A general evaluation method for the diabatic journal bearing

1974 ◽  
Vol 336 (1606) ◽  
pp. 307-325 ◽  
Keyword(s):  
Evaluation Method ◽  
Journal Bearing ◽  
Design Method ◽  
Three Dimensional ◽  
Algebraic Equations ◽  
Mixing Conditions ◽  
General Evaluation ◽  
Wide Range ◽  
Energy Equations ◽  
Independent Parameters

A design method is described for the steadily loaded, full journal bearing. This is presented as a non-iterative set of algebraic equations, where a dependent bearing parameter, e. g. eccentricity or power-loss, is predicted in terms of known independent parameters which include bearing geometry, running conditions and oil characteristics. The method is developed from a regression analysis of accurately computed, fully thermohydrodynamic, solutions for the bearing. These solutions are generated by simultaneously solving the Reynolds and energy equations in the oil film, the Laplace equation in the bearing material and the oil-mixing conditions at inlet. A quasi three-dimensional finite-difference technique is used. Both the particular solutions and the predictions of the design method compare favourably with a wide range of experimental data, the latter showing an improvement in accuracy and economy on existing design methods.

scholarly journals Parametric Design and Kansei Engineering in Goblet Styling Design

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Fong-Gong Wu ◽  
Chii-Zen Yu
Keyword(s):  
Evaluation Method ◽  
Parametric Design ◽  
Design Method ◽  
Three Dimensional ◽  
Transformation Method ◽  
Market Demand ◽  
Kansei Engineering ◽  
Cam Mechanism ◽  
Projective Curves ◽  
Point Data

In this study, we developed a computer-aided product design method for goblet styling design based on two methods. The first was parametric design derived from an adjustable cam mechanism, which was used for shape generation, and the second was Kansei engineering, which was used for shape evaluation. In the shape generation method, motion curves from an adjustable cam were used. Designers can collect feature point data from existing products to define the boundary conditions of adjustable cam motion equations; furthermore, adjustable motion curves allow parametric design. Through adjusting a single parameter, motion curves were changed to be used as projective curves for the styling design of goblets. Then, a coordinate transformation method was applied to support the three-dimensional styling design of goblets. In the shape evaluation method, some goblet stylings were regularly selected to determine adjective degrees by production design experts. Adjective degrees for goblets that had not been selected were determined through interpolation. Market demand was defined as the preference of customers for specific adjective degrees for goblets.

Design for Additive Manufacturing: Valves Without Moving Parts

2017 ◽  
Author(s):  
A. Gaymann ◽  
F. Montomoli ◽  
M. Pietropaoli
Keyword(s):  
Additive Manufacturing ◽  
Gas Turbines ◽  
Design Method ◽  
Three Dimensional ◽  
Automatic Generation ◽  
Two Dimensions ◽  
Steepest Descent Method ◽  
Wide Range ◽  
Tesla Valve ◽  
Moving Parts

This work presents an innovative design method to obtain valves without moving parts that can be built using additive manufacturing and applied to gas turbines. Additive manufacturing offers more flexibility than traditional manufacturing methods, which implies less constraints on the manufacture of engineering parts and it is possible to build complex geometries like the Tesla valve. The Tesla valve is a duct that shows a diodicity behavior: it allows a fluid to flow in one direction with lower losses than in the other one. Unfortunately the design of the Tesla valve is two dimensional and it relies on the designer experience to obtain good performance. The method presented here allows the automatic generation of valves similar to the Tesla one, obtained automatically by a topology optimization algorithm. It is the first time that a three dimensional method is presented, the available algorithms in the open literature works in two dimensions. A fluid sedimentation process enables the creation of a new geometry optimized to meet a prescribed set of performance, such as pressure losses. The steepest descent method is used to approximate the integrals met during the calculation process. The optimizer is used to obtain three dimensional geometries for different multi-objective functions. The geometry is compared to an existing similar solution proposed in the open literature and validated. The results are compared to a Tesla valve to show the performance of the optimized geometries. The advantage of the proposed solution is the possibility to apply the design method with any spatial constraints and for a wide range of mass flow.

Pullout behaviour of plate anchor in clay with linearly increasing strength

2014 ◽  
Vol 51 (1) ◽  
pp. 92-102 ◽  
Author(s):  
Kee Kiat Tho ◽  
Zongrui Chen ◽  
Chun Fai Leung ◽  
Yean Khow Chow
Keyword(s):  
Design Method ◽  
Three Dimensional ◽  
Uplift Capacity ◽  
Direct Design ◽  
Classical Path ◽  
Wide Range ◽  
Element Approach ◽  
Plate Anchor ◽  
Pullout Behaviour ◽  
Square Plate

Plate anchors are widely adopted to provide uplift resistance for structures. For most offshore seabeds, the undrained shear strength profile can be reasonably approximated as varying linearly with depth. At present, there are two possible approximate approaches to determine uplift capacity of a square plate anchor in such a profile, but the validity of both approaches cannot be ascertained due to unavailability of a rigorous solution. This study addresses these uncertainties by establishing the capacity factors for a square anchor in a linearly increasing strength profile using a three-dimensional large-deformation finite element approach for a wide range of geometric and material combinations. It was found that both approaches give the correct solution only under specific conditions. Earlier studies on the uplift capacity of a plate anchor typically follow a classical path of deriving the solution for a weightless soil and extending this solution to a soil with self-weight. The applicability of such an approach to the uplift of a square anchor is examined in this study. A direct design method for a square plate anchor embedded in a linearly increasing strength profile, which enables the capacity factors for a square anchor to be directly obtained without any simplified assumptions, is then proposed.

scholarly journals NUMERICAL SIMULATION OF FCC RISERS

2003 ◽  
Vol 2 (2) ◽  
pp. 17 ◽  
Author(s):  
J. A. Souza ◽  
J. V. C. Vargas ◽  
O. F. Von Meien ◽  
W. Martignoni
Keyword(s):  
Fluid Flow ◽  
Catalytic Cracking ◽  
Three Dimensional ◽  
Gas Oil ◽  
Algebraic Equations ◽  
Heterogeneous Catalytic ◽  
Riser Reactor ◽  
Energy Equations ◽  
Cracking Process ◽  
Physical And Chemical

The catalytic cracking of hydrocarbons in a FCC riser is a very complex physical and chemical phenomenon, which combines a three-dimensional, three-phase fluid flow with a heterogeneous catalytic cracking kinetics. Several researchers have carried out the modeling of the problem in different ways. Depending on the main objective of the modeling it is possible to find in the literature very simple models while in other cases, when more accurate results are necessary, each equipment is normally treated separately and a set of differential and algebraic equations is written for the problem. The riser reactor is probably the most important equipment in a FCC plant. All cracking reactions and fuel formation occur during the short time (about 4-5s) that the gas oil stays in contact with the catalyst inside the riser. This work presents a simplified model to predict the, temperature and concentrations in a FCC riser reactor. A bi-dimensional fluid flow field combined with a 6 lumps kinetic model and two energy equations (catalyst and gas oil) are used to simulate the gas oil cracking process. Based on the velocity, temperature and concentration fields, it is intended, on a next step, to use the second law of thermodynamic to perform a thermodynamic optimization of the system.

Elastohydrodynamic Studies of Three-Lobe Journal Bearings with Non-Newtonian Lubricants

1991 ◽  
Vol 205 (6) ◽  
pp. 379-388 ◽  
Author(s):  
K C Goyal ◽  
R Sinhasan
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Performance Characteristics ◽  
Continuity Equations ◽  
Viscosity Term ◽  
Elasticity Equations ◽  
Wide Range ◽  
Deformation Coefficient ◽  
Three Dimensional Elasticity

A computer aided elastohydrodynamic study of the three-lobe journal bearing with non-Newtonian lubricants is presented for the static and dynamic performance characteristics. The three-dimensional momentum and continuity equations in cylindrical coordinates governing the flow of Newtonian lubricants in the clearance space of a three-lobe journal bearing have been solved using the finite element method. The non-Newtonian effect is introduced by modifying the viscosity term for the model iteratively. Three-dimensional elasticity equations are solved to obtain deformations in the bearing shell. Static and dynamic performance characteristics are presented for a wide range of values of non-dimensional load, deformation coefficient and non-linearity factor.

A Thermohydrodynamic Analysis of Foil Journal Bearings

2006 ◽  
Vol 128 (3) ◽  
pp. 534-541 ◽  
Author(s):  
Z-C. Peng ◽  
M. M. Khonsari
Keyword(s):  
Reasonable Agreement ◽  
Journal Bearing ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Temperature Characteristic ◽  
Journal Bearings ◽  
Bearing Surface ◽  
Wide Range ◽  
Parametric Studies ◽  
Load Conditions

A thermohydrodynamic model is developed for predicting the three-dimensional (3D) temperature field in an air-lubricated, compliant foil journal bearing. The model accounts for the compressibility and the viscosity-temperature characteristic of air and the compliance of the bearing surface. The results of numerical solutions are compared to published experimental measurements and reasonable agreement has been attained. Parametric studies covering a fairly wide range of operating speeds and load conditions were carried out to illustrate the usefulness of the model in terms of predicting the thermal performance of foil journal bearings.

scholarly journals Evaluation Method Applying Fourier Transform Analysis for Conditioned Polishing Pad Surface Topography

2011 ◽  
Vol 5 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Keiichi Kimura ◽  
◽  
Panart Khajornrungruang ◽  
Takahisa Okuzono ◽  
Keisuke Suzuki
Keyword(s):  
Fourier Transform ◽  
Surface Topography ◽  
Laser Scanning ◽  
Evaluation Method ◽  
Three Dimensional ◽  
Power Spectra ◽  
Numerical Data ◽  
Confocal Laser ◽  
Polishing Pad ◽  
Wide Range

The Fourier transform analysis is proposed to quantitatively evaluate the 3D surface topography of Chemical Mechanical Polishing (CMP) pads used for flattening and smoothing processed semiconductor substrates. The conditioned polishing pad surfaces have a wide range of irregular topographies ranging from topographies of a sub-micrometer to those of a hundredmicrometer order. Hence, a Confocal Laser Scanning Microscope (CLSM), which can provide nanometer resolution in wide range of lateral directions by means of linear encoded mechanical stage translation, was employed to obtain numerical data of the three-dimensional topographic surfaces of polishing pad samples. The measured topographic surfaces were analyzed using the spatial Fourier transform. We discuss the power spectrum in the spatial wavelengths of polishing pad surfaces which were conditioned with diamond grits of various shapes. The analyzed power spectra indicated that the surface topography characteristics varied with differently shaped diamond grits of the same size. The diamond grits roughened the polishing pad surface. We also found that a rough polishing pad surface, one that was roughed in a spatial wavelength that of less than 20 micrometers, removed more material than comparatively smooth pad surfaces.

Numerical solution of integral equations for the three-dimensional scalar diffraction problems

2018 ◽  
Author(s):  
С.И. Смагин ◽  
А.А. Каширин
Keyword(s):  
Numerical Solution ◽  
Integral Equations ◽  
Acoustic Waves ◽  
Boundary Integral Equations ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Special Method ◽  
Algebraic Equations ◽  
Linear Algebraic Equations ◽  
Wide Range

Рассматриваются задачи дифракции (трансмиссии) стационарных акустических волн на трехмерных однородных включениях. Методами теории потенциала для них получены два слабо сингулярных граничных интегральных уравнения Фредгольма первого рода с одной неизвестной функцией, каждое из которых эквивалентно исходной задаче. Интегральные уравнения аппроксимируются системами линейных алгебраических уравнений, которые затем решаются численно итерационным методом обобщенных минимальных невязок GMRES. При дискретизации этих уравнений используется специальный метод осреднения интегральных операторов со слабыми особенностями в ядрах, позволяющий получать системы с легко вычисляемыми коэффициентами. Метод допускает эффективное распараллеливание и позволяет проводить расчеты в широком диапазоне волновых чисел. Приводятся результаты вычислительных экспериментов, позволяющие судить о возможностях предлагаемого подхода. Purpose. The purpose of the article is to develop efficient algorithms for numerical solution of the diffraction (transmission) problem of stationary acoustic waves on threedimensional homogeneous inclusions. Methods. By using the combinations of simple and double layer potentials, two Fredholm boundary integral equations of the first kind with one unknown function are obtained for these potentials, each of which is equivalent to the original problem. When sampling these equations, a special method of averaging integral operators with weak singularities in the kernels is applied. Outcomes. The obtained integral equations are approximated by systems of linear algebraic equations with easily-calculated coefficients, which are then solved numerically by means of the generalized method of minimal residuals (GMRES). A series of computing experiments for numerical solution of particular stationary three-dimensional diffraction problems of acoustic waves has been conducted. Conclusions. Computing experiments have shown that the proposed numerical method possesses high accuracy in finding approximate solutions of these problems. It allows both effective parallelization and ability to perform calculations in a wide range of wave numbers and can be used to solve other problems of mathematical physics, formulated in the form of boundary integral equations.

scholarly journals NUMERICAL SIMULATION OF FCC RISERS

2003 ◽  
Vol 2 (2) ◽  
Author(s):  
J. A. Souza ◽  
J. V. C. Vargas ◽  
O. F. Von Meien ◽  
W. Martignoni
Keyword(s):  
Fluid Flow ◽  
Catalytic Cracking ◽  
Three Dimensional ◽  
Gas Oil ◽  
Algebraic Equations ◽  
Heterogeneous Catalytic ◽  
Riser Reactor ◽  
Energy Equations ◽  
Cracking Process ◽  
Physical And Chemical

The catalytic cracking of hydrocarbons in a FCC riser is a very complex physical and chemical phenomenon, which combines a three-dimensional, three-phase fluid flow with a heterogeneous catalytic cracking kinetics. Several researchers have carried out the modeling of the problem in different ways. Depending on the main objective of the modeling it is possible to find in the literature very simple models while in other cases, when more accurate results are necessary, each equipment is normally treated separately and a set of differential and algebraic equations is written for the problem. The riser reactor is probably the most important equipment in a FCC plant. All cracking reactions and fuel formation occur during the short time (about 4-5s) that the gas oil stays in contact with the catalyst inside the riser. This work presents a simplified model to predict the, temperature and concentrations in a FCC riser reactor. A bi-dimensional fluid flow field combined with a 6 lumps kinetic model and two energy equations (catalyst and gas oil) are used to simulate the gas oil cracking process. Based on the velocity, temperature and concentration fields, it is intended, on a next step, to use the second law of thermodynamic to perform a thermodynamic optimization of the system.

Shape Optimization of Transonic Compressor Blades Using Quasi-3D Flow Physics

2000 ◽  
Author(s):  
June Chung ◽  
Ki D. Lee
Keyword(s):  
Design Method ◽  
Computational Cost ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Compressor Blades ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Wide Range

A design method for transonic compressor rotor blades is developed based on Navier-Stokes physics. The method is applied to optimize the blade sections at several span stations, and new three-dimensional blades are constructed by interpolating the geometry of the designed blade sections. The method is demonstrated with NASA Rotor 37, producing new rotor blades with improved adiabatic efficiency over a wide range of operating conditions. The results indicate that the developed design process can find improved designs at an affordable computational cost.

Sign in / Sign up

Export Citation Format

Share Document