Scuffing Failure in Heavily Loaded Slow Speed Conformal Sliding Contacts

1991 ◽  
Vol 113 (1) ◽  
pp. 182-191 ◽  
Author(s):  
M. C. Shen ◽  
H. S. Cheng ◽  
P. C. Stair
Keyword(s):  
Bulk Temperature ◽  
Slow Speed ◽  
Sliding Contacts ◽  
Formation Kinetics ◽  
Speed Range ◽  
Total Temperature ◽  
Scuffing Failure ◽  
Adsorption Desorption ◽  
Major Data ◽  
Good Agreement

Scuffing failure phenomenon is studied experimentally in heavily loaded slow speed conformal sliding contacts of two flat thrust washers in a regime close to boundary lubricated condition. Lubricants used are base oils of pure mineral oil and poly-α-olefin (PAO). Speed range is 0.76–33.0 cm/s. Material studied is hardened 52100 steel for both washers in contact. Scuffing threshold load at failure, friction, and surface bulk temperature are major data measured. The surface total temperature is determined with the measure bulk temperature in addition to the surface flash temperature calculated using Jaeger’s theory. Characteristic scuffing failure mechanisms are categorized in terms of various speed ranges. A simple model is proposed to predict scuffing failure based on theories in adsorption/desorption dominated lubricated wear and metal oxide formation kinetics. Good agreement is found between experimental data and theoretical prediction in terms of threshold load in certain speed range.

Use of a three-dimensional model to predict heavy metal (copper) fluxes in the Oujiang estuary

2014 ◽  
Vol 69 (6) ◽  
pp. 1334-1343 ◽  
Author(s):  
Shasha Lu ◽  
Ruijie Li ◽  
Xiaoming Xia ◽  
Jun Zheng
Keyword(s):  
River Discharge ◽  
Water Surface ◽  
Three Dimensional ◽  
Measured Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Pollutant Concentrations ◽  
Suspended Sediment Concentrations ◽  
Adsorption Desorption ◽  
Good Agreement

Measuring pollutant concentrations in major tributaries is the standard method for establishing pollutant fluxes to the sea. However, this method is costly and difficult, and may be subject to a great deal of uncertainty due to the presence of unknown sources. This uncertainty presents challenges to managers and scientists in reducing contaminant discharges to water bodies. As one less costly method, a three-dimensional model was developed and used to predict pollutant fluxes to the sea. The sorptive contaminant model was incorporated into hydrodynamic and sediment models. Adsorption–desorption of copper by sediments in the Oujiang estuary were described using Henry's law. The model was validated using measured data for water surface elevations, flow velocity/direction, suspended sediment concentrations, and the proportion of copper sorbed to sediment. The validated model was then applied to predict fluxes of copper. Combined with the measured data, the copper concentration in the Oujiang River discharge was calculated as 13.0 μg/L and copper fluxes were calculated as 52 t in 2010. This copper flux prediction was verified using measured dissolved copper concentrations. Comparisons between the modeled and measured results showed good agreement at most stations, demonstrating that copper flux prediction in the Oujiang estuary was reasonably accurate.

Total Temperature Based Correction of the Turbulence Production in Hot Jets

2017 ◽  
Author(s):  
Jens Truemner ◽  
Christian Mundt
Keyword(s):  
Shear Layers ◽  
Efficiency Gain ◽  
Potential Core ◽  
Production Term ◽  
Turbofan Engines ◽  
Free Jet ◽  
Rans Models ◽  
Total Temperature ◽  
Turbulence Production ◽  
Good Agreement

Comparisons with experiments have shown that RANS models tend to underpredict the mixing process in shear layers with strong temperature gradients. In the modeling of jet engine’s exhaust systems this leads to an overpredicted potential core length and underestimated turbulence intensity in the free jet. In addition, the calculated efficiency gain is lower than indicated by measurements in mixed turbofan engines. Based on the findings from scale-resolving simulations a correction to the turbulence production term is proposed and compared with two NASA-experiments on hot jets. This correction is implemented in a Reynolds-stress and a k-ε model. The results are in very good agreement with the experimental data.

Elastohydrodynamic Lubrication in Rolling and Sliding Contacts

1972 ◽  
Vol 94 (4) ◽  
pp. 324-329 ◽  
Author(s):  
C. M. Rodkiewicz ◽  
V. Srinivasan
Keyword(s):  
Film Thickness ◽  
Quadrature Formula ◽  
Fourth Order ◽  
Elastohydrodynamic Lubrication ◽  
Experimental Film ◽  
Kutta Method ◽  
Sliding Contacts ◽  
Runge Kutta Method ◽  
Runge Kutta ◽  
Good Agreement

A solution to the elastohydrodynamic lubrication problem for the case of two rolling cylinders, at different speeds, is presented. The lubricant is assumed compressible throughout the region. The fourth-order Runge-Kutta method for the lubricant and an improved quadrature formula for the elastic calculations are used. Pressure and film-thickness profiles are presented for different rolling velocities. There is a good agreement with the experimental film thickness data, available in literature.

Influence of Surface Roughness Lay Directionality on Scuffing Failure of Lubricated Point Contacts

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
S. Li
Keyword(s):  
Frictional Heat ◽  
Bulk Temperature ◽  
Asperity Contact ◽  
Load Range ◽  
Rolling Velocity ◽  
Sliding Direction ◽  
Disk Contact ◽  
Continuous Surface ◽  
Scuffing Failure ◽  
Resistance Performance

The influence of roughness lay directionality on scuffing failure is studied considering different roughness lay direction combinations of the contacting surfaces of a ball-on-disk contact. Using a recently developed scuffing model Li et al., (2013, “A Model to Predict Scuffing Failures of a Ball-On-Disk Contact,” Tribol. Int., 60, pp. 233–245)., the bulk temperature and flash temperature are predicted for each roughness lay combination within the load range from 0.76 GPa to 2.47 GPa in a step-wise manner under the rolling velocity of 10 m/s and slide-to-roll ratio of −0.5 to show substantial impacts of roughness lay directionality on scuffing resistance performance (SRP). It is found (i) the lay direction combination that results into contacts of asperities with small contact radii leads to increased local contact pressures and frictional heat flux, reducing SRP; (ii) the continuous asperity contact along the sliding direction leads to continuous surface temperature rise and lowers SRP; and (iii) the lubricant side leakage caused by the pressure gradient in the direction normal to the sliding direction leads to reduced SRP. With these main mechanisms in effect, the SRP of a contact decreases as the deviation between the roughness texture orientations of the two surfaces increases. The surfaces with their roughness lay directions both perpendicular to the sliding direction exhibits best SRP. The surfaces with one roughness lay direction positioned in line with the direction of sliding and the other positioned perpendicular to the sliding direction shows worst SRP.

Experimental and Computational Investigation of the Drag of a Towed Hydropower Turbine

2013 ◽  
Author(s):  
G. T. Bryan ◽  
M. F. Platzer ◽  
Y. W. Kwon
Keyword(s):  
Dynamics Analysis ◽  
Crucial Aspect ◽  
Computational Investigation ◽  
Small Hydropower ◽  
Towing Tank ◽  
Computational Fluid Dynamics Analysis ◽  
Production Of Hydrogen ◽  
Speed Range ◽  
Hydro Turbines ◽  
Good Agreement

In a previous paper (IMECE2011-62311) Platzer et al proposed the use of sailing ships equipped with hydropower turbines to generate the electricity required for the production of hydrogen and oxygen by means of electrolysis which then is brought back to land for re-conversion into electric power. A crucial aspect of the practicality of this “energy ship” concept is the drag of the hydro-turbines. Since little information exists about the drag of towed hydropower generators in this paper the drag of a small hydropower turbine was investigated in a towing tank. Drag measurements are presented for a speed range between 0.6 and 1.8 m/s. Comparisons with available data and the predictions by a computational fluid dynamics analysis show good agreement.

Study on the Flow Behavior in Thin Cavity during Water-Assisted Injection Molding

2011 ◽  
Vol 467-469 ◽  
pp. 80-83
Author(s):  
Tang Qing Kuang ◽  
Kun Han
Keyword(s):  
Injection Molding ◽  
Control Volume ◽  
Fluid Model ◽  
Flow Behavior ◽  
Experimental Result ◽  
Bulk Temperature ◽  
Injection Molding Process ◽  
Molding Process ◽  
Injection Location ◽  
Good Agreement

A numerical simulation model for the flow behavior of fluids in thin cavity during water assisted injection molding process is built up by adopting general Newtonian fluid model for the filling stage and non-Newtonian and compressible fluid model for the packing stage separately. Finite element/finite difference/control volume methods are adopted for the simulation of melt front, pressure variation at injection location, water thickness fraction and bulk temperature about a plate with trapezoidal cross-section. The simulated melt front location and shape have good agreement with experimental result. In comparison with the simulation results of conventional injection molding, it turns out that water assisted injection molding can obtain parts with low pressure requirement, perfect surface quality and rapid cooling.

Study on the Flow Behavior in a Tubular Cavity during Water-Assisted Injection Molding

2010 ◽  
Vol 154-155 ◽  
pp. 359-362
Author(s):  
Tang Qing Kuang
Keyword(s):  
Injection Molding ◽  
Control Volume ◽  
Flow Behavior ◽  
Polymer Melt ◽  
Bulk Temperature ◽  
Curved Pipe ◽  
Fluid Behavior ◽  
Simulation Results ◽  
Injection Location ◽  
Good Agreement

A simulation model for the filling of a tubular cavity during water assisted injection molding is proposed. The polymer melt and water are assumed to be incompressible and to follow a Hele-Shaw fluid behavior. The finite element/finite difference/control volume methods are adopted for numerical simulation of the melt front, pressure at injection location variation, water thickness fraction and bulk temperature about a curved pipe, the simulation results have good agreement with the results presented in the former experiment. In comparison with the simulation result of gas-assisted injection molding, water assisted injection molding can give parts with thinner and more uniform walls and more rapid cooling.

scholarly journals Synthesis and CO2 sorption of silica particles, kinetics and thermodynamics

2014 ◽  
Vol 10 (5) ◽  
pp. 2711-2719
Author(s):  
Hasna BOUHALI ◽  
Nabila CHALAL ◽  
Hadj HAMAIZI ◽  
Abdelkader BENGUEDDACH
Keyword(s):  
Mesoporous Silica ◽  
Silica Particles ◽  
Sorption Behavior ◽  
Porous Texture ◽  
Co2 Sorption ◽  
Ordered Mesoporous ◽  
Adsorption Of Co2 ◽  
Adsorption Desorption ◽  
Langmuir And Freundlich Equations ◽  
Good Agreement

Spherical ordered mesoporous silica particles with radially oriented mesopores were successfully prepared by using non-ionic amphiphilic di-block co-polymers CnH2n+1-(EO)x-OH as template and tetraorthosilicate (TEOS) as silica precursor. The synthesized mesoporous silica materials were characterized by XRD, N2 adsorption-desorption and SEM techniques. CO2 adsorption at 0 °C was evaluated by a volumetric method, and the CO2 sorption behavior was described by applying both Langmuir and Freundlich equations. Results indicate a high adsorption capacity of CO2 (5-9 mmol/g), depending essentially on the porous texture of the materials. An adsorption kinetic model was proposed to describe the adsorption of CO2 over template-free mesoporous siliceous materials. A good agreement with experimental data was found.

Numerical Simulation of Impeller–Volute Interaction in Centrifugal Compressors

1999 ◽  
Vol 121 (3) ◽  
pp. 603-608 ◽  
Author(s):  
K. Hillewaert ◽  
R. A. Van den Braembussche
Keyword(s):  
Numerical Simulation ◽  
Boundary Conditions ◽  
Unsteady Flow ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Flow Calculation ◽  
Total Temperature ◽  
Temperature And Pressure ◽  
Good Agreement

A numerical procedure to predict the impeller–volute interaction in a single-stage centrifugal compressor is presented. The method couples a three-dimensional unsteady flow calculation in the impeller with a three-dimensional time-averaged flow calculation in the volute through an iterative updating of the boundary conditions on the interface of both calculation domains. The method has been used to calculate the flow in a compressor with an external volute at off-design operation. Computed circumferential variations of flow angles, total temperature, and pressure are shown and compared with measurements. The good agreement between the predictions and measurements confirms the validity of the approach.

scholarly journals Correlation between Adsorption and Porosity Properties of Alumina Samples as Obtained from Classical Adsorption and Thermal Analysis Methods

2001 ◽  
Vol 19 (5) ◽  
pp. 367-380
Author(s):  
M. Płanda ◽  
P. Staszczuk ◽  
J. Pękalska
Keyword(s):  
Porous Alumina ◽  
Sorption Isotherms ◽  
Liquid Films ◽  
Distribution Functions ◽  
Quasi Equilibrium ◽  
Water Vapour Sorption ◽  
Weight Losses ◽  
Adsorption Desorption ◽  
Active Centres ◽  
Good Agreement

The thermodesorption of benzene and water from alumina samples saturated in vacuum desiccators was studied under quasi-equilibrium conditions. The Q-TG and Q-DTG curves obtained showed multi-step weight losses associated with the evaporation of liquid from pores and physisorbed liquid films from active centres of different energy. The adsorption/desorption isotherms of nitrogen on porous alumina samples were measured using sorptiomatic methods allowing the calculation of the corresponding pore size distribution functions. The water vapour sorption isotherms were measured gravimetrically employing an apparatus fitted with a McBain microbalance. A correlation between the porosity parameters and the volume of desorbed liquid is presented illustrating the good agreement obtained.

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