Raceway Design Research Articles

Research on the Tribological Behavior of Textured Cylindrical Roller Thrust Bearings with Different Distributions of Pits and Nylon Cages under Dry Condition

Differing from the published documents on the effect of texture distributions of sliding tribo-pairs on their friction and wear properties, this study introduced eight patterns to reveal the influence of different distributions of pits on the tribological behavior of textured rolling element bearings with nylon cages under dry condition, namely: Outside-1/4 (OS1/4), Outside-1/2 (OS1/2), Outside-3/4 (OS3/4), Inside-1/4 (IS1/4), Inside-1/2 (IS1/2), Inside-3/4 (IS3/4), Bothside-1/3 (BS) and full (FP). A fiber laser marking system was used to prepare them on the raceways of the shaft washers of cylindrical roller thrust bearings (81107TN). A vertical universal wear test rig was used to obtain their coefficients of friction under an axial load of 2600 N and a rotating speed of 250 RPM, without any lubricant provided. Their wear losses and worn surfaces were characterized. The influence mechanism of different distributions on the tribological properties was also discussed. The results show that the self-lubricating performance of nylon cages can ensure the continuous operation (≥5 h) of cylindrical roller thrust bearings under dry condition. The influence of outside-distributed patterns on the friction and wear properties of bearings is significant. The friction-reducing effect and wear resistance of full textured group is improved but not the best. The friction-reducing and anti-wear behavior of OS1/2 is similar to that of FP. In this work, OS3/4 can provide the best tribological performance under self-lubricating conditions. Compared with the data of smooth bearings, its average coefficient of friction and wear loss can be reduced by 37.68% and 38.85%, respectively. This work would provide a valuable reference for the raceway design and reliability optimization of rolling element bearings.

Tribological behavior of dimples textured rolling element bearings under stepped load and starved lubrication

PurposeThe purpose of this paper is to report the tribological behavior of dimples textured rolling element bearings (REBs) under variable load and starved lubrication.Design/methodology/approachThe pattern parameters include line-diameter of dimples (200 µm, 250 µm, 300 µm), depth of dimples (10 µm, 20 µm, 30 µm). Dimple patterns were prepared on the raceways of the shaft washers of cylindrical roller thrust bearings (CRTBs). A vertical wear test rig was used to obtain their coefficients of friction (COFs) under stepped load (1200–6000 N, with a manually increase of 1200 N every 3600 s) and starved lubrication. The wear losses and worn surfaces were characterized. The tribological performance between stepped load and fixed load (4000 N) was compared. The influence mechanism of dimples on the friction and wear properties of CRTBs under stepped load and starved lubrication was also discussed.FindingsCompared with the data of smooth ones, the average COFs of the dimples textured bearings are almost all reduced under stepped load and starved lubrication, while their mass losses almost all get higher. The depth−diameter ratio and the effective volume coefficient of dimples are the important factors. In this work, compared with the smooth group, when the line-diameter of dimple is 250 µm and the depth is 20 µm, i.e. the depth−diameter ratio is 0.08, its average COF is reduced by 46.8% and its mass loss is reduced by about 7%, showing wonderful friction-reducing effect and good wear resistance.Originality/valueThis work can provide a reference for the raceway design of REBs.

Tribological behavior of laser textured rolling element bearings under starved lubrication

PurposeThe purpose of this paper is to reveal the influence of dimples on the tribological properties of the “washers-cage-rollers” system of rolling element bearing (REB) under starved lubrication.Design/methodology/approachA fiber laser marking system was used to prepare dimples patterns on the raceways of the shaft washers of cylindrical roller thrust bearings (CRTBs). The friction and wear properties of dimples textured CRTBs with different diameter of dimples (200 µm, 250 µm, 300 µm) and depth of dimples (4 µm, 8 µm, 12 µm) were researched through a vertical universal wear test rig using a customized tribo-pair under starved lubrication. The surface stresses and the influence mechanism of dimple units on the tribological behavior of REBs were also compared and discussed.FindingsAlthough the surface stresses on the raceways of dimples textured bearings are significantly higher than that of the smooth group, the coefficients of friction and wear losses of them are all reduced under starved lubrication. When the effective volume of dimples is between 1.13 and 2.25 and the depth of dimples is smaller than 12 µm, the tribological properties of dimples textured CRTBs are significantly improved. In this work, when the diameter of dimples is 250 µm, and the depth of dimples is 8 µm, the textured bearings can provide the excellent friction-reduction ability and outstanding wear resistance.Originality/valueThis work is a valuable reference for the raceway design and optimization of REBs.

Tribological behavior of grooves textured thrust cylindrical roller bearings under dry wear

To prolong the serve life of roller element bearings (REB) and improve the reliability of mechanical system, the tribological behavior of the “washers-cage-rollers” system of grooves textured thrust cylindrical roller bearings (TCRB, 81107TN) under dry wear was researched. The pattern parameters include: width of grooves (WOG, 50, 100, and 150 μm), depth of grooves (DPOG, 7, 11, and 15 μm), as well as groove deflection angle (GDA, 0°, 45°, 90°, and 135°). The influence mechanism of grooves on the tribological properties of REBs is discussed. The results show that: As the GDA is 45°, the coefficient of friction (COF) and mass loss of bearing is the lowest among four angles. The average COFs of grooves textured bearings are much higher than that of smooth one, and their mass losses are all lower than that of smooth bearing. The influence of pattern parameters on the surface stresses of grooves textured bearings is weak. In this work, when the WOG is 50 μm and the DPOG is 7 μm, the wear loss of grooves textured bearing is the lowest, reduced by up to 75.6%. This work can provide a valuable reference for the raceway design and optimization of REBs.

Effect of vein-bionic surface textures on the tribological behavior of cylindrical roller thrust bearing under starved lubrication

To reveal the effect of vein-bionic surface textures on the tribological behavior of cylindrical roller thrust bearings (CRTBs) under starved lubrication, six kinds of leaves (Forsythia, Clausena lansiu, Ash, Purple leaf plum, Pipal and Apricot) were chose and their simplified patterns were fabricated on the shaft washers of CRTBs using laser surface texturing. The coefficients of friction (COFs) of vein-bionic textured bearings were measured using a vertical universal wear test rig. Their mass losses and worn surfaces were also characterized. The results show that: There is important influence of the symmetry of vein-bionic textures and the number of secondary veins on the friction and wear properties of vein-bionic textured CRTBs under starved lubrication. Compared to the smooth group, the COFs and mass losses of vein-bionic textured bearings are all reduced. Among all groups, the tribological performance of bearings with a pattern inspired from Ash is the best. Its wear loss is reduced by 16.23% and its COF is reduced by 15.79%. This work would provide a valuable reference for the raceway design and optimization of roller rolling element bearings.

Influence of Groove Dimensions on the Tribological Behavior of Textured Cylindrical Roller Thrust Bearings under Starved Lubrication

Purpose The purpose of this paper is to reveal the friction and wear performance of grooves textured cylindrical roller thrust bearings with different groove dimensions under starved lubrication. Design/methodology/approach The groove dimensions include: width of grooves (WOG, 50 µm, 100 µm and 150 µm), depth of grooves (DPOG, 7 µm, 11 µm and 15 µm) as well as groove deflection angle (GDA, 45°). A fiber laser marking system was used to prepare groove patterns on the raceways of shaft washers. The friction and wear properties of grooves textured bearings were researched through a vertical universal wear test rig using a customized roller bearing tribo-pair under starved lubrication. Static finite element analyses were conducted to reveal their surface stresses. Through the comprehensive comparison and analyses, the influence mechanism of grooves on the tribological behavior of cylindrical roller thrust bearings was proposed and discussed. Findings When grooves textured bearings run under starved lubrication, their average coefficients of friction (COFs) and wear losses are all significantly reduced and much lower than those of smooth group. The influence of DPOG on the COF curves is significant, while the influence of WOG on the COF curves is a little weak. The influence of groove dimensions on the surface stresses of grooves textured bearings is weak, whether the WOG or DPOG. In this work, when the WOG is 100 µm and the DPOG is 15 µm, its average COF and wear loss are both the lowest, 0.0066 and 0.61 mg, respectively. Compared with the data of smooth group, its friction coefficient is reduced by 75.3% and its mass loss is reduced by 95.8%, showing a significant improvement in this condition. Originality/value This work can provide a valuable reference for the raceway design and reliability optimization of rolling element bearings.

Hydrodynamic analysis of flow in raceway ponds for algae cultivation under versatile conditions

Open looped channels are an energy-efficient and low-cost solution often adopted for the cultivation of algae. These channels are commonly composed by two parallel straight channels interconnected by two curving sections and, as such, are referred as raceway ponds. The scaling up of algae production systems, usually associated with novel usages of algal products, has created new challenges for raceway-based cultivation systems. In particular, the uncertainties of cultivating novel algae cultures, e.g. macroalgae for which optimal inland cultivation conditions are still under-researched, impose further demands for raceway design and operation. Versatile operational conditions for raceways may be thus desirable for pioneering inland cultivation systems for certain species, applications and climate conditions. In this work, raceways of standard design are evaluated in terms of geometry, specifically raceway length, width and operational conditions, i.e. flow depth and operational velocity, with the use of a CFD tool. The hydrodynamic performance of the studied cases is analysed based on velocity uniformity and power consumption.

Application of computational fluid dynamics (CFD) on the raceway design for the cultivation of microalgae: a review.

Microalgae are a potential solution to supersede fossil fuels and produce renewable energy. The major obstacle to the commercialization of microalgae-based biofuels is the high production cost, including nutritional requirements, photobioreactor design, and downstream processes. As for the photobioreactor design, open ponds have been adopted by major commercial plants for their economic advantages. Raceway is a popular type among open ponds. Nevertheless, the fluid dynamics of the raceway operation is quite complex. Software simulation based on Computational Fluid Dynamics is an upcoming strategy for optimizing raceway design. The optimization intends to affect light penetration, particle distribution, mass transfer, and biological kinetics. This review discusses how this strategy can be helpful to design a highly productive raceway pond-based microalgal culture system.

Computational fluid dynamics characterization of a novel mixed cell raceway design

Computational fluid dynamics (CFD) analysis was performed on a new type of mixed cell raceway (MCR) that incorporates longitudinal plug flow using inlet and outlet weirs for the primary fraction of the total flow. As opposed to conventional MCR’s wherein vortices are entirely characterized by the boundary conditions at inlet nozzles and outlet center drains in the center of each cell, the new MCR design can develop a wider variety of fluid behaviors due to the additional boundary conditions at the inlet and outlet walls where the weirs are placed. In this study, we investigated how the primary longitudinal flow would affect vortex formations in the cells by designing three different MCR models and simulating three major cases for each model. Through this process, performances of two numerical CFD models (transition k-kl-ω vs. k-ε) were compared, along with two vortex quantification methods (Q-criterion vs. a proposed method). We found that the k-kl-ω CFD model more accurately predicted vortex formation than the k-ε model. The three MCR models differed only by weir geometry or drain size, in order to see their individual influence on cell vortex formation. Each case had its own unique weir flow rate and center drain loading rate values that combined to a total flow rate resulting in 15-min hydraulic retention time (HRT) for the MCR. The ratio of (expressed as percentage) of center drain loading rate to total flow rate (R = 7.5%, 12.5%, and 20.1%.) was defined to establish a relationship between R and vortex strength or size. Simulations demonstrated that inlet weir aspect ratio impacted cell vortex formation and strength. Unlike weir geometry effects, the drain size had non-significant impacts on fluid behavior other than the velocity very near the drains. While R did have positive correlations with vortex strength, vortex size, and self-cleaning performance, an R of 20.1% was sufficient to create uninterrupted vortex formations. Too low of a center drain rate or R value can result in lack of any meaningful cell vortex formation which then obviates any self-cleaning action in an MCR. Our key finding through extensive computational analysis was that an R value of 20% was required in order to maintain effective vortex formation. Expressed more explicitly, this can be described as maintaining a center drain loading rate of 0.010094 m3/s per cell (160 gpm), which correspond to unit loading rates of 16.3 lpm/m2 per cell (0.40 gpm/ft2 per cell).

REVIEW OF AQUACULTURAL PRODUCTION SYSTEM MODELS

The success and profitability of aquaculture production is highly dependent on the proper management employed during the culture period. This management is synonymous with water management since water of suitable quality and quantity is a pre-requisite for any successful aquacultural production. The knowledge of the environment (water) enhances better management. However, the complexity of an aquaculture system which result from multiple interactions makes it difficult to predict how the aquatic community will respond to changes with simple methods of analysis, especially if the methods address a single stressor at a time. These necessitated the development of numerous aquatic ecosystem models such as the Fish Simulation Culture Model (FIS-C), Tilapia Farming Support Tool (TFST), Farm Aquaculture Resource Management (FARM), Pond-Water Availability Period (PWAP) model, AquaFarm and Raceway design and simulation system (RDSS)),which have been used for years as tools to interpret, predict and better understand water quality changes. This paper reviewed existing simulation models of aquacultural production systems with the aim of adopting a suitable one for predicting the environment, performance of African cultured indigenous fish species under different management scenarioes. The reviewed models were found to have addressed specific problem that pertain to some foreign species, production systems and locality. There was none that could be used to model the effects of different management scenario and their effects on African Catfish (Clarials gariepinus) cultured in intensive static aquacultural system. Hence, the problem of predicting the environmental condition, so as to determine point of diminishing returns and optimize yield in an economical way still remains elusive for most fish farms in Nigeria. There is therefore a serious need to develop models that can predict the effects of environment on the performance of indigenous fish species. This will aid stake holders in predicting different management scenario so as to achieve a better crop (fish) yield. http://dx.doi.org/10.4314/njt.v35i2.29

Contact Stress Analysis and Optimization Design of Ball Cage Patterned Constant Speed Universal Joint

This paper takes ball cage patterned constant speed universal joint of as the research object. Using the 3 d modeling software solidworks to establish solid model and simplified it . Based on ANSYS, do finite element contact stress analysis by the universal joint of the two kinds of condition. find out the weak part,through the improvement of raceway design parameters, Relieve the stress concentration phenomenon, reduces the maximum stress, increases the service life of universal joint.

Feasibility of microalgal cultivation in a pilot-scale airlift-driven raceway reactor

A Scenedesmus sp. was cultivated in a 23-L airlift-driven raceway reactor under artificial lighting and laboratory conditions, in batch and continuous modes. In batch mode, a maximum volumetric biomass productivity of 0.085drygL−1day−1 was achieved under sparging at a CO2-to-air ratio of 1%, and a maximum CO2 utilization efficiency of 33% was achieved at a CO2-to-air ratio of 0.25%. In continuous mode, the maximum volumetric biomass productivity was 0.19drygL−1day−1. Biomass productivities per unit power input achieved in this reactor configuration (0.60–0.69drygW−1day−1) were comparable to or better than those reported in the literature for different photobioreactor designs (0.10–0.51drygW−1day−1). Based on the energy-efficient productivity and the high CO2 utilization efficiency demonstrated in this study, the proposed airlift-driven raceway design holds promise for cost-effective algal cultivation.

Raceway design and simulation system (RDSS): An event-based program to simulate the day-to-day operations of multiple-tank raceways

A software program, called Raceway Design and Simulation System (RDSS), has been built using Visual Basic for Applications in Microsoft ® Excel. The purpose of the software is to allow users to manage their raceways more efficiently by providing a tool to simulate the operation of an existing raceway or to predict conditions in a raceway under a wide variety of operating conditions. The program simulates the conditions in a system of multiple tanks that may be arranged in sets of parallel raceways with serial water flow. The user may specify the use of overflow weirs or customized oxygen injection points in order to reoxygenate the water flow from succeeding tanks in each raceway. During the course of the simulation, the user may specify the size, number, location, and price of any new fish introduced into any raceway tank. Subsequent movement of fish between tanks or removal of part or all of a cohort is tracked by the program. Input data required include properties of the influent water such as temperature, flowrate, dissolved oxygen, pH, total ammonia nitrogen, and salinity. Fish growth is predicted using these input data and stocking information that is provided by the user. Fish mortality may be specified for each tank in a raceway. In addition, the costs of food, the purchase cost of fish, and the revenue from the sale of fish are also tracked. A comprehensive user manual is included with the software that provides information on the basic operation of the program, all the programming features, troubleshooting and, the various error messages that the user may encounter when using the program.

Gait transition speed as an alternate measure of maximum aerobic capacity in fishes

This study demonstrated that the transition from a steady to an unsteady locomotory gait (USTmax) in juvenile brook trout Salvelinus fontinalis can be measured easily using a new tilting raceway design and a simple experimental protocol. It was found that USTmax increased linearly with fork length (LF), and that this relationship was statistically identical in fish that swam volitionally in the raceway and those that were forced to perform, although slightly different data processing methods were needed in the latter to achieve this result. Furthermore, the relationship between LF and USTmax was statistically identical to that between LF and critical swimming speed (Ucrit), although LF in the former relationship explained 83% of the variance compared to 37% in the latter. This finding indicates that gait transition speed can be used to estimate maximum aerobic capacity, with less unexplainable variance than Ucrit. Gait transition speeds were also determined from Ucrit tests; however, this required measuring and incorporating ground speed into the analysis. USTmax as determined in the Ucrit tests was not significantly different from that measured in the raceway, suggesting that gait transition speed can be measured in raceways or swim tunnel respirometers.

Use of computational fluid dynamics (CFD) for aquaculture raceway design to increase settling effectiveness

A computational fluid dynamics model was used to evaluate the impact of potential raceway design modifications on the in-raceway settling of solids. Settling effectiveness was evaluated on the basis of the percentage of solids removed by settling relative to the mass of solids introduced into the raceway, with solids settling primarily in the quiescent zone (QZ). The design modifications were applied to a simulated standard raceway (SSR). The SSR was a rectangular concrete raceway 30.2 m long, 3.0 m wide, 0.9 m deep, with a slope of 0.01. The raceway included a QZ of approximately 5.0 m (length), which was separated from the rearing area by a screen. The flow rate was 0.058 m 3/s. For simulation purposes, six groups of particles were used to account for the total suspended solids (TSS). The representative particle sizes were 692, 532, 350, 204, 61, and 35 μm, for Groups 1–6, respectively. The smallest particles (Groups 5 and 6) are the most difficult to settle because of their low settling velocity. After analyzing the velocity profiles obtained from the SSR and considering various design constraints, several raceway design alternatives were simulated. Among the alternatives tested, six designs were chosen based on their PSR values. The main feature in all the modifications presented is the addition of a baffle before the QZ or at the entrance of the QZ replacing the screen. The main purpose of adding these baffles was to increase the velocities under the baffle, which causes an increase in the accumulation of the solids after the baffle (in the QZ). According to the simulations, the highest PSR was obtained with the combination of a baffle and a screen under the baffle. The overall improvement of PSR with respect to the original system was small, with the most noticeable increases taking place for the smaller groups of particles, from 83 to 84%, 3 to 14%, and 1 to 5% for Groups 4–6, respectively. Further studies should include the evaluation of some of these alternatives in real raceways and the comparison of simulated and experimental PSR results.

Analysis of sediment transport modeling using computational fluid dynamics (CFD) for aquaculture raceways

A simulation model to analyze the water flow and sediment transport in aquaculture raceways was developed using a computational fluid dynamics (CFD) software package. The simulation was used to evaluate the efficiency of solids settling in the quiescent zone of existing trout raceways. This efficiency was based on the percentage of solids removed, which corresponds to the percentage of solids introduced into the raceway that settle in it, with settling taking place primarily in the quiescent zone.The raceway selected for model validation was a rectangular concrete raceway 30.0m long, 3.0m wide, 0.9m deep, with a slope of 0.01. The raceway included a quiescent zone of approximately 5.3m in length, which was separated from the rearing area by a screen. The water flow rate through the raceway was approximately 0.058m3/s. Velocity measurements were recorded at 230 stations along the raceway using an acoustic Doppler velocimeter, for comparison with the results obtained from the simulations.For the purpose of simulating sediment transport, six groups of particles were used to account for the total suspended solids. The sizes of the particles selected were based on an experimentally determined distribution for solids from a similar raceway, and were 692, 532, 350, 204, 61, and 35μm for Groups 1–6, respectively. The particle density for each size was assumed to be 1150kg/m3. Values of the percentage of solids removed for the different particle sizes were 100.0% for the largest particles, and 54.7, 0.9, and 0.1% for the three smallest particles, respectively. This methodology of analyzing the raceway sediment transport in terms of its percentage of solids removed based on CFD simulations can also be used to examine raceway design alternatives for improving the particle removal efficiency.

Raceway Design for the Innovative Blast Furnace

This study tries to design the combustion zone in the highly efficient blast furnace for aiming at great reduction of energy consumption and environmental loads by use of raceway mathematical model. The model treats strictly the discontinuous movement of lump coke particles inside and around raceway, and it considers heat exchange with gas and chemical reactions with gas. In this study, first, the verification of the model is performed. Next, the controllability of raceway by blast conditions is investigated. Finally, the raceway in the top gas recycling process is evaluated in terms of the suitability as combustion zone of the novel blast furnace and of the possibility of its realization. The gas recycling process has the characteristic of blowing top gas without CO 2 , pure oxygen and plastics from tuyere. The results obtained in this work are as follows. 1) Raceway mathematical model has the sufficient ability to represent the characteristics of raceway in all cokes operation and PCI operation. 2) The shape and size of raceway and gas temperature in raceway can be controlled by blast temperature and gas compositions. In addition, nitrogen enrichment in blast is effective to form the uniform and low temperature combustion zone. Raceway in top gas recycling process becomes larger, gas temperature in and around raceway is lower and volumetric flow rate of bosh gas is less than conventional process. Therefore, raceway conditions in the recycling process enable high productivity and high efficiency.

Field Trials with Fumagillin for the Control of Proliferative Kidney Disease in Coho Salmon

Abstract Field trials were conducted at a freshwater production hatchery to investigate the efficacy of oral treatment with fumagillin for the control of proliferative kidney disease (PKD) in coho salmon Oncorhynchus kisutch. During three consecutive years (1993–1995), oral treatment with the drug at a dose of 3.0 mg/kg fish for 14 d starting with the first detection of the PKX organism in kidney tissue caused a reduction in infection rate. In 1993, one group of 1,000 underyearling fish was treated in a trough and a second group of fish was held as a control. At the end of the treatment, the treated group exhibited 20% prevalence of infection, whereas control fish had an infection rate of 60%. In 1994 and 1995, efficacy of the drug was tested on a production scale in four rearing sections, each containing 250,000 underyearlings. Two sections received treated feed and two received untreated feed. In 1994, fish in each of the treated sections exhibited 10% prevalence of PKX at the end of the treatment; fish in each of the untreated sections had an 80% infection rate. In 1995, overall mortality due to PKD was minimal, probably because of changes in raceway design and the absence of concurrent furunculosis. However, the treated sections had about 1.5% mortality after treatment was initiated, whereas the control sections exhibited 3.5% and 4.5% mortality. Treated sections exhibited PKX infection rates of 76% and 56%, whereas the untreated sections had infection rates of 100% and 96% at the time treatment was terminated. No major histological changes or reduction in growth were associated with the treatment.

Software for Raceway Design and Calculation of Cable Installation Forces

Software for Raceway Design and Calculation of Cable Installation Forces

Software for Raceway Design and Calculation of Cable Installation Forces

The pull tension and sidewall bearing pressure experienced by cables during installation determine the lengths of cable installed and splices needed, if any, and influence the cost of installation. For the first time, personal computer software exists which not only estimates these forces, but enhances confidence in the results by showing the user his raceway on the CRT in any of the four (4) standard views. Typically, the installer /estimator uses the estimated forces to determine what kind of pull he can expect - easy or hard - and to consequently exercise any options he may have in the design/bid/installation of the system. He can then quickly input alternate raceways or cable changes, and rerun the program. Twenty-five (25) help screens and ten (10) data libraries aid the user.