Flow of Damp Powder in a Rotating Impervious Cone

2010 ◽  
Vol 78 (2) ◽  
Author(s):  
Arnaud F. M. Bizard ◽  
Digby D. Symons ◽  
Norman A. Fleck ◽  
David Durban
Keyword(s):  
Differential Equation ◽  
Axisymmetric Flow ◽  
Central Zone ◽  
Operating Conditions ◽  
Order Ordinary Differential Equation ◽  
Spherical Coordinate ◽  
Explicit Analytical Solution ◽  
Wide Range ◽  
Governing Differential Equation ◽  
The Mean

A one dimensional analytical model is developed for the steady state, axisymmetric flow of damp powder within a rotating impervious cone. The powder spins with the cone but migrates up the wall of the cone (along a generator) under centrifugal force. The powder is treated as incompressible and Newtonian viscous, while the shear traction at the interface is taken to be both velocity and pressure dependent. A nonlinear second order ordinary differential equation is established for the mean through-thickness velocity as a function of radius in a spherical coordinate system, and the dominant nondimensional groups are identified. For a wide range of geometries, material parameters, and operating conditions, a midzone exists wherein the flow is insensitive to the choice of inlet and outlet boundary conditions. Within this central zone, the governing differential equation reduces to an algebraic equation with an explicit analytical solution. Furthermore, the bulk viscosity of the damp powder does not enter this solution. Consequently, it is suggested that the rotating impervious cone is a useful geometry to measure the interfacial friction law for the flow of a damp powder past an impervious wall.

Free vibration analysis of a rotating double tapered beam with flexible root via differential quadrature method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mustafa Tolga Tolga Yavuz ◽  
İbrahim Özkol
Keyword(s):  
Differential Equation ◽  
Free Vibration ◽  
Differential Quadrature Method ◽  
Differential Quadrature ◽  
Operating Conditions ◽  
Design Parameters ◽  
Quadrature Method ◽  
Content Type ◽  
Uniform Beam ◽  
Governing Differential Equation

Purpose This study aims to develop the governing differential equation and to analyze the free vibration of a rotating non-uniform beam having a flexible root and setting angle for variations in operating conditions and structural design parameters. Design/methodology/approach Hamiltonian principle is used to derive the flapwise bending motion of the structure, and the governing differential equations are solved numerically by using differential quadrature with satisfactory accuracy and computation time. Findings The results obtained by using the differential quadrature method (DQM) are compared to results of previous studies in the open literature to show the power of the used method. Important results affecting the dynamics characteristics of a rotating beam are tabulated and illustrated in concerned figures to show the effect of investigated design parameters and operating conditions. Originality/value The principal novelty of this paper arises from the application of the DQM to a rotating non-uniform beam with flexible root and deriving new governing differential equation including various parameters such as rotary inertia, setting angle, taper ratios, root flexibility, hub radius and rotational speed. Also, the application of the used numerical method is expressed clearly step by step with the algorithm scheme.

Numerical and experimental study on knocking combustion in turbocharged direct-injection engines for a wide range of operating conditions

2021 ◽  
pp. 146808742110601
Author(s):  
Magnus Kircher ◽  
Emmeram Meindl ◽  
Christian Hasse
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Numerical Study ◽  
Direct Injection ◽  
Operating Conditions ◽  
Auto Ignition ◽  
Spark Timing ◽  
Crank Angle ◽  
Wide Range ◽  
The Mean

A combined experimental and numerical study is conducted on knocking combustion in turbocharged direct-injection spark-ignition engines. The experimental study is based on parameter variations in the intake-manifold temperature and pressure, as well as the air-fuel equivalence ratio. The transition between knocking and non-knocking operating conditions is studied by conducting a spark timing sweep for each operating parameter. By correlating combustion and global knock quantities, the global knock trends of the mean cycles are identified. Further insight is gained by a detailed analysis based on single cycles. The extensive experimental data is then used as an input to support numerical investigations. Based on 0D knock modeling, the global knock trends are investigated for all operation points. Taking into consideration the influence of nitric oxide on auto-ignition significantly improves the knock model prediction. Additionally, the origin of the observed cyclic variability of knock is investigated. The crank angle at knock onset in 1000 consecutive single cycles is determined using a multi-cycle 0D knock simulation based on detailed single-cycle experimental data. The overall trend is captured well by the simulation, while fluctuations are underpredicted. As one potential reason for the remaining differences of the 0D model predictions local phenomena are investigated. Therefore, 3D CFD simulations of selected operating points are performed to explore local inhomogeneities in the mixture fraction and temperature. The previously developed generalized Knock Integral Method (gKIM), which considers the detailed kinetics and turbulence-chemistry interaction of an ignition progress variable, is improved and applied. The determined influence of spark timing on the mean crank angle at knock onset agrees well with experimental data. In addition, spatially resolved information on the expected position of auto-ignition is analyzed to investigate causes of knocking combustion.

Static and Dynamic Properties of Partial Journal Bearings

1963 ◽  
Vol 85 (2) ◽  
pp. 247-255 ◽  
Author(s):  
Paul C. Warner
Keyword(s):  
Differential Equation ◽  
Journal Bearing ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
Wide Range ◽  
Governing Differential Equation

The liquid lubricated partial journal bearing is analyzed in an approximate yet accurate manner in order to obtain its static and dynamic properties. The solution of the governing differential equation is analytical rather than numerical, permitting inexpensive computation of results over a very wide range of the parameters involved.

Redistribution of soil water after infiltration

Soil Research ◽  
1971 ◽  
Vol 9 (2) ◽  
pp. 59 ◽  
Author(s):  
AJ Peck
Keyword(s):  
Moisture Content ◽  
Surface Zone ◽  
Order Ordinary Differential Equation ◽  
Mean Values ◽  
Wide Range ◽  
Two Factors ◽  
Homogeneous Soil ◽  
The Mean ◽  
The One ◽  
Different Soils

The one-dimensional vertical redistribution of water is studied following infiltration into deep homogeneous soil with an initially uniform moisture content. There is assumed to be no loss of water by evaporation or transpiration during the redistribution. Assuming two factors to be constants, a first-order ordinary differential equation is derived which can be integrated numerically to compute the mean moisture content in the surface zone of draining soil as a function of the redistribution time. The depth of the draining zone increases with time, and this can be calculated too. That these factors are relatively constant is indicated by analysis of data for several soils and wetting depths over a wide range of redistribution times. Using mean values of the factors for several soils, and only wetting values of the diffusivity and conductivity functions, predicted redistribution behaviour agrees well with experimental data in four of six soils. In the remaining cases calculation of the factors for the particular soils, using an approximate method which includes hysteresis data, gives better results. The model is applied to predict the redistribution behaviour of different soils under identical treatments, and of a single soil for various infiltration quantities and initial moisture contents.

scholarly journals Fluidized Bed Jet Milling Process Optimized for Mass and Particle Size with a Fuzzy Logic Approach

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3303 ◽  
Author(s):  
Jaroslaw Krzywanski ◽  
Dariusz Urbaniak ◽  
Henryk Otwinowski ◽  
Tomasz Wylecial ◽  
Marcin Sosnowski
Keyword(s):  
Fuzzy Logic ◽  
Fluidized Bed ◽  
Rotational Speed ◽  
Milling Process ◽  
Operating Conditions ◽  
Air Pressure ◽  
Practical Significance ◽  
Wide Range ◽  
The Mean ◽  
Jet Milling

The milling process is a complex phenomenon dependent on various technological and material parameters. The development of a fluidized bed jet milling model is of high practical significance, since milling is utilized in many industries, and its complexity is still not sufficiently recognized. Therefore, this research aims to optimize fluidized bed jet milling with the use of fuzzy logic (FL) based approach as one of the primary artificial intelligence (AI) methods. The developed fuzzy logic model (FLMill) of the investigated process allows it to be described as a non-iterative procedure, over a wide range of operating conditions. Working air pressure, rotational speed of the classifier rotor, and time of conducting the test are considered as inputs, while mass and mean Sauter diameter of the product are defined as outputs. Several triangular and constant linguistic terms are used in the developed FLMill model, which was validated against the experimental data. The optimum working air pressure and the test’s conducting time are 500 kPa and 3000 s, respectively. The optimum rotational speed of the classifier is equal to 50 s−1, considering the mass of the grinding product, and 250 s−1 for the mean Sauter diameter of the product. Such operating parameters allow obtaining 243.3 g of grinding product with the mean Sauter diameter of 11 µm. The research proved that the use of fuzzy logic modeling as a computer-based technique of solving mechanical engineering problems allows effective optimization of the fluidized bed jet milling process.

Analysis of Gas Turbine Rotating Cavities by a One-Dimensional Model: Definition of New Disk Friction Coefficient Correlations Set

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Luca Innocenti ◽  
Mirko Micio
Keyword(s):  
Gas Turbine ◽  
Axisymmetric Flow ◽  
Operating Conditions ◽  
Dimensional Model ◽  
Outer Flow ◽  
One Dimensional ◽  
Wide Range ◽  
Air System ◽  
Secondary Air ◽  
Radial Outflow

Reliable design of a secondary air system is one of the main tasks for the safety and unfailing performance of gas turbine engines. To meet the increasing demands of gas turbine designs, improved tools in the prediction of secondary air system behavior over a wide range of operating conditions are needed. A real gas turbine secondary air system includes several components, therefore, its analysis is not carried out through a complete computational fluid dynamics (CFD) approach. Usually, those predictions are performed using codes based on simplified approach, which allows to evaluate the flow characteristics in each branch of the air system requiring very poor computational resources and few calculation time. Generally, the available simplified commercial packages allow to correctly solve only some of the components of a real air system, and often, the elements with a more complex flow structure cannot be studied; among such elements, the analysis of rotating cavities is very hard. This paper deals with a design tool developed at the University of Florence for the simulation of rotating cavities. This simplified in-house code solves the governing equations for steady one-dimensional axisymmetric flow using experimental correlations, both to incorporate the flow phenomena caused by multidimensional effects such as heat transfer and flow field losses, and to evaluate the circumferential component of velocity. Although this calculation approach does not enable a correct modeling of the turbulent flow within a wheel space cavity, the authors tried to create an accurate model, taking into account the effects of inner and outer flow extraction, rotor and stator drag, leakages, injection momentum, and finally, the shroud/rim seal effects on cavity ingestion. The simplified calculation tool was designed to simulate the flow in a rotating cavity with radial outflow, both with the Batchelor and/or Stewartson flow structures. A primary 1D-code testing campaign is available in the literature (2008, “Analysis of Gas Turbine Rotating Cavities by a One-Dimensional Model,” ISROMAC Paper No. 12-2008-20161). In the present paper, the authors developed, using CFD tools, reliable correlations for both stator and rotor friction coefficients and provided a full 1D-code validation, due to the lack of experimental data, comparing the in-house design-code predictions with those evaluated by CFD.

Frictional and Thermal Behaviors of Sliding-Rolling Concentrated Contacts

1978 ◽  
Vol 100 (1) ◽  
pp. 121-128 ◽  
Author(s):  
P. M. Ku ◽  
H. E. Staph ◽  
H. J. Carper
Keyword(s):  
Surface Treatment ◽  
Flow Rate ◽  
Power Loss ◽  
Disk Surface ◽  
Operating Conditions ◽  
Disk Size ◽  
Wide Range ◽  
Oil Flow ◽  
Disk Friction ◽  
The Mean

Sliding-rolling disk scuffing tests were conducted over a wide range of sliding and sum velocities, using a straight mineral oil and three aviation gas turbine synthetic oils in combination with two carburized steels and a nitrided steel. Geometrically-similar disks of two different sizes were tested in two different disk testers of nearly similar designs. In addition to disk size and metallurgy, the surface treatment, surface texture, and surface roughness of the disks were also varied. The investigation further covered variations in the oil supply configuration and flow rate. It is shown that the disk friction coefficient is dependent not only on the oil-metal combination, but also on the disk surface treatment and topography as well as the operating conditions. The quasi-steady disk surface temperature and the mean conjunction-inlet oil temperature are shown to be strongly influenced by the frictional power loss at the contact, but not by the specific makeup of the frictional power loss. They are also influenced by the heat transfer from the disks, mainly by convection to the oil and conduction through the shafts, which are dependent on system design and oil flow rate.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

A Comparison of Physiological Demand between Self-Propelled and Motorized Treadmill Exercise

2018 ◽  
Vol 7 (4) ◽  
pp. 13-21
Author(s):  
Todd Backes ◽  
Charlene Takacs
Keyword(s):  
Respiratory Exchange Ratio ◽  
Treadmill Exercise ◽  
Cardiopulmonary Exercise Testing ◽  
Mean Value ◽  
The Self ◽  
Mixing Chamber ◽  
Wide Range ◽  
The Subject ◽  
The Mean ◽  
Computer Controlled

There are a wide range of options for individuals to choose from in order to engage in aerobic exercise; from outdoor running to computer controlled and self-propelled treadmills. Recently, self-propelled treadmills have increased in popularity and provide an alternative to a motorized treadmill. Twenty subjects (10 men, 10 women) ranging in age from 19-23 with a mean of 20.4 ± 0.8 SD were participants in this study. The subjects visited the laboratory on three occasions. The purpose of the first visit was to familiarize the subject with the self-propelled treadmill (Woodway Curve 3.0). The second visit, subjects were instructed to run on the self-propelled treadmill for 3km at a self-determined pace. Speed data were collected directly from the self-propelled treadmill. The third visit used speed data collected during the self-propelled treadmill run to create an identically paced 3km run for the subjects to perform on a motorized treadmill (COSMED T150). During both the second and third visit, oxygen consumption (VO2) and respiratory exchange ratio (R) data were collected with COSMED’s Quark cardiopulmonary exercise testing (CPET) metabolic mixing chamber system. The VO2 mean value for the self-propelled treadmill (44.90 ± 1.65 SE ml/kg/min) was significantly greater than the motorized treadmill (34.38 ± 1.39 SE ml/kg/min). The mean R value for the self-propelled treadmill (0.91 ± 0.01 SE) was significantly greater than the motorized treadmill (0.86 ± 0.01 SE). Our study demonstrated that a 3km run on a self-propelled treadmill does elicit a greater physiological response than a 3km run at on a standard motorized treadmill. Self-propelled treadmills provide a mode of exercise that offers increased training loads and should be considered as an alternative to motorized treadmills.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

Sign in / Sign up

Export Citation Format

Share Document