New Formulation of a General Three-Dimensional Cascade Theory

1954 ◽  
Vol 96 (6) ◽  
pp. 1651-1654 ◽  
Author(s):  
B. A. Chartres ◽  
H. Messel
Keyword(s):  
Three Dimensional ◽  
Cascade Theory ◽  
New Formulation

A Three-Dimensional Variable Geometry Countercurrent Model for Whole Limb Heat Transfer

1992 ◽  
Vol 114 (3) ◽  
pp. 366-376 ◽  
Author(s):  
M. Zhu ◽  
S. Weinbaum ◽  
D. E. Lemons
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Approximate Theory ◽  
Cross Sectional ◽  
Warm Environment ◽  
Axial Temperature ◽  
Cutaneous Tissue ◽  
New Formulation ◽  
Dimensional Variable

A new formulation of the combined macro and microvascular model for heat transfer in a human arm developed in Song et al. [1] is proposed using a recently developed approximate theory for the heat exchange between countercurrent vessels embedded in a tissue cylinder with surface convection [2]. The latter theory is generalized herein to treat an arm with an arbitrary variation in cross-sectional area and continuous bleed off from the axial vessels to the muscle and cutaneous tissue. The local microvascular temperature field is described by a “hybrid” model which applies the Weinbaum-Jiji [3] and Pennes [4] equations in the peripheral and deeper tissue layers, respectively. To obtain reliable end conditions at the wrist and other model input parameters, a plethysmograph-calorimeter has been used to measure the blood flow distribution between the arm and hand circulations, and hand heat loss. The predictions of the model show good agreement with measurements for the axial surface temperature distribution in the arm and confirm the minimum in the axial temperature variation first observed by Pennes [4] for an arm in a warm environment.

Slab Method of Analysis for Three Dimensional Forward Extrusion of Squared End Section

2010 ◽  
Author(s):  
Amin Samadi Ghoshchi ◽  
Aydin Smadi Ghoshchi ◽  
Sajad Mohammadi Bazargani ◽  
Sajjad Emami
Keyword(s):  
Metal Forming ◽  
Three Dimensional ◽  
Wire Drawing ◽  
Force Balance ◽  
Slab Method ◽  
Equilibrium Equations ◽  
Forward Extrusion ◽  
Long Time ◽  
New Formulation ◽  
Theoretical Results

Slab method of analysis has been used for solving metal forming problems for a long time. However it has been restricted to plane strain and axisymmetric problems due to limitations in its formulations. In this paper a new formulation has been proposed so that it could be applied to three dimensional problems in metal forming. A parametric slab has been considered in this analysis and the force balance on the slab was carried out to obtain equilibrium equations in terms of these parameters. The parameters in fact are related to the geometry of the final extruded shape, the die and the material flow regime assumed in the formulation. In this way most of the limitations encountered in previous formulations were surpassed. In fact the parametric slab considered in this formulation is a very general element that could be adjusted to any changes made in the process. As an example the forward extrusion of a square cross section was analyzed using the new formulation. The effect of reduction of area, frictional conditions and other process parameters on the extrusion pressure was investigated. The theoretical results obtained in this paper were compared with similar results of previous work from other methods and good agreement was observed. Dies were designed and manufactured based on this analysis for several reductions of area. Tests were done using above dies and the experimental data were found to verify the theoretical results. It was concluded that the new slab method of analysis gave reasonable results for the problem analyzed and that it could be applied to other bulk metal forming processes such as rolling, wire drawing and forging.

scholarly journals On the modeling of droplet transport, dispersion and evaporation in turbulent flows

2005 ◽  
Vol 122 (3) ◽  
pp. 42-55
Author(s):  
Jorge BARATA
Keyword(s):  
Turbulent Flows ◽  
Gas Turbines ◽  
Numerical Study ◽  
Droplet Diameter ◽  
Turbulent Transport ◽  
Three Dimensional ◽  
Turbulent Dispersion ◽  
Droplet Transport ◽  
New Formulation ◽  
Evaporation Models

The present paper presents a numerical study on evaporating droplets injected through a turbulent cross-stream. Several models have been used with more or less success to describe similar phenomena, but much of the reported work deals only with sprays in stagnant surroundings. The ultimate goal of this study is to develop an Eulerian/Lagragian approach to account for turbulent transport, dispersion, evaporation and coupling between both processes in practical spray injection systems, which usually include air flows in the combustion chamber like swirl, tumble and squish in I.C. engines or crossflow in gas turbines. In this work a method developed to study isothermal turbulent dispersion is extended to the case of an array of evaporating droplets through a crossflow, and the performance of two different evaporation models widely used is investigated. The convection terms were evaluated using the hybrid or the higher order QUICK scheme. The dispersed phase was treated using a Lagrangian reference frame. The differences between the two evaporation models and its applicability to the present flow are analysed in detail. During the preheating period of the Chen and Pereira [1] model the droplets are transported far away from the injector by the crossflow, while with the Sommerfeld [2] formulation for evaporation the droplet has a continuous variation of the diameter. This result has profound implications on the results because the subsequent heat transfer and turbulent dispersion is extremely affected by the size of the particles (or droplets). As a consequence, droplet diameter, temperature and mass fraction distributions were found to be strongly dependent on the evaporation model used. So, a new formulation that takes into account also the transport of the evaporating droplets needs to be developed if practical injection systems are to be simulated. Also, in order to better evaluate and to improve the vaporization models more detailed measurements of three-dimensional configurations are required.

scholarly journals DESCRIBING STRESS CONCENTRATION FACTORS OF AN INTERNALLY PRESSURIZED CYLINDER WITH AN IMBEDDED HOLE BY NEW FORMULATION

2020 ◽  
Author(s):  
javad jafari fesharaki
Keyword(s):  
Stress Concentration ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Internal Diameter ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
New Formulation ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Pressurized Cylinder

The purpose of this paper is to investigate the stress concentration factor(SCF) for an internallypressurized cylinder with hole and based on detailed three-dimensional elastic FE analysis, a newcomprehensive set of formulas for SCFs are proposed. These stress concentration factors are presentedand discussed as a function of the ratio of cylinder diameter to the thickness of cylinder and hole diameter.The first ratio “D/100t” is equal to 1, 1.25, 1.5, 1.75, 2, 2.5, 2.75, 3, 3.25 and 3.5 and the second ratio“D/10d”, cylinder internal diameter to the hole diameter, varies from 0.6, 0.9, 1.2, 1.5, 1.8, 2, 2.3, 2.7,3.1and 3.5. Results are also presented for SCF of longitudinal, circumferential and Von Mises stresses.

scholarly journals Empirical, Dimensional and Inspectional Analysis in the Design of Bottom Intake Racks

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1035 ◽  
Author(s):  
Juan García ◽  
Luis Castillo ◽  
José Carrillo ◽  
Patricia Haro
Keyword(s):  
Discharge Coefficient ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Design Parameters ◽  
Incoming Flow ◽  
Viscous Forces ◽  
The Mean ◽  
Definition Of ◽  
New Formulation ◽  
Bottom Intake

Flow over bottom racks is highly turbulent, three-dimensional and spatially varied. The design of bottom intake systems has mainly been studied in the laboratory. The comparison of existing experimental studies shows large deviations in the definition of design parameters such as wetted rack length. Each experimental study is limited to a single bar type or to a low range of void ratios, which makes it difficult to generalize the observed data. A combination of empirical, dimensional and inspectional analysis is presented as a useful tool to reduce the number of variables with influence in the design parameters, such as the wetted rack length or the mean discharge coefficient. This work includes a broad experimental campaign in which wetted rack length and mean discharge coefficient are characterized using five different bottom racks with different void ratios (area between bars divided by total area). T-shaped flat and circular bars are considered as well as five different longitudinal slopes. Empirical and inspectional analyses have allowed us to verify, in two different ways, the relation between wetted rack length and incoming flow through potential functions. The influence of the viscous forces has been studied as a function of the incoming flow. Similar results may be obtained when analysing the Froude number at the beginning of the rack, depending on the wetted rack length. A new formulation for calculating the mean discharge coefficient and wetted rack length is proposed.

Cross-gradients joint 3D inversion with applications to gravity and magnetic data

Geophysics ◽  
2009 ◽  
Vol 74 (4) ◽  
pp. L31-L42 ◽  
Author(s):  
Emilia Fregoso ◽  
Luis A. Gallardo
Keyword(s):  
Joint Inversion ◽  
Three Dimensional ◽  
Structural Similarity ◽  
Solution Procedure ◽  
Magnetic Data ◽  
3D Inversion ◽  
Gravity And Magnetic ◽  
New Formulation ◽  
Value Decomposition ◽  
Gravity And Magnetic Data

We extend the cross-gradient methodology for joint inversion to three-dimensional environments and introduce a solution procedure based on a statistical formulation and equality constraints for structural similarity resemblance. We apply the proposed solution to the joint 3D inversion of gravity and magnetic data and gauge the advantages of this new formulation on test and field-data experiments. Combining singular-value decomposition (SVD) and other conventional regularizing constraints, we determine 3D distributions of the density and magnetization with enhanced structural similarity. The algorithm reduces some misleading features of the models, which are introduced commonly by conventional separate inversions of gravity and magnetic data, and facilitates an integrated interpretation of the models.

scholarly journals Assessment of a Three-Dimensional Potential Code for Axial and Radial Blade Row Flows

1986 ◽  
Author(s):  
H.-H. Frühauf ◽  
D. Krämer ◽  
U. Küster
Keyword(s):  
Three Dimensional ◽  
Cross Flow ◽  
Vortex Sheet ◽  
Full Potential ◽  
Aerodynamic Design ◽  
Blade Row ◽  
Circulation Distribution ◽  
Flow Effects ◽  
Downstream Flow ◽  
New Formulation

An assessment of a three-dimensional potential code is presented for axial and radial blade row flows, for which experimental data or computational results are available. The prediction of a flow case with severe cross flow is included. Numerous 3-D potential flow effects will be discussed. The conservative full potential equation for 3-D transonic flow is solved by a robust SLOR method. A new formulation of the downstream flow ensures the computability of blade row flows with arbitrary spanwise circulation distributions. Blade circulation distribution and downstream flow properties are obtained as a part of the solution. The surface representation in parameter form in the geometry definition program and the mesh generation program, as well as the tensor notation of the basic equation and a configuration-independent vortex sheet approximation prediction, ensure the computability of flows through blade rows with arbitrary complex geometries. The CRAY-1/M incore version of the code is inexpensive enough to be used in the aerodynamic design process of new blade rows with irrotational inflows.

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