bluuebunny/crossref_metadata_2025 huggingface dataset:
Innovation in Product Form and Function: Customer Perception of Their Value
Authors: Kim Taehyun , Okudan Gu¨l E. , Ertek Gu¨rdal
Published: July 2010

The goal of product design is to obtain the maximum effect with minimum cost in functionality and aesthetic beauty. Consumers are attracted to the designs that reflect their use behaviors and psychological responses more than they are to the simple visual representations. When product functions and qualities are similar across products, customers make their purchasing decision upon aesthetic form. Form presents a significant competitive factor that improves the value of a product. Overall, the purpose of this study is to examine the most important product design factors that affect the market share trends of mobile phone companies. Study uses product characteristics for 1,028 mobile phones released between 2003 and 2008 as a case study. Multiple linear regression analysis is used to select highly correlated variables that influence the market share, and Mallow’s Cp method is used to determine the best-fitting model. The Partial Regression Coefficients are used to evaluate the relative importance of design criteria. The nine mobile phone design features that affect the market share were identified, and the block form style is determined as the most important design factor. Using these approaches, this study demonstrates how investments should be directed in the next mobile phone design process.
Design and Development of a Chipscale Multifingered Micromanipulator System for Coordinated Microassembly
Authors: Krishnan Sandeep , Pelzmann Christopher , Saggere Laxman
Published: July 2010

This paper presents the design and fabrication of a novel chipscale micromanipulator with multiple fingers that can be independently actuated and coordinated to manipulate and assemble micro-scale objects within a predefined workspace on the chip. The manipulator chip has an overall footprint of 5 mm × 5 mm and the workspace area for micromanipulation is about 4600 μm2. The micromanipulator is integrated with tiny piezoelectric actuators and enclosed in a specially designed and precision machined compact housing, which has an overall size of 5 cm × 5 cm × 1.5 cm, to isolate the workspace area of the manipulator to minimize external disturbances. The topology and shape of the miltifingered micromanipulator chip were obtained through a systematic design optimization process maximizing the operating workspace of the micromanipulator, and a prototype was fabricated in silicon using the standard microfabrication processes. Preliminary experiments have confirmed the predicted behavior of the micromanipulator fingers as well as the feasibility of controlling multiple fingers to achieve a coordinated action to grasp a micro-scale object as commanded by the user.
Multifunctional Enterprise Readiness: Beyond the Policy of Build-Test-Fix Cyclic Rework
Authors: Tang Victor , Otto Kevin N.
Published: July 2010

NASA, the US Government and many companies attempt to manage the development and launch of new technology using Technology Readiness Levels, TRLs. Unfortunately, TRLs as generally defined are outdated and flawed, based on the extent of prototype or hardware use in the field. Urgency in improving TRL levels drives early release of hardware before it is ready, and initiates cyclic rounds of debugging and fixing failures in the field or laboratory. Such a build-test-fix approach to product development is now well documented to be inefficient and wasteful. We present updated definitions of technology readiness levels (TRLs) based on the lean and design-for-six-sigma product design methodology, a radical departure from the “build-test-fix” methodology of conventional TRLs. We argue that the iterative build-test-fix approach of cyclic rework is costly to product development, as well as, downstream manufacturing and services. We call our updated TRL the L-TRL, for Lean TRL. Consistent with our L-TRL, we also present updated definitions for Manufacturing Readiness Levels (MRLs) to address lean and six-sigma manufacturing principles. Hence we call them L-MRL. We address a void in the literature and unveil definitions for service readiness levels (SRLs).
Assessing Fusibility in Enrichment Methods for Disparate Customer Data Sets
Authors: Ghotbi Sina , Scott Michael J. , Donndelinger Joseph A.
Published: July 2010

Model fusion of results from disparate survey methodologies is a topic of current interest in both research and practice. Much of this interest has centered on the enrichment of stated-preference results with revealed-preference data, or vice versa, as it is considered that stated preference methods provide more robust trade-off information while revealed preference methods give better information about market equilibria. The motivation for this paper originates in the automotive industry, and is distinct in that it focuses on the reuse of existing data. Practitioners wish to glean as much information as possible from a large body of existing market research data, which may include minimally overlapping datasets and widely varying survey types. In particular, they wish to combine results from different types of stated preference methods. This paper presents two advancements in model fusion. One is a method for reducing data gathered in open-ended methods such as van Westendorp studies to a form amenable to analysis by multinomial logit, thus enabling the comparison of open-ended data to conjoint data on overlapping data sets. The other is a new statistical test for the fusibility of disparate data sets, designed to compare different methods of data comparison. This test is less sensitive than existing tests, which are most useful when comparing data sets that are substantially similar. The new test may thus provide more guidance in the development of new methods for fusing distinct survey types. Two examples are presented: a simple study of cell phone features administered as a test case for this research using both choice-based conjoint and van Westendorp methodologies, and a pair of existing larger-scale studies of automotive features with some attributes common to both studies. These examples serve to illustrate the two proposed methods. The examples indicate both a need for continued testing and several potentially fruitful directions for further investigation.
Design Curves Utilized for Production Levels Associated With an Ultrafiltration Process
Authors: Foust Henry , Ghosehajra Malay
Published: July 2010

In this paper, an equation for permeate rates associated with dead-end filtration is shown to be applicable to a pilot scale study of an ultrafiltration process being designed and built at the Hanford Department of Energy facility. This permeate rate equation was utilized in mass balance equations for mass of solids and sodium within the system, and forms the basis for design curves to determine the minimal membrane surface area for a prescribed treatment time and other conditions.
Pilot-Scale Hydraulic Testing of Resorcinol Formaldehyde Ion Exchange Resin
Authors: Adamson Duane J.
Published: July 2010

Savannah River National Laboratory (SRNL) performed pilot-scale hydraulic/chemical testing of spherical resorcinol formaldehyde (RF) ion exchange (IX) resin for the River Protection Project-Hanford Tank Waste Treatment & Immobilization Plant (WTP) Project. The RF resin hydraulic cycle testing was conducted in two pilot-scale IX columns, 1/4 and 1/2 scale. A total of twenty-three hydraulic/chemical cycles were successfully completed on the spherical RF resin. Sixteen of these cycles were completed in the 24″ IX Column (1/2 scale column). Hydraulic testing showed that the permeability of the RF resin remained essentially constant, with no observed trend in the reduction of the permeability as the number of cycles increased. The permeability during the pilot-scale testing was 3 times better than the design requirements of the WTP full-scale IX system. The RF resin bed showed no tendency to form fissures or pack more densely as the number of cycles increased. Particle size measurements of the RF resin showed no indication of particle size change (for a given chemical) with cycles and essentially no fines formation. The permeability of the resin bed was uniform with respect to changes in bed depth. Upflow Regeneration and Simulant Introduction in the IX columns revealed another RF resin benefit; negligible radial pressures to the column walls from the swelling of resin beads. The hydraulic and chemical performance of the spherical RF resin during cycle testing was found to be superior to all other tested IX resins. The pilot-scale testing indicates that the RF resin is durable and should hold up to many hydraulic cycles in actual radioactive Cesium (Cs) separation.
Repeatability of Gas Holdup in a Fluidized Bed Using X-Ray Computed Tomography
Authors: Drake Joshua B. , Heindel Theodore J.
Published: July 2010

Characterizing the hydrodynamics in fluidized beds is important to many processes from producing biofuels to coating pharmaceuticals. X-ray computed tomography (CT) can quantify local time-averaged phase fractions in multiphase systems that are highly dynamic, like fluidized beds. This paper describes the calibration methods used to produced CT images of a 15.24 cm diameter fluidized bed, how in-house software used these CTs to calculate gas holdup, and how well multiple CTs of a dynamic fluidized bed produced repeatable results while varying bed material and superficial gas velocities. It was concluded there is a very high degree of repeatability using the calibration methods and in-house software developed.
Molecular Tagging Techniques for Micro-Flow and Micro-Scale Heat Transfer Studies
Authors: Hu Hui , Koochesfahani Manoochehr
Published: July 2010

We report recent progresses made in development of novel molecule-based flow diagnostic techniques, named as Molecular Tagging techniques, to achieve simultaneous measurements of multiple important flow variables (such as flow velocity and temperature) for micro-flows and micro-scale heat transfer studies. Instead of using tiny particles, specially-designed phosphorescent molecules, which can be turned into long-lasting glowing molecules upon excitation by photons of appropriate wavelength, are used as tracers for both velocity and temperature measurements. A pulsed laser is used to “tag” the tracer molecules in the regions of interest, and the movements of the tagged molecules are imaged at two successive times within the photoluminescence lifetime of the tracer molecules. The measured Lagrangian displacement of the tagged molecules between the two image acquisitions provides the estimate of the fluid velocity vector. The simultaneous temperature measurement is achieved by taking advantage of the temperature dependence of phosphorescence lifetime, which is estimated from the intensity ratio of the tagged molecules in the two images. The implementation and application of the MTV&T technique are demonstrated by conducting simultaneous velocity and temperature measurements to qunatify the transient behavior of electroosmotic flow (EOF) inside a microchannel and to reveal the unsteady heat transfer, mass transfer and phase changing process inside micro-sized water droplets pertinent to wind turbine icing phenomena.
Unsteady Flow Numerical Simulation in a Double Channel Pump and Measurements of Pressure Fluctuation at Volute Outlet
Authors: Liu Hou-lin , Lu Ming-zhen , Lu Bin-bin , Tan Ming-gao , Wang Yong , Wang Kai
Published: July 2010

Adopting the Reynolds averaged Navier-Stokes equation and RNG k-ε turbulent model, the unsteady flow in the double channel pump is simulated with sliding mesh technique. Detecting points in the impeller and volute passages are to capture the pressure fluctuation law at different time. The pressure fluctuation around the outlet of the volute is measured by pressure transducer, then the frequency domain pattern under different conditions comes out. With the Fast Fourier transform (FFT) analysis, the pressure changing law of time domain at the outlet of the volute is investigated under different operating conditions. It shows that the pressure fluctuation in the volute differs under different conditions. The pressure changing law obtained by the numerical simulation at the outlet of the volute accords with the measurement results. Also the pressure fluctuation at the outlet of the volute is closely related to the interaction between impeller and volute.
Compressible Advection Through an Elastomer Seal: A Porous Media Approach to Seals for Space Applications
Authors: Garafolo Nicholas G. , Daniels Christopher C.
Published: July 2010

Gas permeability characterization is of the utmost importance in space seals applications. Space seals must maintain acceptable mass losses in harsh environments where temperatures widely vary under vacuum conditions. Silicone elastomers are commonly used in space as they offer significant sealing performance at temperature extremes and are capable of meeting stringent outgassing requirements necessary for vacuum environments. Traditional models of leak rates solely rely on a diffusive transport mechanism; mass is transported across a membrane through molecular flow induced by a concentration gradient under isostatic conditions. In the application of space seals, the pressure gradients are large, resulting in advection dominated transport. Conventional applications of advection utilize Darcy’s law; however, the fluid is assumed incompressible and fails to capture the nonlinear pressure gradient under compressible situations. Consequently, employing Darcy’s law incorrectly predicts the leak rate. A novel model in compressible advection through an elastomer seal is presented. A phenomenological approach is taken to determine the specific discharge. Through the conservation of mass, the governing equation for pressure is derived. An exact analytical solution exists for one-dimensional flow in the form of a Generalized Emden-Fowler equation and as a result, an analytical expression for mass flow is developed. A series of experiments is presented to deduce permeability constants and Klinkenberg parameter of silicone S0383-70 under one-dimensional flow conditions. The leak rates of the model and experiments are compared. Through the presented compressible advection model, the mass leak rate of any candidate seal geometry can be evaluated.
Synthetically Aerodynamic Design and Optimization on the Stationary Units of Centrifugal Compressor
Authors: Wang Rui , Qi Datong , Mao Yijun
Published: July 2010

The operating efficiency of a centrifugal compressor installed in air-separation plant was lower than the design parameter. In order to analyze the cause, a flow simulation on the whole centrifugal compressor was carried out on a parallel computational platform. The numerical results show that the inefficiency of the compressor was mainly caused by the flow loss in the stationary units. A synthetically aerodynamic redesign and optimization on the stationary units of the centrifugal compressor was performed to improve its polytrophic efficiency. Firstly, radial splitter vanes were appended in the flow passage of suction chamber to balance the flow loss and depress inlet flow distortion. Secondly, the meridian curve of the crossover and return channel was numerically optimized by using a combined neural network and genetic algorithm (GA) approach. Lastly, the b3/b2 of the vaneless diffuser was advanced to improve its total pressure recovery coefficient. An experimental measurement was carried out to validate the coupling effect of the improved stationary units to the centrifugal compressor performance. The experimental result shows that 4% advancement of the polytrophic coefficient of the centrifugal compressor has been achieved.
Research on the Theory and Design Methods of the New Type Submersible Pump for Deep Well
Authors: Shi Wei-dong , Lu Wei-gang , Wang Hong-liang , Li Qi-feng
Published: July 2010

Submersible pump for deep well, widely used in the countryside, mines, geothermal utilization and so on, are the main equipment for pumping underground water. Due to the working conditions, the pump diameter is limited by the well diameter, and the single-stage head designed by traditional methods is low. In order to increase the single-stage head, the maximum diameter design method of impeller was created for the first time. The impeller front shroud diameter is almost equal to the inner casing diameter, and the back shroud diameter is almost the average of the impeller front shroud diameter and the guide vane shroud diameter. The blade extends to the impeller inlet to lengthen the back shroud streamline, which could prevent the back flow at the impeller outlet, and the front shroud is designed in a cone shape to make the outlet streamline upward, by which the pump efficiency increases. A new return guide vane with twisted inlet and 3D curved surface was designed to reduce the cost, and the hydraulic loss. The self-balancing design method of impeller axial thrust was accomplished by using the end-face seal at the impeller inlet and adopting the sliding fit between the pump shaft and impeller; the impeller axial thrust is self-balanced because the areas of the impeller front shroud and back shroud are almost equal. The interior flow was simulated based on Fluent RANS CFD, both numerical simulation and test results showed that the performance of the new type well pump was better than the traditional products. A series of submersible pumps for deep well were designed, manufactured and tested, compared to the similar products at market home and abroad, the single-stage head increases 20% to 50%, the efficiency increases 3% to 9%, and the whole axial length and weight decreases around 1/3.
Design of High-Speed Magnetic Pump Based on the Numerical Simulation
Authors: Kong Fanyu , Wang Zhiqiang , Gao Cuilan , Zhang Hongli
Published: July 2010

The high-speed magnetic pump has the characteristic of zero leakage, small volume and high efficiency. In order to enhance the performance of high-speed magnetic pump and shorten the design period, the hydraulic components and magnetic coupling are designed on the basis of numerical simulation. The hydraulic components designed initially are applied by the design method of high-speed partial emission pump. The internal flow field of the pump is simulated with the FLUENT CFD software. The distributions of absolute velocity, relative velocity and total pressure of pump are gained. The inlet structure and geometry of the magnetic pump are modified based on the simulation results. The magnetic coupling is designed by using empirical factors. The magnetic field of the magnetic coupling is simulated with 2-D Magnetic Vector Potential (MVP) formula using the ANSYS software. The distributions of magnetic force line at origin, working situation and maximum magnetic rotating angle are obtained. The magnetic torque simulated value approaches the result calculated with the empirical formula. The test results of the improved magnetic pump show that the hydraulic performance and outline dimensions meet requirements. The method of design-simulation-improvement-test is successful.
Controlling and Monitoring Tool for Reliable and Optimal Operation of Boiler Feed Water Pump
Authors: Ahmed Sohail , Leithner Reinhard , Kosyna Guenter , Wulff Detlev
Published: July 2010

Challenges of operational safety and reliability as well as optimal operation of boiler feed water pump define the requirement of a competent and efficient controlling as well as monitoring tool. The monitoring module of this tool should effectively record the life time consumption of both casings and rotors and also monitor the small gaps between casings and rotors. The controlling module of this tool should ensure the safety and reliability during the operation of the boiler feed water pump based on the feed back from the monitoring module and also should take appropriate actions in order to ensure that the pump operates within the allowable design limits. This tool could enable operators to start up the boiler feed water pump without any unnecessary waiting period and change load rapidly without causing any damage or any life consumption rate getting increased. In this research paper, the methodology of such a tool is explained, having monitoring as well as controlling modules. Similar monitoring and controlling tools, as presented in the paper, can be applied to all turbomachines e.g. gas turbines, steam turbines, compressors etc.
Effect of Nanoscale Additives on External Gear Pump Performance
Authors: Martorana Philip J. , Bayer Ilker S. , Steele Adam , Loth Eric
Published: July 2010

In this study, the effect of ultrafine graphite and multi-walled carbon nanotube (CNT) additives on the performance of an external gear pump was investigated. Colloidal suspensions of each additive were created in ethanol with concentrations varying from 200 ppm to 1550 ppm, low enough that there was no significant change in the viscosity of the solution. These solutions were run through a hydraulic closed loop equipped with a 0.5 HP/1725 RPM external gear pump. Pressure, volumetric flow rate, temperature, and electric power consumption data were recorded for each additive concentration. An increase of up to 0.75 L/min in volumetric flow rates over the baseline ethanol case (additive concentration of 0 ppm) was observed for certain concentrations of graphite and CNTs, possibly suggesting reduced internal leakage or improved lubrication. As opposed to conventional viscosity modifiers which showed similar improvements, these nanostructrued additives had no effect on the viscosity of the working fluid. The surface morphology of the graphite and the CNTs was examined both prior to and after pumping the solutions through the gear pump by taking scanning electron microscopy (SEM) images of the additives after allowing a solution sample to evaporate on a microscope slide.
Analytical Solutions for Laminar Fully-Developed Flow in Microchannels With Non-Circular Cross-Section
Authors: Tamayol A. , Bahrami M.
Published: July 2010

Analytical solutions are presented for laminar fully-developed flow in micro/minichannels of hyperelliptical and regular polygonal cross-sections. The considered geometries cover a wide range of common simply connected shapes including circle, ellipse, rectangle, rhomboid, star-shape, equilateral triangle, square, pentagon, and hexagon. Therefore, the present approach can be considered as a general solution. Predicted results for the velocity distribution and pressure drop are successfully compared with existing analytical solutions and experimental data collected from various sources for a variety of geometries, including: polygonal, rectangular, circular, elliptical, and rhombic cross-sections.
Unsteady Flow Field in the Wake of an Airfoil
Authors: Sadeghi Hamed , Mani Mahmoud
Published: July 2010

An experimental investigation was carried out to study the unsteady flow field behind a sinusoidally pitching airfoil at reduced frequencies 0.091, 0.182 and 0.273. Streamwise instantaneous velocity and streamwise mean velocity in the wake were measured by hot-wire anemometer at downstream distance from trailing edge of 0.25 chord. To assess the effect of mean incidence, data were taken at mean incidence angles of 0, 2.5 and 5 degrees. In all cases, the oscillation amplitude was set at 8 degree, and the Reynolds number, based on the chord length, was 50000. It is found that the mean incidence angle and reduced frequency have important influences on the instantaneous velocity profiles. As reduced frequency increases, more uniformity and stability in the wake are observed. When mean incidence angle is larger, more variations on thickness of profiles and velocity defect are found. Furthermore, mean velocity profiles and estimations of the momentum deficit coefficients are obtained. The results show that with increasing mean incidence, the velocity defect and momentum deficit increase. Instead, the higher reduced frequency decreases the momentum deficit and wake thickness.
Turbulence Model Investigation of Water Flow in Rough Micro Channels
Authors: Zadeh Shobeir Aliasghar , Radespiel Rolf
Published: July 2010

Three-dimensional laminar and turbulent water flows in smooth and rough micro channels with rectangular cross-section were numerically simulated. The hydraulic diameter of the smooth micro channel is 190 μm and 191 μm for the rough one. The roughness inducing surfaces, which were modelled by three rectangular elements placed on the sidewall of the micro channel, are 50 μm high and 50 μm wide. The simulations were conducted for Reynolds numbers between 100 and 4000. The effects on the friction factor and flow characteristics due to the roughness elements, varying Reynolds numbers and low-Reynolds number turbulence models were investigated and compared with the experimental values reported by Hao et al. [1]. Furthermore, the velocity profiles in various Reynolds number and flow regimes have been compared with μPIV measurements. At Reynolds numbers less than 2100 the computed friction factors in the smooth micro channel agree well with the measurements and the values of the conventional theory. For the micro channel with roughness elements, the friction factor approaches the value of measurements and conventional theory, when Re < 900. Transition from laminar to turbulent flow occurs at about Reynolds numbers of 2100 and 900 in smooth and rough micro channel, respectively. Comparison of simulated results using the Spalart-Allmaras and SST K-ω turbulence models with experimental values show good agreement. By contrast, the K-ε model overestimates the pressure loss in micro channels.
Effect of Bubble Size and Angle of Tapered Upriser Pipe on the Effectiveness of a Two Phase Lifting Pump
Authors: Hanafizadeh P. , Saidi M. H. , Zamiri A. , Karimi A.
Published: July 2010

Two phase lifting pumps are devices with the ability of lifting liquid phase by injecting the gas phase. Parameters which affect the performance of these pumps are divided into two groups. The first group contains design parameters such as diameter of the pipe, tapering angle of the upriser pipe and the submergence ratio which is the ratio of immersed length to the total length of the upriser. The second group includes operating parameters, such as the gas flow rate, bubble diameter, bubble distribution and inlet gas pressure. In this research, the performance of two phase lifting pump is investigated numerically for different submergence ratios and different diameter of the upriser pipe. For this purpose the two phase pump with a riser length of 914 mm and different diameters (6, 8 and 10 mm), and seven tapering angles (0°, 0.25°, 0.5°, 1°, 1.5°, 2° and 3°) are numerically modeled and analyzed. Different submergence ratios are used, namely: 0.4, 0.6 and 0.8. The numerical results are compared with the existing experimental data in the literature showing a reasonable agreement. The results indicate that decrease in size of the bubble diameter increases mass flow rate of liquid at constant submergence ratios. The present study reports the improved performance of this pump with decrease in bubble size and increase in angle of tapered upriser pipe. Moreover, the results show that the tapered upriser pipe with 3° tapering angle gives the highest efficiency at nearly all submergence ratios. Further, the highest efficiency of the pump is shown to be at the largest submergence ratio, namely 0.8.
Influence of Tip Shape on Structure of Wing-Tip Vortex at Low Reynolds Numbers
Authors: Kamari Djavad , Tadjfar Mehran
Published: July 2010

An important phenomenon in three-dimensional flow over a wing is the existence of wingtip vortex. It has significant effects on the aerodynamics of flying vehicles. In this computational study, we investigate the effects of geometry of the wingtip on the structure of the wing-tip vortices. Here, we consider a rectangular half-wing with NACA0012 airfoil as cross section. The aerodynamic coefficients and the flow-field variables are computed at low Reynolds numbers below 50,000. As the edge-shape parameter is increased the wing tip vortex is weakened. This influence is higher at higher values of Reynolds number. But, the increase of angle of attack does not change the shape or rate of this increase.
Analysis of Francis Pump-Turbine Runner Cavitation Flows in Pump Mode
Authors: Zhang Lanjin , Jing Xingying , Wang Zhengwei , Chang Jinshi , Peng Guangjie
Published: July 2010

Pump-turbine works in pump and turbine modes, and its hydraulic performance in pump mode is more important than that in turbine mode. The cavitation is an important factor influencing hydraulic performance in pump, especially when designing the runner. The paper studies pump cavitation flow of model pump-turbine runner and its cavitation performance. That can be a method to help design and chose pump-turbine runner. The hydraulic performance and cavitation is analyzed in different net positive suction head (NPSH) and discharge. The result shows that NPSH simulated by cavitation flow is better than that simulated by no cavitation flow. The simulation result also shows that cavitation places near the band of pump blade inlet on suction side when the pump discharge is small, and cavitation sites near the band of pump blade inlet on pressure side when the discharge is large. The hydraulic performance of pump runner will not change until water vapor accounts for about 42 percent of total volume.
Three-Dimensional Laminar Wall Jet Flows
Authors: Adane Kofi K. , Tachie Mark F.
Published: July 2010

The present article reports on both experimental and numerical study of three-dimensional laminar wall jet flows. The wall jet was created using a circular pipe of diameter 7 mm and flows into an open channel. The Reynolds numbers based on the pipe diameter and jet exit velocity were varied from 310 to 1300. A particle image velocimetry (PIV) was used to conduct detailed velocity measurements at various streamwise-transverse and streamwise-spanwise planes. A complete nonlinear incompressible Navier-Stokes equation was also solved using a co-located finite volume based in-house computational fluid dynamic (CFD) code. This code was used to compute the experimental flow geometry. From the PIV measurements and CFD results, velocities profiles and jet-half-widths were extracted at selected locations. It was observed that the numerical results are in reasonable agreement with the experimental data. The distributions of the velocities, jet-half-widths and visualisation of the secondary flows were used to provide insight into the characteristics of three-dimensional wall jet flows.
Investigation of Internal Flow and Characteristic Instability of a Mixed Flow Pump
Authors: Miyabe Masahiro , Furukawa Akinori , Maeda Hideaki , Umeki Isamu
Published: July 2010

The relationship between pump characteristic instabilities and internal flow was investigated in a mixed flow pump with specific speed of 700 (min−1 m3/min, m) or 1.72 (non-dimensional) by using a commercial CFD code and a dynamic PIV (DPIV) measurement. This pump has two positive slopes of a head-flow characteristic at the flow rates of about 60%Qopt and 82%Qopt. In the authors’ previous study, it was clarified that the characteristic instability at 82%Qopt is caused by the diffuser rotating stall (DRS) and the backflow near the hub of the vaned diffuser plays an important role on the onset of the diffuser rotating stall. In the present paper, the investigation is focused on the instability at about 60% Qopt. Based on both of experimental and numerical results, it was clarified that the characteristic instability at 60%Qopt is caused by the backflow at the inlet of the impeller tip and the leakage flow from the impeller pressure surface to the suction surface plays an important role on the onset of the backflow. The behaviors of backflow at the impeller inlet were visualized by the DPIV measurements and CFD simulation. Moreover, internal flow was investigated in detail and the occurrence of characteristic instability is assumed as follows: At the partial flow rate, the flow angle at the inlet of the impeller tip decreases and the flow hits the impeller pressure surface. Then, the blade loading at the inlet of impeller tip is increased and the recirculation at the leading edge and the leakage flow rate from pressure surface to suction surface increases. The leakage flow causes to generate vortices at the inlet of the suction surface of the impeller. As the flow rate is further decreased, the vortices develop to backflow with swirl. The leakage flow has peripheral component of absolute velocity and the swirling energy is continuously supplied by the backflow. Therefore, even the passage flow at the inlet of the impeller has been getting pre-swirling. The theoretical head, the Euler head is decreased due to the pre-swirling. Moreover, based on the CFD results, the pre-swirling and unsteady vortices near the suction surface of the impeller causes pump characteristic instability. When the flow rate is decreased further more, total head rises because the flow pattern in the impeller changes to centrifugal type due to the backflow from the vaned diffuser at the hub region.
Open Channel Flow Over Pairs of Rectangular and Streamlined Cylinders at Incidence
Authors: Agelinchaab M. , Tsikata J. M. , Tachie M. F. , Katopodis C.
Published: July 2010

This paper reports an experimental investigation of the mean flow and turbulence characteristics around pairs of identical rectangular and streamlined cylinders in an open channel. The cylinder pairs were inclined at different angles of incidence angles relative to the streamwise direction of the approach flow. The rectangular cylinders and the 12% symmetric airfoils cylinders are made of transparent acrylic plates of length, L = 100 mm and maximum thickness, D = 12 mm. The centre-to-centre spacing between the cylinders was 51 mm. The blockage ratio produced by the cylinder pairs was 0.13 at zero angle of incidence. For each cylinder pair inclination, a high resolution particle image velocimetry technique was used to conduct detailed velocity measurements in the streamwise-spanwise plane. From these measurements, iso-contours and profiles of the mean velocities and turbulence statistics were obtained to study the effects of cylinder geometry and inclination on the flow around the cylinder pairs.
Experimental Study of Airflow Around the Syracuse CoE Building
Authors: Kehs Joshua , Bohl Dougal , Ahmadi Goodarz , Tavakoli Behtash
Published: July 2010

The Center of Excellence (CoE) in Environmental and Energy Building in Syracuse is currently under construction and is planned for completion in 2009. In this study, wind tunnel experiments of the CoE Building were performed. A 3D CAD model was created from architectural blueprints and was used to create a scale (1/16th inch = 1 foot) physical model using the stereo-lithography techniques. The details of the building structure were captured in the model for features with characteristic lengths greater than 1% of the building height. The physical model included 54 surface pressure taps located over the model’s exterior surface. The model was installed on a turntable built into the floor of the wind tunnel. Pressure measurements were taken at several wind speeds for different wind directions. PIV measurements were performed in 2 planes for the same wind directions and speeds. From the PIV measurements, 2D mean and root-mean square (RMS) velocities mean and RMS vorticity were calculated. The experimental data was compared with the computer simulation study and good agreement was found.
Computational Modeling of Airflow and Particulate Pollutant Transport Around the Syracuse CoE Building
Authors: Tavakoli Behtash , Ahmadi Goodarz , Bohl Doug , Kehs Joshua
Published: July 2010

A computer model for analyzing the airflow and particle transport and deposition around the Center of Excellence (CoE) Building in Syracuse was developed. The k-ε and the k-ω turbulence models in addition to the Reynolds stress transport model was used in the analysis. The airflow fields for the wind tunnel scale model of the building were simulated for different wind speeds and various directions including north to south and west to east. The computer pressure and velocity fields were compared with the corresponding experimental data obtained by Particle Image Velocimetry (PIV) and good agreement was found. Applications of the computational model for predicting particulate pollutant dispersion and deposition near the CoE building were discussed.
Numerical Investigation of Turbulent Flow Around a Stepped Airfoil at High Reynolds Number
Authors: Boroomand Masoud , Hosseinverdi Shirzad
Published: July 2010

This study presents the numerical simulation of flow development around NACA-2412 airfoil which utilized the backward facing step to explore the possibility of enhancing airfoil aerodynamic performance by trapped vortex lift augmentation. This article concentrate on the effect of separated flow and following vortex formation which is created by backward facing step on pressure distribution and subsequently on lift and drag coefficient. Reynolds number that based on the free stream velocity and airfoil chord is 5.7×106. The two-equation shear stress transport (SST) k-ω turbulence model of Menter is employed to determine accurately turbulent flow, as well as the recirculation pattern along the airfoil. The Reynolds-averaged Navier Stokes (RANS) equations are solved numerically using finite volume based solution with second-order upwind Roe’s scheme. Steps are located on both suction side and pressure side of the airfoil, at different locations, different lengths and various depths in order to determine their effects on lift, lift to drag ratio and near stall behavior. The modeling results showed that all stepped airfoil cases studied experienced higher drag compared to the base airfoil. Considerable lift enhancement was found for airfoil with backward facing step on pressure side at all values of angle of attack because of trapped vortex. The results suggest that the steps on the lower surface that extended back to trailing edge can lead to more enhancement of lift to drag ratio for some angles of attack; while the rear locations for the step on upper surface was found to have negative effect on lift to drag ratio. Based on this study, the backward facing step on suction surface offers no discernable advantages over the conventional airfoil but showed some positive effect on delaying stall.
Experimental Investigation of the Two-Phase Phenomena in a Small Discharge Installed on a Large Pipe With Stratified Gas-Liquid Flow
Authors: Bowden Robert , Saleh Wael F. , Hassan Ibrahim
Published: July 2010

Experiments were performed in a 50.8 mm diameter horizontal pipe with co-current stratified gas-liquid flow. A single, 6.35 mm diameter, downward oriented discharge was located at 1829 mm from the horizontal pipe’s inlet. Water and air, operating at a pressure of 312 kPa and adiabatic conditions, were used. The objectives of the study were to investigate gas entrainment in the discharge branch. Qualitative flow visualization of the two-phase entrainment flow structure was conducted, and measurements of the critical liquid height, two-phase mass flow rate, and quality, are provided. The results were compared with available correlations and showed good agreement with selected models.
Analysis of Pulsatile Flow in a Separated Flow Region
Authors: Salek M. Mehdi , Dol Sharul S. , Martinuzzi Robert J.
Published: July 2010

A Backward-Facing Step (BFS) is widely used as an in-vitro model to investigate the influence of flow separation and recirculation observed in biomedical devices, arterial bifurcations and stenoses. In this study we numerically investigate the flow over a BFS with an expansion ratio of 2 and pulsed velocity at the inlet. The main objective is to study the effects of oscillation frequency and amplitude on flow evolution and interaction between vortices. The pulsatile flow leads to a breakdown of the primary recirculation vortex and the generation of a secondary upper wall instability at lower Reynolds numbers than in the steady case. The results show that the amplitude coefficient plays a dominant role in the primary vortex formation but the frequency determines the amount of circulation convected downstream.
Influence of Airflow Separation on the Turbulent Flow Structure Over Wind-Generated Water Waves
Authors: Shaikh Nasiruddin , Siddiqui Kamran
Published: July 2010

An experimental study is conducted to investigate the airside flow behavior within the crest-trough region over wind generated water waves. Two-dimensional velocity fields in a plane perpendicular to the surface were measured using particle image velocimetry (PIV). The experiments were conducted in a wind wave flume 0.45 m wide, 0.9 m high and 3 m long. The measurements were made at a fetch of 2.1 m and at the wind speeds of 3.7 and 4.4 m s−1. An algorithm was developed to segregate separated and non-separated velocity fields within the measured dataset. The results show lower magnitudes of the streamwise velocity and higher magnitudes of Reynolds stress and turbulent kinetic energy for the separated flow fields than that for the non-separated flow fields, indicating that the flow separation significantly enhances turbulence in the near surface region. The enhanced Reynolds stress is positive which indicates that the flow separation increases downward momentum transfer from wind to the wave. The two dimensional plot of instantaneous velocity showed that the separation vortices are restricted to the region bounded by the wave crest and trough. The presented results demonstrate that the flow separation plays a significant role in the interfacial transport processes and therefore, it can be concluded that the understanding of the airflow field within the crest-trough region is vital to improve our knowledge about the air-water heat, mass and momentum exchange.
Numerical Simulation of Cavitating Flow in Mixed Flow Pump With Closed Type Impeller
Authors: Kobayashi Katsutoshi , Chiba Yoshimasa
Published: July 2010

LES (Large Eddy Simulation) with a cavitation model was performed to calculate an unsteady flow for a mixed flow pump with a closed type impeller. First, the comparison between the numerical and experimental results was done to evaluate a computational accuracy. Second, the torque acting on the blade was calculated by simulation to investigate how the cavitation caused the fluctuation of torque. The absolute pressure around the leading edge on the suction side of blade surface had positive impulsive peaks in both the numerical and experimental results. The simulation showed that those peaks were caused by the cavitaion which contracted and vanished around the leading edge. The absolute pressure was predicted by simulation with −10% error. The absolute pressure around the trailing edge on the suction side of blade surface had no impulsive peaks in both the numerical and experimental results, because the absolute pressure was 100 times higher than the saturated vapor pressure. The simulation results showed that the cavitation was generated around the throat, then contracted and finally vanished. The simulated pump had five throats and cavitation behaviors such as contraction and vanishing around five throats were different from each other. For instance, the cavitations around those five throats were not vanished at the same time. When the cavitation was contracted and finally vanished, the absolute pressure on the blade surface was increased. When the cavitation was contracted around the throat located on the pressure side of blade surface, the pressure became high on the pressure side of blade surface. It caused the 1.4 times higher impulsive peak in the torque than the averaged value. On the other hand, when the cavitation was contracted around the throat located on the suction side of blade surface, the pressure became high on the suction side of blade surface. It caused the 0.4 times lower impulsive peak in the torque than the averaged value. The cavitation around the throat caused the large fluctuation in torque acting on the blade.
Study on Performance and Flow Condition of Cross-Flow Wind Turbine With a Symmetrical Casing
Authors: Fukutomi Junichiro , Shigemitsu Toru , Daito Hiroki
Published: July 2010

Wind turbine has been attracted as the technology for clean and renewable energy and many kinds of the researches and the developments are performed. Cross-flow wind turbine has a characteristic of good self-starting, low noise and high stability. Therefore, it is expected as the small-sized wind turbine for urban district. But the maximum power coefficient of the cross-flow wind turbine is extremely low as 10%. Wind in an urban region and a coastal place has a prevailing wind of two directions to occur in a specific condition frequently. Then, a casing suitable for this prevailing wind was designed in this research and the effect of the casing was investigated by experimental and numerical analysis. In the experiment, a wind tunnel with a square discharge 500mm×500mm was used and main flow velocity was set as 20m/s to reduce the influence of measurement error on performance. A torque meter, a rotational speed pickup and a motor were assembled with the same axis at low position of a test wind turbine which was set vertically and rotational speed and tip speed ratio were changeable by a rotational speed controller. The casing was set around the cross-flow rotor and flow distribution at the rotor inlet and the outlet was measured by a one-hole pitot tube. The maximum power coefficient was obtained as Cpmax = 0.19 with the casing, however as Cpmax = 0.098 without the casing. And it was clarified that the inlet and the outlet flow condition was improved by the casing. In the present paper, in order to improve the performance of a cross-flow wind turbine, a symmetrical casing suitable for the prevailing wind of two directions is proposed. Then performance and internal flow condition of the cross-flow wind turbine with the casing is clarified. Furthermore, the influence of a symmetrical casing on performance is discussed and the relation between flow condition and performance is considered.
A Method to Optimize the Operation of Pumping System
Authors: Liu Chao
Published: July 2010

There are many pumps working in generating plant for pumping water in the cooling system. The pumps consume a big amount of electricity especially in large generating plant which operates continuously for long time. Therefore, the electric power cost will increase with increasing of operation cost of the pumping system. It is very important to minimize the operation cost of the pumping system to optimize the use of generating plant assets. In order to optimize the operation of pumping system the method of adjusting pump rotation speeds are often adopted. The fundamental factor of optimizing pump operation is to obtain the operation performance. Theoretically the affinity law (special modeling Equation) of pumps can be applied to convert the performances of pumps under rated speeds to variable rotation speeds. However the affinity law can only be applied in the region of pump operation around Best Efficiency Point with an acceptable precision. Also the affinity law derived from the Modeling Equation can only be valid to pump or pump bowl rather than pumping system. In this paper a method was conducted to determine the performances of pumping system based on the computational and experimental results. The principle of optimizing the pumping system is discussed. Finally the optimizing operation alternative of the pumping system is presented.