Numerical and Experimental Study on Combined Seals With the Consideration of Stretching Effects

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Chao Peng ◽  
Xiaoping Ouyang ◽  
Katharina Schmitz ◽  
Shengrong Guo ◽  
Huayong Yang
Keyword(s):  
Experimental Data ◽  
Hydraulic Systems ◽  
Interference Fit ◽  
Sealing Performance ◽  
Standard Geometry ◽  
Sealing Zone ◽  
Axisymmetric Modeling ◽  
Stretching Ratio ◽  
First Time ◽  
Sealing Elements

Abstract Combined seals, as a kind of reciprocating seals, are widely used in hydraulic systems. The combined seal usually contains two or more elements to achieve the sealing function. Not only the interference fit between the seal and the rod/groove should be considered, but the assembling parameters between the inner sealing elements are also essential to be investigated. Stretching ratio, as an indicator for the interference fit, usually exerts a significant influence on the sealing performance. However, in the studies of stretching effects on combined seals, the traditional axisymmetric modeling method will introduce the overstretching problems, resulting in large errors. To overcome this problem, this paper proposed a putter-movement method, where an extra putter is introduced into the model, and a mixed-lubrication theory was employed to study macro and micro characteristics among the sealing zone. As a typical kind of combined seals, the VL seal is utilized as the research object, and the material’s plastic effects are included in the reciprocating-seal modeling for the first time. The numerical results are compared with the experimental data, and good agreements are obtained. The proposed method is then employed to discuss the sealing characteristics under different interference-fit conditions systematically. The results indicate that the stretching mainly affects the contact pressure on the cavity side. Compared to the performance of the seal with the standard geometry, in the extra-stretching condition, the leakage is increased, but the friction is decreased.

Simulation of Laminar Liquid Jets in Gaseous Crossflow Before the Onset of Primary Breakup

2011 ◽  
Author(s):  
C.-L. Ng ◽  
K. A. Sallam
Keyword(s):  
Experimental Data ◽  
Fuel Injection ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Jet Breakup ◽  
Primary Breakup ◽  
Density Ratios ◽  
First Time ◽  
Two Sides ◽  
Reduced Pressures

The deformation of laminar liquid jets in gaseous crossflow before the onset of primary breakup is studied motivated by its application to fuel injection in jet afterburners and agricultural sprays, among others. Three crossflow Weber numbers that represent three different liquid jet breakup regimes; column, bag, and shear breakup regimes, were studied at large liquid/gas density ratios and small Ohnesorge numbers. In each case the liquid jet was simulated from the jet exit and ended before the location where the experimental data indicated the onset of breakup. The results show that in column and bag breakup, the reduced pressures along the sides of the jet cause the liquid to move to the sides of the jet and enhance the jet deformation. In shear breakup, the flattened upwind surface pushes the liquid towards the two sides of the jet and causing the gaseous crossflow to separate near the edges of the liquid jet thus preventing further deformation before the onset of breakup. It was also found out that in shear breakup regime, the liquid phase velocity inside the liquid jet was large enough to cause onset of ligament formation along the jet side, which was not the case in the column and bag breakup regimes. In bag breakup, downwind surface waves were observed to grow along the sides of the liquid jet triggered a complimentary experimental study that confirmed the existence of those waves for the first time.

scholarly journals Simulative investigation of ring creep on a planetary bearing of a wind turbine gearbox

2021 ◽  
Author(s):  
Jonas Gnauert ◽  
Felix Schlüter ◽  
Georg Jacobs ◽  
Dennis Bosse ◽  
Stefan Witter
Keyword(s):  
Experimental Data ◽  
Finite Element Method ◽  
Sensitivity Analysis ◽  
Planetary Gear ◽  
The Finite Element Method ◽  
Relative Movement ◽  
Wind Turbine Gearbox ◽  
Interference Fit ◽  
Planetary Gears ◽  
Module Coefficient

AbstractWind turbines (WT) must be further optimized concerning availability and reliability. One of the major reasons of WT downtime is the failure of gearbox bearings. Some of these failures occur, due to the ring creep phenomenon, which is mostly detected in the planetary bearings. The ring creep phenomenon describes a relative movement of the outer ring to the planetary gear. In order to improve the understanding of ring creep, the finite element method (FEM) is used to simulate ring creep in planetary gears. First, a sensitivity analysis is carried out on a small bearing size (NU205), to characterize relevant influence parameters for ring creep—considered parameters are teeth module, coefficient of friction, interference fit and normal tooth forces. Secondly, a full-scale planetary bearing (SL185030) of a 1MW WT is simulated and verified with experimental data.

Dose-window dependence on Si crystal orientation in separation by implanted oxygen substrate formation

2004 ◽  
Vol 19 (12) ◽  
pp. 3607-3613 ◽  
Author(s):  
H. Iikawa ◽  
M. Nakao ◽  
K. Izumi
Keyword(s):  
Experimental Data ◽  
Numerical Analysis ◽  
Crystal Orientation ◽  
Oxygen Ion ◽  
The Difference ◽  
First Time ◽  
Good Agreement

Separation by implemented oxygen (SIMOX)(111) substrates have been formed by oxygen-ion (16O+) implantation into Si(111), showing that a so-called “dose-window” at 16O+-implantation into Si differs from Si(100) to Si(111). In SIMOX(100), an oxygen dose of 4 × 1017/cm2 into Si(100) is widely recognized as the dose-window when the acceleration energy is 180 keV. For the first time, our work shows that an oxygen dose of 5 × 1017/cm2 into Si(111) is the dose-window for the formation of SIMOX(111) substrates when the acceleration energy is 180 keV. The difference between dose-windows is caused by anisotropy of the crystal orientation during growth of the faceted buried SiO2. We also numerically analyzed the data at different oxidation velocities for each facet of the polyhedral SiO2 islands. Numerical analysis results show good agreement with the experimental data.

scholarly journals Performance of Turbulence Models and Near-Wall Treatments in Discrete Jet Film Cooling Simulations

1998 ◽  
Author(s):  
Jeffrey D. Ferguson ◽  
Dibbon K. Walters ◽  
James H. Leylek
Keyword(s):  
Experimental Data ◽  
Film Cooling ◽  
Turbulence Models ◽  
Viscous Sublayer ◽  
Reynolds Stress Model ◽  
Quality Data ◽  
Wall Functions ◽  
First Time ◽  
Near Wall ◽  
Non Equilibrium

For the first time in the open literature, code validation quality data and a well-tested, highly reliable computational methodology are employed to isolate the true performance of seven turbulence treatments in discrete jet film cooling. The present research examines both computational and high quality experimental data for two length-to-diameter ratios of a row of streamwise injected, cylindrical film holes. These two cases are used to document the performance of the following turbulence treatments: 1) standard k-ε model with generalized wall functions; 2) standard k-ε model with non-equilibrium wall functions: 3) Renormalization Group k-ε (RNG) model with generalized wall functions; 4) RNG model with non-equilibrium wall functions: 51 standard k-ε model with two-layer turbulence wall treatment; 6) Reynolds Stress Model (RSM) with generalized wall functions; and 7) RSM with non-equilibrium wall functions. Overall, the standard k-ε turbulence model with the two-layer near-wall treatment, which resolves the viscous sublayer, produces results that are more consistent with experimental data.

scholarly journals Hysteresis in Muscle

2017 ◽  
Vol 27 (01) ◽  
pp. 1730003 ◽  
Author(s):  
Jorgelina Ramos ◽  
Stephen Lynch ◽  
David Jones ◽  
Hans Degens
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Hysteresis Loop ◽  
Mechanical Systems ◽  
Single Fibre ◽  
Scientific Disciplines ◽  
Main Components ◽  
First Time ◽  
Muscle Models ◽  
Clockwise Hysteresis

This paper presents examples of hysteresis from a broad range of scientific disciplines and demonstrates a variety of forms including clockwise, counterclockwise, butterfly, pinched and kiss-and-go, respectively. These examples include mechanical systems made up of springs and dampers which have been the main components of muscle models for nearly one hundred years. For the first time, as far as the authors are aware, hysteresis is demonstrated in single fibre muscle when subjected to both lengthening and shortening periodic contractions. The hysteresis observed in the experiments is of two forms. Without any relaxation at the end of lengthening or shortening, the hysteresis loop is a convex clockwise loop, whereas a concave clockwise hysteresis loop (labeled as kiss-and-go) is formed when the muscle is relaxed at the end of lengthening and shortening. This paper also presents a mathematical model which reproduces the hysteresis curves in the same form as the experimental data.

Le spectre des états électroniques de Kr I mesuré par spectrométrie électronique

1975 ◽  
Vol 53 (19) ◽  
pp. 2079-2084 ◽  
Author(s):  
A. Delage ◽  
J.-D. Carette
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Inelastic Scattering ◽  
Electronic States ◽  
Resolving Power ◽  
Electron Spectrometer ◽  
Energy Incident ◽  
First Time ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The spectrum of electronic states of krypton I has been measured by inelastic scattering of monoenergetic electrons with the aid of an electron spectrometer which has a high resolving power, ΔE/E = 0.02. Electron energy loss spectra have allowed us to detect and identify numerous electronic states of krypton I for the first time by the means of this experimental method. The relative heights of the peaks corresponding to an energy loss, which are related to the probability of excitation of the atom by electron impact to a given state, have been measured from experimental data as a function of the energy incident electrons and as a function of the scattering angle.

Modeling of functionally graded materials to estimate effective thermo-mechanical properties

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Royal Madan ◽  
Shubhankar Bhowmick
Keyword(s):  
Experimental Data ◽  
Functionally Graded Materials ◽  
Coefficient Of Thermal Expansion ◽  
Functionally Graded ◽  
Graded Materials ◽  
Content Type ◽  
Wide Range ◽  
Metal Metal ◽  
Novel Material ◽  
First Time

Purpose Functionally graded materials are a special class of composites in which material are graded either continuously or layered wise depending upon its applications. With such variations of materials, the properties of structure vary either lengthwise or thickness wise. This paper aims to investigate models for effective estimation of material properties, as it is necessary for industries to identify the properties of composites or functionally graded materials (FGM’s) before manufacturing and also to develop novel material combinations. Design/methodology/approach Available models were compared for different material combinations and tested with experimental data for properties such as Young’s modulus, density, coefficient of thermal expansion (CTE) and thermal conductivity. Combinations of metal–ceramic and metal–metal were selected such that their ratios cover a wide range of materials. Findings This study reveals different models will be required depending on the material used and properties to be identified. Practical implications The results of the present work will help researchers in the effective modeling of composites or FGM’s for any analysis. Originality/value This paper presents a comparison and review of various analytical methods with experimental data graphically to find out the best suitable method. For the first time, the Halpin-Tsai model was extended in the analysis of the CTE which shows good approximations.

Performance Improvement of RF Inductors Using LTCC Technology

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000054-000058 ◽  
Author(s):  
Goran Radosavljević ◽  
Andrea Marić ◽  
Walter Smetana ◽  
Ljiljana Živanov
Keyword(s):  
Experimental Data ◽  
Low Temperature ◽  
Design Optimization ◽  
Quality Factor ◽  
Performance Improvement ◽  
Air Gap ◽  
Frequency Range ◽  
Operating Frequency Range ◽  
Rf Inductors ◽  
First Time

This paper presents for the first time a parallel comparison of the performance of RF inductors realized on different substrate configurations. Presented inductors are meander type structures fabricated in Low Temperature Co-fired Ceramic (LTCC) technology. Also, chosen material is never before implemented for inductor fabrication. The performance improvement is achieved by design optimization of different substrate configurations that incorporate placement of an air-gap beneath the inductor and/or introduction of an additional shielding layer on the top. Designed structures are characterized on the basis of simulation and experimental data, achieving good correlation between obtained results. Presented results show over 30 % increase in quality factor and widening of the operating frequency range by over 55 %.

scholarly journals Rheological Behavior of Glycyrrhiza glabra (Licorice) Extract as a Function of Concentration and Temperature: A Critical Reappraisal

Foods ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1872
Author(s):  
Laleh Nasiri ◽  
Mohsen Gavahian ◽  
Mahsa Majzoobi ◽  
Asgar Farahnaky
Keyword(s):  
Experimental Data ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Soluble Solids ◽  
Licorice Root ◽  
Rotational Viscometer ◽  
Unit Operations ◽  
Licorice Extract ◽  
Solids Content ◽  
First Time

In the present study, rheological properties of twelve different licorice root extracts were evaluated using a rotational viscometer as a function of soluble solids content (15–45 °Bx) and temperature (30–70 °C). Response Surface Methodology was used to understand the relationships between the parameters. The experimental data were then fit into mathematical models. The results, for the first time, revealed that the licorice solutions had non-Newtonian shear-thinning behaviors with flow behavior indexes of 0.24 to 0.91, depending on the licorice extract samples, temperature, and °Bx. These observations were different from those reported in the literature and the present study elaborated on reasons for such observations. Further, the shear-thinning behavior generally increased by increasing the °Bx and decreasing the temperature. In addition, the power-law model was found to be suitable for predicting the experimental data. The newly revealed information can be particularly important in designing the unit operations for licorice extract processing.

A laboratory simulation of mixing across tidal fronts

1996 ◽  
Vol 309 ◽  
pp. 321-344 ◽  
Author(s):  
P. J. Thomas ◽  
P. F. Linden
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Laboratory Simulation ◽  
Shallow Sea ◽  
Mixing Rate ◽  
Tidal Front ◽  
Laboratory Results ◽  
The Cross ◽  
First Time ◽  
Oceanographic Conditions

A laboratory study which simulates the dynamics of shallow sea fronts and the mixing across a tidal front is described. The experiments show, for the first time, that it is possible to simulate a stationary tidal front with the inclusion of buoyancy effects, Coriolis effects and turbulence in the laboratory. Experimental data obtained for the cross-front mixing rate are presented. The data analysis shows that the mixing rate increases with stratification and decreases with rotation. A theoretical model of the flow which collapses the experimental data is developed which shows that the cross-front mixing is controlled by baroclinic processes. The model enables an extrapolation of the laboratory results to oceanographic conditions. Estimates of the cross-front mixing velocity for oceanographic conditions give values consistent with estimates obtained from North Sea data.

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