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Статті в журналах з теми "Sharpening of internal grooves"
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Allen, J. R. L. "Tilestones into Whetstones in Seven Steps: the Brownstones, Pennant Sandstone and Stonesfield Slate at Silchester (Calleva Atrebatum), North Hampshire." Britannia 50 (May 6, 2019): 321–30. http://dx.doi.org/10.1017/s0068113x19000047.
Повний текст джерелаАнотація:
ABSTRACTRoughly two-thirds of an assemblage of 156 whetstones from three collections representing two late Roman sites at Silchester can be assigned geologically to the Brownstones (Devonian), Pennant sandstone (Carboniferous) or Stonesfield Slate (Jurassic), imported from the west and north into the town as roof-tiles. The latter were put to further, secondary use as whetstones, some small and portable but others large and laid flat and kept stationary. The whetstones are polished through use, typically on both faces, and a high proportion carry grooves. On some the grooves are short and fine and could represent the sharpening of such items as pins, needles, meat skewers, styli and engraving tools. These grooves are typically found on whetstones from Insula IX, where artisanal and, at best, ‘light-industrial’ activities are recorded. At the forum-basilica, by contrast, the whetstones are more substantial and typically show large grooves of two kinds that point to the shaping and finishing in considerable numbers of iron objects such as knives, cleavers, swords and even possibly ladles. The industrial activity at this site had a distinctly ‘heavier’ quality. The biography of these whetstones — objects seemingly simple and unpretentious — was complex, wherever they were found.
2
Metel, Alexander, Marina Volosova, Enver Mustafaev, Yury Melnik, Anton Seleznev, and Sergey Grigoriev. "Plasma-Beam Processing of Tools Made of SiAlON Dielectric Ceramics to Increase Wear Resistance When Cutting Nickel–Chromium Alloys." Coatings 12, no. 4 (March 30, 2022): 469. http://dx.doi.org/10.3390/coatings12040469.
Повний текст джерелаАнотація:
This research aimed at an increase in wear resistance of round cutting plates manufactured with SiAlON dielectric ceramics through deposition of wear-resistant coatings. To increase effectiveness of the coatings, their adhesion was improved by the removal of defective surface layers from the cutting plates before the deposition. As the depth of caverns and grooves appearing on the cutting plates due to manufacturing by diamond grinding reached 5 µm, a concentrated beam of fast argon atoms was used for the removal of defective layers with a thickness exceeding the depth of caverns and grooves. At the equal angles of incidence to the front and back surfaces of the cutting wedge amounting to 45 degrees, two-hour-long etching of rotating cutting plates provided removal of defective layers with thickness of ~10 µm from the surfaces. After the removal, the cutting edge radius of the plates diminished from 20 to 10 µm, which indicates the cutting plates’ sharpening. Wear-resistant TiAlN coatings deposited after the etching significantly improve the processing stability and increase wear resistance of the cutting plates by not less than 1.7 times.
3
Sun, Meng, Zhen Yu Zhang, and Wen Jun Kong. "Design of Sealing Structure and Analysis of the Flow Field in Micro Internal Combustion Swing Engine." Applied Mechanics and Materials 670-671 (October 2014): 930–35. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.930.
Повний текст джерелаАнотація:
A multistage groove sealing structure in Micro Internal Combustion Swing Engine (MICSE) was designed. By machining several grooves on the center-swing, it provides non-contacting control of internal leakage. The sealing principle of this structure may be described as follows. Gas at high pressure enters through the clearance of adjacent grooves to accelerate, then expands isentropically in the grooves. Once crossing several such grooves, gas emerges at the other end of the sealing structure at significantly reduced pressure. Numerical simulations were utilized to analyze the influences of pressure ratio and groove depth on leakage characteristics. The results demonstrate that at pressure ratio smaller than 2.0, turbulence eddy dissipation process in grooves cannot dissipate kinetic energy obtained during the throttling process completely, which results in poor sealing effect, at pressure ratio lager than 2.5, the two processes reach dynamic balance and sealing effect no longer changes. There is an optimal value in groove depth, undersize or oversize may lead to imperfect throttling effect or turbulence eddy dissipation process.
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Zeng, Yuan Song. "Finite Element Simulation and Experimental Research on the Internal Rolling Connection for Titanium Alloy Tubes." Materials Science Forum 475-479 (January 2005): 3287–90. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.3287.
Повний текст джерелаАнотація:
In this paper, the internal rolling process is presented to connect the titanium tubes to the tube fitting with the mechanical method. The material flow, the distribution of stress and strain and the connecting mechanics are analyzed by using the finite element method(FEM) for two kinds of the tube fitting structures, the triangle grooves and the rectangle grooves. Rolling experiments and tests for pressure durability, gas-sealing ability, surface finish and contact percent are also introduced. Results show that the tube joints with the triangle grooves has very excellent connecting strength, and the FE analysis agrees well with the experiments.
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Lin, Mingtuan, and Chenglong Lin. "2D Gain Enhancement Based on Single-Layer SIW Corrugated Technique with Slot Array Feeder." International Journal of Antennas and Propagation 2018 (2018): 1–6. http://dx.doi.org/10.1155/2018/3684197.
Повний текст джерелаАнотація:
Novel slot-array-based SIW corrugated technique is demonstrated to achieve 2D gain enhancement, namely, sharpening the beamwidths in both E-plane and H-plane. Compared to other metallic corrugated methods to realize 2D gain enhancement, the proposed design, with SIW grooves to reduce the beamwidth in E-plane and slot array to increase the directivity in H-plane, has a lower profile, weight, and design complexity, which can be easily fabricated with the common printed circuit board (PCB) technique. A prototype is designed and fabricated, with measurement presenting a low reflection coefficient less than −10 dB from 26.4 GHz to 28.2 GHz and an enhanced gain up to 18 dB. Overall, our proposed technique will be beneficial for the design of high-gain antenna in 5G wireless terminals.
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Jenkins, C. "Sharpening the clinical diagnostic borders of chronic obstructive pulmonary disease." Internal Medicine Journal 33, no. 12 (December 2003): 551–53. http://dx.doi.org/10.1111/j.1445-5994.2003.00498.x.
Повний текст джерела
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Sobczak, K., H. Dyja, and A. Kawałek. "The Influence of the Shape of Grooves on the Intensity of Closing Axial Material Discontinuities During Rolling." Archives of Metallurgy and Materials 60, no. 1 (April 1, 2015): 461–68. http://dx.doi.org/10.1515/amm-2015-0075.
Повний текст джерелаАнотація:
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.
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Zhou, Mingxue, Cheng Wu, Fengjiang An, Shasha Liao, Dongyu Xue, and Jian Liu. "Dynamic Disintegration of Explosively-Driven Metal Cylinder with Internal V-Grooves." Materials 14, no. 3 (January 27, 2021): 584. http://dx.doi.org/10.3390/ma14030584.
Повний текст джерелаАнотація:
Machining V-shaped grooves to the internal surface of cylindrical shells is one of the most common technologies of controlled fragmentation for improving warhead lethality against targets. The fracture strain of grooved shells is a significant concern in warhead design. However, there is as yet no reasonable theory for predicting the fracture strain of a specific grooved shell; existing approaches are only able to predict this physical regularity of non-grooved shells. In this paper, through theoretical analysis and numerical simulations, a new model was established to study the fracture strain of explosively driven cylindrical shells with internal longitudinal V-grooves. The model was built based on an energy conservation equation in which the energy consumed to create a new fracture surface in non-grooved shells was provided by the elastic deformation energy stored in shells. We modified the energy approach so that it can be applicable to grooved shells by adding the elastic energy liberated for crack penetration and reducing the required fracture energy. Cylinders with different groove geometric parameters were explosively expanded to the point of disintegration to verify the proposed model. Theoretical predictions of fracture strain showed good agreement with experimental results, indicating that the model is suitable for predicting the fracture strain of explosively driven metal cylinders with internal V-grooves. In addition, this study provides an insight into the mechanism whereby geometric defects promote fracturing.
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Elangovan, S., and E. Rathakrishnan. "Studies on high speed jets from nozzles with internal grooves." Aeronautical Journal 108, no. 1079 (January 2004): 43–50. http://dx.doi.org/10.1017/s000192400000498x.
Повний текст джерелаАнотація:
Experiments were carried out on jets issuing from circular nozzles with grooved exits and the results compared with those of the plain nozzle. The plain nozzle had an exit diameter of 10mm. Because of the introduction of semi-circular grooves at the exit, the effective or equivalent diameter of the grooved nozzles was 10·44mm. The groove lengths were varied as 3, 5 and 8mm. The nozzles were operated at fully expanded sonic and underexpanded exit conditions. The corresponding fully expanded Mach numbers were 1·0 and 1·41. The shock cell structure of the underexpanded jets from grooved nozzles appeared to be weaker than that of the plain nozzle, as indicated by lesser amplitudes of the cyclic variation of the Pitot pressure. The iso-Mach contours indicate that the jet spread along the grooved plane is significantly higher than that along the ungrooved plane. Off-centre peaks were observed in the mean pressure profile of underexpanded jets from grooved nozzles. They were probably due to the streamwise vortices shed from the grooves.
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Li, Wei, Sen Li, Yeheng Wang, and Junying Yun. "Study on Personnel Detection Based on Retinex and YOLOv4 in Building Fire." Journal of Physics: Conference Series 2185, no. 1 (January 1, 2022): 012039. http://dx.doi.org/10.1088/1742-6596/2185/1/012039.
Повний текст джерелаАнотація:
Abstract When a fire occurs in a building, the internal environment is full of dense smoke, which will greatly hinder the evacuation and rescue of the trapped persons. If the evacuation and rescue are not in time, the life safety of the trapped persons will be seriously threatened. In response to this problem, this paper proposes a method for quickly detecting trapped persons in building fires. This method uses a combination of multi-scale Retinex image sharpening algorithm and YOLOv4 person detection algorithm. First obtain the image information of the fire scene, use the multi-scale Retinex algorithm based on the Gaussian pyramid to perform the sharpening process, and then use the YOLOv4 model to perform the personnel detection on the sharpened fire scene image. The experimental results show that the confidence of image person detection after Retinex sharpening processing has been significantly improved.
Дисертації з теми "Sharpening of internal grooves"
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Таран, Євгеній Сергійович. "Оправка розточна збірна". Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/31456.
Повний текст джерелаАнотація:
Метою дипломного проекту є проектування оправки розточної збірної,
яка застосовується для обробки внутрішніх та зовнішніх циліндричних
поверхонь, свердління отвору, точіння внутрішніх канавок та підрізання
торця. Даний інструмент оснащений змінними твердосплавними пластинами,
які надійно закріплені в корпусі інструменту. Також було проаналізовано
конструкції інструментів для оброблення різних типів поверхонь, створене
робоче креслення та 3D модель інструменту, розроблено технологію
виготовлення і розраховано режими різання, вибрано та розраховано
технологічне пристосування для фрезерування посадочних поверхонь під
пластину з твердого сплаву, представлена керуюча програма для верстату з
ЧПК та візуалізація процесу обробки.The purpose of the diploma project is the design of the mandrel of the blade assembly, which is used for the treatment of internal and external cylindrical surfaces, drilling a hole, rolling the grooves and triming the ends. This tool is equipped with replaceable carbide plates, which are securely mounted in the tool casing. The structure of the tools for processing various types of surfaces was also analyzed, a working drawing and a 3D model of the tool were created, a production technology was developed and cutting patterns were calculated, a technological device for milling the landing surfaces under a solid alloy plate was selected and calculated, the control program for the CNC machine and visualization of the processing process are presented.
Частини книг з теми "Sharpening of internal grooves"
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Han, Luyi, Guangchun Wang, Xin Wang, and Zhao Liu. "Study on Precision Forging Methods of Difficult-to-Knockout Components with Non-parallel Internal Grooves." In Forming the Future, 2167–78. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-75381-8_182.
Повний текст джерелаТези доповідей конференцій з теми "Sharpening of internal grooves"
1
Mahmood, Gazi I., and Aasa Samson. "Internal Groove Influenced Thermohydraulic Performance on an Air-Channel." In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83236.
Повний текст джерелаАнотація:
Internal fins, protrusions, and porous foams enhance the local convective heat transfer at the channel walls in the heat exchangers, electronic chips for cooling, and solar panels for cooling and heating by promoting the local turbulence in flow. However, the fluid pumping power in the channel suffers due to the blockage and high pressure drop caused by the fins, protrusions, and foams. The present article reports the experimental friction factors and Nusselt numbers in a rectangular channel with an array of internal grooves in one wall. The grooves provide the minimum flow blockage, but still promote the local turbulence to enhance the surface heat transfer. The cylindrical grooves are machined at 45° to the mean air-flow direction in one of the wide walls of the channel of aspect ratio of 40.6:1. The ratio of groove print-diameter to depth is 2.83:1. The objectives are to investigate the effects of groove pitch on the thermal performance in the channel as the flow Reynolds number (Re) varies between 600 and 15000. Two ratios of groove-pitch to print-diameter are employed — 3.2:1 and 4.5:1. The measurements include the distributions of the wall staticpressure and heat transfer coefficient along the channel wall having the grooves. The pressure distributions are obtained at the adiabatic condition. The heat transfer coefficients are obtained with the constant heat flux boundary condition from the grooved surface. The measurements are also obtained in the smooth channel when the grooved wall is replaced by a smooth wall for comparisons with the grooved channel. The results indicate the ratio of Darcy friction factor (f/fo) for the grooved channel (f) to that for the smooth channel (fo) increases with the Re by 27% and 41% at the maximum for the two grooves. The f/fo ratios are slightly higher for the grooves with the smaller pitch. The fully developed Nusselt number ratio (Nu/Nuo) for the grooved channel (Nu) to that for the smooth channel (Nuo) increases with the Re by 37% at the maximum for the two grooves. However, the thermal performance quantified by the ratio (Nu/Nuo)/(f/fo)1/3 is higher for the smaller pitch grooves for most of the Reynolds numbers > 2000. The results thus contribute to the design of heat exchangers and cooling channels for high thermal performance with the ratio (Nu/Nuo)/(f/fo)1/3 > 1.0 based on the smaller surface area, pumping power, and heat duty.
2
PENG, X., G. PETERSON, and X. LU. "Rewetting analysis of capillary induced flow in circular channels with internal grooves." In 30th Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1992. http://dx.doi.org/10.2514/6.1992-127.
Повний текст джерела
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Takatsu, Yasuyuki, Takashi Masuoka, and Takahiro Nomura. "Natural Convection in a Vertical Enclosure With Grooves." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39179.
Повний текст джерелаАнотація:
The natural convection in a vertical enclosure with grooves has been numerically studied. To identify the structure of the thermal boundary layer along the discontinuous vertical surface, the iso-flux condition is imposed to each heating (or cooling) portion of the discontinuous vertical surface, and the adiabatic condition is applied to the other solid walls including the grooves. We focus on the behavior of the thermal boundary layer along the discontinuous vertical surface, and clarify the dual structure of the thermal boundary layer. The whole thermal boundary layer develops along the discontinuous vertical surface, while the internal thermal boundary layer forms on each solid portion of the discontinuous flat surface. We can recognize from the isotherms near the solid portion that the internal thermal boundary layer develops from the leading edge to the trailing edge of the solid portion. The internal thermal boundary layer plays an important role in the heat transfer enhancement. As the thin thermal boundary layer forms at the leading and trailing edges, the heat transfer coefficient near the leading and trailing edges takes higher values.
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Ma, Renlian, Salaheldin A. Mohamad, Xiqun Lu, and Wanyou Li. "Numerical Analysis and Experimental Evaluation of Cylinder Liner Macro-Scale Surface Texturing." In ASME 2015 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icef2015-1074.
Повний текст джерелаАнотація:
An experimental and theoretical study is presented to study the effect of surface texturing in the form of circumferential oil grooves on improving the tribological properties of piston ring-cylinder liner tribosystem. Tests were performed on a reciprocating test rig with actual piston rings and cylinder liner segments, and a numerical model has been developed. A comparison was made between the performance of the textured cylinder liners and un-textured cylinder liners. It was found that with the smaller oil groove area density, the reduction in friction force is more obvious, Parabolic and triangular oil grooves are more efficient in friction reducing, and the prediction results by numerical model match the experimental results well in most case.
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Mrozek, Krzysztof, Roman Staniek, and Marek Szostak. "Research on External and Internal Induction Heating Effectiveness of Injection Molds by Means of Thermovision Measurements." In ASME 2014 12th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/esda2014-20317.
Повний текст джерелаАнотація:
The aim of this work is to compare the effectiveness of two induction heating methods of injection molds by means of thermovision measurement. The problem of selecting external or internal induction heating for thin-walled moldings used in electrical and electronic industry is taken into consideration. At first, the boundary conditions were defined. Then a group of three moldings with different defects were selected. The defects that have been taken to remove by means of induction heating are: weld lines, breaking hinges, air traps and diesel effect. In order to compare the methods of heating two models were created. The first one was made as a block of steel with milled grooves with a width of 2mm and a depth varying from 1 to 12mm. The second model consisted of two parts, one being placed in the second. The research stand consisted of prepared models, induction generator with power of 10kW, specially shaped inductor, thermovision camera and temperature sensor of PT100 type as a reference. First, the surface with milled grooves was heated in four different sectors (because of the shape of inductor) in time of 2s. The area of low-depth grooves heated up to 154°C while the surface with 12 mm grooves heated up to 120°C. It comes from eddy currents flowing. This phenomenon shows that effectiveness of external heating of grooved surface decreases with increasing of grooves depth. In the second case the cavity insert was heated as a coil inside the inductor which was located inside the mold. The measured value was the time of heat transfer from heated area to the forming surface in three configurations.
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Lin, Gang, Karsten Kusterer, Viktor Merkel, and Dieter Bohn. "Heat Transfer Enhancement Using Wedge-Shaped Detached Ribs With Grooves in Internal Cooling Channel." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25863.
Повний текст джерелаАнотація:
As the state of the art internal cooling configuration the serpentine passage with angled ribs has been developed for many decades and is now widely used in almost all the blade internal cooling applications. To further increase the thermal efficiency of gas turbine, the development of new internal cooling configurations is necessary. In the present study, a new internal cooling configuration, which is characterized by placing modified wedge-shaped detached ribs above the grooves, has been obtained and investigated. Under this new cooling configuration, the main effect for enhancement of heat transfer in standard ribbed channel, the separation and reattachment of the main flow, has been retained. Additional improvements can be found in several areas as follows: (1) flow near rib corner is not stagnant anymore and both corner vortexes near the rib have been eliminated, (2) the increased velocity in groove leads to locally high heat flux. With the same channel dimension, ribs pitch-height ratio, boundary conditions and the Reynolds number based on hydraulic diameter the new cooling configuration shows higher Nusselt number ratio at the ribbed wall by approximately 25–32%. The globally-averaged thermal performance parameter shows a 19–25% better heat performance by this kind of cooling configuration.
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Stark, Matthias, and Richard Mittler. "Lubricant Flow Optimization of Large Two Stroke Marine Diesel Engine Piston Ring Packs." In ASME 2016 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icef2016-9326.
Повний текст джерелаАнотація:
Approaching a characterization of different contributors to the lube oil balance of an engine becomes important when aiming at enhancing lubrication performance and reducing its contribution to exhaust gas emissions. It is essential to quantify relevant data helping to determine lubrication losses related to particular tribosystem components. Recent activities focused on rating distinct tribosystem component effects on their contribution to total lube oil consumption and the possibility to most effectively modify those. This paper thus describes the most effective tribosystem component modifications, consisting of the application of a substantially modified piston ring pack and the introduction of lube oil accumulating grooves in order to considerably enhance lubrication performance. A proper prediction of piston ring pack dynamics and tribodynamic effects on the lube oil film is essential to design a superior piston ring pack in terms of an optimized piston running behaviour and lube oil transportation. One major step designing such a ring pack is based on the consequent application of a novel 3D piston ring pack simulation tool to enhance lube oil transportation characteristics and distribution. Lube oil accumulating grooves are introduced to reduce lubrication losses due to so called ring pack spray. The ring pack spray is a result of accumulated lubricant in the pressurized piston ring pack expanding into the scavenge air receiver during the scavenging phase. Mentioned effect was analysed in detail in order to determine the amount of related lubricant losses. Investigations in this context lead to the application of lube oil accumulating grooves and hence can be considered an important design aspect to reduce total lube oil consumption. Tribosystem performance validation was performed on the basis of the application of an SO2 tracing technology on a full scale engine test in order to determine relevant tribosystem component modifications in real time. The sulphur content of fuel and lube oil considerably influences the formation of particulate matter in the exhaust gas, following chemical reactions of sulphur oxidation. Hence detecting SO2 in the exhaust gas is a direct measure to determine the amount of lubricant in the exhaust gas composition. Finally this report demonstrates measurement results describing the superior performance of the modified tribosystem.
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Shimura, Takashi, Satoshi Kawasaki, Masaharu Uchiumi, and Jun Matsui. "Internal Flow and Axial Thrust Balancing of a Rocket Pump." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-06027.
Повний текст джерелаАнотація:
Internal flow of a cryogenic rocket turbopump is rather complicated compared to ordinary pumps. In order to design and predict characteristics of the axial thrust balancing system, analyses of the internal flow system is essential. In the present study, the calculation method for analyzing the internal flow system taking into account effects of boundary layer conditions and angular momentum change in chambers is applied. The characteristic of an axial thrust balancing system, which is comprised of a balance piston and grooves on the stationary wall, was evaluated. Calculated results showed that the system has a wide self-balancing range and is suitable for rocket turbopumps.
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Saha, Krishnendu, and Sumanta Acharya. "Heat Transfer Enhancement Using Angled Grooves as Turbulence Promoters." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95818.
Повний текст джерелаАнотація:
An experimental study is conducted on a simulated internal cooling channel of a turbine airfoil using angled grooves and combination of grooves-ribs to enhance the heat transfer from the wall. The grooves are angled at 45° to the mainstream flow direction and combinations of four different geometries are studied that include: (1) angled grooves with a pitch, p/δ = 10, (2) angled groove with a larger pitch, p/δ = 15, (3) combination of angled groove and 45° angled rib, and (4) combination of angled groove with transverse rib. Transient liquid crystal experiments are conducted for a Reynolds number range of 13,000–55,000, and local and averaged heat transfer coefficient values are presented for all the geometries. Pressure drops are measured between the inlet and the exit of the grooved channel and friction factors are calculated. The combination of the angled groove and 45° angled rib provided the highest performance factor of the four cases considered, and these values were higher or comparable to among the best-performing rib geometries (45-degree broken ribs) commonly used in gas turbine airfoils.
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Takata, Rosalind, Yong Li, and Victor W. Wong. "Effects of Liner Surface Texturing on Ring/Liner Friction in Large-Bore IC Engines." In ASME 2006 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/icef2006-1525.
Повний текст джерелаАнотація:
Well-designed surface texturing may be used to reduce ring/liner friction and increase efficiency in internal combustion engines. This study investigated the effects of textures of either grooves or dimples on ring/liner friction, in the hydrodynamic and mixed regimes. Existing MIT models were used to conduct this research. The ring-pack model is based on averaged flow-factor Reynolds analysis, and is used in conjunction with a deterministic model for flow factor calculation. Although this advanced model is applicable in a wide range of cases, the surface textures studied here are very different than a typical liner surface, and can be represented only approximately by the averaged analysis upon which the ring simulation is based. For this reason, this analysis of surface features has focused on a parametric study, the goal of which is to analyze trends relating ring/liner friction to surface parameters, and to make a general evaluation of the potential of surface texturing to reduce ring-pack losses. In the hydrodynamic and mixed regimes, surface texturing affects the fluid pressure in the lubricant between ring and liner, thus affecting the ability of the oil film to support the ring load. If the effect of the texturing is to impede the flow of lubricant, the result will be an increase in oil film thickness. This causes friction reduction in two ways: if asperity contact was present, it is reduced; and the increase in film thickness causes a decrease in shear rate, thus decreasing oil shear stress. It was found that surfaces with both dimpled and grooved textures could cause friction reduction through this mechanism, with deeper features and more transverse groove patterns causing the greatest reduction. Friction also decreased with increasing area ratio (the percentage of the surface that is occupied by the surface features) for both grooves and dimples, and was only slightly dependent on groove width and dimple diameter. Because the effect of the surface texturing is on hydrodynamic effects in the oil, it is strongly coupled with lubricant properties. If surface texturing and lubricant viscosity are optimized together side effects such as oil consumption and wear can be mitigated, while friction can be reduced even further than it is via surface texturing alone. This possibility was also briefly considered in this study.