFV) that adjusts the amount of flow by rotating the valve disk by means of its shafts which is usually located in the middle of the flow. Despite its common usage in various applications, the BFV is known to cause a high-pressure drop. Conversely, the pinch valve is another type of flow control device that uses a pinching mechanism to open and close the inner tube by pinching at different degrees. The absence of flow-controlling mechanisms in the flow path, such as the valve disk and its shaft, contribute to the minimal pressure drop in pinch valves. The high-pressure drop in BFVs and the minimal pressure drop in pinch valve flow make it worthwhile to investigate and compare their flow at all opening positions of the two valves. Therefore, this work numerically explores the potential of using the pinch valve as an alternative to the BFV in terms of its ability to attain a lower pressure loss, hence better flow rate. The influence of various BFV parameters such as shaft diameter, valve thickness, and valve disk edge were examined. The performance characteristics of both valves were obtained using CFD models formed on the SolidWorks program. This CFD model solves the differential equations using the finite element method. Moreover, a mathematical model to determine the area of the pinch valve at various pinching degrees was developed and compared with the results obtained from other mathematical models and CFD. It was shown that using a flat 1 mm valve disk thickness with round edges resulted in a 7.5% increase in mass flow rate compared to standard BFVs. On the other hand, using the pinch valve resulted in over a 700% mass flow rate compared to the BFV at a 25% opening position and a 49% increase in flow rate at a 75% opening position. Thus, the pinch valve has the potential to replace the BFV due to its better flow characteristics in any application.

Research on stability and control strategies for a spring-loaded valve with bypass outlet

The stability and control strategies of a spring-loaded valve with bypass outlet have been studied by combining numerical and theoretical analysis. First, a nonlinear dynamical model and a CFD model of a spring-loaded valve with bypass outlet are developed. The theoretical analysis requires parameters such as discharge coefficients and fluid forces obtained from CFD simulations. The equivalent area of the fluid forces and discharge coefficients are similar at different pressure differences, leading to a reduced-order formulation that serves the theoretical analysis of nonlinear dynamics. Second, the valve disc oscillates at small constant flow rates by nonlinear dynamical analysis. The oscillation frequency is a superposition of the Helmholtz cavity and the mass spring system, which increases as the valve disc impacts the seat or the upper limiter. More importantly, there is a frequency lock-in phenomenon at small fluctuating flow rates, which vanishes at large flow rates. The oscillations are not symmetric during the opening and closing processes, and the oscillations are more severe during the opening processes. Finally, the bypass outlet has a great effect on the stability of valve disc, which can appropriately kill the nonlinear component in the dynamic equation. A reasonable bypass sleeve design can reduce the unstable flow range and oscillation amplitude. This paper provides a reference for the design of spring-loaded valves.