Investigation of Vortex Reacting Flows in Asymmetric Meso Scale Combustor

2013 ◽  
Vol 388 ◽  
pp. 246-250 ◽  
Author(s):  
Mostafa Khaleghi ◽  
Mazlan A. Wahid ◽  
Mohsin M. Seis ◽  
Aminuddin Saat
Keyword(s):  
Flame Structure ◽  
Three Dimensional ◽  
Reacting Flows ◽  
Experimental Investigations ◽  
Flame Stability ◽  
Three Dimensional Flow ◽  
Asymmetric Vortex ◽  
Wide Range ◽  
Basic Characteristics ◽  
Exceptional Stability

In the current study computational and experimental investigations of a turbulent asymmetric vortex flame is presented. The three dimensional flow fields have been described using a computational methodology that impalements the kε turbulence model. The computational model is validated for isothermal flow. Moreover, the visible flame structure was captured by direct photography at a wide range of equivalence ratios in order to emphasize the exceptional stability of such flame. The mechanism of flame stability and interaction with the forced vortex field is preliminarily discussed. Finally, the basic characteristics of the asymmetric vortex flames are concluded.

Three-Dimensional Sloshing of Water on Decks

1988 ◽  
Vol 25 (04) ◽  
pp. 253-261
Author(s):  
Michael S. Pantazopoulos
Keyword(s):  
Hyperbolic Equations ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Nonlinear Hyperbolic Equations ◽  
Complex Flow ◽  
Random Choice ◽  
Three Dimensional Flow ◽  
Random Choice Method ◽  
Wide Range ◽  
Choice Method

A methodology is proposed to solve the problem of the three-dimensional flow of water sloshing on the deck of a vessel, and to calculate the resulting forces and moments at the center of gravity. The Eulerian equations of motion of the water particle for incompressible inviscid shallow water flow are formulated with respect to a system attached to the oscillating vessel. The system of the nonlinear hyperbolic equations of motion is solved numerically using Glimm's method (random-choice method). Complex flow patterns consisting of oblique bores and "swirling" motions of the water on deck were revealed, for a vessel oscillating in roll and pitch motions, for a wide range of excitation frequencies. Large accumulation of water occurs at the corners while parts of the deck become dry. Significant rolling moments due to sloshing are exerted on the vessel. These must be taken into account when the dynamic response of the vessel is studied.

scholarly journals Calculation of 3D Coordinates of a Point on the Basis of a Stereoscopic System

2018 ◽  
Vol 8 (1) ◽  
pp. 109-117
Author(s):  
R.R. Mussabayev ◽  
M.N. Kalimoldayev ◽  
Ye.N. Amirgaliyev ◽  
A.T. Tairova ◽  
T.R. Mussabayev
Keyword(s):  
Optical System ◽  
Three Dimensional ◽  
Material Point ◽  
Experimental Investigations ◽  
Unknown Parameters ◽  
Wide Range ◽  
Stereoscopic System ◽  
3D Scene ◽  
The Right ◽  
The Given

Abstract The solution of three-dimensional (3D) coordinate calculation task for a material point is considered. Two flat images (a stereopair) which correspond to the left and to the right viewpoints of a 3D scene are used for this purpose. The stereopair is obtained using two cameras with parallel optical axes. The analytical formulas for calculating 3D coordinates of a material point in the scene were obtained on the basis of analysis of the stereoscopic system optical and geometrical schemes. The detailed presentation of the algorithmic and hardware realization of the given method was discussed with the the practical. The practical module was recommended for the determination of the optical system unknown parameters. The series of experimental investigations were conducted for verification of theoretical results. During these experiments the minor inaccuracies were occurred by space distortions in the optical system and by it discrecity. While using the high quality stereoscopic system, the existing calculation inaccuracy enables to apply the given method for the wide range of practical tasks.

The 3-D Structure of Swirl-Stabilized Flames in a Lean Premixed Multi-Nozzle Can Combustor

2015 ◽  
Author(s):  
Janith Samarasinghe ◽  
Stephen J. Peluso ◽  
Bryan D. Quay ◽  
Domenic A. Santavicca
Keyword(s):  
Gas Turbine ◽  
Tomographic Reconstruction ◽  
Flame Structure ◽  
Combustion Process ◽  
Three Dimensional ◽  
Static Stability ◽  
Dimensional Structure ◽  
Reconstruction Technique ◽  
Flame Stability ◽  
The Relationship

Flame structure is an important aspect of the combustion process which must be considered in the design of gas turbine combustors as it can have a significant effect on the combustor’s static stability (blowoff) and dynamic stability (combustion instability). The relationship between flame structure and flame stability has been studied extensively in single-nozzle combustors. However, relatively few studies have been conducted in multi-nozzle combustor configurations typical of actual gas turbine combustion systems. In this paper, a chemiluminescence-based tomographic reconstruction technique is used to obtain three-dimensional images of the flame structure in a laboratory-scale five-nozzle can combustor. The images reveal the complex three-dimensional structure of this multi-nozzle flame, as well as, the effects of interacting swirling flows, flame-flame interactions and flame-wall interactions on flame structure.

An Efficient CFD Model for Air/Particle Saltating Flows

2002 ◽  
Author(s):  
S. Ji ◽  
A. G. Gerber ◽  
A. C. M. Sousa
Keyword(s):  
Particle Concentration ◽  
Particle Surface ◽  
Three Dimensional ◽  
Phase System ◽  
Cfd Model ◽  
Computationally Efficient ◽  
Dynamics Model ◽  
Three Dimensional Flow ◽  
Two Phase ◽  
Wide Range

The study reports on the development of a computational-fluid-dynamics model is presented suitable for computationally efficient evaluation of particle transport along loose surfaces. These surfaces can be described within the context of an interaction with a two-phase air/particle mixture in a state of combined suspension and saltation. The results suggest an approach for approximating the two-phase system with coupling to a moving surface, along with the inclusion of impact and entrainment fluxes at the surface that is generally extendable to a wide range of particle/surface conditions. The model results are compared to available experimental data on particle concentration profiles along saltating surfaces, and applied to geometry involving complex three-dimensional flow to show the generality of the approach.

Prediction of Surface Roughness and Incidence Effects on Turbine Performance

1993 ◽  
Author(s):  
R. J. Boyle
Keyword(s):  
Surface Roughness ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Wide Range ◽  
Loss Models

The use of a Navier-Stokes analysis to predict the change in turbine efficiency resulting from changes in blade surface roughness or incidence flow angles is discussed. The results of a midspan Navier-Stokes analysis are combined with those from a quasi-three-dimensional flow analysis code to predict turbine performance. A quasi-three-dimensional flow analysis code was used to determine turbine performance over a range of incidence flow angles. This analysis was done for a number of incidence loss models. The change in loss due to changes in incidence flows computed from the Navier-Stokes analysis is compared with the results obtained using the empirical loss models. The Navier-Stokes analysis was also used to determine the effects of surface roughness using a mixing length turbulence model, which incorporated the roughness height. The validity of the approach used was verified by comparisons with experimental data for a turbine with both smooth and rough blades tested over a wide range of blade incidence flow angles.

The Occurrence of Humping in Welding with Highest Beam Qualities

2007 ◽  
Vol 344 ◽  
pp. 731-743 ◽  
Author(s):  
Claus Thomy ◽  
Thomas Seefeld ◽  
Frank Vollertsen
Keyword(s):  
Three Dimensional ◽  
Welding Process ◽  
Single Mode ◽  
Fibre Laser ◽  
Experimental Investigations ◽  
Single Mode Fibre ◽  
Inviscid Incompressible Fluid ◽  
Wide Range ◽  
Welding Processes ◽  
Mode Fibre

The availability of lasers with highest beam qualities at laser powers of 1 kW (such as single-mode fibre laser, which nowadays come close to the theoretical limits) provides a unique tool to investigate welding process phenomena in a wide range of potential applications from welding with penetrations of some 50 "m to penetrations of some mm. Thus covering the field of micro welding as well as of macro welding, scalability of welding processes as well as size effects associated with the underlying physical phenomena may be of significance. In this paper, the humping effect will be given a closer look, as this periodic melt pool instability is an important limitation to possible welding speeds both in the micro and the macro range. Based on experimental investigations with a single-mode fibre laser (YLR-1000, laser power 1 kW, BPP < 0.4 mm*mrad), a model based on a modification of Rayleigh’s considerations on the stability of an inviscid incompressible fluid which is freely suspended in space and maintained only by surface tension is developed and discussed. It is shown that, within the scope of the investigations, humping to a large extent can be explained by Rayleigh’s theory, permitting to neglect the influence of three-dimensional melt flow.

Topology of three-dimensional steady cellular flow in a two-sided anti-parallel lid-driven cavity

2017 ◽  
Vol 826 ◽  
pp. 302-334 ◽  
Author(s):  
Francesco Romanò ◽  
Stefan Albensoeder ◽  
Hendrik C. Kuhlmann
Keyword(s):  
Reynolds Number ◽  
Limit Cycle ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Convection Cell ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Driven Cavity ◽  
Dimensional Flow ◽  
Wide Range

The structure of the incompressible steady three-dimensional flow in a two-sided anti-symmetrically lid-driven cavity is investigated for an aspect ratio $\unicode[STIX]{x1D6E4}=1.7$ and spanwise-periodic boundary conditions. Flow fields are computed by solving the Navier–Stokes equations with a fully spectral method on $128^{3}$ grid points utilizing second-order asymptotic solutions near the singular corners. The supercritical flow arises in the form of steady rectangular convection cells within which the flow is point symmetric with respect to the cell centre. Global streamline chaos occupying the whole domain is found immediately above the threshold to three-dimensional flow. Beyond a certain Reynolds number the chaotic sea recedes from the interior, giving way to regular islands. The regular Kolmogorov–Arnold–Moser tori grow with increasing Reynolds number before they shrink again to eventually vanish completely. The global chaos at onset is traced back to the existence of one hyperbolic and two elliptic periodic lines in the basic flow. The singular points of the three-dimensional flow which emerge from the periodic lines quickly change such that, for a wide range of supercritical Reynolds number, each periodic convection cell houses a double spiralling-in saddle focus in its centre, a spiralling-out saddle focus on each of the two cell boundaries and two types of saddle limit cycle on the walls. A representative analysis for $\mathit{Re}=500$ shows chaotic streamlines to be due to chaotic tangling of the two-dimensional stable manifold of the central spiralling-in saddle focus and the two-dimensional unstable manifold of the central wall limit cycle. Embedded Kolmogorov–Arnold–Moser tori and the associated closed streamlines are computed for several supercritical Reynolds numbers owing to their importance for particle transport.

Experimental Study on Hydrodynamic Performance of Mini-AUV in Non-Uniform Flow Field

2019 ◽  
Author(s):  
Jiayuan Zhuang ◽  
Jian Cao ◽  
Yumin Su ◽  
Lei Zhang ◽  
Xianzhao Yu
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Lateral Force ◽  
Uniform Flow ◽  
Hydrodynamic Performance ◽  
Experimental Investigations ◽  
Complex Flow ◽  
Three Dimensional Flow ◽  
Drift Angle ◽  
Current Profiler

Abstract Experimental investigations of hydrodynamic performance of mini-AUV in non-uniform flow field were conducted in the basin of Harbin Engineering University, the revolved body and flat body of mini-AUV model were tested respectively. The three dimensional flow fields were generated by local jet of the underwater pump, and circulated in the basin. The three dimensional velocity distributions at different positions were measured by a Doppler current profiler. The three component balance was used to measure the drag, lateral force and yawing moment acting on the mini-AUV models depending on drift angle in the flow field, and the influence of complex flow field to the hydrodynamic performance of mini-AUV indicated that drag was not sensitive to drift angle and yawing moment was increased obviously. The conducted experiments could supply reference to the maneuverability research of mini-AUV in real marine environments in the future.

Prediction of Surface Roughness and Incidence Effects on Turbine Performance

1994 ◽  
Vol 116 (4) ◽  
pp. 745-751 ◽  
Author(s):  
R. J. Boyle
Keyword(s):  
Surface Roughness ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Wide Range ◽  
Loss Models

The use of a Navier–Stokes analysis to predict the change in turbine efficiency resulting from changes in blade surface roughness or incidence flow angles is discussed. The results of a midspan Navier–Stokes analysis are combined with those from a quasi-three-dimensional flow analysis code to predict turbine performance. A quasi-three-dimensional flow analysis code was used to determine turbine performance over a range of incidence flow angles. This analysis was done for a number of incidence loss models. The change in loss due to changes in incidence flow computed from the Navier–Stokes analysis is compared with the results obtained using the empirical loss models. The Navier–Stokes analysis was also used to determine the effects of surface roughness using a mixing length turbulence model, which incorporated the roughness height. The validity of the approach used was verified by comparisons with experimental data for a turbine with both smooth and rough blades tested over a wide range of blade incidence flow angles.

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