Characteristics Of Valve Research Articles

Fluid-structure interaction analysis on flow field and vibration characteristics of gas proportional valve

Fluid-structure interaction analysis on flow field and vibration characteristics of gas proportional valve

Physical properties of Korean normal aortic valves based on fluid–structure interactions

Recently, numerical methods such as computational fluid dynamics (CFD), have been widely used in heart valve research. The CFD approach has fewer restrictions compared to clinical and experimental methods as it involves interpretations through computer calculations, and it can be used to predict and analyze fluids. For valve numerical analysis using CFD, the mechanical properties of the valve must be defined based on the physical properties. However, most of the existing heart valve numerical analysis studies have been conducted for westerners, and only a few studies on the same topic have focused on Asians. Thus, in this paper, we aim to determine the physical property parameters suitable for defining the mechanical properties of the normal aortic valves of Koreans over time. In this study, we used a fluid−structure interaction technique for the valve simulation and applied three representative valve characteristics presented in previous aortic valve simulation studies. Herein, the valve patency rates in case of simulation and multidetector computed tomography images were compared and analyzed through statistical techniques. Our results revealed that the physical properties, such as density (1050 kg/m3), Young’s modulus (2 MPa), and Poisson’s ratio (0.3), are like those of the Korean aortic valve over time. If hemodynamic evaluation of the Korean aortic valve is performed through simulation using these conditions, it can be effective in identifying the factors of heart valve disease.

Determination of Static Flow Characteristics of A Prototypical Differential Valve Using Computational Fluid Dynamics

Abstract The paper describes the numerical calculations of a conceptual air brake valve of a trailer equipped with a differential section, which is intended to shorten response time and braking distance. The static flow characteristics have been determined using computational fluid dynamics (CFD). Mixed (global and local) computational meshes were used in the paper to determine the static flow characteristics of the valve sections. The use of the local mesh was relevant for valve openings smaller than 0.5mm. Using CFD, it was possible to determine the static flow characteristics of the main, auxiliary feed and the differential sections, which were linear, degressive and progressive depending on the section. The analyzes, which have not yet been described in the literature, showed a significant difference in the MFR of the additional and main feed tracts, which reached 52.29%.The results are applicable to the configuration of the braking system. Further research will include performing dynamic simulations using dedicated software and building a test rig to validate the CFD calculation results.

Analysis of erosion and sealing characteristics of V-regulating ball valves for coal chemical industry

Purpose This study aims to research the erosion wear characteristics and sealing performance of V-regulating ball valve in coal chemical process pipelines, which provides a theoretical reference for improving its antiwear and sealing performance. Design/methodology/approach Taking the V-regulating ball valve as the research object, based on the computational fluid dynamics and the theory of erosion wear, the authors studied its erosion characteristics under different medium parameters and analyzed the sealing performance under the heat-fluid–solid coupling working condition. Findings The erosion wear mechanism of the valve sealing surface is the simultaneous action of cutting and deformation. When the medium flow velocity, particle mass flow rate and particle size increase, the maximum erosion rate and average erosion rate in the V-regulating valve increase. The inner diameter Mises contact stress of the sealing surface is symmetrically distributed in a “wing shape,” and the contact stress of the outer diameter is distributed in a “butterfly shape.” Due to the superposition of thermal stress and pressure stress in the contact transition zone to produce a significant stress concentration. Practical implications The findings will provide a theoretical basis for improving the erosion resistance and sealing performance of V-regulating ball valve in coal chemical industry. Social implications V-type regulating ball valve is widely favored by coal chemical enterprises and petrochemical enterprises because of its wide adjustment ratio and good erosion resistance. Originality/value The V-regulating ball valve wear mechanism for cutting and deformation simultaneously, and its wear rate is positively correlated with the medium flow rate, particle mass flow rate and particle size. After the valve is opened, there is a significant stress concentration occurs in the contact transition zone due to the superposition of thermal stress and compressive stress. The findings will provide a theoretical basis for improving the erosion resistance and sealing performance of V-regulating ball valve in coal chemical industry. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0205/

Hydraulic parameter estimation for district heating based on laboratory experiments

In this paper we consider calibration of hydraulic models for district heating networks based on operational data. We extend previous theoretical work on the topic to handle real-world complications, namely unknown valve characteristics and hysteresis. We generate two datasets in the Smart Water Infrastructure Laboratory in Aalborg, Denmark, on which we evaluate the proposed procedure. In the first data set the system is controlled in such a way to excite all operational modes in terms of combinations of valve set-points. Here the best performing model predicted volume flow rates within roughly 5 and 10 % deviation from the mean volume flow rate for the consumer with the highest and lowest mean volume flow rates respectively. This performance was met in the majority of the operational region. In the second data set, the system was controlled in order to mimic real load curves. The model trained on this data set performed similarly well when evaluated on data in the operational range represented in the training data. However, the model performance deteriorated when evaluated on data which was not represented in the training data.

Numerical analysis of fluid-thermal-structure coupling characteristics of CO2 booster pump valve

CO2 booster pump valves are key components in the CO2 oil drive industry, and their reliability is critical to the safe operation of pumping booster systems. Due to the special nature of CO2, heat transfer occurs during valve movement, which can cause damage to the valve body and poppet, and thus in-depth studies on CO2 properties are needed to better predict the locations where the valve is vulnerable to damage. However, relatively few studies have been conducted to analyze the fluid-thermal-solid coupling failure of CO2 booster pump valves. This paper establishes a multi-physics coupled thermodynamic model of CO2 booster pump valves, analyzes the transient simulation of valves at different valve openings, pressures and temperatures, and investigates the thermal properties of four different poppet materials. The results show that: with the increase of valve opening, the maximum deformation of the valve decreases sharply, and then tends to stabilize; in the process of pressure increasing from 4.77 MPa to 10.52 MPa, the turbulent kinetic energy inside the valve increases by about 78 %; it is also found that the thermal deformation of different poppet materials is directly proportional to the coefficients of thermal expansion of the materials, among which the deformation of aluminum alloy poppet is the largest. In addition, the results of thermal deformation and thermal stress distribution indicate that the failure region of the valve is usually concentrated in the poppet and its corresponding body wall. These results provide theoretical references for optimizing the structural design of CO2 booster pump valves and help reduce the risk of failure of CO2 booster pump valves.

Air Leakages at Microvalves: Pressure Decay Measurements and Extended Continuum Modelling of Knudsen Flows

To improve the performance of valves in relation to the leakage rate, a comprehensive evaluation of the valve characteristics and behavior during pressure exposure is important. Often, these low gas flow rates below 0.1 cm3/min cannot be accurately measured with conventional flow sensors. This paper presents a small and low-cost test rig for measuring gas leakage rates accurately, even far below 0.1 cm3/min, with the pressure decay method. These leakage flows are substantiated with a flow model, where we demonstrate the feasibility of modeling those gas flows with an extended Navier–Stokes framework to obtain more accurate theoretical predictions. As expected, the comparison to the experimental results proves that the classical Navier–Stokes system is unsuitable for modeling Knudsen flows. Hence, self-diffusion of gas, a wall-slip boundary condition, and an effective mean free path model were introduced in a physically evident manner. In terms of the calculated mass flow, while self-diffusion and slip boundary conditions explain deviations from the classical Navier–Stokes equation for Knudsen numbers already smaller than 1, the effective mean free path model has an effect, especially when Kn > 1. For simplified conditions, an analytical solution was presented and compared to the results of an OpenFOAM CFD-solver for flow rates through more complex gap-flow geometries of the flap valve. Hereby, acceptable deviations between 10% and 20% were observed. A comparison with measurement results was carried out. The reproducibility of the measurement method was verified by comparing multiple measurements of one silicon microvalve sample to a state-of-the-art flow sensor. Three geometrically similar passive silicon microvalves were measured with air overpressure decreasing from 15 kPa relative to atmospheric pressure. Maximum gas volume flowing in a blocking direction of 1–26 µL/min with high reproducibility and marginal noise were observed.

Orifice erosion effect and variable gain control method for hydraulic servo spool valve

The hydraulic servo valve orifice becomes blunted due to erosion caused by solid particle contaminants in the oil, leading to a decline in the valve's static and dynamic performance. This study analyzes the working edge scanning model and proposes using a quarter-ellipse curve to fit the working edge contour for the precise calculation of the valve orifice area. Through AMESim simulation, this study investigates the relationship between valve orifice erosion and the static and dynamic characteristics of hydraulic servo slide valves and proposes a variable gain control method for addressing valve orifice erosion. Results show that the orifice area model based on the quarter elliptic curve is accurate. As erosion increases, the nonlinear area of the valve orifice curve expands, and the valve orifice degrades into a positive opening. The ratio of the long diameter to the short diameter of the ellipse is approximately linearly related to the pressure gain and leakage in the static characteristics of the hydraulic servo valve. After variable gain control, the static and dynamic characteristics of the servo valve closely resemble those of an ideal servo valve, with the maximum deviation between the flow characteristics and the ideal valve orifice approximately 1 %. Regarding pressure characteristics, the pressure drop before the zero position is below 0.2 MPa. This study establishes the internal relationship between orifice erosion and performance degradation and provides a novel approach to enhancing the erosion resistance of hydraulic servo valves.

Dynamics and experimental study of a novel proportional directional valve with displacement feedback groove controlled by high-speed switching valves

The intelligence of hydraulic roof support is an important guarantee for unmanned fully mechanized coal mining face. The water-based medium proportional directional valve is the main factor that restricts the intelligent realization of support system. The support control valve needs to meet the 2/3 (two-position three-way) structure, taking into account both manual and electro-hydraulic control functions. The current water-based proportional valve does not satisfy the structural or functional demands of the support system. In this paper, a novel 2/3 water-based proportional directional valve is presented based on the displacement-flow feedback principle, which has two control modes: manual on-off control and electro-hydraulic proportional control. The proportional valve comprises two main valve spools and two pilot valves. The pilot valve is composed of a 2/3 on-off valve with manual operation capability and a high-speed switching valve group controlled by PWM (Pulse Width Modulation). The mathematical model of the proportional valve is established, and the experimental system is built to verify the characteristics of proportional valve. The proportional valve can meet the special functional requirements of the support. In the proportional control mode, the adjustment of spool displacement is regulated through the modulation of PWM duty ratio, resulting in effective control performance of the proportional valve. Furthermore, the discontinuous flow of the high-speed switching valve causes the pressure fluctuation of the pilot hydraulic bridge. Increasing the carrier frequency of PWM can reduce the amplitude of control chamber pressure and spool displacement fluctuation. The findings of the study can offer valuable insights for the continued advancement and enhancement of water-based proportional valves used in hydraulic roof support systems.

Research on the characteristics of a pneumatic proportional valve

Abstract The execution of autonomous driving in heavy-duty trucks necessitates stringent regulation of their braking torque output. Hydraulic retarder serves as a widely auxiliary braking system in heavy-duty vehicles, with the pneumatic proportional valve functioning as the core component of its control system, regulating the output response and control precision of the braking torque of the hydraulic retarder. To improve the accuracy of brake torque control for hydraulic retarders, it is critical to conduct thorough research on the control system, especially the pneumatic proportional valve. Therefore, A detailed analysis of the working mechanism of pneumatic proportional valves was conducted, encompassing the construction of mathematical and simulation models. The efficacy of the simulation model was confirmed via experimental validation. When the control pressure increases, the simulation results are close to the experimental results, with a maximum discrepancy of 18%; when the control pressure decreases, the simulation results show a similar trend to the experimental results. The research can aid in formulating control methodologies for pneumatic proportional valves and offer theoretical guidelines for future exploration into boosting the precision of hydraulic retarder braking torque control.

Impact of Non-Valvular Atrial Fibrillation on Mitral Valve Anatomic Features: A Study of Three-Dimensional Mitral Valve by Transesophageal Echocardiography and Automatic Analysis Software.

Mitral regurgitation (MR) is frequently observed in non-valvular atrial fibrillation (NVAF) patients and is a significant risk factor for its progression. This study aims to investigate the three-dimensional anatomical characteristics of the mitral valve (MV) in patients with different types of NVAF to elucidate the underlying mechanisms of MR. A retrospective analysis was conducted on 82 paroxysmal atrial fibrillation patients (PAF group) and 66 persistent atrial fibrillation patients (PerAF group) who underwent real-time three-dimensional transesophageal echocardiography (RT 3D-TEE) before initial ablation. Additionally, 30 patients undergoing RT 3D-TEE for the assessment of patent foramen ovale were selected as the control group. Basic echocardiographic variables were measured, left atrioventricular volume and strain parameters were calculated using automated software (Dynamic-HeartModel and AutoStrain). MV anatomic features were analyzed using the 4D-MV Assessment software (TomTec Imaging Systems). The maximum left atrial volume (LAVmax) was highest in the PerAF group, followed by the PAF and control groups, with statistically significant differences (p<0.01). Left atrial reservoir strain (LASr) showed an opposite trend, being the lowest in the PerAF group (p<0.01). The proportion of moderate to severe MR was significantly higher in the PerAF group (27.3%) compared to the PAF group (11.0%) (p<0.01). Compared to controls, the AF groups exhibited mitral annular (MA) dilation, flattening of the MA plane, and increased leaflet area (all p<0.05). Correlation analysis between effective regurgitant orifice area (EROA) and left atrioventricular structure and function parameters, as well as various annular parameters, showed that EROA was significantly correlated with left ventricular end-diastolic volume (LVEDV), LAVmax, LASr, anterior and posterior diameter, annular area, ratio of annular height to commissural diameter (AH/CD ratio), posterior leaflet area, posterior leaflet length, and the C-shaped annulus length (all p<0.05). Significant remodeling of the MV apparatus occurs in NVAF patients, with more pronounced changes in PerAF patients, contributing to a higher incidence of moderate to severe MR. RT 3D-TEE-based MV automated assessment offers significant advantages in accurately diagnosing MV remodeling and supporting the evaluation of MR in NVAF patients.

Investigation on the Dynamic Characteristics of a New High-Pressure Water Hydraulic Flow Control Valve

Investigation on the Dynamic Characteristics of a New High-Pressure Water Hydraulic Flow Control Valve

Analysis and Optimization of Multi-Physical Field Coupling in Boom Flow Channel of Excavator Multiway Valves

The multiway valve is the core control element of the hydraulic system in construction machinery, such as excavators. Its complex internal structure, especially the flow channels, significantly impacts the machine’s efficiency and reliability. This study focuses on the boom flow channel of excavator multiway valves and establishes a multi-physical field coupling simulation model. We propose six key flow channel structural parameters and analyze changes in the valve’s flow field, temperature field, and structural field using orthogonal test simulation data. The range analysis method identifies the primary and secondary influences of structural parameters on pressure loss, temperature, stress, and strain. A multi-objective optimization model was developed using a neural network and the Non-dominated Sorting Genetic Algorithm II(NSGA-II), with pressure loss and maximum stress as the optimization objectives. The Pareto front solution set for key flow channel parameters was calculated. The optimization results showed a 9.0% reduction in pressure loss and a 40.7% reduction in maximum stress. A test bench verified the simulation model, achieving prediction accuracies of 94.8% for pressure loss in the inlet area and 92.3% in the return area. This method can provide a reference for the optimal design of the dynamic characteristics of high-pressure multiway valves.

Research on Constant-Flow Water-Saving Device Based on Dynamic Mesh Transient Flow Field Analysis

For the control of the outlet flow rate of a constant-flow water-saving device under different water pressures, this study developed and implemented a custom User-Defined Function (UDF) program to simulate the dynamic motion of the water-saving valve within the Fluent environment. This simulation realistically represents the valve’s behavior under varying water pressures, thereby accurately predicting the valve opening height to comply with national regulatory standards. Firstly, a dynamic grid transient CFD simulation model of the water-saving valve was established using a Fluent UDF program written in C language. The parameters of the elastic elements in the water-saving device flow control system were designed to achieve control of the outlet flow rate. Then, the benchmarking analysis of the aforementioned simulation model was completed based on the flow rate test results of the water-saving device. Finally, the relationship between physical quantities and flow field distribution characteristics of the water-saving valve was analyzed under three different water pressures specified in the national standard. Based on the optimization calculations, the valve opening heights under three different water pressures were obtained, ensuring that the outlet flow rates meet the regulatory standards set by the national authorities. Compared with traditional methods that rely solely on steady-state simulations or empirical data, the method proposed in this paper represents a significant advancement.

Research on positioning control strategy of hydraulic support pushing system based on multistage speed control valve

The precise position control of the hydraulic support pushing system in the coal mining face is a key technical support for intelligent coal mining. At present, the hydraulic support pushing system uses the electro-hydraulic directional valve as the control element. However, the electro-hydraulic directional valve has problems such as discrete input values, low switching frequency, delay, inability to adjust flow, and large flow fluctuations during the switching process, which results in relatively low positioning control accuracy of the hydraulic support pushing system. Therefore, this study introduces a multi-stage speed control valve that is suitable for underground coal mine conditions and can achieve flow regulation. At the same time, a segmented control strategy combining Bang-Bang control and online predictive control is proposed. Bang-bang control is used for fast propulsion with large flow rate, large range, and short time. Online predictive control method is used to achieve precise positioning control with small flow rate and small range, thereby solving the problem of low positioning control accuracy caused by the imperfect characteristics of electro-hydraulic directional valves. Finally, this study verified the effectiveness of the proposed scheme through simulation and experiments. The results showed that compared with existing logic positioning control methods based on electro-hydraulic directional valves, the proposed scheme can improve the accuracy of single cylinder positioning control from 62 mm to within 10 mm.

Characteristic Progress and New Solutions for Nozzle Baffle Type Electro-Hydraulic Servo Valve

Background: This article outlines the working principle of the nozzle baffle type electro- hydraulic servo valve and analyzes the progress of research on its characteristics more fully. Objective: Firstly, it summarizes the research progress on the characteristics of the cavitation phenomenon, which is a common failure of nozzle baffle type electro-hydraulic servo valves; secondly, it comprehensively discusses the structural characteristics of nozzle baffle type electrohydraulic servo valves: moving-iron torque motors and moving-coil torque motors, as well as the progress of the research on the characteristics of the power-stage valve spools and direct-injection valve spools. Method: It suggests to the readers other optimization methods that can be made for the cavitation phenomenon in the future, and brings innovative ideas for the readers in terms of moving-iron vs. moving-coil torque motors and other aspects that can be improved for the power-stage spools vs. direct-injection spools. Again, for the typical technical problems of nozzle baffle type electrohydraulic servo valves, we have searched and organized the related technical patents at home and abroad and clearly outlined the current improvements for nozzle baffle type electro-hydraulic servo valves. Results: Through the discussion of related articles and patents, it is found that although many methods have been proposed at home and abroad to address the shortcomings of the nozzle baffle type electro-hydraulic servo valve, it still has a high failure rate and has not been comprehensively solved, there is still a lot of room for optimization. Conclusion: Finally, the new solutions proposed for the performance deficiencies of nozzle baffle type electro-hydraulic servo valves are summarized, and the future development trend of nozzle baffle type electro-hydraulic servo valves is predicted and outlooked.

The value of percutaneous transcatheter mitral valve regurgitation repair in the combination treatment of chronic heart failure patients: Results from a 6-month observational prospective study

Rationale: Surgical interventions have been recognized as the main method to repair of valvular disorders. Percutaneous transcatheter intervention with a clipping system is being actively introduced into the treatment of chronic heart failure (CHF) patients and mitral valve insufficiency (MVI) for correction of mitral regurgitation (MR), along with drug therapy. Aim: To establish the effect of the mitral valve leaflet clipping in the combination treatment of CHF patients on the clinical course of heart failure and the remodeling process. Methods: This single center prospective comparative study included 80 patients with CHF NYHA class II–IV and secondary MR grade 3–4. The patients were on optimal medical treatment (OMT) for CHF for at least 3 months before inclusion into the study. The main group included 55 patients who underwent transcatheter mitral valve repair with the use of MitraClip system, and the control group consisted of 25 patients in whom the surgery for MR was waived for various reasons (refusal of the surgery by the patient, some valve characteristics), and only OMT for CHF was used. At baseline, main clinical and demographic characteristics of the patients in the both groups were comparable. The duration of the follow-up was 6 months. Echocardiography (echoCG), a 6-minute walk test, and measurements of the brain natriuretic propeptide level were performed in all patients at baseline and at 6 months of the follow-up. Results: At 6 months, there was a significant reduction in CHF NYHA class and an increase in the 6-minute walk test distance and a decrease in diuretic requirements (converted to furosemide, from 58.4 ± 17.2 to 38.1 ± 20.7 mg daily, р = 0.02) in the group with the MitraClip implant, but not in the control group. In the OMT only group, there were no changes over 6 months in the diuretic requirements (48.1 ± 6.68 and 43.8 ± 27.15 mg daily, respectively, р = 0.8). The number of hospital readmissions due to CHF decompensation was 7 (12.7%) in the implanted MitraClip group and 4 (16%) in the OMT group (р = 0.69). EchoCG performed at 6 months after the surgical intervention identified no cases of MR grade 2. In the MitraClip implant group, there was a decrease in the size and volumes of the left atrium (р = 0.02 and р = 0.05, respectively), left ventricle (for end-diastolic diameter p = 0.002, end-diastolic volume p = 0.03), mean pulmonary artery pressure (p = 0.03), as well as an increase in cardiac output (р = 0.04). In the patients receiving OMT only, there were no significant changes in EchoCG parameters over time. Conclusion: Our study has shown benefits of the implantation of the mitral valve leaflet clipping system, compared to OMT only, in CHF. The clipping procedure promotes a significant improvement in clinical course of CHF, reverse myocardial remodeling, and reduction in diuretic requirements.

Header Height Detection and Terrain-Adaptive Control Strategy Using Area Array LiDAR

During the operation of combine harvesters, the cutting platform height is typically controlled using manual valve hydraulic systems, which can result in issues such as delays in adjustment and high labor intensity, affecting both the quality and efficiency of the operation. There is an urgent need to enhance the automation level. Conventional methods frequently employ single-point measurements and lack extensive area coverage, which means their results do not fully represent the terrain’s variations in the area and are prone to local anomalies. Given the inherently undulating terrain of farmland during harvesting, a control strategy that does not adjust for minor undulations but only for significant ones proves to be more rational. To this end, a sine wave superposition model was established to simulate three-dimensional ground elevation changes, and an area array LiDAR was used to collect 8 × 8 data for the header height. The effects of mounds and stubble on the measurement results were analyzed, and a dynamic process simulation model for the solenoid valve core was developed to analyze the on/off delay characteristics of a three-position four-way electromagnetic directional valve. Moreover, a physical model of the hydraulic system was constructed based on the Simscape module in Simulink, and the Bang Bang switch predictive control system based on position threshold was introduced to achieve early switching of the electromagnetic directional valve circuit. In addition, an automatic control system for cutting platform height was designed based on an STM32 microcontroller. The control system was tested on the hydraulic automatic control test rig developed by Shanxi Agricultural University. The simulation and experimental results demonstrated that the control system and strategy were robust to output disturbances, effectively enhancing the intelligence and environmental adaptability of agricultural machinery operations.

Aortic valve performance after remodelling versus reimplantation in a propensity-matched comparison.

Both aortic root remodelling and aortic valve (AV) reimplantation have been used for valve-sparing root replacement in patients with aortic root aneurysm with or without aortic regurgitation. There is no clear evidence to support one technique over the another. This study aimed to compare remodelling with basal ring annuloplasty versus reimplantation on a multicentre level with the use of propensity-score matching. This was a retrospective international multicentre study of patients undergoing remodelling or reimplantation between 2010 and 2021. Twenty-three preoperative covariates (including root dimensions and valve characteristics) were used for propensity-score matching. Perioperative outcomes were analysed along with longer-term freedom from AV reoperation/reintervention and other major valve-related events. Throughout the study period, 297 patients underwent remodelling and 281 had reimplantation. Using propensity-score matching, 112 pairs were selected and further compared. We did not find a statistically significant difference in perioperative outcomes between the matched groups. Patients after remodelling had significantly higher reintervention risk than after reimplantation over the median follow-up of 6 years (P = 0.016). The remodelling technique (P = 0.02), need for decalcification (P = 0.03) and degree of immediate postoperative AV regurgitation (P < 0.001) were defined as independent risk factors for later AV reintervention. After exclusion of patients with worse than mild AV regurgitation immediately after repair, both techniques functioned comparably (P = 0.089). AV reimplantation was associated with better valve function in longer-term postoperatively than remodelling. If optimal immediate repair outcome was achieved, both techniques provided comparable AV function.

Study on Vehicle Stability and Vibration Damping Effect According to Magnetic Material Characteristics of MR Damper Solenoid Valve

Study on Vehicle Stability and Vibration Damping Effect According to Magnetic Material Characteristics of MR Damper Solenoid Valve