Edge Groove Research Articles

Particle motion analysis and performance investigation of a fertilizer discharge device with helical staggered groove wheel

Enhancing the uniformity of fertilizer particles flow is crucial in fertilizer discharge device research, and the analysis of particle motion process contributes to improving fertilization performance. In this study, the discrete element method was employed to conduct a phenomenological analysis and numerical investigation of the particle motion characteristics influenced by structural feature parameters of the groove wheel-type fertilizer discharge device. A performance evaluation model based on the uniformity of fertilizer discharge and supplemented by the flow characteristics and mechanical properties of particles was established. The results demonstrated that the particles flow within the fertilizer bin exhibits a recirculating surge induced by the rotation of the groove wheel. The geometric morphology of the outer edge grooves and their spatial distribution along the groove wheel circumference affect the uniformity of fertilizer filling and discharge mass flow rate. The force exerted on the fertilizer particles and their potential breakage are primarily concentrated during the fertilizer compaction stage, while the particles flow forms a convergence due to the sliding of the fertilizer along the discharge slope. After optimization, the discharge CV is reduced from 91.54 % to 31.48 %, and the uniformity is improved by 60.06 %. This study proposes a helical staggered groove wheel fertilizer discharge device structural model, providing new insights for the optimization of agricultural fertilization machinery equipment.

Experimental Investigation of a Large Tilting-Pad Journal Bearing—Comparison of a Flooded and Non-Flooded Design

In tilting-pad journal bearings (TPJB), power loss corresponds to the internal friction in the shearing of the oil. Besides the lubrication gap, intermediate spaces between the pads account for a notable amount of frictional losses. Against the background of increasing demands for efficiency and sustainable use of resources, the reduction of power loss takes a key position in the further development of bearings. In our research, we compare two bearing lubrication concepts of a five-pad TPJB. Our objective is to work out the influence of different lubrication methods and bearing housing designs on the bearing operation characteristics. We conduct experimental testing of a 500 mm TPJB in two different bearing configurations with respect to the lubrication concept: an oil-flooded and non-flooded bearing design. In the flooded bearing design, oil is supplied via spray-bars and axial seals ensure the inter-pad spaces to be completely filled with oil. The non-flooded design comes without axial seals but oil drain channels to avoid oil accumulation in the bearing. In the latter design, oil is fed in via leading edge grooves (LEG). For the non-flooded bearing design, the experimental data show that the unloaded pads are not completely filled with oil and therefore, no pressure build-up occurs. The absence of additional load on the lower pads compared to the flooded design results in an increase of minimum film thickness. With the non-flooded design, power loss at high speeds is reduced to almost half. As a result, the efficiency of the entire turbomachinery application can be considerably improved.

FORMAS DEL SURCO DEL BORDE DE GRANO EN LA SUPERFICIE DE HIELO PURO

In this work we studied the evolution of the groove that forms the grain boundary (BG) when it emerges to a free surface, in the presence of different processes of matter transport. By using a confocal microscope, the shape of the grain edge groove was obtained in an ice sample with orientation <1010>/50◦at −5◦C ; after keeping it 3 h in an environment with dry air. The shapes and depths of the grain boundary groove obtained experimentally, at regular time periods, were satisfactorily fitted considering a process of transport of matter developed by Srinivasan and Trivedi. In this model the transport of matter is mainly ruled by gaseous diffusion and not by surface diffusion.

FORMAS DEL SURCO DEL BORDE DE GRANO EN LA SUPERFICIE DE HIELO PURO

In this work we studied the evolution of the groove that forms the grain boundary (BG) when it emerges to a free surface, in the presence of different processes of matter transport. By using a confocal microscope, the shape of the grain edge groove was obtained in an ice sample with orientation< 1010 >/50◦ at −5◦C ; after keeping it 3 h in an environment with dry air. The shapes and depths of the grain boundary groove obtained experimentally, at regular time periods, were satisfactorily fitted considering a process of transport of matter developed by Srinivasan and Trivedi. In this model the transport of matter is mainly ruled by gaseous diffusion and not by surface diffusion.

Electrical discharge turning by assistance of external magnetic field, part I: Study of MRR and dimensional accuracy

Hybrid machining process is increasing its importance toward processing of advanced materials with complex geometries. Electrical discharge machining is a type of non-conventional machining process that is extensively used for creating micro and macro features in hard material. The process has capability to be used for flat samples and round bars that former application is more common. In the present study an experimental work has been made to produce sharp edge grooves in round bard made of AISI D2 by electrical discharge turning process. To do so, an external magnetic flux density has been applied around machining gap to enhance the performance measures. Series of experiments have been carried out in order to find effect of magnetic flux density (0, 0.2 and 0.4T), discharge current (5, 10, 15A), pulse on time (600, 800 and 1000μs), and work rotational speed (50, 150 and 250RPM) on material removal rate (MRR) and overcut (OC). Finally optimization has been carried out in different machining modes to find how the optimum value of magnetic field is varied in roughing and finishing. Results indicated that irrespective to the machining regime, application of high intensity magnetic field (i.e. 0.4T) is dominant in increasing the machining rate as well as enhancing the dimensional accuracy. Therefore, the method can be useful for performing the electrical discharge turning process.

Combined Reduced Phase Dual-Directional Illumination Digital Holography and Speckle Displacements for Shape Measurement

We present a digital holographic method to increase height range measurement with a reduced phase ambiguity using a dual-directional illumination. Small changes in the angle of incident illumination introduce phase differences between the recorded complex fields. We decrease relative phase difference between the recorded complex fields 279 and 139 times by changing the angle of incident 0.5° and 1°, respectively. A two cent Euro coin edge groove is used to measure the shape. The groove depth is measured as ≈300 μm. Further, numerical refocusing and analysis of speckle displacements in two different planes are used to measure the depth without a use of phase unwrapping process.

Experimental investigation on effects of varying volume fractions of SiC nanoparticle reinforcement on microstructure and mechanical properties in friction-stir-welded dissimilar joints of AA2024-T351 and AA7075-T651

Abstract

Theoretical and Experimental Analyses of Directly Lubricated Tilting-Pad Journal Bearings With Leading Edge Groove

Flooded lubrication of tilting-pad journal bearings provides safe and robust operation for many applications due to a completely filled gap at the leading edge of each pad. Direct lubrication by leading edge grooves (LEG) located on the pads represents an alternative to restrictive end seals to ensure these conditions at the entrance to the convergent lubricant film. A theoretical model is presented that describes the specific influences of LEG design on operating characteristics. First, in contrast to conventional tilting-pad journal bearing designs, the LEG is a self-contained lube oil pocket, which is generally connected to an outer annular oil supply channel. Consequently, each LEG can feature a specific speed and load-dependent effective pocket pressure, which influences the pad tilting angle. Second, the thermal inlet mixing model must consider the specific flow conditions depending on the main flow direction within the film as well as the one between outer annular channel and pocket. The novel LEG model is integrated into a comprehensive bearing code and validated with test from a high performance test rig for a four tilting-pad bearing in load between pivot orientations. Within the investigated operating range good agreement between theoretical and experimental data is achieved if all boundary conditions are accurately considered. Additionally, the impact of single simplifications within the model is studied and evaluated. Finally, the test data are compared to results from the same test bearing with modified lubricant oil supply conditions in order to identify specific properties of LEG design.

High-precision calibration method for shear ratio based on the shearing wavefront feature extraction of a phase plate.

A new method based on the shearing wavefront feature extraction (SWFE) of a phase plate is proposed to accurately estimate the shear ratio of the system. The relationship between the shear ratio of a quadriwave lateral shearing interferometer based on a randomly encoded hybrid grating (REHG) and the measurement sensitivity, dynamic range, and wavefront retrieval accuracy is analyzed to provide a theoretical guidance for practical application. The simulation result of the SWFE method shows that the relative error of the shear ratio value is about 1.8×10-3, within the acceptable range of the system. In the experiment, two fused quartz phase plates etched with step change edge grooves were introduced to calibrate the shear ratio of the REHG wavefront diagnosis system. Then, the etching depths of these two phase plates and the figure error of a spherical surface were characterized by the REHG. A comparison with a ZYGO GPI interferometer exhibits that the testing results by the REHG are highly precise, which further confirms the effectiveness of the SWFE method in the shear ratio calibration. This shear ratio calibration method is available for similar kind of shearing interferometric wavefront sensor.

Microgrooving of a single-crystal diamond tool using a picosecond pulsed laser and some cutting tests

Irradiation of a single-crystal diamond tool was performed with a picosecond pulsed laser to produce a tool with a microgrooved edge. This tool was then used in a metal cutting process to transfer the edge grooves onto a workpiece. Suitable conditions for laser irradiation on the diamond tool were experimentally investigated in terms of groove shape and laser-induced damage to diamond. Two different kinds of cutting experiments were performed; a uniformly grooved surface and a hierarchically structured surface were obtained. The chip formation mechanisms in the metal grooving process were examined. A copper workpiece was rapidly machined the surface of which had microgrooves with a pitch of a few micrometers. An increase of the contact angle was observed on the grooved surface, indicating the improvement of water repellency. This study presents an efficient method to machine microgrooves on metal materials for functional surfaces.

10 MW급 초임계 CO₂ 발전용 축류 터빈의 구성 설계 및 회전체 동역학 해석

This paper presents component design and rotordynamic analysis results of axial turbine applied to a 10 MW super-critical CO₂ cycle. The axial turbine consists of 3 stage turbine blades and a shaft supported by two fluid film bearings. To prevent the leakage, we installed two seals near the turbine inlet and exit side. We adopts a tilting pad bearing for the stable operation of the rotor. The tilting pad bearing consists of 5 pads and leading edge grooves are installed for the effective thermal management. Based on the rotor layout, we conduct a rotordynamic analysis. The dynamic coefficients of the tilting pad bearings were calculated based on the thin film lubrication theory. Turbine blades, thrust collar and seals were modeled as equivalent inertia. The predicted Campbell diagram showed that there are three critical speeds, namely the conical and the first , second and third bending critical speeds under the rated speed and it is predicted that the rotor have 20% separation margin for the fourth bending critical speed. In addition, unstable modes are not presented under the rated speed and the unbalance response prediction showed that vibration levels are controlled within 0.02 mm for all speed ranges owing to the high damping ratio of the modes.

Component level study of an actively lubricated LEG Tilting Pad Bearing: Theory and experiment

Abstract This article constitutes the second step in a research effort aiming at evaluating the feasibility of introducing active characteristics into standard leading edge groove (LEG) tilting pad journal bearings. The strategy proposed is to control the LEG inlet flow using a servovalve. This work portrays the first experimental study for the“proof of concept” of this configuration, as well as a comparison with theoretical results. A simplified setup, featuring a rigid rotor supported by a single pad arrangement is the subject of study. The obtained results prove the viability of the proposed active bearing design, validate the available simulation tool and exemplify on a conceptual level the operational benefits from introducing this technology into standard LEG Tilting Pad Bearings.

Characteristics of a Spherical-Seat TPJB With Four Methods of Directed Lubrication—Part I: Thermal and Static Performance

Static and thermal characteristics (measured and predicted) are presented for a four-pad, spherical-seat, tilting-pad journal bearing (TPJB) with 0.5 pivot offset, 0.6 L/D, 101.6 mm nominal diameter, and 0.3 preload in the load-between-pivots orientation. One bearing is tested four separate times in the following four different lubrication configurations: (1) flooded single-orifice (SO) at the bearing shell, (2) evacuated leading edge groove (LEG), (3) evacuated spray-bar blocker (SBB), and (4) evacuated spray-bar (SB). The LEG, SBB, and SB are all considered methods of “directed lubrication.” These methods rely on lubrication injected directly to the pad/rotor interface. The same set of pads is used for every test to maintain clearance and preload; each method of lubrication is added as an assembly to the bearing. Test conditions include surface speeds and unit loads up to 85 m/s and 2.9 MPa, respectively. Static data include rotor–bearing eccentricities and attitude angles. Thermal data include measured temperatures from 16 bearing thermocouples. Twelve of the bearing thermocouples are embedded in the babbitt layer of the pads, while the remaining four are oriented at the leading and trailing edge of the loaded pads exposed to the lubricant. Bearing thermocouples provide a circumferential and axial temperature gradient. The pivot stiffness (pad and pivot in series) is measured and incorporated into predictions.

Characteristics of a Spherical Seat TPJB With Four Methods of Directed Lubrication—Part II: Rotordynamic Performance

Measured and predicted rotordynamic characteristics are presented for a four-pad, spherical-seat, tilting-pad journal bearing (TPJB) with 0.5 pivot offset, 0.6 L/D, 101.6 mm nominal diameter, and 0.3 preload in the load-between-pivots orientation. One bearing is tested four separate times in the following four different lubrication configurations: (1) flooded single-orifice (SO) at the bearing shell, (2) evacuated leading edge groove (LEG), (3) evacuated spray-bar blocker (SBB), and (4) evacuated spray-bar (SB). The same set of pads is used for every test to maintain clearance and preload; each method of lubrication is added as an assembly to the bearing. Test conditions include surface speeds and unit loads up to 85 m/s and 2.9 MPa, respectively. Dynamic data includes four sets (one set for each bearing configuration) of direct and cross-coupled rotordynamic coefficients derived from measurements and fit to a frequency-independent stiffness-damping-mass (KCM) matrix model. The pivot stiffness (pad and pivot in series) is measured and incorporated into predictions.

Modelling of LEG tilting pad journal bearings with active lubrication

This work constitutes the first step in a research effort aimed at studying the feasibility of introducing an active lubrication concept in tilting pad journal bearings (TPJBs) that feature the leading edge groove (LEG) lubrication system. The modification of the oil flow into each pad supply groove by means of servovalves renders the bearing active. This article focus on obtaining and validating a numerical model capable of simulating the studied system, in terms of its steady state and dynamics characteristics. The developed model is then used to simulate a simple system, in order to portray the feasibility of affecting its static and dynamic properties by introducing this novel active bearing design.

Relative Significance of Multiple Parameters on the Mechanical Specific Energy and Frictional Responses of Polycrystalline Diamond Compact Cutters

A high pressure single polycrystalline diamond compact (PDC) cutter testing facility was used to investigate the effect of five factors on PDC cutter performance on Alabama marble. The factors include: depth of cut (DOC), rotary speed, back rake angle, side rake angle, and confining (wellbore) pressure. The performance is quantified by two parameters: mechanical specific energy (MSE) and friction angle. Fractional factorial design of experiments methodology was used to design the experiments, enabling detection of potential interactions between factors. Results show that, in the range tested, the only statistically significant factor affecting the MSE is DOC. In other words, DOC's influence is predominant and it can mask the effect of all the other factors. These results could have applications in real time pore pressure detection. Further, the results show that back rake angle is the most statistically significant factor in friction angle. Side rake angle and depth of cut also affect the friction angle, but in a relatively unimportant manner. The MSE–DOC behavior is explained and modeled by cutter edge–groove friction and the circular cutter shape. It is speculated that high cutter edge friction overwhelms the actual cutting process. A comparison of five currently present models in the literature with these results is presented and the conclusion is that the future PDC cutter models should digress from the traditional shear failure plane models.

The Influence of the Shape of Grooves on the Intensity of Closing Axial Material Discontinuities During Rolling

Abstract The article discusses the influence of rolling in the newly designed slitting-bending grooves on closing internal material discontinuities in continuous ingots. The defects located in the axial area of a strand, i.e. axial porosity and contraction cavity, were analysed. Numerical and experimental studies of the rolling process of flat bars for feedstock with marked materials discontinuities simulating actual defects occurring in an ingot were conducted. For comparison purposes, rolling of feedstock with discontinuities in traditional grooves was conducted. The numerical simulations were carried out using the Forge 2008¯software programme. The experimental studies were conducted in a D150 laboratory rolling mill. In the research, the S355J2G3 structural steel and lead were used. Distributions of temperature, intensity of deformation and stress in a cross-section of strands after rolling were analysed. Changes in the surface areas of the discontinuities in feedstock after rolling in shape and traditional grooves were examined. It was concluded that introduction of grooves with complex shapes may contribute to the improvement of internal quality of finished products. The complex shape of the tools has allowed for an almost 100% closure of the discontinuities located in the central part of a strand, already at the initial stages of the process, unlike in case of the traditional production method, where the discontinuities were transferred even until the final product. Applying the newly designed slitting-bending grooves enables utilisation of a smaller number of edge grooves at the initial stage of the rolling process, where reopening of freshly welded defects might occur.

중집광형 태양광 집광장치 용 선형 프레넬 렌즈의 최적화설계연구

본 논문에서는 25배 태양광 집광장치에 적용될 선형 프레넬 렌즈의 최적화에 대해 서술한다. 이 선형 프레넬 렌즈는 각기 다른 패턴을 가진 <TEX>$10{\times}10$</TEX> mm 크기의 선형 프레넬 렌즈가 <TEX>$5{\times}5$</TEX>의 형태로 결합된 렌즈이다. 각 프레넬 렌즈는 같은 크기의 태양전지로 태양광이 입사할 수 있도록 최적화되어 있다. 최적화된 프레넬 렌즈의 설계치는 패턴높이 35 <TEX>${\mu}m$</TEX>, 구배각 <TEX>$4^{\circ}$</TEX>, 모서리 라운드 1 <TEX>${\mu}m$</TEX>로 각각의 선형 프레넬 렌즈에 모두 같은 값이 부여되었지만 사면경사각은 <TEX>$14.1^{\circ}{\sim}31.2^{\circ}$</TEX>로 각기 다르다. 이렇게 설계된 선형 프레넬 렌즈의 태양광 집광효율은 80%이상이며 기존의 25배 집광용 단일 프레넬 렌즈보다 오정렬 및 제작공차 측면에서 강력한 성능을 가진다. 설계된 선형 프레넬 렌즈의 민감도 분석을 통해 모서리 라운드가 1 <TEX>${\mu}m$</TEX>씩 증가할수록 집광효율이 ~5%씩 저하되는 것을 파악하였고 이에 모서리 라운드가 최소한의 수치로 유지되어야 함을 확인하였다. This paper presents a combination of linear Fresnel lenses optimized for <TEX>${\times}25$</TEX> solar concentration. The combined lens consists of <TEX>$5{\times}5$</TEX> linear Fresnel lenses. Each Fresnel lens is of <TEX>$10{\times}10$</TEX> mm and optimized to tilt the incoming light onto a solar cell of the same size. All of the optimized Fresnel segments have the same pattern height of 35 <TEX>${\mu}m$</TEX>, draft angle of <TEX>$4^{\circ}$</TEX>, and edge groove round of 1 <TEX>${\mu}m$</TEX> but with different facet angles varying from <TEX>$14.1^{\circ}$</TEX> to <TEX>$31.2^{\circ}$</TEX>. The solar concentrating efficiency of the combination is shown to be over 80% and more robust than a conventional single <TEX>${\times}25$</TEX> circular Fresnel lens in terms of pointing misalignment and manufacturing errors. A sensitivity analysis finds that the edge groove round should be kept as small as machining allows since the concentrating efficiency drops ~5% per 1 <TEX>${\mu}m$</TEX> increase of the edge groove.

A new species and two new records of Minicopenaeon Bourdon, 1981 (Crustacea: Isopoda: Bopyridae) from China

Three species of the parasitic isopod genus Minicopenaeon Bourdon, 1981 (Crustacea: Isopoda: Bopyridae) are reported from China, one new to science and two new records from mainland China. Minicopenaeon crosnieri (Bourdon, 1979) formerly known from Madagascar, the Philippines and Taiwan, is recorded from Zhejiang province. Minicopenaeon intermedium Bourdon, 1981 previously recorded from the Philippines and Japan, is recorded from China for the first time. The new species Minicopenaeon liuruiyui n. sp. is recorded from the East and South China Seas. As with other species of the genus, females of the new species have rudimentary coxal plates on the second pereomeres on the short side. The new species can be distinguished from other species by the presence of a widely open brood pouch, head with bilobate anterior edge and median concave groove, and male head with curved posterior margin of the pleon. A key to species of Minicopenaeon is provided and the subspecies M. intermedium curvatum Bourdon, 1981 is synonymised with M. intermedium Bourdon, 1981. Metapenaeopsis philippii (Bate, 1881) and M. coniger (Wood-Mason, 1891) are newly recorded as host species for bopyrids.

Fire Performance Properties of Solid Wood and Lignocellulose-Plastic Composite Deck Boards

Traditionally fire performance properties of externally located deck boards have been characterized by their flame spread index (FSI) as determined by UL 723/ASTM E 84. In this test a nominal 0.6 m wide by 7.3 m long array of deck boards is exposed to an approximately 90 kW ignition source fire for 10 min in the Steiner Tunnel. More recently the University of California Forest Products Laboratory developed a new fire test protocol based the principles of oxygen consumption calorimetry, California SFM 12-7A-4, Part A: Under-Deck Flame Test. This protocol addresses the potential ignition of a deck from underneath as may occur during a wildfire. In this protocol a nominal 0.44 square meter deck-system of deck boards mechanically fastened to wood joists is subjected to an 80 kW ignition source fire for 3 min. For this study the fire performance characteristics of more than thirty-five deck board types were evaluated by the above two methods and by a smaller-scale material-based test, ASTM E 1354 cone calorimeter. Deck boards were selected to represent a range of materials (untreated wood, lignocellulose-polymer composite), structures (solid, voided, microcellular foam), and cross-sectional profiles (width, thickness, presence of hidden fastener system longitudinal edge grooves). The results from this study were used to: 1. Develop correlations for deck boards between the material-based cone calorimeter tests and system-based under-deck tests. 2. Develop correlations for deck boards between the small-scale cone calorimeter tests and large-scale Steiner Tunnel tests. 3. Estimate the significance of ASTM D 2898 Method A accelerated weathering on fire performance.