Three-dimensional Flow Analysis Research Articles

Simulations of Three-dimensional Second Grade Fluid Flow Analysis in Converging-Diverging Nozzle

Very little work have been reported on the computational methods for non-Newtonian fluid turbulent flows. This is due to nonlinear system of elliptic partial differential equations that makes the solution very difficult. Another concern is the meshing of flow domain that accounts for complications in solving most problems. In this work we present standard Galerkin finite element method for the steady incompressible non Newtonian fluid flow in a convergingdiverging nozzle. The flow is fully three-dimensional with turbulent characteristics. The main aim is to study the velocity and shear stress profiles. Shock profiles are noted for specific pressure boundary conditions. Moreover the plotted results shows variations of velocity components, pressure and turbulence energy dissipation. It is observed that for non-Newtonian fluid flow the mass flow rate and pressure loss effects are significant in diverging part of nozzle.

The Design Method of Axial Flow Runners Focusing on Axial Flow Velocity Uniformization and Its Application to an Ultra-Small Axial Flow Hydraulic Turbine

We proposed a portable and ultra-small axial flow hydraulic turbine that can generate electric power comparatively easily using the low head of open channels such as existing pipe conduits or small rivers. In addition, we proposed a simple design method for axial flow runners in combination with the conventional one-dimensional design method and the design method of axial flow velocity uniformization, with the support of three-dimensional flow analysis. Applying our design method to the runner of an ultra-small axial flow hydraulic turbine, the performance and internal flow of the designed runner were investigated using CFD analysis and experiment (performance test and PIV measurement). As a result, the runners designed with our design method were significantly improved in turbine efficiency compared to the original runner. Specifically, in the experiment, a new design of the runner achieved a turbine efficiency of 0.768. This reason was that the axial component of absolute velocity of the new design of the runner was relatively uniform at the runner outlet in comparison with that of the original runner, and as a result, the negative rotational flow was improved. Thus, the validity of our design method has been verified.

클린룸 내 다관절 로봇 주위의 유동해석

We carried out three-dimensional flow analysis in a clean room. Flow field in a robot experiment system, induced from the moving robot, is numerically studied in this paper. The effects of moving robot in a clean room are investigated in order to find the section of dust accumulation. Contamination on the bottom produced from the moving robot is predicted from the analysis results from the flow fields. Results show that a large swirl flow is formed around the moving robot. Consequently, the optimal flow condition can be obtained by controlling the fluid velocity through the fixing of inlet or outlet position.

Analysis of Three-Dimensional Complex Fluid Flow and Temperature Distribution in the End Region of a Turbogenerator

Distribution of complex fluid flow is an important factor that affects the temperature distribution of the end parts in the end region of a turbogenerator. In this paper, a turbogenerator is considered as an example; the fluid flow velocity and pressure values obtained from flow network calculations are applied to the end region as boundary conditions, and the losses obtained from electromagnetic field calculations are applied to the end region as heat sources in a fluid and thermal coupling field. Furthermore, mathematical and geometric models of 3-D fluid and thermal coupling of the end region are established. The distributions of the complex fluid velocity and fluid temperature in the turbogenerator end region are investigated in detail. Moreover, the temperature distribution of the end parts is determined. Comparison of measurement results of the temperature of the end parts with the corresponding calculation results shows their good agreement.

Numerical simulation and analysis of solid-liquid two-phase three-dimensional unsteady flow in centrifugal slurry pump

Based on RNG k-e turbulence model and sliding grid technique, solid-liquid two-phase three-dimensional (3-D) unsteady turbulence of full passage in slurry pump was simulated by means of Fluent software. The effects of unsteady flow characteristics on solid-liquid two-phase flow and pump performance were researched under design condition. The results show that clocking effect has a significant influence on the flow in pump, and the fluctuation of flow velocity and pressure is obvious, particularly near the volute tongue, at the position of small sections of volute and within diffuser. Clocking effect has a more influence on liquid-phase than on solid-phase, and the wake-jet structure of relative velocity of solid-phase is less obvious than liquid-phase near the volute tongue and the impeller passage outlet. The fluctuation of relative velocity of solid-phase flow is 7.6% smaller than liquid-phase flow at the impeller outlet on circular path. Head and radial forces of the impeller are 8.1% and 85.7% of fluctuation, respectively. The results provide a theoretical basis for further research for turbulence, improving efficient, reducing the hydraulic losses and wear. Finally, field tests were carried out to verify the operation and wear of slurry pump.

Design and performance analysis of radial-inflow turboexpander for OTEC application

Ocean thermal energy conversion (OTEC) is a potential source of renewable energy. In order to design a turbine for maximizing the output power for very low working temperature application like OTEC, careful one-dimensional design followed by detailed three dimensional simulation is required. In this work a radial-inflow turbine with R-22 as working fluid is designed for a closed-cycle ocean thermal energy conversion plant of 2 kWe capacity. Design speed of the turbine is 34000 rpm. Inlet and outlet temperatures of designed turbine are 24.5 °C and 14 °C respectively. Three-dimensional fluid flow analysis inside the turbine at design and off-design conditions were carried out. Important dimensions of the turbine are: rotor tip and shroud radii of 24 mm and 19 mm respectively; blade widths at rotor inlet and outlet of 6 mm and 11 mm respectively; axial length of 17.5 mm; diffuser of 62 mm long. Volute casing designed has a circular cross section. The importance of the number of blades, blade filleting and stagger angle from the point of view of turbine performance are reported.

Development of natural circulation analysis methods for a sodium cooled fast reactor

A natural circulation evaluation methodology has been developed to insure safety of a sodium cooled fast reactor (SFR) of 1500 MWe adopting a natural circulation decay heat removal system (NC-DHRS). The methodology consists of a one-dimensional safety analysis which can be applied to safety evaluation for SFR licensing taking into account the temperature flattening effect due to buoyancy force in the core, and a three-dimensional fluid flow analysis which can evaluate thermal-hydraulics for local convection and thermal stratification in the primary system and DHRSs. The one-dimensional safety analysis method and the three-dimensional fluid flow analysis method have been validated using the test results of a water test apparatus and a sodium test loop for some typical transient events selected from the design basis events of the SFR. Finally, it has been confirmed that a good agreement between the test results and analysis results has been obtained, and reliability of each method has been demonstrated.

Analysis of three-dimensional boundary-layer nanofluid flow and heat transfer over a stretching surface by means of the homotopy analysis method

In this paper, an investigation is made of the three-dimensional flow and heat transfer of a nanofluid in the boundary-layer region over a flat sheet stretched continuously in two lateral directions. With the help of a series of similarity transformations, this problem is reduced to a set of three coupled differential equations. The homotopy analysis method (HAM) is then applied to derive the explicit solutions for both the velocity and the temperature distributions. A mathematical analysis shows that these solutions decay exponentially at far field. Besides, the influences of the nanoparticle volume fraction ϕ on the velocity and temperature profiles, as well as the reduced local skin friction coefficients and the reduced local Nusselt numbers are studied. It is found that the heat transfer conductivity of the nanofluid is superior to that of the pure fluids.

Full three-dimensional power flow analysis of single-emitter-plasmonic-nanoantenna system.

We present a full three-dimensional (3D) power flow analysis of an emitter-nanoantenna system. A conventional analysis, based on the total Poynting vector, calculates only the coupling strength in terms of the Purcell enhancement. For a better understanding of the emitter-nanoantenna system, not only the Purcell enhancement but also complete information on the energy transfer channels is necessary. The separation of the pure scattering and emitter output Poynting vectors enables the quantification of the individual energy transfer channels. Employing the finite-difference time-domain method (FDTD), we examine a nanodisk antenna that supports the bright dipole and dark quadrupole resonance modes for which the power flow characteristics are completely distinct, and we analyze the power flow enhancements to the energy transfer channels with respect to the wavelength, polarization, and position of the emitter coupled to the antenna. The 3D power flow analysis reveals how the constructive or destructive interference between the emitter and the antenna resonance mode affects the power flow enhancements and the far-field radiation pattern. Our proposed power flow analysis should play a critical role in characterizing the emitter-antenna system and customizing its energy transfer properties for desired applications.

극지 해양 파이프라인 내부 유체의 온도별 영향 및 내부 충돌침식 분석

This paper describes thermal flow characteristic in various pipelines: straight pipeline and curved pipeline. In the Arctic and ocean area, pipelines are exposed to a extremely low temperature (0 ~ -40°C). In this situation, three-dimensional flow analysis should be analyzed to investigate thermal effects such as pressure drop, temperature change, velocity deficit and distribution change of liquid droplet of internal fluid. Also, due to freezing of water droplet, impingement erosion is expected in the curved pipeline. The stability of the pipelines can be influenced by impingement erosion. In this paper, multi-phase and multi-species analysis was introduced to analyze the flow characteristics and impingement erosion of Arctic and ocean pipelines.

Development of an evaluation methodology for the natural circulation decay heat removal system in a sodium cooled fast reactor

A natural circulation evaluation methodology has been developed to ensure the safety of a sodium-cooled fast reactor (SFR) of 1500 MW adopting the natural circulation decay heat removal system (NC-DHRS). The methodology consists of a one-dimensional safety analysis which can evaluate the core hot spot temperature taking into account the temperature flattening effect in the core, a three-dimensional fluid flow analysis which can evaluate the thermal-hydraulics for local convections and thermal stratifications in the primary system and DHRS, and a statistical safety evaluation method for the hot spot temperature in the core. The safety analysis method and the three-dimensional analysis method have been validated using results of a 1/10 scaled water test simulating the primary system of the SFR and a sodium test simulating a part of the primary system and the DHRS with about a 1/7 scale, and the applicability of the safety analysis for the SFR has been confirmed by comparing with the three-dimensional analysis adopting the turbulence model. Finally, a statistical safety evaluation has been performed for the SFR using the safety analysis method.

Three-dimensional magnetohydrodynamic two-phase flow and heat transfer analysis in electroslag remelting process

A transient three-dimensional (3D) coupled mathematical model is developed in this paper in order to explore the electromagnetic, flow, and temperature fields, as well as the solidification in the electroslag remelting (ESR) process. Maxwell's equations are solved by the Finite Volume Method. The Joule heating and electromagnetic force (EMF), the source terms in the energy and momentum equations, are recalculated during each iteration as function of the phase distribution. The movement of the metal droplets is described by the Volume of Fluid (VOF) approach. Additionally, the solidification of the metal is modeled by an enthalpy-based technique, where the mushy zone is treated as a porous medium with a porosity equal to the liquid fraction. The results show that the electric current tends to go through the metal droplet first. The EMF varies with the falling metal droplet, always blocking the motion of the metal droplet. The zone with the highest temperature appears under the outer radius of the inlet. A larger Joule heating density, as well as a higher average temperature of the molten slag, is obtained when the current increases. Bigger metal droplets form with more heat and momentum, resulting in a deeper liquid metal pool.

WATER BALANCE ANALYSIS CONSIDERING RUNOFF OF UNGAUGED CATCHMENTS IN IWAKI RIVER BASIN, NORTHERN JAPAN

For integrated and sustainable water resource management, it is essential to understand water balance of river basin. Infiltration calculated by subtracting evapotranspiration and from precipitation is a key factor for groundwater resource development and is an important input data for three-dimensional groundwater flow analysis. For estimation of runoff, it needs a great challenge to establish a method for in ungauged catchments, because gauging stations are usually set up in the limited main rivers. This paper focused on close relation between topography and runoff. Then, the of ungauged catchments in the Iwaki River Basin was estimated by runoff derived from results of geomorphometry and multivariate statistics using digital elevation model data. Comparisons between indices and measured data, showed clear positive correlations. This result proved that index was useful for estimation, and suggested that it was possible to estimate of ungauged catchments from index by linear regression equation.

Developing the Flow Pass for the Intermediate and High Pressure Cylinders of the Steam Turbine K-1250 Using the Computing Methods of 3-D Viscous Flows

The data of the computational analysis of three-dimensional flows in the flow section of intermediate and high pressure cylinders (IHPC) used for the new steam turbine K-1250 built by the PJSC “Turboatom” for the units of nuclear power plants have been given. The numerical investigation was done using the software system IPMFlow. The flow pass of the intermediate and high pressure cylinder IHPC K-1250 was designed using the method of parameterization and analytical profiling of the blades that was developed by IPMash of the National Academy of Sciences of Ukraine. It has been shown that due to use of advanced approaches to the profiling of blade rows and the formation of meridional by-passes the efficiency factor for the flow sections of the high pressure cylinder (HPC) and intermediate pressure cylinder (IPS) for the proposed IHPC made up 96, 6 % and 96,4 %, respectively.

1319 渦法による三次元流れの解析 : サメの解析

1319 渦法による三次元流れの解析 : サメの解析

마르텐사이트계 경화 육성용접부의 희석율 해석을 통한 Cr함량 예측에 대한 연구

Abstract High-temperature corrosion resistance of martensitic-hardfaced weldment is generally evaluated by the Cr content depending on dilution rate. Present study used a commercial program(SYSWELD) applying three-dimensional heat flow analysis to predict temperature distribution of weld. Configuration of weld bead can be determinedby the contour of melting temperature and simultaneously dilution rate is calculated to predict Cr content. Experimental study also has been conducted to measure Cr content of harfaced surface welded by FCAW. Results indicated that computational results were well matched with those obtained from experiments.Key Words : Hardfacing, SYSWELD, FCAW, Dilution rate, Corrosion resistance, Chromium content ISSN 1225-6153Online ISSN 2287-8955 n      : Area [mm 2 ]: Dilution rate [%]: Pass Number: Property of weld metal: Property of base metal: Property of welding wire - 기호설명 - 1. 서 론 경화 육성용접이란 내마모 성능과 내식성이 떨어지는 모재의 표면에 해당 특성을 보강한 용접재료를 균일하게 용착시켜 재료의 표면성질을 향상시키는 표면처리 방법이다. 제철, 화학, 시멘트, 제지설비 등 산업전반에 널리 이용되고 있으며

Optimization and Simulation of Hydro-Turbine Nozzle in Based on Ansys Analysis

This paper presents Optimization and Simulation of hydro -turbine nozzle in based on ansys analysis. Based on three-dimensional numerical flow analysis, the flow characteristics through the water turbine with nozzle are predicted. The Pressure and Velocity distribution of hydro-turbine nozzle is different points were calculated and analyzed for a Structural analysis and CFD analysis. The simulation results show that using nozzle can increase the pressure drop across the turbine and extract more power from available water energy. These results provide a fundamental understanding of the composite water turbine, and this design and analysis method is used in the design process.

RECENT IMPROVEMENTS IN THE CUPID CODE FOR A MULTI-DIMENSIONAL TWO-PHASE FLOW ANALYSIS OF NUCLEAR REACTOR COMPONENTS

The CUPID code has been developed at KAERI for a transient, three-dimensional analysis of a two-phase flow in light water nuclear reactor components. It can provide both a component-scale and a CFD-scale simulation by using a porous media or an open media model for a two-phase flow. In this paper, recent advances in the CUPID code are presented in three sections. First, the domain decomposition parallel method implemented in the CUPID code is described with the parallel efficiency test for multiple processors. Then, the coupling of CUPID-MARS via heat structure is introduced, where CUPID has been coupled with a system-scale thermal-hydraulics code, MARS, through the heat structure. The coupled code has been applied to a multi-scale thermal-hydraulic analysis of a pool mixing test. Finally, CUPID-SG is developed for analyzing two-phase flows in PWR steam generators. Physical models and validation results of CUPID-SG are discussed.

Three-dimensional viscous flow and heat transfer over a permeable shrinking sheet

This paper presents a numerical analysis of a steady three-dimensional fluid flow and heat transfer towards a permeable shrinking sheet. The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations by a similarity transformation, which are then solved numerically by a shooting method. The effects of the governing parameters on the skin friction and heat transfer from the surface of the shrinking surface are illustrated graphically. It is found that dual solutions exist for the shrinking case. A comparison with known results from the open literature has been done and it is shown to be in excellent agreement.

임펠러 입출구각에 따른 양흡입 원심송풍기 성능특성

Effects of design variables on the performance of a double-inlet centrifugal blower have been analyzed based on the three-dimensional flow analysis. Two design variables, blade inlet and outlet angles, are introduced to enhance a blower performance. General analysis code, ANSYS-CFX13, is employed to analyze internal flow and a blower performance. SST turbulence model is employed to estimate the eddy viscosity. Throughout the shape optimization of an impeller at the design flow condition, the blower efficiency and pressure are successfully increased by 4.7 and 1.02 percent compared to reference one. It is noted that separated flow observed near cut-off region can be reduced by optimal design of blade angles, which results in stable flow pattern in the blade passage and increase of a blower performance. The stable flow at the impeller also makes good effects at the outlet of a volute casing.