Ring Groove Research Articles

A Study on the Oil Film Thickness Between the Lower Rail of Oil Control Ring and Lower Flank of Oil Control Ring Groove of an Engine

Abstract Lubricating oil consumption (LOC) of engines causes particulate matter in exhaust gas and abnormal combustion like pre-ignition which becomes a serious problem in hydrogen engines. Lubricating oil transports upward into the combustion chamber of an engine via the sliding surface, the gap, and the side and back of a piston ring. The target of this study was to clarify the mechanism of oil flowing between an oil control ring lower flank and the groove which was the first entrance of lubricating oil supplied from the crankshaft. Oil film thickness at the lower flank of the oil control ring was measured by laser-induced fluorescence method using optical fibers embedded in the lower flank of the ring groove. The measured oil film thickness was compared with forces acting on the lower rail of three-piece type oil control ring. The oil film thickness change was well explained using those forces and it was found that friction force at the sliding surface and pressure in the ring groove were dominant on the oil film thickness under all operating conditions tested in this study.

Single-step self-punching lockbolt process for aluminum sheets without pre-hole

For the mechanical joining of aviation-grade aluminum alloys, the study introduces an innovative approach using self-punching lockbolts. This method involves the utilization of a profiled collar and a specially designed bolt to seamlessly join EN AW-2024 T42 aluminum sheets, up to a thickness of 8.0 mm, without the need for pre-holes. In this process, when the aluminum sheets are punched, the collar undergoes slight deformation, effectively functioning as a die. Subsequently, the collar is systematically formed by applying increased force. By fine-tuning the design of the bolt ring groove, it becomes feasible to create a joint with a bolt length that accommodates sheet thickness variations of up to 1.6 mm. To facilitate this development, the joining process was meticulously designed and the auxiliary part was optimized with the aid of numeric simulation tools. The process simulation enabled the identification of deformation mechanisms within the collar, accounting for both geometry and material properties. The important factors influencing collar deformation include collar thickness, shoulder height, and shoulder diameter. Furthermore, experimental investigations were conducted to assess the mechanical properties of the joint and evaluate how material-specific factors influence joint failure behavior. It can be seen that the formation of the mechanical fit is influenced by the ring groove depth and the fitting position. The joints failed under shear tensile load exclusively at the bolt head.

Multifunctional coding metasurface for focusing and beam deflection based on polarization selection

ABSTRACT In this paper, a full-space multifunctional coding metasurface (MS) with reflection and transmission integration is proposed to realize the independent manipulation of electromagnetic waves at two different frequencies. The unit consists of two layers of dielectric substrate and three layers of metal patch, the upper reflective layer is composed of a ring and a split ring (URSR), the middle layer is a split ring groove (MSR), and the lower transmission layer is a split ring (LSR). The transmission mode works at 13.4 GHz, incoming linear polarization (LP) waves to realize beam deflection with a deflection angle of 34°. While the reflection mode works at 17.9 GHz, beam focusing to achieved under the action of circular polarization (CP) waves. In order to verify the feasibility of the design, a circularly polarized antenna is placed at 80 mm in the metasurface -Z direction, and the gain increases from 7.5 dB to 22.5 dB. Meanwhile coding metasurface and circularly polarized microstrip antennas is fabricated and measured, and the results are consistent with the simulation results. The proposed method provides the possibility of high-rate transmission of information of multifunctional devices in communication systems.

Strong circular dichroism chiral metasurfaces generated by quasi bound state in continuum domain

Bound states in the continuum (BIC) were initially observed in quantum mechanics as a phenomenon capable of maintaining localized wave behavior. This effect has been extensively studied across various material systems, including piezoelectric materials, graphene, and photonic crystals. Recently, the BIC mode has employed to achieve strong optical chirality in metamaterials with symmetry breaking. In this work, we propose a silicon metasurface with an interrupted ring groove, which has a fourfold rotationally symmetry. By breaking the in-plane inversion symmetry of the unit cell, we achieve quasi-BICs with the high quality factor and conspicuous chirality. Moreover, by analyzing topological charges in momentum space, we reveal that the unique topological characteristics of quasi-BIC are generated by the internal resonance of metasurface. When the symmetry breaking reaches a certain level, our proposed symmetry-broken metasurface shows a strong circular dichroism and its value is –0.93, which indicates that the quasi-BIC mode can has a strong chiral selectivity. For chiral sensing applications, the chiral metasurface exhibits a spectral resolution of approximately 0.003. The findings presented in this work have great potential applications in chiral sensing, nonlinear chiral optics, low-threshold lasers, and other related fields.

Experimental study on Q355 steel T-stubs connected through high-strength ring groove rivets

High-strength ring groove rivet connections have several advantages over bolt connections, including anti-loosening performance and high fatigue resistance. This research aims to investigate the mechanical properties of high-strength ring groove rivet assemblies and load resistances of riveted T-stubs. Experimental tests on high-strength ring groove rivet assemblies were firstly carried out, including coupon tests, preload measurements, and load-bearing tests. Q355 steel T-stubs connected through ring groove rivets were subsequently tested. The effects of certain geometrical parameters and material grades of the rivets on the performance of the T-stubs were analyzed. The applicability of the Eurocode 3 and Demonceau methods to the T-stubs was discussed. The results show that the Grade 10.9 rivet possesses higher yield strength and strain, and lower ultimate strain, in comparison to the Grade 8.8 rivet. Increasing the diameter of the rivet is beneficial for the T-stubs, whereas increasing the flange thickness is not always advantageous. The Eurocode 3 method is unsuitable for the T-stubs connected through ring groove rivets, whereas the Demonceau method is conservative. The findings of this research provide guidance for engineering designs of high-strength ring groove rivet assemblies and steel T-stubs connected through ring groove rivets.

Effect of ring groove in a heat-insulating insert on efficiency of its work in blast channel of blast furnace tuyere

One of the main disadvantages when supplying natural gas to the air tuyere of a blast furnace is low intensity of its combustion inside the tuyere blast channel. Ring groove on the surface of blast channel improves the mixing of natural gas with blast and increases completeness of gas combustion in it, but reduces the tuyere durability. One of the ways to simultaneously solve these problems is to install a heat-insulating ceramic insert in the tuyere blast channel. The insert significantly reduces heat losses through the tuyere surface, improves natural gas combustion in the blast channel due to its contact with hot walls of the insert instead of cold copper walls in its absence. This increases the temperature of the hot blast at the tuyere outlet. In addition, the insert affects the tuyere durability by reducing the heat flow acting on the tuyere. In this work, we studied influence of the ring groove and its parts in the insert on efficiency of its work. In the Ansys 21.1 software, the processes occurring in the blast channel of a blast furnace tuyere with a ceramic insert installed in it, having a groove of a quadrangular section in the form of a ring or its part in the circumferential direction, were simulated. It was established that improvement of natural gas combustion in the tuyere blast channel is achieved using a ring groove or part of it from the side of gas supply.

Bionic Ring Grooves Design and Experiment of the Suction Cup Applied in Oil-Immersed Substrate

The vacuum suction cup is often used as an end effector and widely used in wall-climbing operations. However, there are few vacuum suction cup designs and applications for oil-immersed substrates. Inspired by the surface morphology of the octopus sucker, bionic suction cups with different numbers, diameters, and spacings of the ring grooves were designed. Their normal adsorption force was evaluated on the untreated and polished steel plate in oil. The test results showed that ring grooves positively affected the adsorption force. The bionic suction cup with a groove number of 3, a diameter of 0.5 mm, and a spacing of 3 mm was the most excellent in the test. It achieved normal adsorption forces of 54.83 ± 0.48 N and 43.89 ± 0.69 N on the untreated and polished steel plate. Compared with the standard suction cup, it increased by 32.31% and 12.28% on the untreated and polished steel plate. The regression model between the normal adsorption force and design factors was established based on the adsorption force test results, and the influence law of the ring groove structure parameters on the adsorption force of suction cups on oil-immersed substrates was analyzed. The order of significant effects of groove design parameters on normal adsorption forces was groove diameters, spacings, and numbers. The finite element analysis (FEA) results show that the ring grooves could significantly increase the contact pressure, frictional stress, and sliding distance between the suction cup and the substrate. The ring groove structure effectively improves the adsorption force of the suction cup on the oil-immersed surface by forming a more effective seal and increasing the friction force and adsorption area. This study could provide a reference for developing the actuator of the oil-immersed or lubricated climbing machine.

Study on corrosion behavior of 13Cr gate valve using weld deposited gate and seat in well operation environments

The different types of corrosion behavior occurred on a 13Cr gate valve using weld deposited gate and seat after about sixteen months of service in an oilfield in China, resulting in the leakage failure. In this study, the corrosion causes were investigated through visual inspection, mechanical performance testing, scanning electron microscopy, energy dispersive spectrometer and electrochemical analysis. The results demonstrated that the corrosion on the sealing surface of the valve body was related to the galvanic corrosion between the 304 SS ring gasket and 13Cr SS ring groove, which presented a significant potential difference in the spent acid environment. In addition, due to the C element diffusion from deposits during the spray weld on the surface of the gate and seat, a large amount of Cr enrich carbides were formed at the prior austenite grain boundaries in the 13Cr SS matrix side, which further induced the intergranular corrosion and cracking along the interface in service.

Optimization Design of Thin Wall Angular Contact Ball Bearing Based on MATLAB Genetic Algorithm

The bearing for industrial robots is desired to have a long service life. To address that, an optimization study was conducted on a thin wall angular contact ball bearing used for a robot. Firstly, an optimization model was established with the basic rated life as the objective function and the curvature radius coefficient of the inner ring groove, curvature radius coefficient of the outer ring groove, ball diameter, pitch diameter, and the number of balls as the design variables. Then, taking the angular contact ball bearing ZR76/82C as an example, the optimization model was solved quickly based on a genetic algorithm via MATLAB software in two ways: calling the ga function and optimization toolbox, and the optimal structural parameters of the bearing were obtained. After the optimization, the basic rated life of the bearing was increased by 52%. The orthogonal test optimization design method was applied to validate the calculations, and the validation results showed that the two optimization results were very close to each other. The results show that the two approaches based on MATLAB genetic algorithm are efficient and feasible for solving optimization issues, and are of reference value for the study of solving other optimization issues.

Construction and method of assessment and research of the parameters of a load-lifting winch with a sectional disc drum

The object of the study is a load-lifting winch with a sectional-disc drum for single-row multi-layer laying of flexible elements, cargo cables and power cables, during their winding, electrically protected. The winch is intended for suspension and lifting and lowering of illuminated devices and equipment in closed rooms. In the process of research (constructive development, determination and analysis of parameters), the problem of creating a winch design of the specified type with a qualitatively increased overall level of functionality is solved according to the indicators: 1) electrical insulation, compactness and necessary strength of fastening of flexible elements, lifting cables and power cables on the drum; 2) controllability of the drive: in transitional periods – to ensure smooth acceleration-stopping of the suspension; in the period of constant movement – to ensure a constant speed of the suspension during raising and lowering. Electrical insulation between the power cable, the drum and other parts of the winch is created by using parts (discs) made of synthetic insulating material, for example, fiberglass, in the construction of the drum. Clamping of flexible elements between the disks in specially profiled C-shaped ring grooves, on the ends of the hub, of the disks ensures the necessary strength and compactness of the attachment. The smoothness of starting (stopping) of the drive and the constant speed of the suspension during the period of constant movement are established by adjusting the frequency converter in the drive control system according to the parameters determined by a specially developed methodology. The obtained results, constructive solutions and methods of research (estimation and analysis) of winch parameters can be used in the design of the structure and adjustment of the control system of lifting devices of this type.

An experimental study on wear, deposits, performance, and emissions of bio-fueled motorcycle engines

ABSTRACT The study investigated the impact of gasoline and ethanol-gasoline blend E5 on motorcycle engine wear, deposits, performance, and emissions following an endurance run test. The dimensions, appearance of the major components, and engine performance and emission have been measured to compare. Compared to the E0 case, the ring grooves and piston’s skirt in the case of E5 fueling were relatively cleaner. The piston skirt wear was 0.06 mm for E0 and 0.04 mm for the E5 case. After the endurance run test, the mass of deposits on the intake valves and valve seats was 247.3 mg for the E0 and 323.8 mg for the E5 case. In addition, the electrode gap of the spark increased gradually up to 50% after 200 h of running for E0, but the gap was only 31.5% raised for E5. A slight increase of 1.63% and 1.51% on average brake power was observed for E0 and E5 cases after 100 h of operation. However, the observed power drop of 2.55% for E0 and 1.86% for E5 as the test engines reached 200 h of operation. The CO emission was reduced by 1.73% to 4.81% for E0-engine and 0.58% to 2.35% for E5-engine after 100 h. But, after 200 h, CO increased 1.12% to 8.07% for E0 and 0.24% to 0.38% for the E5-engine within speeds 4000 rpm to 7000 rpm. HC increased by 4.69% to 14.14% for the E0-engine and 1.55% to 6.98% for the E5-engine after the endurance run test. There was an unpredictable tendency of NOx emission after 100 h and 200 h of operation for both test engines.

Experimental Investigation of Oil Transport during Low Load to High Load Transient in Internal Combustion Engines

Reducing the Lubricating Oil Consumption (LOC) has been a critical focus for engine manufacturers. LOC not only depends on engine operating condition but also the history of the operating condition variations. This work seeks to understand the oil transport in the ring pack during the low load to high load transient through experimental investigations. An optical engine with 2D Laser Induced Fluorescence (2D-LIF) technique, equipped with a modern low-tension Three-Piece Oil Control Ring (TPOCR), was applied to investigate the oil transport in the ring pack. It was found that, after the engine stayed under the blowby separation line long enough, a sudden increase to high load can result in a huge increase of oil ejection to the liner from the top ring groove in the expansion strokes. The mechanism behind it is that, when the load is increased, the oil accumulated inside the top ring groove during the low load condition is pushed out by the gas flow after the peak cylinder pressure is reached. Different combinations of load, speed, rate of change in load and time duration at low load were tested to examine their influence on this leakage mechanism. An operation with a gradual increase of engine load was found to be able to reduce the amount of oil leaked to the liner by releasing more oil to the second land. These findings can help the effort to reduce the oil emission (OE) generated from Spark Ignited (SI) engines equipped with TPOCR in the real-world transient driving conditions as well as the emission tests.

Pool boiling heat transfer enhancement on the hybrid surfaces coupling capillary wick and minichannels

Pool boiling heat transfer can fully utilize the latent heat of the vaporization, to meet the heat dissipation needs of high-power electronic components. In this study, several enhanced hybrid surfaces were designed and processed by sintering spherical copper powder on the minichannels in different ways. The coupled effects of various parameters of capillary wick and minichannels were considered to enhance the pool boiling heat transfer performance of these hybrid surfaces using HFE-7100 as the working fluid. The bubble dynamic behaviors were captured and analyzed by the high-speed camera. The results indicate that the ring groove around the minichannels and the capillary wick have a significant impact on the boiling heat transfer of these hybrid surfaces. This is because the capillary wick provide a large number of nucleation sites and large specific surface area, which can greatly reduce the contact thermal resistance between the capillary wick and the minichannels. At ΔTsub = 30 K, the critical heat flux (CHF) of hybrid surfaces coupling capillary wick and minichannels is up to 147.4 W/cm2, and its maximum heat transfer coefficient (HTC) is 2.69 W/(cm2·K). Compared with minichannels without capillary wick covered, the CHF and HTC are increase by 86.8% and 192.0%, respectively. Furthermore, a correlation for predicting CHF on these hybrid surfaces covered capillary-wick is proposed. Dimensionless parameters such as the subcooled Jakob coefficient (Jasub), the outer surface area enhancement ratio (AER), the particle distribution coefficient (PDC) and the ratio of inner to outer surface area of capillary wick (IOR) are defined to estimate the effect of different factors on the CHF.

Numerical Analysis of the Effect of Retaining Ring Structure on the Chemical Mechanical Polishing Abrasive Motion State

Optimizing the retaining ring structure can improve the quality of Chemical Mechanical Polishing (CMP). This study establishes a two-dimensional Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model, while the model is validated by experiments. The results graphically demonstrate the influence of the retaining ring groove design on the motion of the slurry abrasive particles. The size of the retaining ring groove appears to have a threshold value, above which the abrasives start to have significant distribution in the wafer region. As the groove size continues to increase, the number of abrasives entering the ring increases abruptly and oscillates at specific nodes. The abrasive transfer rate increases with the number of grooves in the early stage but reaches a limit at a certain number of grooves. Meanwhile, the retaining ring position affects the transfer of the abrasives. This study provides a base for optimizing the design of retaining rings.

Piston Compression Ring Elastodynamics and Ring–Liner Elastohydrodynamic Lubrication Correlation Analysis

Friction loss in an internal combustion engine largely depends on elastohydrodynamic lubrication. The piston compression ring is a contributor to such parasitic losses in the piston subsystem. The complex elastodynamics of the ring are responsible for the transient and regime-altering film that affects the elastohydrodynamic lubrication of the ring liner contact conjunction. The current paper will discuss the ring radial, lateral deformation, and axial twist, and its effect on the film profile of the compression ring and its subsequent effect on tribological characteristics like elastohydrodynamic pressure, friction, and lubricant. A finite difference technique is used to solve the elastohydrodynamic issue of elastodynamic piston compression by introducing the elastodynamically influenced film thickness into the lubrication model. The results show that consideration of the elastodynamics predicts a 23.53% reduction in friction power loss in the power stroke due to the elastodynamic ring compared to the rigid ring. The elastodynamic effect improves the lubricant oil flow into the conjunction. A finite element simulation predicts a von-Mises stress of 0.414 N/mm2, and a maximum deformation of 0.513 µm at the core and coating interface is observed at the ring–ring groove contact. The sustainability of EHL in this case largely depends on the ring–liner elastodynamics.

A fully coupled tribo-dynamic model for piston-ring-liner system

As key friction pairs affecting the whole engine reliability, the piston-ring-liner system generates more than 45% of the whole engine friction loss. But so far, three-dimensional tribo-dynamic models considering its complex motions are very limited. This paper proposes a new method from the perspective of multi-flexible-body dynamics to realize a fully coupled modeling of the system’s deformation, dynamics, and lubrication characteristics. The study considers the ring-groove contact characteristics and calculates the system boundary loads through the blow-by model. The effect mechanism of ring groove deformation on ring properties is revealed, and the system’s complex tribo-dynamic behaviors such as twisting and fluttering are characterized. After fully coupled modeling, piston deformation at the ring groove position can be 65.80 µm, resulting in a 1.33 µm reduction in the minimum oil film thickness compared to the uncoupled model, and ring wear unevenness is aggravated.

Effect of Blowby on the Leakage of the Three-Piece Oil Control Ring and Subsequent Oil Transport in Upper Ring-Pack Regions in Internal Combustion Engines

The lubricating oil consumption (LOC) in internal combustion engines contributes to emission and deteriorates the performance of the aftertreatment. In this work, an optical engine with a 2D Laser-induced fluorescence (2D-LIF) system was used to study operating conditions critical to real driving oil emissions. Additionally, numerical models were used to analyze the ring dynamics, oil flow and gas flow. It was found that the intake pressure that results in zero blowby is the separation line between two drastically different oil flow patterns in the ring pack. With intake pressure lower than the separation line, the oil accumulation of the three-piece oil control ring groove (TPOCR) begins to increase, followed by the drastic increase of the oil accumulation in the third land, second land, and finally visible oil leaking through the top ring gap, given enough time. The time required for the oil to leak through different rings was investigated using both measurements and modeling. The effects of drain holes and rail gaps, as well as their relative rotation on oil accumulation and leakage from the TPOCR groove, were analyzed. These findings contribute to improving ring pack designs and engine calibration in spark ignition (SI), gas, and hydrogen engines equipped with TPOCR to minimize the negative impacts of LOC.

Buried Defect Detection Method for a Blowout Preventer Seal Ring Groove Based on an Ultrasonic Phased Array.

This study aims to investigate an accurate detection method to detect defects in the gasket ring groove of the blowout preventer (BOP) using the ultrasonic phased array technology. Traditionally, it is difficult to accurately determine the type and size of defects in the gasket ring groove due to the complexity of the BOP configuration and the interference between the defect echo and the structural echo when using the ultrasonic phased array detection technology. In this study, firstly, the appropriate detection process parameters are determined by using simulation software for simulating and analyzing the defects of different sizes and types in the gasket ring groove of a BOP. Thereafter, according to the detection process parameters determined by the simulation analysis, we carry out a corresponding actual detection test. Simulation analysis and detection test results show that the relative amplitude of the test results and the simulation results differ within 1 dB, and the simulation results have a guiding role for the actual detection. The defect echo and structure echo can be clearly distinguished by selecting appropriate detection process parameters, such as probe frequency 5 MHz, array elements 36, and probe aperture 16 mm. The research results can provide theoretical reference for the detection of blowout preventer.

Investigation on leakage cause of 13Cr pipe flange used for a Christmas tree in a high-pressure and high-temperature gas well

The martensitic stainless steel pipe flange used for the 138 MPa Christmas tree failed to leak during ultra-deep high-pressure, high-temperature gas well operations. In order to study the cause of leakage, non-destructive testing, chemical composition analysis, mechanical property analysis, metallographic structure testing, surface characterization, cracking characterization and finite element analysis were performed in the present research. The results show that the leakage failure is related to the crack in the ring groove. The cracks initiated from the edge of the corrosion pits and propagated along the delta ferrite/martensite interfaces. The Cr-rich carbides in the matrix reduced the pitting resistance, while delta ferrite deteriorated the crack resistance, which was the main factor contributing to the failure. In addition, the stress level in the sealing structure of the Type 6BX flange further influenced the crack propagation behavior.

Study on the Three-Dimensional Tribo-Dynamic Analysis of Piston Ring Pack Considering the Influence of Piston Secondary Motion

Abstract More detailed and accurate modeling is very important for analyzing and optimizing the tribological performance of the piston-ring-cylinder liner system. However, due to the difficulty of modeling and solving, theoretical studies on the three-dimensional (3D) tribodynamics of piston rings are limited. The tribodynamic model which couples the dynamics, mixed lubrication, and blow-by of piston-ring pack assemblies has not been found yet. Therefore, in this study, a 3D tribodynamic model of the piston-ring pack is developed considering the influence of piston secondary motion and the interaction forces and moments between piston ring and cylinder liner as well as between piston ring and ring groove. In addition to the ring end gaps, the influence of ring dynamics is also contained in the blow-by model. Coupled with gas flows and piston rotation, ring motions in the ring groove are investigated. It is found that ring dynamics has significant effects on the tribological performance, the axial reversing movement of piston ring is the main cause of gas pressure oscillation, piston motion has an obvious influence on the ring dynamics, the interaction forces and moments between piston and rings increase the secondary motion amplitude of piston, especially near the fire top dead center.