bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aeroacoustic Sound Prediction of a Diaphragm by a Hybrid Method
Authors: Bayati Morteza , Tadjfar Mehran 
Published: December 2013

Most of the noise prediction methods, which has already been used, only applicable at low frequency range, below the first transverse duct mode. A developed method at this work, which suggested by Schram, avoided many simplification assumptions and is quite powerful for high Helmholtz numbers, i.e. when the turbulence/body interaction region is acoustically non-compact. By using numerical methods and an appropriate Green function, the method is applied to the prediction of sound in a duct obstructed by a diaphragm. The source fluctuations of the flow field are computed by a large-eddy simulation (LES) and are fed to the following acoustical computation as input data.
The predicted power spectrum shows a fairly good agreement with a direct noise computation (DNC) results.
Efficiency Optimization of a 30MW Main Boiler Feedwater Pump Using CFD and Scaled Model Tests
Authors: Teesink Pieter , Visser Frank , Jochems Jeroen 
Published: December 2013

Environmental impact of electricity production has come under increasing international scrutiny over the last few decades. In particular, fossil fuel-fired power plants constitute a significant portion of the world’s carbon dioxide emissions. One of the main internal energy-consuming components in a thermal power plant is the main boiler feedwater pump, and its efficiency is a contributor to overall plant efficiency.
This paper reports the design optimization of a 30 MW multistage, double-case, volute pump in order to increase overall efficiency by at least three percentage points. The six stage barrel pump produces 3865 m (12680 ft) of head at a capacity of 2750 m3/hr (12100 USGPM) at a speed of 4665 RPM. The machine is installed at the coal-fired supercritical Nuon Hemweg 8 power station in Amsterdam, the Netherlands, as the main boiler feedwater pump.
The design study employed Computational Fluid Dynamics (CFD) to identify energy losses and evaluate design iterations. This paper describes the optimization of several individual components, including volutes, short and long crossovers, suction box and final discharge. Scaled model tests were conducted on series stages to validate the CFD results. Additional design constraint that had to be taken into account was that new hardware had to be installed within the limits of the existing pressure boundary components, sealing device and bearing design, which confines the design space considerably. Hardware has, at the time of writing this paper, entered production and is planned to be installed during a May 2013 plant outage.
Validation Study on Forced and Mixed Convection in the Rotatable Buoyancy Tunnel
Authors: Lance Blake W. , Harris Jeff R. , Iverson Jared M. , Spall Robert E. , Johnson Richard W. , Smith Barton L. 
Published: December 2013

The Rotatable Buoyancy Tunnel (RoBuT) at Utah State University, built for validation measurements incorporating a high level of data completeness, is described along with the results from validation data sets for forced and mixed convection. One wall of the tunnel test section is heated while the other three are transparent for optical access. All boundary conditions, including geometry, wall temperature and inflow temperature and velocity, are measured and their uncertainties are reported. The tunnel’s design is unique in that the test section can be inverted by rotating the entire facility to generate mixed convection with either buoyancy aided or buoyancy opposed flow. The RoBuT can also produce forced or natural convection, either steady or transient.
Measurements for forced and buoyancy-aided mixed convection over a vertical heated plate are described. The RoBuT allows for simultaneous measurements of velocity, wall and inlet air temperature, heat flux measurements on the heated wall, and pressure drop across the test section. The fluid velocity is measured by time-averaged particle image velocimetry (PIV). The first validation case is forced convection since this flow is well understood. Both forced and mixed convection results are compared to published correlations and computational fluid dynamics (CFD) studies. The CFD is steady and 3-D using as-built measurements of the geometry. Experimental wall and inlet temperatures are used for CFD boundary conditions, as well as the inlet velocity and turbulence profiles. Three research groups perform simulations with varying levels of knowledge of the experimental results.
Computational Fluid Dynamics (CFD) Analysis of a Single-Stage Downhole Turbine
Authors: Satti Rajani , Pillalamarri Narasimha Rao , Scholz Eckard 
Published: December 2013

In this study, the application of computational fluid dynamics (CFD) is explored to predict the performance characteristics in a typical single-stage downhole turbine. The single-stage turbine model utilized for this study consists of a stator and a rotor. A finite-volume based CFD approach was implemented to simulate the complex flow field around the turbine. The analysis is based on transient, three-dimensional, isothermal turbulent flow in an incompressible fluid system. The inlet flow rates and angular velocity of the rotor were varied to encompass the operating regime.
Comparison with experimental data revealed excellent agreement, proving reliability of the model in predicting the performance characteristics. Motivated by the successful model validation, a parametric study (considering blade tip clearance and blade count) was also conducted to understand the effects of the design parameters on the performance of the turbine. Detailed flow visualizations and efficiency calculations were also done to provide further insight into the overall performance of the turbine. As part of the present study, significant efforts were also spent in the following areas: standardization of CFD methodology and assessment of commercial software to develop an integrated CFD-driven design process.
Unsteady Phenomena Induced Pressure Pulsation and Radial Load in a Centrifugal Pump With Slope Volute
Authors: Zhang Ning , Yang Minguan , Gao Bo , Li Zhong 
Published: December 2013

Vibration in centrifugal pump still remains a tough problem to solve. Many studied have been done to find the relationship between hydraulic design and vibration. Both experiments and numerical simulation methods have been proposed to make clear the influence of pump parameters related to vibration. It is evident that unsteady phenomena in centrifugal pump are the main factors causing vibration. Also motor-stator interaction of impeller and volute keeps predominant role considering hydraulic factors.
Till now almost all reported researches consider pump geometry parameters, but the shape of volute is rarely proposed. To reduce interaction between impeller and volute tongue, a special volute with slope diffuser section is put forward in this paper. The relative position of volute tongue changes compared to the conventional spiral volute. Thus the effect of flow field striking with volute tongue can be receded effectively, and vibration will be reduced.
As the developing of computer technology, it is possible for us to achieve the unsteady flow field inner pump by using numerical simulation methods. A commercial software Fluent was adopted to analyze pressure pulsation and radial load of model pump. Slant angle and clearance rate were optimized considering pressure magnitude. It is observed that pressure amplitude at blade passing frequency achieve the lowest level at slant angle 15°. Pressure magnitude decreases significantly with the increasing of clearance, but limited to radial size of volute, it is suggested to be in the range of 0.134∼0.250.
Several monitor points are selected along the volute to have overall understanding of pressure pulsation characteristics. Pressure pulsation at blade passing frequency keeps the predominant in motor-stator interaction. Amplitude of both pressure and radial load increase rapidly when pump operating at off designed conditions.
Development of Double Suction Volute Pump for High Efficiency
Authors: Kobayashi Katsutoshi , Hagiya Isao , Akiniwa Hideki , Yoda Hiroaki , Senba Daijirou 
Published: December 2013

The double suction volute pump consists of three components: a double suction flow path in upstream, an impeller with five blades, and a double volute flow path in downstream. The double suction was designed to improve a flow on the inlet surface of impeller. A significantly high pre-swirl velocity and low pre-swirl velocity were observed in original double suction, however its high pre-swirl velocity was slowed down and its low pre-swirl velocity was speeded up in designed double suction. As a result, the designed double suction had a more uniform velocity distribution on the inlet surface of impeller.
The impeller had twenty design parameters and those parameters were optimized by genetic algorithm (GA) to improve the impeller efficiency. A high total pressure loss was observed on the outlet surface of impeller and near the shroud wall of impeller meridian surface. On the other hand, its total pressure loss was decreased in optimized impeller, and the impeller efficiency increased by +0.7[%].
The cross-sectional surfaces, which were defined on a main streamwise curve of double volute, were designed to decrease a total pressure loss occurring inside double volute. In designed double volute, a secondary vortex on the cross-sectional surface was suppressed and a high circumferential velocity was decreased near the tongue and front edge of partition wall. As a result, the total pressure loss was decreased inside designed double volute.
The hydraulic pump performance for designed pump, which consisted of the designed double suction, optimized impeller and designed double volute, was predicted by numerical simulation. Efficiencies in double suction, impeller and double volute were increased by 0.6[%], 0.4[%] and 1.1[%] respectively and the total improvement of pump efficiency was 1.9[%]. The designed pump was manufactured and its hydraulic performance was measured by experiment. The numerical results of pump efficiency agreed well with experimental ones. The efficiency of designed pump increased by 2.0[%] compared with that of original pump in experiment.
The Influence of Working Fluid Characteristic Parameters on Turbine Performance for the Small Scale ORC System
Authors: Zhang Lei , Zhuge Weilin , Zheng Xinqian , Zhang Yangjun 
Published: December 2013

The small scale Organic Rankine Cycle (ORC) using a turbine as expanders is considered as one of the most efficient ways to convert the waste heat energies of automobile engine into electrical energy, in the power range from several kW up to dozens of kW. In general, two important factors must be taken into account when designing the ORC turbine: the real gas effects of the organic fluid and the high expansion ratio presented in the machinery due to thermodynamic and efficiency factors. The characteristic parameters of R245fa have great difference compared with air. When designing an ORC turbine, the initial problem is the influence of the working fluid characteristic parameters on the turbine performance. Similarity analysis method is used to analyze this problem. When using the similarity theory to design two similar operating conditions, gas constant R and dynamic viscosity μ are easy to be taken into account as they have a dimension; specific heat ratio κ is hard to be taken into consideration. In this paper, a high expansion ratio ORC turbine is generated for a small scale ORC system working with the organic fluid R245fa, and the influence of κ on the turbine performance parameters analyzed.
Firstly, the turbine geometry is designed in an iterative process using the commercial design tool Concepts-NREC Rital program, and the designed operating condition is determined. Secondly, the similarity criterion numbers are deduced with no consideration of the specific heat ratio κ, and the similar operating condition is calculated by the deduced similarity criterion numbers. The results achieved by the one-dimensional design software Rital shows that the deviation of similarity criterion numbers is small, which indicates that the two operating conditions are similar. Then, to verify the conclusion above, the flow field simulation using one channel model is conducted based on the R245fa operating condition and air operating condition using the computational fluid dynamics (CFD) code NUMECA-FineTurbo. However, deviations of the similarity criterion numbers from the CFD results are more than twice to those from the one-dimensional results. The larger deviation may indicate that the influence of the specific heat ratio κ cannot be ignored. After that, the distributions of the total pressure, total temperature, the relative Ma number and entropy in the nozzle and rotor channel are compared. These results show that except the total temperature the distributions of the other three parameters are very similar. The similar distribution may indicate that the specific heat ratio κ has little influence on the efficiency and expansion ratio, but κ has greater influence on the temperature and output power. All of these conclusions are made according to the simulation results, the accuracy should be verified through the test results.
Multi-Color Imaging Pyrometry Techniques for Gas Turbine Engine Applications
Authors: Estevadeordal Jordi , Tralshawala Nilesh , Badami Vivek 
Published: December 2013

As part of a Department of Energy/GE sensors program multicolor pyrometry (MCP) imaging techniques were evaluated for incorporation into single color IR camera systems for gas turbine engine applications. MCP offers advantages over single-color band imaging pyrometry such as having less restrictive assumptions on wavelength dependent emissivity and capability to correct for optical density changes, contamination and fouling.
Several prototype imaging designs were built, tested and calibrated in jugular laboratory experiments and a design was implemented and demonstrated in gas turbine full-speed, full-load engine tests. Results of multicolor-color imaging and MCP temperature and apparent emissivity calculations are presented for a variety of laboratory experiment conditions, as well as for various blade conditions in the hot gas path region of turbine blades of a gas turbine engine. MCP and image processing algorithms are designed and applied to characterize the temperature and emissivity changes in the viewed surfaces in these experiments.
Effect of Rotor-Stator Configuration in the Generation of Vortical Scales and Wake Mixing in Single Stage Axial Fans: Part I — LES Modelling and Experimental Validation
Authors: Galdo Vega Mónica , Fernandez Oro Jesus Manuel , Argüelles Díaz Katia María , Santolaria Morros Carlos 
Published: December 2013

The unsteadiness and vortical structures associated to impinging wakes convected through rotor and stator passages have been studied in detail in a single-stage low-speed axial fan, with 9 blades and 13 inlet/outlet guide vanes. In particular, in this first part, the effect of complementary rotor-stator (RS) and stator-rotor (SR) configurations has been addressed in terms of wake mixing and generation of vortical structures in both absolute and relative frames of reference.
A LES simulation of the midspan section (in a 2.5D model) is introduced to resolved the largest scales of the vortical motion within the wakes, related to vortex shedding, especially at off-design conditions. Chopping mechanisms and periodic interactions of the coherent turbulent structures are described and the presence of turbulent spots due to wake-wake interactions is revealed. Another relevant flow pattern, like the advection of leading edge separation through the downstream passage, is also identified and linked to the periodic potential interaction of upstream vanes (SR) or blades (RS).
Additionally, complete experimental databases of the time-resolved and the turbulent scales of the flow are available for both configurations by means of hot-wire anemometry measurements. Wake transport and viscous mixing are identified in corresponding measuring windows, and primary flow structures at midspan are also recovered and compared with the numerical results for validation.
From the comparison of experimental and numerical results it can be concluded that the numerical modeling is able to reproduce accurately the unsteady phenomena that occur inside the axial fan, and shows the potentiality of LES techniques to resolve with high fidelity the main turbulent structures present in the flow, especially at off-design flow rates.
Performance Evaluation of a Centrifugal Blower Using Optimal Design Method
Authors: Jang Choon-Man , Lee Jong-Sung , Yang Sang-Ho 
Published: December 2013

Effects of design variables on the performance of a centrifugal blower have been analyzed based on the three-dimensional flow analysis. Two design parameters defined the shape of a volute casing are introduced to enhance a blower performance. To analyze three-dimensional flow field in the centrifugal blower, general analysis code, CFX, is employed in the present work. SST turbulence model is employed to estimate the eddy viscosity. Boundary condition at the interference plane between rotational and stationary domains is applied by a stage method. Unstructured grids are used to represent a composite grid system including blade, casing and inlet guide.
In the present study, throughout the shape optimization of the centrifugal blower at the design flow condition, the blower efficiency and pressure are successfully increased by 0.5 and 1.6 percent compared to reference one. It is found that the casing height of design variables is more sensitive on the object function of efficiency compared to that of the casing width. And secondary flow due to velocity gradient and low velocity region increase pressure loss, leading to make low efficiency. Detailed flow field inside a centrifugal blower is also analyzed and compared.
Development of a Recombinant Protein-Based Enzyme-Linked Immunosorbent Assay for Diagnosis of Mycoplasma bovis Infection in Cattle
Authors: Wawegama Nadeeka K. , Browning Glenn F. , Kanci Anna , Marenda Marc S. , Markham Philip F. 
Published: December 2013

ABSTRACTMycoplasma boviscauses a range of diseases in cattle, including mastitis, arthritis, and pneumonia. However, accurate serological diagnosis of infection remains problematic. The studies described here aimed to identify an antigen that might be used to develop a more specific and sensitive diagnostic assay. A 226-kDa immunogenic protein was consistently detected in Western blots by antibodies in sera from calves experimentally infected withM. bovis. This protein was shown to be a membrane protein with lipase activity and was named mycoplasma immunogenic lipase A (MilA). Different regions of MilA were expressed inEscherichia colias glutathioneS-transferase (GST) fusion proteins and recombinant products from the amino-terminal end shown to have strong immunoreactivity withM. bovis-specific bovine sera. The most immunoreactive fusion protein, GST-MilA-ab, was used to develop indirect IgM and IgG enzyme-linked immunosorbent assays (ELISAs). The IgM ELISA detectedM. bovis-specific IgM antibody 2 weeks after infection with 97.1% sensitivity and had a specificity of 63.3%, while the IgG ELISA detectedM. bovis-specific IgG 3 weeks after infection with 92.86% sensitivity and had a specificity of 98.7%, demonstrating that the IgG ELISA has potential for use as a sensitive and specific assay for detecting infection in cattle.
Ocular Immune Responses in Steers following Intranasal Vaccination with Recombinant Moraxella bovis Cytotoxin Adjuvanted with Polyacrylic Acid
Authors: Angelos John A. , Edman Judy M. , Chigerwe Munashe 
Published: December 2013

ABSTRACTInfectious bovine keratoconjunctivitis (IBK) caused byMoraxella bovisis the most common eye disease of cattle. The pathogenesis ofM. bovisrequires the expression of pili that enable the organism to attach to the ocular surface and an RTX (repeats in the structural toxin) toxin (cytotoxin or hemolysin), which is cytotoxic to corneal epithelial cells. In this pilot study, ocular mucosal immune responses of steers were measured following intranasal (i.n.) vaccination with a recombinantM. boviscytotoxin adjuvanted with polyacrylic acid. Beef steers were vaccinated with either 500 μg (n= 3) or 200 μg (n= 3) of recombinantM. boviscytotoxin plus adjuvant. Control group steers (n= 2) were vaccinated with adjuvant alone, and all steers were given a booster on day 21. Antigen-specific tear IgA and tear IgG, tear cytotoxin-neutralizing antibody responses, and serum cytotoxin-neutralizing antibody responses were determined in samples collected prevaccination and on days 14, 28, 42, and 55. Changes in tear antigen-specific IgA levels from day 0 to days 28, 42, and 55 were significantly different between groups; however, inpost hoccomparisons between individual group pairs at the tested time points, the differences were not significant. Our results suggest that i.n. vaccination of cattle with recombinantM. boviscytotoxin adjuvanted with polyacrylic acid effects changes in ocular antigen-specific IgA concentrations. The use of intranasally administered recombinantM. boviscytotoxin adjuvanted with polyacrylic acid could provide an alternative to parenteral vaccination of cattle for immunoprophylaxis against IBK.
Colorimetric Sensor Array Allows Fast Detection and Simultaneous Identification of Sepsis-Causing Bacteria in Spiked Blood Culture
Authors: Lim Sung H. , Mix Samantha , Xu Zeyu , Taba Brian , Budvytiene Indre , Berliner Anders N. , Queralto Nuria , Churi Yair S. , Huang Richard S. , Eiden Michael , Martino Raymond A. , Rhodes Paul , Banaei Niaz 
Published: December 2013

ABSTRACTSepsis is a medical emergency demanding early diagnosis and tailored antimicrobial therapy. Every hour of delay in initiating effective therapy measurably increases patient mortality. Blood culture is currently the reference standard for detecting bloodstream infection, a multistep process which may take one to several days. Here, we report a novel paradigm for earlier detection and the simultaneous identification of pathogens in spiked blood cultures by means of a metabolomic “fingerprint” of the volatile mixture outgassed by the organisms. The colorimetric sensor array provided significantly faster detection of positive blood cultures than a conventional blood culture system (12.1 h versus 14.9 h,P< 0.001) while allowing for the identification of 18 bacterial species with 91.9% overall accuracy within 2 h of growth detection. The colorimetric sensor array also allowed for discrimination between unrelated strains of methicillin-resistantStaphylococcus aureus, indicating that the metabolomic fingerprint has the potential to track nosocomial transmissions. Altogether, the colorimetric sensor array is a promising tool that offers a new paradigm for diagnosing bloodstream infections.