Characteristics Of Valve Research Articles

MICRO- AND ULTRAMICROSCOPIC STRUCTURE OF THE LEFT ATRIA-VENTRICULAR VALVULAR APPARATUS IN HUMAN AT THE MATURE AGE IN NORM

This article presents the morphological characteristics of the mitral valve of a normal heart of an adult at a mature age.The purpose of our investigation is to find out the peculiarities of the morphology of the structural components of the mitral valve apparatus of the heart of a person of mature age in the norm.Material and methods. The study was performed on 32 preparations of mitral valves of adult human hearts. A complex of morphological research methods was used: methods of light and electron microscopy, histochemical method.Results. With the use of a complex of morphological research methods, a study of the structural components of the mitral valve apparatus of a normal mature person was carried out and their histoarchitectonics was established at the micro- and sub-microscopic levels.Conclusions. The leaflets of the mitral valve are connective tissue plates covered with a single-layer flat epithelium - endothelium. The leaflets are formed by fibrous connective tissue of different density, as a result of which three layers are identified: spongy, fibrous and ventricular. Typical chordae tendineae in the form of connective tissue threads extend from the papillary muscles to the leaflets of the mitral valve and attach to their ventricular surface. The skeleton of chordae tendinea is formed by dense fibrous connective tissue. Striated cardiac muscle tissue is found in some chordae tendinea in the areas on the side of the papillary muscles. The papillary muscles are formed by the working fibers of cardiomyocytes, which form a kind of network due to branches and anastomoses. The working fibers of cardiomyocytes are accompanied by layers of loose fibrous connective tissue, which includes a large number of blood vessels.

Leakage Characteristics of Proportional Directional Valve

This paper deals with the analysis of leakage characteristics of the proportional directional valve. These characteristics distinguish a real directional valve from an ideal one. The ideal directional valve is characterized by zero leakage due to its perfect geometry. The investigated element is the three-position four-way proportional directional valve with zero spool lap and feedback from the spool position. The spool position is measured by the inductive position sensor and processed by external electronics. Internal leakage occurs due to axial and radial clearances between the spool and the sleeve. The magnitude of axial clearances that occur at throttle edges and their effect on the directional valve leakage is the subject of research. The blocked-line pressure sensitivity curve, the leakage flow curve and the center flow curve are determined by experiment. Individual characteristics are determined for different working fluid temperatures and different supply pressures. The flow through internal leaks in the center position of the valve spool is determined by analytical calculations. The flow through internal leaks is also simulated using the Ansys Fluent software. Subsequently, the geometry of the flow simulation model is modified to take into account manufacturing tolerances. From simulation results, the effect of the manufacturing tolerance magnitude on the internal leakage of the directional valve is evaluated. Finally, simulated dependencies are compared with experimentally determined characteristics.

Influence of the flow area around the ball valve on the flow characteristics of the injector control valve

The increase in common rail pressure can lead to increased cavitation inside the injector, resulting in degradation of injector performance and reduced life. The paper investigates the effect of the pressure block structure parameters (initial flow area around the ball valve) on the velocity field, pressure field, fuel gas phase volume fraction and drain rate of the control valve. The relationship between the initial flow area around the ball valve on the cavitation strength and unloading rate inside the valve was revealed. The results show that both the reduction of the flow area around the ball valve and the increase of the cavitation intensity inhibit the rate of oil discharge from the control valve. The reduction of the fuel flow area inhibits the expansion of the low-pressure region (0–1 MPa) within the flow layer, thus limiting the development of cavitation. The reduction of the cavitation area increases the fuel flow rate, however, the increase in flow rate increases the cavitation phenomenon, and these changes form a cycle (Reviewer 5. comment 2). The increase in cavitation inhibits the control valve pressure relief rate more significantly than the decrease in the initial flow area around the ball valve. Based on this, a stepped-pressure block model is proposed. The stepped pressure block model can effectively reduce the cavitation strength near the seal and enhance the oil discharge rate of the control valve. The study can provide a reference for the engineering optimization design of high-pressure common rail injector control valves.

Armature Structure Optimization of Annular Multipole Solenoid Valves Based on Electromagnetic Force Distribution

To improve the dynamic response speed of high-speed solenoid valves in electric fuel injection systems of marine diesel engines, a numerical simulation model of the solenoid valve is described in this paper. The accuracy of the simulation model was verified on the test bed of the solenoid valve. The effect of the punch position and the size of the dynamic response of the solenoid valve were investigated by using the distribution law of the electromagnetic force in the armature. The results of the test showed that armature drilling in the inter-yoke zone can optimize the solenoid closing response time, but it has little impact on the solenoid opening response time. From this rule, two groove schemes were further designed. Through comparison and calculation, it can be concluded that the fan groove scheme is better than the trapezoidal groove scheme, and that the opening and closing response times of the solenoid valve should be targeted in order to multi-target optimize the fan groove geometric parameters and the armature thickness. The results show that after optimization, the weight of the motion part is reduced by 21.6%, the opening response time of the solenoid valve is reduced by 11.1%, and the closing response time is reduced by 30.0%. While reducing the oil film damping of the armature motion, the overall dynamic response characteristics of the solenoid valve are improved.

Theoretical and experimental study on performance of compound-driven MR valve-controlled damper

A compound-driven magnetorheological (MR) valve is designed to cope with the low reliability and high energy consumption of traditional MR valves. The operating magnetic field of the valve is applied by both the excitation coil and ring magnet, maintaining excellent pressure drop performance even at zero current. To analyze the performance and obtain the variation law of the magnetic flux density and pressure drop, a pressure drop mathematical model and a magnetic field simulation model are established. The key parameters of the MR valve are also optimized using non-dominated sorting genetic algorithms-II. A dynamic performance test system is built, and the influence of the load on the pressure drop and hysteresis characteristics of the MR valve is studied. The results show that the optimized pressure drop and adjustable coefficient are improved by 4.7% and 8.6% respectively. The pressure drop grows nonlinearly with the electric current and reaches saturation at a current of 1.5 A, and a pressure drop of 1485 kPa is still generated at zero current. The output damping force of the compound-driven MR valve-controlled damper can be continuously adjustable, indicating that the dynamic performance of the damper can be controlled by adjusting the input current.

Experimental study on the correlation between erosion microstructure and performance degradation of hydraulic servo spool valve

Surface topography plays an important role in determining the performance of hydraulic components, which often leads to component failure. The dual nozzle electro-hydraulic servo valve is composed of torque motor, pilot nozzle flapper valve and servo spool valve, whereas the failure is at the level of servo spool valve. In more details, the degradation of the static characteristic parameters of the hydraulic servo valve, which is experimentally studied by artificially controlling the fillet radius of the spool working edges, is one of these failures. In addition, the microstructure characteristics of the MOOG J761 valve working edges and the circumferential distribution law of the fillet radius are obtained. The research shows that valve orifice erosion caused fillet on the working edges and increases the dispersion of the circumferential distribution. The erosion micromorphology of the working edge is mainly characterized by surface peeling, notches, grooves, and chamfers. The average and variance of the fillet of the spool working edge at the high-pressure oil exceed those of the working edge of the return oil. When the average fillet radius of the working edge increases by 2.71 times and the average fillet variance increases by 2.55 times, the maximum leakage increases by 5.08 times, the flow gain decreases, and the positive and negative flow gains are asymmetric, decreasing by 7.78% and 1.75%, respectively. The pressure gain decreases significantly by 40.30%. The relation between the microstructure of the orifice working edge and the performance degradation provides a new idea for the performance evaluation and manufacture of hydraulic spool servo valve.

Pollution characteristics of full-scale butterfly valves: Risk assessment of heavy metal release behavior influenced by the bacterial communities and corrosion products

Given that contamination of butterfly valves has not been well understood in drinking water distribution systems (DWDSs), this study aimed to investigate the synergistic adsorption/release effects of microorganisms and corrosives on heavy metals. Results showed that outer layer scales were relatively loose, while hard black inner scales were mainly composed of Fe3O4 and Fe2O3, allowing Ca, As, Cr, Tl, and Pb to accumulate with low-diverse bacteria, primarily Desulfovibrio. Loose black inner layer scales were mainly formed by Fe(OH)3 and Fe(OH)2, enabling Ca, Cr, and Pb to accumulate with high-diverse bacteria, notably Desulfovibrio, Xanthobacteraceae, and Gallionellaceae. Metals involved in the metabolic activity of bacteria showed a negative correlation with these bacteria. Metals complexed and precipitated extracellularly in bacteria exhibited a positive correlation with these bacteria. Individual Pollution Factor (ICF), Global Pollution Factor (GCF), and Risk Assessment Code (RAC) demonstrated high bio-availability risks for Cd, especially in loose deposits with significant mobility.

СРЕДНЕСРОЧНЫЕ И ОТДАЛЕННЫЕ РЕЗУЛЬТАТЫ ИНТЕРВЕНЦИОННОГО ЛЕЧЕНИЯ ФУНКЦИОНАЛЬНОЙ МИТРАЛЬНОЙ НЕДОСТАТОЧНОСТИ У ПАЦИЕНТОВ С КАРДИОМИОПАТИЕЙ

The article presents the outcomes of treatment of patients with cardiomyopathy and pronounced functional mitral insufficiency 6, 12 and 24 months after MitraClip device implantation. We observed that 6 months after the intervention, there was regression of left heart chamber remodeling, as well as positive dynamics of right ventricular ejection fraction and pulmonary artery pressure against the background of mitral valve improvement. The achieved effect of improved intracardiac hemodynamics persisted in 12 months after mitral valve clipping. After 12 months, there were signs of left ventricular remodeling without significant changes in valve characteristics and left atrial parameters. During the first 6 to 12 months after MitraClip implantation, the distance walked in the 6-minute walk test and peak oxygen consumption increased, with retention of high values of these indicators in 24 months of follow-up.

Characteristics of Electrohydraulic Control System for Electromechanical Coupled Transmission of Plug in Hybrid Electric Vehicles

This study focuses on exploring the characteristics of the electromechanical coupling transmission electro-hydraulic control system of plug-in hybrid electric vehicles, and proposes corresponding optimization measures to improve the performance and economy of the vehicle, and reduce the impact on the environment. Firstly, we analyze the working mode of plug-in hybrid vehicles; then design the structure of electromechanical coupling with variable speed and the main components of the electro-hydraulic control system, including flow control system, cooling lubrication circuit, brake and shift control circuit, hydraulic valve and spring. Finally, we applied AMESim simulation software to analyze the response characteristics of each hydraulic valve and optimized the relevant parameters of the valve based on the simulation results. By establishing a dynamic simulation model for the electro-hydraulic control system, in-depth analysis is conducted on the pressure and flow response characteristics of the clutch under slope and step signal control.

Thermal characteristics of a novel non-return valves equipped synthetic jet impingement:

Thermal characteristics of a novel non-return valves equipped synthetic jet impingement:

Influence of electronic expansion valve on heating performance of vehicle heat pump system

In this paper, based on the regulation characteristics of electronic expansion valve, an experimental platform is built for studying a vehicle heat pump system. Under an ultra-low temperature condition of -10?C, the influence of the super-heat setting value of the electronic expansion valve on the main heating performance parameters of the system is analyzed. The results show that when the superheat setting value of the main valve increases from 2 K to 8 K, the discharge temperature of the compressor increases, the heating capacity of the system decreases by 12.6%, and the compressor power decreases by 15.9%. When the superheat setting value of make-up valve increases from 15 K to 30 K, the discharge temperature of the compressor increases, the heating capacity of the system decreases by 17.7%, and the compressor power decreases by 22.0%.

THE INFLUENCE OF PROCESSING IN GRANULAR MEDIUM THE TIMING VALVES OF UMZ-4216 ENGINE TO CHANGE THEIR STRENGTH CHARACTERISTICS

Valves of the valve mechanism of an internal combustion engine are the most critical parts that largely determine the power parameters of the engine and its resource. High demands are placed on both mechanical (strength, hardness, etc.) and service properties (corrosion resistance, heat resistance, etc.) of valves. The article shows the results of hardening critical surfaces of valves in granular medium. The research is aimed at solving the urgent problem of increasing the strength characteristics of the timing valve while reducing the total material costs for its production.

Position Control Characteristics of the Water Proportional Valve with Three-core Follow-up Mechanism

Position Control Characteristics of the Water Proportional Valve with Three-core Follow-up Mechanism

Dynamic characteristics evaluation of balance valve for seawater hydraulic variable ballast system considering the depth variation

ABSTRACT A seawater hydraulic variable ballast system (SHVBS) is used to dynamically adjust the weight of the submersible. The balance valve is a crucial component of SHVBS which has two working conditions called charging and discharging process. In this paper, an experiment simulating the ocean is built to obtain the dynamic characteristics of the balance valve, including the starting pressure and the pressure difference. Then there are analyzed by a kinematic model. The results show that as the depth increases, the pressure difference increases during charging process, while it remains unchanged during discharging process. Charging process is much worse than discharging process for balance valve. When the depth is 600 metres, the pressure difference during charging process is 45 times higher than during discharging process. Furthermore, friction force is the main factor that affects the starting pressure, while the hydraulic force mainly affects the pressure difference.

Comprehensive study on EEVs regulation characteristics of vapor-injection CO2 heat pump for electric vehicles

The regulation characteristics of electronic expansion valves (EEVs) are critical to improving the comprehensive energy efficiency of the heat pump system for electric vehicles. In this paper, a vapor-injection transcritical CO2 heat pump system for electric vehicles was first established to experimentally study the impacts of EEV1 and EEV2 openings on the overall system performance. The results show that the cooling capacities of the vapor-injection system are respectively increased by 3.13% / 5.75% with the EEV1’s opening of 15% / 25% and injection ratio of 0.0975 / 0.8305, compared against these of the basic system without vapor injection. As the injection ratio rises, the cooling capacity increment tends to increase while the cooling coefficient of performance (COP) declines from 1.7 to 1.51. Then, the regulation characteristics of EEV1 and EEV2 were quantitively analyzed, indicating that the evaporation pressure is mainly determined by EEV2’s openings. By adjusting EEV1’s opening, the COP of the CO2 vapor-injection heat pump can be maximized at 1.9, with EEV1’s opening at 20% and outdoor/indoor ambient temperature at 0°C / 20°C. When adjusting EEV2’s opening, the maximum injection pressure corresponds to the maximum COP of 1.84, with EEV2’s opening at 65% under 35°C/ 27°C. When the COP reaches the maximum, the refrigerant at the outlet of EEV1 is just saturated liquid under cooling conditions, while it is located in the two-phase region under heating conditions. Besides, the optimal COP regulation strategy of the CO2 vapor-injection heat pump was further formulated based on two modes, as the strategy in the cooling mode differs from that in the heating mode.

Superconducting Valve Exploiting Interplay between Spin-Orbit and Exchange Interactions.

We theoretically investigated the proximity effect in SNSOF and SF'F structures consisting of a superconductor (S), a normal metal (NSO), and ferromagnetic (F',F) thin films with spin-orbit interaction (SOI) in the NSO layer. We show that a normal layer with spin-orbit interaction effectively suppresses triplet correlations generated in a ferromagnetic layer. Due to this effect, the critical temperature of the superconducting layer in the SNSOF multilayer turns out to be higher than in a similar multilayer without spin-orbit interaction in the N layer. Moreover, in the presence of a mixed type of spin-orbit interaction involving the Rashba and Dresselhaus components, the SNSOF structure is a spin valve, whose critical temperature is determined by the direction of the magnetization vector in the F layer. We calculated the control characteristics of the SNSOF spin valve and compared them with those available in traditional SF'F devices with two ferromagnetic layers. We concluded that SNSOF structures with one controlled F layer provide solid advantages over the broadly considered SF'F spin valves, paving the way for high-performance storage components for superconducting electronics.

Optimization of Steam Distribution Mode for Turbine Units Based on Governing Valve Characteristic Modeling

With the extensive application of renewable energy generation, thermal power units are required to participate in peak-regulating operations. The mode of steam distribution significantly influences the economy when the steam turbine operates at a low load. The turbine unit’s governing valve characteristics and steam distribution modes are studied in this paper, and the optimal sliding pressure operation curve is derived. Firstly, the theoretical model of the governing stage and the governing valve is derived, and the reliability is verified with field data. Secondly, the overall simulation model of the turbine unit is established, and the turbine off-design performance is analyzed with variable main steam pressure. Finally, the advantages and disadvantages of the three steam distribution modes are discussed thoroughly. The steam distribution modes and optimal main steam pressures are analyzed. The results show that a precise composite sliding pressure operation scheme is recommended, and a sliding pressure operation mode is adopted under 470 MW and constant pressure operation for others.

A novel study on bypass module in self-regulated pipeline inspection gauge to enhance anti-blocking capability for secure and efficient natural gas transportation

Bypass pigging technology is an emerging strategy with promising potential to reduce the velocity of pipeline inspection gauge (PIG) and mitigate pigging-induced slug volume for oil and gas transportation systems. Nonetheless, the critical issue of bypass pigs being blocked in pipelines is a major concern for wide implementations of this new technology. To this end, this study newly proposes an intelligent self-regulated bypass pig prototype by developing an internal bypass regulating module to enhance the anti-blocking capability for pigging operations. To facilitate the optimal design of the bypass regulating module, force variation characteristics of the bypass valve in blocked bypass pigs are of great significance. Accordingly, this study thoroughly investigates bypass valve forces for bypass pigging under the blockage status both experimentally and numerically. The experimental results show that an increase in gas velocity can almost linearly increase the valve force, which is mainly affected by the driving gas flow rate. Specifically, when the gas velocity increases from 1.26 to 4.4 m/s, the valve force can be increased from 1.46 to 12.88 N on average. In addition, a CFD-based numerical model was developed and experimentally validated to calculate valve forces. The numerical model, which has the mean bias error below −0.886 N with the index of agreement over 0.98, can be used as an effective approach to valve force analyses. Finally, the optimal design scheme for bypass pigging with anti-blocking capability was proposed, which can considerably facilitate the secure and efficient pigging performance and natural gas transportation.

A new assessment mechanism of primary frequency regulation capability for a supercritical thermal power plant in deep peaking

AbstractWith the rapid development of renewable energy, the primary frequency control (PFC) is becoming more critical and significant to ensure the stability of the electrical power system. As the main role of PFC, the thermal power unit tends to in a wide operation interval, and the changes in PFC characteristics along with working conditions are inevitable. By decomposing and quantifying the dynamic energy conversion process, this paper proposes a novel mechanism to evaluate the PFC capability for the supercritical thermal power plants that covered 30%–100% of the rated load. In the mechanism, a refined steam turbine model is established to reflect the short‐term dynamic response of PFC by combining it with the coupling characteristics of the main steam valve and main steam pressure in the later phase. Meanwhile, as a new prior assessment index, the equivalent electricity has been put forward to quantify the PFC capability for the power plant. In a case study of a 600 MW supercritical power plant, the capacities of PFC under 30%–50% of the rated load are quantified for the first time. Comparison results between theoretical calculation and real PFC test show that the proposed PFC capability assessment mechanism has acceptable accuracy of 96.1%, which could be effective to assess the frequency response reserve and stability margin in the grid.

Fluid-structure interaction analysis on vibration characteristics of sleeve control valve

As a key device affecting the safety and economy of the pipeline system of nuclear power plants, the control valve regulates the medium pressure and flow rate. In this paper, taking the sleeve control valve as the research object, lift coefficient of flow field and vibration analysis of valve stem and plug are conducted with fluid–structure interaction (FSI) method to investigate the vibration characteristics of the sleeve control valve. The results show that the vortex moves downward and the intensity decreases with the rising of valve opening. The dominant frequency of vortex shedding occurs around 449 Hz. The lift coefficient CL is maximum at small valve opening. CL reaches about 2400 at Lmin-op, while CL is about 850 at Lmax-op. On M1 of stem, the total vibration level decreases with the rising of the valve opening, increasing by 4 % and 3 % on the Y-axis and Z-axis respectively. On M2 of plug, the total vibration level decreases with the decrease of the valve opening, and the total vibration level is down nearly 7.5 % on the X-axis. With the rising of the valve opening, the total vibration level difference between M1 and M2 is increasing, which reach 25.47 dB and 8.48 dB on the X-axis and Z-axis respectively. This work provides a certain reference value for the research on vibration reduction and noise reduction of sleeve control valves.