bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Wrap Angle of Blade on the Internal Flow Field and Hydraulic Performance of Double Suction Pump
Authors: Chang Hao , Shi Weidong , Li Wei , Liu Jianrui , Zhou Ling , Wang Chuan , Fu Wei , Li Xiaowei
Published: October 2018

In order to study the influence rule of wrap angle of blade on the internal flow field and hydraulic performance of double suction pump, 5 kinds of wrap angles of blade with 100°, 110°, 120°, 130° and 140° are designed in this paper. The turbulence model and the grid type are analyzed, the performance of ES350-575 double suction pump is obtained by employ the software CFX. The static pressure and velocity distributions in the cross-section are analyzed. Therefore, the optimal model is obtained, and the relevant external characteristic test is conducted. The result shows that the reasonable increase of the wrap angle of blade can enhance the performance of the pump effectively, which can improve the static pressure and velocity distributions of the internal flow field.
Simulating the Emptying of a Water Bottle With a Multi-Scale Two-Fluid Approach
Authors: Mer Samuel , Praud Olivier , Magnaudet Jacques , Roig Véronique
Published: October 2018

Multiple industrial processes involve gas-liquid flows characterized by a wide range of spatial and temporal scales. Simulating such flows remains a major challenge nowadays, as the computational cost associated with Direct Numerical Simulation still makes it unaffordable. For such configurations, an interesting alternative to DNS is the use of multi-scale approaches. In the latter, large enough bubbles are fully resolved and may deform over time, while smaller bubbles are modeled as a dispersed phase using subgrid scale models. The interfacial momentum transfer terms are then tailored to the local flow configuration. The closure models still involved in these approaches and the influence of the cut-off length separating the resolved and modeled bubbles definitely need to be validated against detailed experiments. In order to assess the validity of these models, we present a one-to-one comparison between experiments performed in a simple configuration, namely the emptying of a water bottle, and numerical simulations using the aforementioned approach. The results are found to reliably reproduce the genesis of the oscillation mechanism, which is governed by the bubble formation at the bottle neck. The multi-scale model also qualitatively reproduces the fragmentation process of large bubbles during their rise in the water column. However local experimental data are required to assess more quantitatively these results.
Geometrical Optimization of a Steam Jet-Ejector Using the Computational Fluid Dynamics
Authors: Darbandi Masoud , Sabzpoushan Seyedali , Schneider Gerry E.
Published: October 2018

The vacuum systems play crucial role in various industries including, but not limited to, power generation, refrigeration, desalination, and aerospace engineering. There are different types of vacuum systems. Among them, the ejector or vacuum pump is highly utilized due to its low capital cost and easy maintenance. Generally, the better operation of a vacuum system can dramatically affect the performance of its upper-hand systems, e.g., the general efficiency of a thermal power plant cycle. This can be achieved if such vacuum systems are correctly designed, implemented, and operated. The focus of this work is on an existing steam jet-ejector, whose primary flow is a high pressure superheated steam and the suction flow is a mixture of steam and air. The main goal of this work is to optimize the geometry of the ejector including the nozzle exit position (NXP), the primary nozzle diverging angle, and the secondary throat length, etc. From the computational fluid dynamics perspective, there are some major challenges to simulate this ejector. It requires predicting the correct turbulent fluid flow and heat transfer phenomena with great complexities in treating the mixed subsonic and supersonic flow regimes, very high and very low pressure regions adjacent to each other, and complex mixing two phase flow jets. Indeed, the latter one has been almost neglected in literature. The main concern of this study is to reduce the consumption of motive steam, i.e., to increase the entrainment ratio via modifying the ejector geometry and investigating its performance under different operating conditions that helps to save the water consumption.
Numerical Investigation of Impinging-Film Heat Transfer and Flow Characteristics of Turbine Inner Casing
Authors: Tong Fujuan , Gou Wenxuan , Gao Wenjing , Li Lei , Yue Zhufeng
Published: October 2018

An efficient cooling method for the turbine inner casing is essential with the increasing of the turbine inlet temperature. The heat transfer and flow characteristics of a coupled cooling system in the turbine inner casing part, i.e., three rows of impingement jets and film holes, have been studied numerically according to the real turbine operating conditions. Seven inclined angles of the film holes along the mainstream direction (90°, ±60°, ±45°, ±35°) and the impingement jets arrangements have been researched. The positive inclination is that the angle between the fluid flow from the film holes and the mainstream is less than 90°. Otherwise, it would be negative. The numerical validation reveals that the selected computational method can provide a good prediction of the reported experimental results of the impinging-film cooling system. Then the method has been applied in the investigation of the local/average temperature, film-cooling effectiveness, and the flow patterns on the film-cooled surface.

The results show that the inclined angle can achieve a significant improvement in the film cooling performance. With the positive inclination of film holes, the average temperature of the interaction surface between the mainstream and the turbine inner casing can decrease 50K compared with that of 90°. And the average temperature on the interaction surface with the negative inclined angle can even be reduced by more than 100K. Additionally, the average film-cooling effectiveness can be increased by up to 31.79%. Such results prove that decreasing the value of inclined angle can achieve a better heat transfer performance. Moreover, the negative inclination of film holes can improve the uniformity of the film-cooling effect. On the other hand, the influence of impingement jets arrangements on the film cooling behavior is negligible. Further analysis of the flow streamline illustrates that the coolant jet from the inclined film holes can attach to the interaction surface more firmly, which will achieve a better protection away from the high-temperature turbine gas. The research will provide direct guidance for the cooling design of the turbine inner casing and improve the thermal efficiency of the gas turbine system.
Careful Parameter Study to Enhance the Effect of Injecting Heavy Fuel Oil Into a Crossflow Using Numerical Approaches
Authors: Darbandi Masoud , Fatin Ali , Schneider Gerry E.
Published: October 2018

The flow and spray parameters can have noticeable roles in heavy fuel oil (HFO) spray finesse. As known, the interaction between droplets and cross flow should be considered carefully in many different industrial applications such as the process burners and gas turbine combustors. So, it would be so important to investigate the effect of injecting HFO into a crossflow more subtly. In this work, the effects of various flow and spray parameters on the droplet breakup and dispersion parameters are investigated numerically using the finite-volume-element method. The numerical method consists of a number of different models to predict the droplets breakup and their dispersion into a cross flow including the spray-turbulence interaction one. An Eulerian–Lagrangian approach, which suitably models the interaction between the droplets and turbulence, and also models the droplets secondary breakup is used to investigate the interactions between the flow and the droplet behaviors. After validating the computational method via comparing them with the data provided by the past researches, four test cases with varying swirl number, air axial velocity, droplet size, and fuel injection velocity are examined to find out the effects of preceding parameters on some spray characteristics including the droplets path, sauter mean diameter (SMD), and dispersed phase mass concentration. The results show that the droplets inertia and the flow velocity magnitude have significant effects on spray characteristics. As the droplets become more massive, the deflection of spray in flow direction becomes less. Also, increasing of flow velocity causes more deflection for sprays with the same droplet sizes.
Refractive Index Matching for Optical Flow Investigation With High Density Stratification
Authors: Krohn Benedikt , Qin Sunming , Manera Annalisa , Petrov Victor
Published: October 2018

Turbulent mixing in density stratified environments represents a challenging task in experimental turbulence research. When optical measurement techniques like Particle Image Velocimetry (PIV) are applied to stratified liquids, it is common practice to combine two aqueous solutions with different densities but equal refractive indices. As a result, light deflections/distortions due to the mixing of the fluids can be suppressed. While refractive image matching (RIM) was developed in the late ’70s, the limit of a 4% density ratio had yet to be reported before this work. In the present work, a methodology based on the behavior of changes in a multi component system while mixing is presented. This methodology allows RIM for solutions with higher density differences. The applicability of this methodology is experimentally demonstrated with a turbulent buoyant jet using a ternary combination of water, isopropanol and glycerol, for which an index matched density ratio of 8.6% has been achieved (Krohn et al. 2018). Measurements were conducted with a high fidelity synchronized PIV/PLIF system and the results are qualitatively compared in terms of turbulent statistics.
In-Plane Hydraulic Resistance Through Paper-Thin Porous Media
Authors: Doser Stefan , Lee Sang-Joon John
Published: October 2018

This work investigates the special case of in-plane fluid flow of a Newtonian incompressible fluid at low Reynolds numbers across a paper-thin porous medium in a confined conduit. Fluid transport in sheets with these characteristics are used in emerging devices such as microscale paper-based analytical devices (μPADs) and “e-paper” displays. Darcy’s law is applied and tested to determine if experimentally measured pressures at two flow rates of 5 μL/min and 10 μL/min agree with predicted values. A test device was designed using kinematic design principles to ensure a deterministic 318 μm gap that directs prescribed flow, unidirectionally across porous filter paper. The paper used was Grade 50 Whatman filter paper with an average pore size of 2.7 μm. Pressure was measured along the direction of flow over a 125 mm distance by six pressure ports placed at uniform increments of 25 mm to determine a profile of pressure along the flow path. Measurements were recorded at discrete time intervals over a period up to 48 hours with at least four replicates. Experimental measurements of the pressure profile show a linear relationship as predicted by Darcy’s law, allowing material permeability to be calculated. Among replicates measured under the same set of controllable conditions, experimental data also show a nonlinear relationship. The nonlinearity suggests evidence of transition into an inertia region, providing insight into the factors and behavior of the Darcy-Forchheimer transition for this special case of porous media flow.
Theoretical Analysis of CFD-DEM Mathematical Model Solution Change With Varying Computational Cell Size
Authors: Volk Annette , Ghia Urmila
Published: October 2018

Successful verification and validation is crucial to build confidence in the application of coupled Computational Fluid Dynamics - Discrete Element Method (CFD-DEM). Model verification includes ensuring a mesh-independent solution, which poses a major difficulty in CFD-DEM due to the complicated solution relationship with computational cell size. In this paper, we investigate the theoretical relationship between the solution and computational cell size by tracing the effects of a change in cell size through the mathematical model. The porosity profile for simulations of fixed-particle beds is determined to be Gaussian, and the average and standard deviation of the representative distribution are reported against cell size. We find the standard deviation of bed porosity increases exponentially as the cell size is reduced, and the drag calculations are very sensitive to changes in the porosity standard deviation, resulting in an exponential change in expected drag when the cell size is small relative to the particle diameter. The divided volume fraction method of porosity calculation is shown to be superior to the centred volume fraction method, as it reduces the porosity standard deviation. The sensitivity of five popular drag laws to changes in the porosity profile is presented, and the Ergun and Beetstra drag laws are shown to be the least sensitive to changes in the cell size.
Experimental and Numerical Investigation of Sediment Transport in Sewers
Authors: Alihosseini Maryam , Thamsen Paul Uwe
Published: October 2018

Sewer sediment deposition represents a crucial aspect of the maintenance of wastewater systems and has negative effects on the system itself as well as the environment. Therefore, it is important to design combined sewers, as sewage collection systems with high deposition risk, with adequate self-cleansing velocity to avoid the deposition. Despite the large number of investigations, the lack of knowledge about the particle behaviour in sewers remains a major problem in the field of sewer management. In the present work, the transport of sediments in partially filled channels is investigated experimentally and the results are compared to 3D-simulations performed with a coupled Computational Fluid Dynamics (CFD) model and Discrete Element Method (DEM). This research aims to investigate the self-cleansing design concept for uniform non-cohesive sediments based on moving of existing sediments on the sewer bed. The CFD part of the simulation is carried out in the commercial CFD software ANSYS Fluent, which is two-way coupled to the commercial DEM software EDEM through its User Defined Function. EDEM enhances the particle handling capability by resolving particle contacts, modelling bonded particles and non-spherical particles. The multiphase model Volume of Fluid (VOF) is used to capture the water and air interaction and the Discrete Phase Model (DPM) is applied to track the injected EDEM-particles. This paper also examines the applicability and limitations of this coupling method in simulation of sewer systems.
Effect of Liquid Level on Gas Carry-Under in GLCC Compact Separators
Authors: Kolla Srinivas Swaroop , Mohan Ram S. , Shoham Ovadia
Published: October 2018

Gas Carry-Under (GCU) is one of the two undesirable phenomena that occurs in the GLCC©1 (Gas-Liquid Cylindrical Cyclone) separators. Initial studies have shown that maintaining liquid level below the inlet of the GLCC© under control configuration affects the GCU in GLCC©. Also, it has been hypothesized that effective formation of vortex that is formed in the lower part of the GLCC©, or a stable gas core enhances the separation of gas entrained in the liquid. However, there has not been a systematic study on the effect of liquid level and the stability of the vortex on the GCU. This detailed and extensive experimental study attempts to fill that gap, investigating the effect of different liquid levels maintained below the inlet on the GCU. These studies are performed under the NOC (Normal operating Conditions) below the OPEN for liquid carry-over using control configuration to maintain the liquid level in the GLCC©. This study focuses on measuring the cumulative GCU in the liquid leg of the GLCC© over a period of time. The experimental investigations for GCU are conducted in a state of the art experimental facility for air-water and air-oil flow incorporating pressure and level control configurations. The experiments were carried out using a 3″ diameter GLCC© equipped with gas trap sections to measure simultaneously the GCU in the liquid leg of the GLCC©. The equilibrium liquid level is controlled at 4 different settings starting at 6″ below the GLCC© inlet and increasing to 2 feet below the inlet. It has been observed that the liquid level has tremendous effect on the complex swirling flow behavior in the lower part of the GLCC© and vortex stability, which in turn affects the GCU in the liquid leg of the GLCC©. Also, it has been noted that the liquid level has a significant effect on the Gas Void-Fraction in the liquid leg of the GLCC©, which is a critical parameter for multiphase pump operations.
Phase Separation in Vertical Header of Microchannel Condensers: A Mechanistic Model
Authors: Li Jun , Hrnjak Pega
Published: October 2018

Phase separation has been proven to increase performance of condensers of energy conversion systems (in vapor compression systems). Instead of conventional design, the inlet to a microchannel condenser prototype is in the middle of the height. After the first pass, in the vertical second header of the condenser, vapor phase separates from liquid phase due to gravity and sometimes other effects. In ideal case vapor should go to the top and liquid to the bottom, resulting in increased heat transfer. Due to interaction between vapor and liquid, separation is not perfect, expressed through the separation efficiency.

A mechanistic model presented in the paper is built to predict the phase separation efficiency based on force balance analysis for the liquid phase and correlations for the two-phase pressure drop. For the force balance criteria, liquid phase is divided into droplets and film and treated separately. The model captures the experimental observations first in asymptotic sense: separation efficiency can be 100% at low liquid mass flux and low vapor mass flux, but also in quantitative. Initial agreement with experiment is achieved to be within 15%.
Simulation of Coalescence and Breakup of Dispersed Water Droplets in Continuous Oil Phase
Authors: Yuan Shuxia , Dabirian Ramin , Mohan Ram S. , Shoham Ovadia
Published: October 2018

Petroleum industry uses shear devices such as chokes, valves, orifices and pumps, which cause droplet coalescence and breakup making the downstream separation process very challenging. Droplet-droplet coalescence leads to formation of larger droplets, which accelerate the phase separation, whereas the breakup of larger droplets into smaller ones delays the separation process.

Computational Fluid Dynamic (CFD) simulations are conducted by ANSYS-Fluent software to track the droplet breakup and droplet-droplet coalescence, where the interfaces between the two phases are tracked by the Volume of Fluid (VOF) model. The material of droplet is water, while the continuous phase is oil. In this study, the effect of variables such as droplet diameter, droplet relative velocities as well as droplet motion directions on the time evolution of droplet-droplet coalescence and breakup is evaluated.

The simulation results confirm that smaller droplet collisions lead to coalescence under wide ranges of droplet relative velocities, while larger droplet collisions result in droplet breakup at higher relative velocities. During coalescence, two droplets combine into one droplet, which deform in several times from one direction to orthogonal direction until recovering its shape or breakup. In addition, the simulation results show that fastest coalescence takes place when droplet collisions occur at optimum relative velocity, whereas droplet breakup occurs at higher velocities than the optimum velocity, and delay in coalescence happens at lower velocity. Furthermore, the simulation results clearly show that droplet moving direction play an important role in the occurrence of droplet coalescence and breakup. Comparison of the simulation results with the collected experimental data from literature confirm that the simulations are capable of predicting the evolution time of the droplet coalescence and breakup with high accuracy.
Foam Breakup in CFC/GLCC© System
Authors: Dabirian Ramin , Nababan Ardian , Gavrielatos Ilias , Mohan Ram S. , Shoham Ovadia
Published: October 2018

Foaming is a common phenomenon in the petroleum industry. Foams can be desirable for drilling applications, whereby the cutting bits are lubricated, and cuttings are carried up to the surface. However, foam can be undesirable for production operation, which hinders the gas-liquid separation process.

Experimental investigation has been conducted on foam break-up in a standalone Churn Flow Coalescer (CFC), a standalone Gas Liquid Cylindrical Cyclone (GLCC©) and a combined CFC/GLCC© system. A 1-inch Foam Characterization Rig (FCR) is utilized. The FCR is equipped with a 3-inch diameter CFC, which is connected in series to a 2-inch diameter GLCC©. A total of 30 experimental runs are conducted for both Gas Mode (GM) and Liquid Mode (LM) operations. A surfactant (SI-403) with concentration of 0.025%, superficial liquid velocities of 0.1 and 0.15 m/s and superficial gas velocities of 0.5, 1, and 1.5 m/s are used in the experiments.

The experimental results show that for the GM operation, the foam break-up in combined CFC/GLCC© system is more efficient than that in the standalone GLCC©, for the same flow conditions. Lowering the superficial gas velocity or increasing the superficial liquid velocity produce less stable foam, larger gas bubbles and lower half-life time. The outlet clear liquid flow rate (with no foam) under the LM operation increases with increasing superficial liquid velocity or decreasing superficial gas velocity. The recommended operational conditions for the CFC are at low superficial gas velocities, lower than the transition boundary to churn flow in the CFC.
Experimental Investigation of a Flapping Motion Downstream of a Backward Facing Step
Authors: Li Zhuoyue , Gao Nan
Published: October 2018

The flow field downstream of a backward facing step with Reynolds numbers of 1050–3890 were studied using stereoscopic particle image velocimetry (PIV) with field-of-views perpendicular to the incoming flow. It was found that the separated shear layer underwent a flapping motion with a frequency fH/Uo ≲ 0.04, much smaller than the shedding frequency (fH/Uo ≈ 0.1) for Reynolds number larger than 2000. Here H is the step height and Uo is the freestream velocity. The low frequency flapping motion appeared to be two dimensional, i.e. the motion was in-phased in the spanwise direction. The cause of the flapping motion is still not clear.
Lattice Boltzmann Model for Incompressible Axisymmetric Thermal Flows With Swirl
Authors: Mehrez Insaf , Gheith Ramla , Aloui Fethi , Ben Nasrallah Samia
Published: October 2018

This paper presents a Lattice Boltzmann (LB) model for incompressible axisymmetric thermal flows. The forces and source terms are added into the Lattice Boltzmann Equation (LBE) and the incompressible Navier-Stokes equations are recovered by the Chapman-Enskog expansion. The model of Zhou [1] is applied for axial, radial and azimuthal velocities and the model of Q.Li et al [2] is computed for temperature variation. The source term of the scheme is simple and without velocity gradient terms. This approach can solve problems including several physical phenomena and complicated force forms as the flow between two coaxial cylinders. Good agreement is obtained between the present work, the analytic solutions and results of previous studies in cylindrical pipe. It proves the efficiency and simplicity of the proposed model compared to other ones. The Taylor-Couette (TC) system is treated with water flow characterized by a radius ratio η = 0.5 and an aspect ratio Γ = 3.8. Three Reynolds numbers of 85, 100 and 150 are tested. The influence of the end-wall boundary conditions and the influence of thermal conditions on the flow structure and on the temperature distribution along the inner and outer cylinders are analyzed.
Effect of Corner-Arc on the Flow Structures Around a Square Cylinder
Authors: Many Hariprasad Chakkalaparambil , Srinivasan Vishnu Chandar , Raghavan Ajith Kumar
Published: October 2018

In this paper, flow structures around a corner modified square cylinder (side dimension, Bo) are presented and discussed. Cylinders with various corner arcs (circular) were considered (arc radius ‘r’). For various Corner Ratios (CR = r/Bo), values ranging from 0 to 0.5, flow visualization experiments were conducted in a water channel and the results are reported at Re = 2100 (based on Bo). Results presented are for two cases (a) stationary cylinders reporting the values of CD (coefficient of drag), St (Strouhal no.), and D (vortex size) and (b) oscillating cylinders at fe/fs = 1 (fe is the cylinder excitation frequency and fs is the vortex shedding frequency) and a/Bo = 0.8 (a is the cylinder oscillation amplitude). The work is aimed to explore the most effective configuration for drag reduction. Cylinder with corner ratio of 0.2 is proved to be the most effective one among the cases considered in this study with 19.3% drag reduction. As a major highlight, in contrast to the results of the previous studies, current study do not reveal a monotonous decrease of drag with increasing corner modification. Instead, it is shown here that, there is a specific value of CR ratio where the drag is the minimum most. A peculiar type of vortex structure was observed in the cases of stationary cylinders with CR > 0.2, contributing to the increase in drag. In the case of oscillating cylinders, description of one complete cycle for all CR ratios at various time instances are presented. The near-wake structures were observed to be dependent on the CR ratio. Counter intuitively, cylinder oscillation does not bring major difference in vortex size compared to the stationary case.
Numerical Analysis of Alternating Strand Diameter in Spiral Wound Membrane to Maximize Permeate Flux
Authors: Shoukat G. , Sajid M. , Uddin E. , Ali Z.
Published: October 2018

Membrane desalination is a pressure driven process which is being employed on a large scale in areas which do not have an easy access to fresh water resources. The large energy consumption of this process has encouraged researchers to explore the different spacer designs for maximizing permeate per unit of energy consumed. Computational fluid fynamics (CFD) was used to simulate the mass transfer enhancement in a reverse-osmosis desalination unit employing spiral wound membranes lined with zigzag spacer filaments of alternating diameters. Finite Volume based open source software OpenFoam was used to resolve the flow properties in a two-dimensional model by varying the Reynolds number until the onset of instability. Diamters of alternate strands were varied between ratios of 1, 1.5 and 2. The research provides guidelines based on comprehensive data set of velocity contours, pressure distribution, wall shear stresses and steady state vortex systems for using alternating strand design in zigzag configuration for maximum mass transfer and least pressure drop taking into account the concentration polarization.
Numerical Simulation of Airflow and Ellipsoidal Particle Deposition in Human Upper Respiratory Tract
Authors: Kiasadegh Morteza , Abouali Omid , Emdad Homayoun , Ahmadi Goodarz
Published: October 2018

In this study, unsteady flow field and fibrous particle deposition in a realistic model of human upper airway system including vestibule to the end of trachea were investigated using the CFD technique. The airway passage model was constructed from the CT image of a 24 year old healthy woman.

Unsteady airflow patterns during a full breathing cycle were simulated by solving the Navier-Stokes and continuity equations. For ellipsoidal fiber trajectory analysis under cyclic breathing condition, several user defined functions (UDFs) were coupled to the ANSYS-Fluent discrete phase model (DPM). The presented formulation accounted for solving the coupled translational and rotational equations of motion of ellipsoidal fibers.

Total and regional depositions for a range of fiber sizes were evaluated. The transient particle deposition fraction was compared with those obtained from the equivalent steady flow condition. The presented results showed that the steady simulation can predict the total fibrous particle deposition during cyclic breathing with reasonable accuracy but cannot properly predict the regional deposition of particles.
Mechanistic Modeling of Liquid Carry-Over for 3-Phase Flow in GLCC© Compact Separators
Authors: Kolla Srinivas Swaroop , Mohan Ram S. , Shoham Ovadia
Published: October 2018

Gas-Liquid Cylindrical Cyclone (GLCC©) Separators have been in use in petroleum and other related industries for over two decades. Prediction of Liquid Carry-Over Operational Envelope (LCO-OE) is essential for designing and proper operation of GLCC©. Earlier mechanistic models for predicting LCO-OE were based on gas-liquid phase flow. A new mechanistic model has been developed for the prediction of the LCO-OE incorporating the effect of watercut and fluid properties for a GLCC© under liquid level and pressure control configuration. The new model captures the effect of viscosity and surface tension on the LCO-OE and the effect of water cut on the onset of annular mist velocity. Comparison between the developed mechanistic model predictions for LCO-OE with the experimental data show a good agreement.
Estimating Fatigue Life of Thermowells in Supercritical Operation
Authors: Diwakar Philip , Liu Yuqing , Jaouhari Matt
Published: October 2018

Designing structures resistant to failure due to fluid induced vibration is a challenge. This paper shows a methodology of evaluating the cycles to failure of thermowells placed in a fluid flow through a large pipe in supercritical operation. The ASME PTC guide describes using Finite Element Analysis (FEA) to evaluate these conditions on a case by case basis. One case from several validated cases is presented using measurements available from the field.
Strength Analysis of PV Components on Solar Tanker Based on Fluid-Structure Interaction
Authors: Dongxu Zhang , Hong Li , Fangfang Xu
Published: October 2018

Solar energy, as a major source of clean energy, has gradually been applied in ship industry, but it has rarely been used in large transport vessels. This paper takes VLCC (Very Large Crude Carrier) as the study object and presents a design scheme of PV (photovoltaic) modules and their supports on the deck of an oil carrier. In accordance with current ship norms and standards, the rocking inertia force and wind pressures acting on both the PV modules and the supports at different wind velocities are computed using the finite element software of Ansys and Fluent, and the simulated wind pressures are compared to the formula-based calculation results. Stress and displacement of the supporting leg in marine environment are calculated and the supports is structurally optimized as well. In the end, a simulation method for checking the strength of the solar-powered oil carrier is presented, and the scheme of adding a knee plate to decrease stress concentration at the intersection of the three tubes of the leg is proposed.
Design and Multiparameter Optimization of Jet-Pumps in a Pipeline Loops Using CFD Tools
Authors: Toteff Jens , Asuaje Tovar Miguel
Published: October 2018

Despite their low efficiency compared with centrifugal pumps, jet-pumps are highly reliable robust equipment with modest maintenance which is ideal for many applications, mostly in the oil & gas industry. For example, jet-pumps could result attractive compared to other multiphase pump systems in terms of reactivating transport lines of heavy crude oil. Nevertheless, their design method and performance analysis are rarely known in the literature and keep a high experimental component like most of the pumping equipment. Starting with a pump designed by a traditional method, this paper aims to evaluate the effect of multiple geometrical and operational variables that influence the jet-pump performance combining CFD (Computational Fluid Dynamics) simulation and optimization algorithms using commercials software (ANSYS CFX® and PIPEIT® tool). Automatically, the geometric parameters are modified according to the rules of the optimization routines seeking to maximize the flow capacity, respecting restrictions such as energy consumption.

A case study is presented for the preliminary design of a pump to boost flow capacity in a trunk line of a heavy oil field. As preliminary design all simulations were carried out using single phase water flow. With this method, it was possible to quickly evaluate around 400 geometries of jet-pumps. The geometry of the optimum final pump is consistent with other pumps reported by other works. This pump enhances the fluid capacity of the line in 17% over the traditional design for the same parameters of power or consumed energy.
Dynamic Measurement of Liquid Sheet Formed by Impinging Jets via Partial Coherent Interferometry
Authors: Shang Weixiao , Chen Jun
Published: October 2018

In this work, the thicknesses of impinging liquid sheets formed by two alike impinging jets with different flow rates are investigated via a non-intrusive measurement technique, the Partial Coherent Interferometry. The Reynolds number and Weber number are 720 to 780 and 120 to 150, respectively. An interferometer with the calibrated partial coherence property is used to record the interference pattern by passing one branch of the two optical paths through the impinging sheet. By examining the phase and the degree of coherence of the pattern, the absolute thickness distribution of the impinging sheet is measured. The thicknesses with different experimental conditions are compared to the previous theoretical models and the influences of the flow rate and impinging angle are concluded.
Characterization of the Bag Breakup of Liquid Drop Using High-Speed Digital In-Line Holography
Authors: Yao Longchao , Chen Jun , Sojka Paul E. , Wu Xuecheng
Published: October 2018

Quantifying the early stage of bag-type breakup of droplet is an important way to study the mechanism of drop breakup, but remains a challenge due to the lack of spatial-temporal resolved diagnostic technique. High-speed digital in-line holography at 20 kHz is employed to characterize secondary droplets formed in bag rupture of an ethanol drop exposed in the gas stream. Droplets as small as 10 μm are resolved at the beginning of bag rupture at Weber number of 11. The velocities of secondary droplets can almost reach that of the gas stream. Then the thin wall shrinks to form wrinkles that will generate relatively larger secondary droplets with smaller velocities. Droplet diameters are statistically displayed and the relationship between velocity and diameter as well as time is analyzed. This will help the further understanding of fuel spray generation in gas turbine engines.
Blood Flow and Mixing Analysis in Split-and-Recombine Micromixer With Offset Fluid Inlets
Authors: Husain Afzal , Khan Farhan A. , Al-Rawahi Nabeel Z. , Samad Abdus
Published: October 2018

In this study, a variant of 3D split-and-recombine micromixer is proposed for enhanced micromixing. The mixing analysis was carried out for water and blood flows through the three-dimensional numerical model. The blood flow was modeled using several non-Newtonian fluid models existed in the literature and performance was compared for mixing index. Further, the performance of the proposed micromixer was compared with several other designs of micromixers available in the open literature for a wide range of Reynolds numbers covering diffusion, transient, and advection-dominated flow regimes. Finally, Carreau-Yasuda model was used to carry out parametric analysis of the proposed micromixer for mixing index.
Testing of a Cooling Fan for Wing-Bay Electro-Mechanical Actuators
Authors: Corona J. J. , Kwarteng A. A. , Warwick G. , Kaddoura K. , Mesalhy O. , Leland Q. H. , Chow L. C. , Kizito J. P.
Published: October 2018

The scope of the work is to develop a cooling system which uses wing-bay air to cool the Electro-Mechanical Actuators (EMA). The wing-bay is enclosed. The system will operate between 20% and 100% of atmospheric pressure. Using high speed fans as a means of cooling the EMAs it is important to understand the characteristics of the fan. The study also closely observed the results obtained experimentally with that of the fan scaling analysis. The fan laws can be derived from dimensionless analysis of volumetric flow rate, static pressure, and power equations. Considering the current experimental data, the fan scaling laws can be used to verify the proper nature of the fan curves when using a certain measurement at the baseline. In this study, the results have been verified for various rotational speeds and ambient pressure conditions. Consequently, there are two fans that have been tested within the loop. The first fan is a 2 bladed fan whereas the other fan has a 12 bladed propeller. The fan performance curves will determine the cooling capacities of each and provide a means to compare geometrically different fans.
Comparative Evaluation of Single/Twin Round and Elliptic Jets Using Particle Image Velocimetry
Authors: Aleyasin Seyed Sobhan , Tachie Mark Francis
Published: October 2018

Twin round and elliptic jets with nozzle spacing of S/d = 2.8 are investigated and the results are compared with those obtained from single jets. The measurements were performed at Re = 10000 using particle image velocimetry. The results show that the twin elliptic jets merge and combine faster than the round jets. However, the twin elliptic jets have lower spreading than their corresponding single jet but in the round jets it is opposite. The vortical structures obtained using swirling strength analysis are more intense in the elliptic jets compared with the round jets; consistent with their higher spreading. In the shear layers, the velocity skewness is considerably positive due to the diffusion of high-speed jet fluid towards the ambient. On the other hand, the streamwise skewness on the centerline is negative because of the entrainment of low-speed ambient fluid; resulting in centerline velocity decay. In addition, the joint and weighted joint probability density functions are used to understand the dominant events which contribute into the mixing of the jets with their surrounding fluid.
Investigation on Loading-Induced Fluid Flow in Osteogenesis Imperfecta Bone
Authors: Shrivas Nikhil V. , Tiwari Abhishek Kumar , Kumar Rakesh , Tripathi Dharmendra , Sharma Vasu Raman
Published: October 2018

Osteogenesis Imperfecta (OI) is a genetic bone disorder which is typically characterized by brittle bones with frequent fractures. It is also known as brittle bone disease. Surgical procedure is one of the ways adopted by clinicians for the management of OI. In recent years, it has however become clear that physical activity is equally important for managing OI in both children and adults. Exogenous mechanical stimulation e.g. prophylactic exercises may be useful in improving the bone mass and strength of OI bones as loading-induced mechanical components e.g. normal strain and canalicular fluid flow stimulate remodeling activities. Several studies have characterized the strain environment in OI bones, whereas, very few studies attempted to characterize the canalicular fluid flow. In the present study, we anticipate that canalicular fluid flow reduces in OI bone as compared to healthy bone under physiological loading. This work accordingly computes the canalicular fluid distribution in the single osteon model of OI and control/normal bones subjected to normal physiological loadings. A transversely isotropic poroelastic model of osteon is developed. Loading is applied in accordance with gait cycles reported for OI and healthy bones. Fluid distribution patterns computed for OI and healthy bones are compared at different time-points of stance phase of the gait cycle. A significant reduction in fluid flow is observed in case of OI bone as compared to healthy bone. This clearly indicates that improvements in physical activities or exercises can be designed to enhance the level of canalicular fluid flow to initiate possible osteogenic activities and the bone.
Influence of Pulsating Flow on Turbine Performance Investigated by DES and PIV
Authors: Nakamura Yohei , Chinen Manato , Sakakibara Masamichi , Miyagawa Kazuyoshi
Published: October 2018

Recently, the downsizing of engine using turbocharger attracts more and more attention. Generally speaking, a turbocharger is usually designed based on its steady performance curve. However, the operating point of a turbocharger turbine does not match the steady operating point: instead it shows hysteresis behavior because of the pulsating flow generated by the engine valves. Unfortunately, turbine efficiency drops under pulsating flow conditions, but the loss mechanisms of the turbine under these conditions are not understood. Internal flow measurements under pulsating flow are actually very difficult. In this study, the internal flow under pulsating conditions was measured using a high speed PIV (Particle Image Velocimetry) system. The loss mechanisms were investigated by experimental investigation and computational fluid dynamics (CFD). The instantaneous pressure, velocity and torque were measured using a turbine experimental apparatus at WASEDA University. To generate the pulsating flow, a pulse generator was placed upstream of the turbine: a rotational disk with holes that only lets the flow through periodically. The pulsating frequency could be changed freely by changing the rotational speed of the disk. The visualization using PIV was performed at a frequency of 1 kHz at the turbine outlet.

Many fine vortices which rotate in various directions were observed under pulsating flow. Such vortices mix in the exhaust diffuser and under low frequency flow, mixing of vortices took a long time. It was observed that one loss mechanism under unsteady conditions is the mixing of vortices at the turbine outlet.

CFD was performed using ANSYS-CFX, with approximately 10 million nodes. Turbulent flows were treated by using the Reynolds-averaged Navier-Stokes (RANS) and Detached Eddy Simulation (DES) with the SST k-ω turbulence model.

It was confirmed that the wheel and exhaust diffuser total pressure loss under pulsating flow was higher under steady flow conditions. In addition, the total pressure loss is proportional to the flow pulsation frequency. The analysis with DES agreed with the PIV results qualitatively. On the other hand, the analysis with RANS could not simulate the flow pattern at the turbine outlet.
The Influence of Heat Source Orientation on PCM Flow Behavior During Phase Transition
Authors: Jevnikar Steven , Siddiqui Kamran
Published: October 2018

The present study reports the characterization of the transient flow behavior in the liquid PCM domain during the melting process, initiated by a planer heat source. Experiments were conducted at three angles of inclination of the heat source (0, 8 and 18-degrees) from the vertical. Paraffin wax was used as the PCM and was enclosed in an insulated, optically clear, thin rectangular chamber. Particle image velocimetry (PIV) was used during the melting process to measure the instantaneous velocity of the PCM and obtain two-dimensional velocity fields within the liquid domain. Results clearly show the presence of a dominant recirculation zone occurring at all angles. This recirculation zone was enhanced by an increase in the inclination of the heat source, supporting a direct correlation between the tilt angle and the bulk fluid flow in the melted region. The melting rate decreased with the progression of time for all investigated cases. A growing region of stagnant fluid flow within the center of the recirculation zone contributed to the reduction in the melt rate. The size of this stagnant region decreased with increases in the tilt angle due to the enhancement of natural convection. The data demonstrates significant changes in transient flow behavior with orientation in the liquid PCM domain. These results further our understanding of the phase change and associated heat transfer processes in PCM and have wide applicability to PCM-based thermal energy storage.
A Combined Small Modular Reactor and Gas Turbine Cycle With Reheat
Authors: Stakenborghs Robert , Kramer Gregory
Published: October 2018

A novel combined small modular reactor (SMR) and gas turbine cycle is presented. This SMR-GT cycle is modeled using fundamental thermodynamic relationships and compared to existing state-of-the-art power generation cycles. The SMR-GT cycle includes an 82 MWe SMR cycle that is combined with a 54 MWe gas turbine cycle. A heat exchanger is used to extract energy from the gas turbine exhaust to create superheated main steam and provide reheat downstream of the LP turbine. This results in a 32 MWe increase in the SMR cycle for total unit output of 136 MWe.

Comparisons of thermal efficiency, heat rate, CO2 emissions, and net generation are made between a stand-alone SMR, a typical combined cycle gas turbine (CCGT), standalone gas turbine and the combined SMR-GT cycles. Several advantages of the SMR-GT cycle are discussed.

In addition, the rapid deployment of a gas turbine allows for a power station to deliver power and earn revenue prior to completion of the more complex SMR portion of the plant. The SMR portion of the cycle also reduces the overall fuel cost volatility associated with gas turbine based power station.
Overview of the U.S. Department of Energy Advanced Waste Forms Development
Authors: Gray Kimberly , Vienna John , Paviet Patricia
Published: October 2018

In order to maintain the U.S. domestic nuclear capability, its scientific technical leadership, and to keep our options open for closing the nuclear fuel cycle, the Department of Energy, Office of Nuclear Energy (DOE-NE) invests in various R&D programs to identify and resolve technical challenges related to the sustainability of the nuclear fuel cycle. Sustainable fuel cycles are those that improve uranium resource utilization, maximize energy generation, minimize waste generation, improve safety and limit proliferation risk. DOE-NE chartered a Study on the evaluation and screening of nuclear fuel cycle options, to provide information about the potential benefits and challenges of nuclear fuel cycle options and to identify a relatively small number of promising fuel cycle options with the potential for achieving substantial improvements compared to the current nuclear fuel cycle in the United States. The identification of these promising fuel cycles helps in focusing and strengthening the U.S. R&D investment needed to support the set of promising fuel cycle system options and nuclear material management approaches. DOE-NE is developing and evaluating advanced technologies for the immobilization of waste issued from aqueous and electrochemical recycling activities including off-gas treatment and advanced fuel fabrication. The long-term scope of waste form development and performance activities includes not only the development, demonstration, and technical maturation of advanced waste management concepts but also the development and parameterization of defensible models to predict the long-term performance of waste forms in geologic disposal. Along with the finding of the Evaluation and Screening Study will be presented the major research efforts that are underway for the development and demonstration of waste forms and processes including glass ceramic for high-level waste raffinate, alloy waste forms and glass ceramics composites for HLW from the electrochemical processing of fast reactor fuels, and high durability waste forms for radioiodine.