Valve Plate Research Articles

Application and structural optimization design of magnetic fluid sealing in valve plate pairs of plunger pumps

Application and structural optimization design of magnetic fluid sealing in valve plate pairs of plunger pumps

Synergistic Effect of Elliptic Textures and H-DLC Coatings for Enhancing the Tribological Performance of CuAl10Fe5Ni5 Valve Plate Surfaces

Axial piston pumps with compact structures and high efficiency are widely used in construction machinery. The efficiency and lifetime strongly depend on the tribological performance of the pump’s valve plate pair. To enhance the tribological performance of the valve plate pair, surface textures, and H-DLC coatings were fabricated to modify the CuAl10Fe5Ni5 surfaces. The influences of elliptic textures of different sizes and textured H-DLC coatings on the surface friction and wear properties of the valve plate surface under oil lubrication were evaluated using a ring-on-disk tribometer. The results reveal that the friction and wear properties of the CuAl10Fe5Ni5 surfaces are significantly enhanced by elliptic textures, and the friction coefficient and wear rate of textured CuAl10Fe5Ni5 with E90 are maximally decreased by 95% and 87%, respectively. Compared with the surface textures and H-DLC coatings, the textured H-DLC coating has the greatest ability to reduce wear and adhesion. The wear rate of the textured H-DLC coating is further reduced by 98%. This improvement can be explained by the synergistic effect of the elliptic textures and H-DLC coatings, which are attributed to the reduced contact area, debris capture, and secondary lubrication of the elliptic textures, and increased surface hardness.

Flow field torque analysis and valve plate optimization of butterfly anti-stick bleed valve

The main function of the bleed valve (BV) is to release part of the air from the axial compressor to prevent the aero-engine from stalling and surging. The stuck fault of the BV seriously affects the stable operation and safety of the aero-engine. An anti-stick BV design incorporating an eccentric valve plate is proposed to mitigate the issues of valve sticking caused by contamination particles and deformation. To address the issue of large flow field torque (FFT) during the operation of the anti-stick BV, computational fluid dynamics (CFD) methods were employed to investigate the FFT across various opening angles and flow channel structures. The results indicate that the FFT is primarily induced by the asymmetry of pressure distribution at the surfaces of the valve plate. The main strategies to reduce the FFT resulting from the valve plate structure include increasing the maximum closing angle β, reducing the valve thickness, and shifting the inlet surface closer to the shaft. The optimized valve plate structure reduces the maximum FFT of the BV by 60.7 %. Experimental testing of the optimized prototype demonstrates significantly improved opening and closing characteristics.

FSI investigation on the discharge valve lift in a R32 rotary compressor and its verification

R32 rotary compressor is commonly applied in the household air conditioner. The valve motion is significant to the performance and reliability of rotary compressor. Valve lift is an important factor which directly affects the valve motion. A suitable valve lift can both reduce power consumption and fracture risk of valve plate. Based on a compressor prototype, this paper developed a FSI model to simulate the working process of discharge valve. The simulation results show that a large valve lift means a large discharge effective flow area and a low indicated power. But both the velocity of valve plate impacting the retainer and the impact stress of valve plate are relatively large, which will lead to the fracture in the valve plate. The simulated initial impact location on the head of valve plate is near the oblique incision due to the uneven pressure distribution in the discharge port and the torsional movement of valve plate. The maximum impact stress distribution areas on the valve plate obtained from simulation results are matched with the fracture areas of two valve plate samples, which proves that the simulation results are accurate enough to guide the optimization design of discharge valve in the rotary compressor.

Surgical Outcomes of a Human Umbilical Cord Allograft Over the Ahmed Glaucoma Valve Plate for Refractory Glaucoma.

To report the surgical outcomes of sterile dehydrated human umbilical cord allograft over the Ahmed glaucoma valve (AGV) plate for refractory glaucoma. Thirty-four eyes of 34 patients with refractory glaucoma who underwent AGV with umbilical cord allograft (AmnioPlast THICK™; Life Cell International Private Limited, Mumbai, India) placed over the AGV plate between September 2021 and 2022 at a tertiary eye care centre were included (group1) and compared with 30 eyes of 30 patients undergoing AGV without amnioblasts (group 2). The intraocular pressure (IOP) at day one, one month, six months, and final IOP; the necessity for medications; or additional surgeries for IOP control were extracted from the hospital database. Success was defined as achieving an IOP below 22 mm Hg with or without glaucoma medications. IOP spikes after surgery were identified as a rise in pressure beyond 22 mm Hg at any point beyond six weeks post-surgery following an initial reduction of pressure exceeding 30% from the baseline pre-surgical IOP. A notable reduction in intraocular pressure (37 ± 7.9 mm Hg preoperative versus 14 ± 3.7 mm Hg at the final follow-up and 28 ± 3.6 mm Hg versus 18 ± 6.7 mm Hg in group 1 and 2, respectively) was observed in all eyes, with successful outcomes observed in 23 out of 34 eyes (67%). Ten eyes experienced a pressure spike, occurring at a median time of 12 months (range: 6-18 months), predominantly beyond six months post-surgery in group 1, while group 2 had similar pressure spikes in 21 of 30 eyes at a median time of two months (range: 1-5 months). No eyes necessitated supplementary glaucoma procedures, concluding with a final IOP of 14 ± 3.7 mm Hg at 1.9 ± 0.8 years. Vision loss occurred in only one of the 11 eyes that failed owing to non-glaucoma-related causes in group 1. The human umbilical cord allograft plate over the AGV plate may help in postponing the onset of intraocular pressure spikes beyond traditionally defined timelines. This helps in reducing and delaying the hypertensive phase occurring due to fibrosis.

Research on Multi-Objective Optimization of Low Pulsation Unloading Damping Groove of Axial Piston Pump

The high- and low-pressure switching of the axial piston pump is realized by the structure of the valve plate, and the buffer-groove structure on the valve plate is very important to reduce the pressure shock and flow fluctuation. In order to optimize the structural parameters of the buffer tank of the piston pump, the influence of the triangular-groove structure on the outlet pressure–flow characteristics was analyzed, and the low-pulsation buffer-groove structure was designed. First, the relationship between the structure of the triangular buffer tank and the output pressure and flow characteristics of the pump was analyzed theoretically. The Computational Fluid Dynamics (CFD) method was used to calculate the pressure and flow characteristics of the whole pump flow field of the triangular-groove structure, and the influence of the buffer-groove structure parameters on the outlet flow pulsation characteristics was studied. The multi-objective optimization algorithm was used to optimize the structure parameters of the buffer tank, and the optimized structure significantly reduced the outlet pressure–flow pulsation of the piston pump. The results show that, after optimization, the width angle of the front and rear triangular groove is 82.3°, the depth angle is 12.7°, the optimized pressure pulsation rate is 0.3%, and the optimized flow pulsation rate is 13.7%.

ВАРИАНТ РЕКОНСТРУКЦИИ РЕКТИФИКАЦИОННОЙ КОЛОННЫ ДЛЯ ВЫДЕЛЕНИЯ БЕНЗОЛА ИЗ ДЕАЛКИЛАТА УСТАНОВКИ «ПИРОТОЛ»

A method for increasing the efficiency of a distillation column designed to isolate benzene from dealkylate at a benzene production plant "Pyrotol" is considered. The reconstruction consists in re-placing the contact devices with more efficient ones, namely, replacing the valve plates with a regular "Propak» nozzle

Lightweight Type-IV Hydrogen Storage Vessel Boss Based on Optimal Sealing Structure

The seal and weight of the Type IV hydrogen storage vessel are the key problems restricting the safety and driving range of fuel cell vehicles. The boss, as a metal medium connecting the inner liner of the Type IV hydrogen storage vessel with the external pipeline, affects the sealing performance of the Type IV hydrogen storage vessel, and there is no academic research on the weight of the boss. Therefore, according to the force characteristics of the boss, this paper divides the upper and lower areas (valve column and plate). The valve column with seal optimization and light weight is manufactured with a 3D printing additive, while the plate bearing and transferring the internal pressure load is manufactured by forging. Firstly, a two-dimensional axisymmetric simulation model of the sealing ring was established, and the effects of different compression rates on its seal performance were analyzed. Then, the size and position of the sealing groove were sampled, simulated, and optimized based on the Latin Hypercube method, and the reliability of the optimal seal structure was verified by experiments. Finally, the Solid Isotropic Material with Penalization (SIMP) topology method was used to optimize the weight of the boss with optimal sealing structure, and the reconstructed model was checked and analyzed. The results show that the weight of the optimized boss is reduced by 9.6%.

Image-based corn seed embryo orientation detection and adjustment for precision planting

Research has indicated that positioning a corn seed with its embryo side facing upward and its long axis perpendicular to a seeding row leads to the corn leaves growing perpendicular to the seeding row. This positioning results in an increased rate of light interception and yield for the crop. An identification and adjustment prototype was designed to rearrange corn seeds into the aforementioned seed orientation. The main parts are the teeth plate, V-shaped groove, photo sensor, camera, LED light, and pneumatic solenoid valve. When a corn seed enters the prototype, it will first be led to a leaning state, then go through an image acquisition and processing process, where the template matching method will be used to find a region of interest (ROI) on a corn seed image. The embryo side will be identified based on the average normalized saturation value in the ROI. The pneumatic solenoid valve will then be activated to adjust the seed accordingly to the targeted seed orientation. Trial results showed a success rate of 84 % and an average adjustment time of 1.438 s. The proposed method of embryo side direction identification and adjustment will contribute to the development of corn-oriented seeding technology.

Description of two new species of Haliplectus Cobb, 1913 (Nematoda, Plectida, Haliplectidae) from mangrove areas of Sandspit backwater, Karachi, Pakistan

Haliplectus shahinae n. sp. and H. sandspitensis n. sp. two free-living marine nematodes of the family Haliplectidae Chitwood, 1951 collected from mangrove areas of Sandspit backwater, Karachi, Pakistan, are being described and illustrated. Both new species belong to a group of species characterized by the presence of a bipartite basal esophageal bulb with striated or unstriated valve plates. H. shahinae n. sp. is characterized by its comparatively shorter body length (0.4–0.44 mm); annulated cuticle; amphidial fovea at 6–9 µm from the anterior end; bipartite basal bulb with unstriated valve plates; reproductive system mono-prodelphic with reflexed ovary, presence of post uterine sac and vulva at 52–57% of body length and tail short conoid, straight, 1.5–1.8 times anal body width long. H. sandspitensis n. sp. is characterized by more than 1 mm body length (1.0–1.2 mm); annulated cuticle; amphidial fovea at 8–12 µm from the anterior end; bipartite basal bulb with striated valve plates; didelphic reproductive system, with the vulva at 40–47% of body length and tail elongated, conoid, 1.4–2.2 times anal body width long. A dichotomous identification key is provided for the valid species of Haliplectus Cobb, 1913.

Numerical and experimental investigation of the hybrid piston compressor using the novel multi-time-scale OpenFOAM®-based model

Strongly coupled thermodynamic and heat exchange models of the hybrid piston compressor with regenerative heat exchange are developed, calibrated, and experimentally validated. The main challenge is the consideration of gas dynamics and heat transfer processes appearing at time scales different by three orders of magnitude. The Finite Volume Method (FVM) within the OpenFOAM® framework is used to discretize the actual three-dimensional compressor domain for heat exchange computation. On the other hand, the lumped zero-dimension approximation is used for gas dynamics. The present study is the first attempt to suggest a multi-time-scale numerical model of the hybrid piston compressor with no constraints on the domain geometry in the heat exchange part. The compressor’s heating during operation was reported to cause a reduction in its energy efficiency. Analysis of the three-dimensional fields of temperature and heat flux demonstrated that the piston and the valve plate are the hottest parts of the domain. Their cooling is not possible with standard approaches to heat exchange enhancement, while regenerative heat exchange within the hybrid compressor helps to circumvent such a constraint. The parametric investigation was carried out by determining the hybrid piston compressor transient processes and its integral characteristics using the proposed numerical model.

Effects of the cross angle on output characteristics and tilting behaviour for 750 mL/r axial piston pumps

Large displacement axial piston pumps (>500 mL/r) are the core power components of large construction machineries' hydraulic system. The demand for higher power in large construction machinery is increasing. High pressure and large displacement are the primary areas of focus for enhancing the power of piston pumps. However, this may exacerbate issues with the pumps' output characteristics, such as flow or pressure pulsation and leakage. This paper uses a cross angle of the swash plate to optimize the pulsation and leakage for the 750 mL/r axial piston pumps. Piston and cylinder dynamics affect flow and pressure pulsations, and leakage is related to cylinder tilting behaviour. The pumps’ flow distribution, kinematics and dynamics of the piston and cylinder, output flow and pressure are analysed. A virtual prototype is built based on the rigid-flexible-hydraulic coupling model. The oil film flexible body of the valve plate pair is added. The maximum principal stress and strain of the oil film flexible body are used as indicators of tilting behaviour. Effects of the cross angle on output characteristics and tilting behaviour are investigated through the numerical solution. Results show that the cross angle of −0.5° can effectively reduce the pressure pulsation rate by 0.89% and the flow pulsation rate by 3.77% while optimizing the tilting behaviour of the cylinder. In addition, the cylinder’s tilting behaviour is verified by the wear detection on the valve plate surface.

A novel wear prediction method and wear characteristic analysis of piston/cylinder pair in axial piston pump

The wear of the piston/cylinder pair in the axial piston pump is a significant factor that adversely affects pump performance. To conduct a thorough investigation into the wear characteristics of the piston/cylinder pair, a dynamic model based on the equivalent load method is established. Then, a novel wear prediction method for the piston/cylinder pair is proposed by integrating the Archard wear model. The validity of the proposed method is confirmed through experimental verification. The results demonstrate that specific circumferential areas of the cylinder bore exhibit severe wear, and the distribution of these areas remains relatively stable over time. At the swash plate side, the most severe wear area along the circumference direction is concentrated in the range of approximately 200°–320°, which means the area that deviates from the extreme position in the radial direction of the pitch circle by a specific angle, with the deviation direction being opposite to the rotational speed. Conversely, at the valve plate side, the most severely worn circumferential area is situated in the range of about 0°–120°, which is opposite to the area at the swash plate side. The proposed wear prediction method offers improved computational efficiency, providing valuable support for analyzing the wear characteristics and failure mechanisms of piston pumps.

Experimental development and validation of tribological run-in strategies to reduce friction in hydraulic applications

A particularly demanding contact in axial piston pumps is the one between cylinder block and valve plate. The tribological behavior of the contact can be changed by a run-in process. Publications on fast and efficient run-in are rare as this knowledge is often considered confidential. For this paper, tests have been carried out on a disc-on-disc tribometer to examine the run-in behavior of a material pairing and to identify suitable parameters for run-in. A methodology has been developed which can be used to find the optimal normal load and rotational speed for the run-in process to shorten the run-in time significantly.

Flow pulsation characteristics of variable displacement piston pump considering coupling effects cavitation bubble and swash plate inclination angle vibration

Variable-displacement piston pumps, in comparison with quantitative pumps, offer high volumetric efficiency, energy savings, and variable displacement advantages. The outlet flow pulsation of these pumps is influenced by several factors, including swash plate inclination angle vibration, cavitation bubbles, flow distribution structure, and valve control structure. This complexity poses challenges in accurately predicting the flow pulsation at the outlet of variable-displacement piston pumps. In response to this challenge, a novel outlet flow pulsation model for variable-displacement piston pumps is proposed, taking into account the coupling effects of cavitation bubbles and swash plate inclination angle vibration, building upon an existing model. Initially, the effects of cavitation bubbles and swash plate inclination vibrations on flow pulsation were analyzed. Subsequently, a comprehensive flow pulsation model for variable-displacement piston pumps was developed, considering the coupling effects of cavitation bubbles and swash plate inclination angle vibrations. This model was compared with three other existing flow pulsation models. The accuracy of the results was validated using a constructed test bench, with an accuracy improvement of approximately 12% compared to traditional theoretical models. Finally, an optimization model for outlet flow pulsation was proposed. The structural parameters of the valve plate, aimed at minimizing flow pulsation, were determined using the multi-agent particle swarm optimization algorithm. These findings underscore the importance of considering the coupled effects of cavitation bubble and swash plate inclination angle vibration in the design optimization process for reducing low-flow pulsation. This study provides a theoretical foundation for the design of variable-displacement piston pumps with minimized vibration and noise levels.

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.

Pseudaphelenchus taedae n. sp. (Tylenchina: Aphelenchoididae) found in loblolly pine logs from the USA and peat from Lithuania

Summary Pseudaphelenchus taedae n. sp., isolated from loblolly pine logs (Pinus taeda L.) from the USA and peat from Lithuania, is described and figured. It is characterised by the male 355 (305-401) μm and female 427 (318-520) μm body lengths and by the presence of three equal incisures in the lateral field. The slender stylet has small but conspicuous basal knobs. Valve is located at posterior part of metacorpus. The excretory pore is located at the same level as valve plates or anterior. Spicules are paired, thorn-like, separate, condylus broadly rounded, rostrum conical or triangular with a bluntly pointed tip, calomus smoothly tapering together with lamina, thin and strongly arcuate in middle then tapering towards bluntly pointed distal tip, cucullus absent. A narrow bursa surrounds three quarters of tail but is inconspicuous in most cases. The conical male tail is bluntly rounded but mostly with a short pointed or blunt mucron. The female tail is conical in various shapes, smoothly tapering, slightly ventrally bent or curved, with broadly rounded or pointed terminus. Detailed phylogenetic analysis based on the 18S and D2-D3 region of 28S sequences confirmed the status of this nematode as a new species.

Research on Bearing Mechanism of Spherical Valve Pairs of Axial Piston Pumps

The hydraulic system drives the cutter head mechanism to realize the excavation of large tunnel boring equipment, which puts forward the technical requirements of high pressure and large flow to the pump source. The traditional small displacement axial piston pump uses a planar valve plate. However, under high flow and heavy load conditions, the planar valve plate configuration is prone to uneven wear due to the high-pressure and -velocity (PV) value and pressure shock, which ultimately affects the reliability of the system. A simulation analysis of the load-bearing characteristics of the spherical valve plate mechanism is conducted. The Computational Fluid Dynamics (CFD) method was used to construct flow field models for different valve plate oil film structures to calculate differences in their load-bearing capacities. Additionally, the reasons for variations in load-bearing characteristics based on the curvature radius of the spherical valve plate were analyzed. The simulation results demonstrate that the spherical valve plate exhibits superior leak and load-bearing performance compared to the traditional flat valve plate. Furthermore, the curvature radius of the spherical valve plate directly affects the pulsation characteristics of the piston pump. Smaller curvature radii increase the contact area of the oil film, resulting in greater fluctuation in oil film load-bearing, whereas larger curvature radii lead to increased oil film leakage. Using simulation calculations on heavy-load, high-displacement axial piston pumps, it is determined that the optimal curvature radius for stable load-bearing is 350 mm.

Study on Friction and Wear Characteristics of Axial Piston Pump Valve Plate Pairs Modified with Different Surface Energies

To explore the friction and wear performance of the valve pair with different wetting combinations under various working conditions in hydraulic oil lubrication, a low surface energy modification method was adopted in this paper to improve the surface wettability of the upper sample composed of SAF2507 and the lower sample composed of CFRPEEK, and to prepare valve plate pairs with different wetting combinations. The MMU-5G friction and wear testing machine was used to investigate its friction and wear characteristics under hydraulic oil lubrication. The results show that the surface free energy of SAF2507 and CFRPEEK decreased significantly after the treatment with a low surface energy solution, and the surface free energy of the upper and lower samples decreased by 41.9% and 42.2%, respectively. The oil contact angle of samples remained lipophilic, but the oil contact angle increased significantly. Under the working condition of low speed (800 r/min), the surface wettability of the valve plate pair has a great influence on its friction and wear characteristics. When operating at high speed (1200 r/min), the surface wettability of the valve plate pair has little influence on its friction and wear characteristics.

Effect of Loading Pressure on Tribological Properties for Valve Plate Pair during the Running-In Process

The friction and wear performance of the valve plate pair significantly affects the service life and reliability of axial piston pumps. Loading pressure during the running-in process is crucial to its contact characteristics, friction coefficient, running-in time, wear rate, etc. In this article, mixed lubrication modeling and analysis of the effects of loading pressure on tribological performance for valve plate pair were conducted. A finite element model was established using fractal theory and a coupled Euler-Lagrange method. Ring-on-block tests were conducted to simulate the movement and tribological properties of the valve plate pair during the running-in process. Running-in tests of the axial piston pump were carried out to detect the valve plate’s wear. Results show that the effect of increased loading pressure on the maximum contact pressure decreases gradually. The increased loading pressure can shorten the running-in time without increasing the friction coefficient. The wear mechanisms are abrasive wear and adhesive wear during the running-in process. This study provides a reference for the running-in test of axial piston pumps.