Three－Dimensional Numerical Simulation of Natural Convection Heat Transfer in an Inclined Cylindrical Annulus

Ｔｈｒｅｅ－ＤｉｍｅｎｓｉｏｎａｌＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆＮａｔｕｒａｌＣｏｎｖｅｃｔｉｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎａｎＩｎｃｌｉｎｅｄＣｙｌｉｎｄｒｉｃａｌＡｎｎｕｌｕｓＪ．Ｇ．ｗｅｉ；Ｗ．Ｑ．Ｔａｏ（ＳｃｈｏｏｌｏｆＥｎｅｒ...     

The Numerical Study of Marangoni Flow and Its Stability in Czochralski Crystal Growth

ＴｈｅＮｕｍｅｒｉｃａｌＳｔｕｄｙｏｆＭａｒａｎｇｏｎｉＦｌｏｗａｎｄＩｔｓＳｔａｂｉｌｉｔｙｉｎＣｚｏｃｈｒａｌｓｋｉＣｒｙｓｔａｌＧｒｏｗｔｈＸｉｎｏ－ＢｏＷｕ；ＸｕＧｅｎｇ；Ｚｅｎｇ－ＹｕａｎＧｕｏ（Ｄｅｐｔ．ｏｆＥｎｇｉｎｅｅｒｉｎｇＭｅｃｈ...     

Numerical Simulation of a Negative Impulsive Wave

ＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆａＮｅｇａｔｉｖｅＩｍｐｕｌｓｉｖｅＷａｖｅＴｏｓｈｉａｋｉＳＥＴＯＧＵＣＨＩ；ＭａｎａｂｕＴＡＫＡＯ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇｍｅｅｒｉｎｇ，ＳａｇａＵｎｉｖｅｒｓｉｔｙ，Ｈｏｎｊ...     

Vortex Simulation of Axisymmetrical Flows in Cylindrical Geometries．PartI：Numerical Algorithm

ＶｏｒｔｅｘＳｉｍｕｌａｔｉｏｎｏｆＡｘｉｓｙｍｍｅｔｒｉｃａｌＦｌｏｗｓｉｎＣｙｌｉｎｄｒｉｃａｌＧｅｏｍｅｔｒｉｅｓ．ＰａｒｔＩ：ＮｕｍｅｒｉｃａｌＡｌｇｏｒｉｔｈｍ￥ＡｎｄｒＧｉｏｖａｎｎｉｎｉ（ＵｎｉｖｅｒｓｉｔｅＰａｕｌＳａｂａｔｉｅｒａｎ...     

Numerical Study of Natural Convection on Horizontal Strips Embedded in an Vertical Adiabatic Substrate

ＮｕｍｅｒｉｃａｌＳｔｕｄｙｏｆＮａｔｕｒａｌＣｏｎｖｅｃｔｉｏｎｏｎＨｏｒｉｚｏｎｔａｌＳｔｒｉｐｓＥｍｂｅｄｄｅｄｉｎａｎＶｅｒｔｉｃａｌＡｄｉａｂａｔｉｃＳｕｂｓｔｒａｔｅＸｉａｏ－ＢｏＷｕ；Ｚｅｎｇ－ＹｕａｎＧｕｏ（Ｄｅｐｔ．ｏｆＥｎｇｉｎｅ...     

Vortex Simulation of Axisymmetrical Flows in Cylindrical Geometries．PartII：Application to Pipes Incorporating an Orifice Plate

ＶｏｒｔｅｘＳｉｍｕｌａｔｉｏｎｏｆＡｘｉｓｙｍｍｅｔｒｉｃａｌＦｌｏｗｓｉｎＣｙｌｉｎｄｒｉｃａｌＧｅｏｍｅｔｒｉｅｓ．ＰａｒｔＩＩ：ＡｐｐｌｉｃａｔｉｏｎｔｏＰｉｐｅｓＩｎｃｏｒｐｏｒａｔｉｎｇａｎＯｒｉｆｉｃｅＰｌａｔｅ￥ＡｎｄｒＧｉｏｖａｎｎ...     

Numerical Simulation of the Flow over a Model of the Cavities on a Butterfly Wing

ＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｏｆｔｈｅＦｌｏｗｏｖｅｒａＭｏｄｅｌｏｆｔｈｅＣａｖｉｔｉｅｓｏｎａＢｕｔｔｅｒｆｌｙＷｉｎｇＲｏｄｒｉｇｕｅＳａｖｏｉｅ；ＹｖｅｓＧａｇｎｏｎ（ＵｎｉｖｅｒｓｉｔｙｄｅＭｏｎｃｔｏｎ，Ｃａｍｐｕｓｄ＇Ｅｄｍｕ...     

Water－Aromatic Liquid－Liquid－Vapour Equilibrium Calculation Using a Cubic Equation of State

Ｗａｔｅｒ－ＡｒｏｍａｔｉｃＬｉｑｕｉｄ－Ｌｉｑｕｉｄ－ＶａｐｏｕｒＥｑｕｉｌｉｂｒｉｕｍＣａｌｃｕｌａｔｉｏｎＵｓｉｎｇａＣｕｂｉｃＥｑｕａｔｉｏｎｏｆＳｔａｔｅＧｕａｎｇｈｕａＧａｏ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ...     

Energy System Selection for Small Underwater Vehicles

ＥｎｅｒｇｙＳｙｓｔｅｍＳｅｌｅｃｔｉｏｎｆｏｒＳｍａｌｌＵｎｄｅｒｗａｔｅｒＶｅｈｉｃｌｅｓ￥Ｇ．Ｔ．Ｒｅａｄｅｒ；Ｉ．Ｊ．Ｐｏｔｔｅｒ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ＵｎｉｖｅｒｓｉｔｙｏｆＣａｌｇａｒｙｔＣ...     

A New Calculation Method of the Axial and Radial Velocity and Grade──Efficiency for High──Efficiency Cyclones

Ａ　Ｎｅｗ　Ｃａｌｃｕｌａｔｉｏｎ　Ｍｅｔｈｏｄ　ｏｆ　ｔｈｅ　Ａｘｉａｌ　ａｎｄ　Ｒａｄｉａｌ　Ｖｅｌｏｃｉｔｙ　ａｎｄ　Ｇｒａｄｅ──Ｅｆｆｉｃｉｅｎｃｙ　ｆｏｒ　Ｈｉｇｈ──Ｅｆｆｉｃｉｅｎｃｙ　ＣｙｃｌｏｎｅｓＡＮｅｗＣａｌｃｕｌａｔｉｏｎＭ...     

A FULL 3-DIMENSIONAL ADAPTIVE FINITE VOLUME SCHEME FOR TRANSPORT AND PHASE-CHANGE PROCESSES,PART I: FORMULATION AND VALIDATION

A full three-dimensional (3-D) numerical formulation for accurate simulation of transport and phase-change processes is presented. These processes are characterized by a variety of flow and heat transfer mechanisms in irregular domains with or without the movement of phase-change interfaces and free surfaces. A generalized 3-D nonorthogonal curvilinear finite volume formulation is developed in conjunction with a robust mesh generation scheme known as multizone adaptive grid generation (MAGG) to tackle such problems. The coupling between the interfacial dynamics and transport phenomena in the bulk of the phases is inherent in this formulation. A 3-D k-epsilon model is also incorporated to tackle the turbulent flows in these applications. The unified numerical model is validated against classical 3-D problems such as turbulent natural convection in a differentially heated cube, solidification in a cavity, and so on. In a companion paper, Part II (see this issue), application of this formulation to 3-D simulation of hydrothermal crystal growth and low and high pressure Czochralski (Cz) crystal growth is presented.     

A κ—ε—PDF Two—Phase Turbulence Model for Simulating Sudden—Expansion Particle—Laden FLows

A κ-ε-PDF model based on statistical theory for turbulent gas-particle flows is proposed.and a numerical procedure combining the finite difference and finite fluctuaing-velocity-group methods is used.The obtained statistically averaged equations have the same form as those obtained by using the Reynolds averaging.Using the κ-ε-PDF model(PDF particle turbulence model combined with the κ-ε- gas turbulence model),amny terms,such as the diffusion term in particle Reynolds Stress equations,can be accurately calcuated for verifying the second-moment-closure model,the κ-ε-PDF model is used to simulate sudden-expansion particle-laden flow.comparison of the predictions using both κ-ε-PDF and the κ-ε- models with experimental results shows that the κ-ε-PDF model give more reasonable non-siotropic features of particle turbulence.     

Numerical simulation of air flow field in high-pressure fan with splitter blades

For a deeper understanding of the flow characteristics in the high-pressure centrifugal blower of a fan of Model 9–26 with splitter blades, a three dimensional (3-D) numerical simulation of air flows in the fan was conducted with FLUENT software. The standard k-ε turbulent model and unstructured grids were used. The computational fluid dynamics (CFD) results showed that the performance of a fan could be improved by adding the splitter blades in the channel among the leaf blades. Under operational conditions, with the presence of splitter blades, the air flow rate of the fan increased about 5% and the total pressure at the outlet of the fan increased about 10% on average. It was also found that the length of the splitter blades affected the air flow and pressure drop. There is an optimal value for the length. The simulation results provide helpful information for improving the fan performance. __________ Translated from Fluid Machinery, 2007, 35(10): 29–32 [译自:流体机械]     

Three—Dimensional Flow Characteristics in One Ceramic Candle Filter

INTRODUCTIONThe stringent regulation of CO2, SOx or NOx,which are the main cause of the environmental contamination, is getting strengthened to save earth.Since it has influence on the energy industries, Integrated Gasification Combined Cycle (IGCC) amongthe clean coal technologies has attracted the increasing attention to meet restrictions on the environmental contamination and to promote high efficiency. TheClean Coal Technology (CCT) requires a competenthot-gas cleanup facility …     

Numerical Computations of Confined Swirl Flows in Augmentor of Jet Engines and Comparisons with Experiments

This paper describes the design of four types of swirlers which produce different velocity profiles.The dataof confined turbulent swirling flowfields are obtained from experiments and numerical calculations.The actualflow profiles at the swirler exit basically agree with the desired profiles.Two kinds of turbulence models,k-ε model and DDC model,are used to predict the flowfields producedby swirl augmentors.The results show that the DDC model,based on interaction between dissipation anddispersion,can overcome the defect of k-ε model and predict the swirling flowfields more accurately than k-εmodel.     

STREAMLINE ADAPTIVE GRID METHOD FOR COMPLEX FLOW COMPUTATION

A concept of generating and adapting grids according to flow streamlines is employed in the prediction of complex fluid flows. In general, this method retains the merits of body-fitted coordinates in the near-wall regions. Moreover, this approach generates new coordinate lines according to the streamline patterns of the preceding solution based on either Cartesian or curvilinear grid systems and adapts sufficient grids in regions where high resolutions are needed so that the difficulty of numerical diffusion is significantly reduced, To give systematic coordinate transformations, conservation equations applicable in the general nonorthogonal curvilinear coordinate system are derived by the method of generalized tensors. A treatment of near-wall turbulence suitable in the general curvilinear coordinate system is also presented. The superiorities of the present approach are demonstrated by studying the laminar/turbulent flow over a backward facing step and the flow induced by a two-dimensional turbulent jet injected into cross flow. The results show remarkable successes for the case of laminar flow over a backward facing step in the whole domain and the case of a turbulent jet into cross flow in the prediction of detailed flow structures.     

Prediction of dynamic and aerodynamic characteristics of the centrifugal fan with forward curved blades

The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteris- tics based on numerical modeling. Three variants of geometry were investigated. The first, basic ＂A＂ variant con- tains 12 blades. The geometry of second ＂B＂ variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant ＂C＂ contains 24 blades without semi-blades. Numerical calculations were per- formed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine char- acteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also par- tially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calcula- tion stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.     

Computationally Efficient Large-Eddy Simulation of Periodic Unsteady Flow using Harmonic Balance Method

To improve the efficiency and fidelity of the numerical analysis for cascade flutter, we propose an efficient scale-resolving simulation method dedicated to time-periodic flows by incorporating the harmonic balance approach into the large-eddy simulation. This method combined convergence calculations of the steady-state problem based on the harmonic balance method for periodic components, and the nonlinear time-marching method for turbulent fluctuations. Using the proposed method, deterministic periodic components and stochastic turbulent fluctuations were calculated simultaneously, and the effect of turbulent fluctuations on deterministic periodic components was directly calculated without using turbulence models. In this paper, we explain the algorithm and feature of this simulation technique and present the results of the computation for channel flow excited in the streamwise direction as an analysis example using the proposed method. In order to validate the proposed method, an analysis of sinusoidally pulsating channel flow at the central friction-velocity Reynolds numbers Rer = 180 was conducted, confirming that the amplitude and phase of the mean velocity oscillation computed by the proposed method were in good agreement with those of the conventional LES. The present calculation achieved an order of magnitude improvement in computational efficiency compared to conventional LES.     

A κ-ε Turbulence Model Considering Compressibility in Three-Dimensional Transonic Turbulent Flow Calculation

Based on the standark κ-ε turbulence model,a new compressible κ-ε model considering the pressure expansion influence due to the compressibility of fluid is developed and aplied to the simulation of 3D transonic turbulent flows in a nozzle and a cascade.The Reynolds averaged N-S equations in generalized curvilinear coordinates are solved with implementation of the new model,the high resolution TVD scheme is used to discretize the convective terms.The numerical results show that the compressible κ-ε odel behaves well in the simulation of transonic internal turbulent flows.     

Treatment of Checkerboard Pressure in the Collocated Unstructured Finite-Volume Scheme

In this article, a new concept, “local triangle,” is described. A smoother pressure field is then obtained through the utilization of local triangles in a multiblock local triangulation method. The cell face velocity is corrected with a pressure-correction term which is usually underrelaxed. It is demonstrated that this relaxation factor has to be one, and it cannot be the general relaxation factor. It is indicated that the checkerboard oscillations are more significant at higher cell Reynolds numbers and, in turn, in this article, numerical simulations are mainly performed in turbulent flow.