bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Numerical Study on Flow Characteristics Through Orifice Flowmeter and Measurement Accuracy Depending on Upstream Straight Length
Authors: Lee Jang Il , Cheong Ae Ju , Min Bok Ki 
Published: October 2017

In this numerical study, Commercial CFD (Computational Fluid Dynamics) code, ANSYS CFX ver. 17.1, is used to analyze the 3-Dimensional flow characteristics through orifice plate (β = 0.6) with two 90 degree bends in different planes. The purpose of this numerical study is to evaluate measurement accuracy and flow characteristics of orifice flowmeter depending on upstream straight length from 12D to 56D.
Thus, numerical calculations of pressure drop caused by swirling flow and distortion of axial velocity profile on orifice plate are performed by using numerical analysis. In addition, numerical analysis results are compared with recommended upstream straight length of ASME Performance Test Codes 19.5 for orifice plates and nozzles.
The results show that if upstream straight length of orifice flowmeter is more than 40D, there is a little deviation of differential pressure. Moreover, it is found that up-down asymmetry of recirculation zones is relatively attenuated as the upstream straight length increases.
Measured Static and Rotordynamic Characteristics of a Smooth-Stator/Grooved-Rotor Liquid Annular Seal
Authors: Moreland J. Alex , Childs Dara W. , Bullock Joshua T. 
Published: October 2017

Electric submersible pumps utilize grooved-rotor seals to reduce leakage and break up contaminants within the pumped fluid. Additionally, due to their decreased surface area (when compared to a smooth seal), grooved seals decrease the chance of seizure in the case of rotor-stator rubs. Despite their use in industry, the literature does not contain measurements for smooth-stator/circumferentially-grooved-rotor liquid annular seals.
This paper presents test results consisting of leakage measurements and rotordynamic coefficients for a smooth-stator/circumferentially-grooved-rotor liquid annular seal. Both static and dynamic performance for the grooved seal are investigated for various imposed pre-swirl ratios, static eccentricities, axial pressure drops, and running speeds. The grooved seals′ static and dynamic performance are compared to those of a smooth seal with identical length, diameter, and radial clearance.
Results show that adding grooves reduces leakage at lower speeds (less than 5 krpm) and higher axial pressure drops, but does little at higher speeds. The grooved seal’s direct stiffness is generally negative, which would be detrimental to pump rotordynamics. Furthermore, increasing pre-swirl increases the magnitude of cross-coupled stiffness and increases the whirl frequency ratio. When compared to the smooth seal, the grooved seal has smaller effective damping coefficients, indicative of worse stability characteristics.
First Attempt on Numerical Prediction of Cavitation Damage on a Centrifugal Pump
Authors: Leclercq Christophe , Fortes-Patella Regiane , Archer Antoine , Cerru Fabien 
Published: October 2017

The cavitation erosion remains an industrial issue for many applications, mainly for hydraulic machines. This paper deals with the cavitation intensity, which can be described as the fluid mechanical loading causing cavitation damage. The estimation of this intensity is a challenging problem both in terms of modeling the cavitating flow and predicting the erosion due to cavitation. For this purpose, a numerical methodology was proposed to estimate cavitation intensity from 3D unsteady cavitating flow simulations. CFD calculations were carried out using Code_Saturne, which solves U-RANS equations for a homogeneous fluid using the Merkle’s model [1], coupled to a k-ε turbulence model with the Reboud’s correction.
A cavitation intensity prediction model was developped based on pressure and void fraction derivatives obtained through CFD calculations. It was previously applied to study cavitation damage [2] on a NACA65012 hydrofoil.
The article briefly presents this validation case as well as the prediction of the cavitation intensity on the blades of a centrifugal pump called “SHF pump” and tested at EDF R&D laboratory [3]. The numerical predictions of cavitation damage are in good agreement with experimental results obtained by pitting.
Influence of Gas-Liquid Multiphase-Flow on Acoustic Behavior and Performance of Side Channel Pumps
Authors: Fleder Sebastian , Hassert Frank , Böhle Martin , Zientek-Strietz Beate 
Published: October 2017

Side-channel pumps (SCP) are a niche product, able to deliver relatively high heads at low flow rates, which corresponds in a low specific speed. They are closing the gap between classical radial centrifugal pumps and positive displacement pumps, combining the advantages of both without having all the negative effects. The hydraulic efficiency of SCP seems low at first sight. But classical centrifugal pumps are often working under part load conditions, when working at this volume flow and specific speed range, which means they are not able to perform at their BEP. This reduces the efficiency of centrifugal pumps and creates a major benefit of SCP, which are able to work in their BEP.
The acoustic behavior and the characteristic pulsations and vibrations of a side channel pump are measured with various measurement methods, such as vibrometry, sound level measurement and sound cartography using an acoustic camera. The characteristic vibrations are shown and compared to the characteristic pressure-pulsations of the working fluid.
The two-phase liquid-gas flow has, beside the effects on the characteristic curves such as head drop and efficiency reduction, many side effects on the behavior of the pump. This could be acoustical and vibrational effects. When gas is present in the working fluid, the emitted noise from the pump reduces significantly. This effect is shown by sound intensity measurements as well as measurements with an acoustic camera and laser vibrometry and compared to the results for single-phase flow.
The maximum amount of gas for the test pump is measured at different rotational speeds. Some theories to improve the maximum amount of gas in the working fluid are presented and the modifications are tested on a test rig. These modifications consist of the idea that a pump without NPSH-impeller could process higher amounts of gas in multiphase-flow conditions. An additional gas outlet hole is added to the pump to allow a phase separation and therefore a better two-phase flow handling of the pump. The effect of these changes on the maximum amount of gas are presented and evaluated.
Design Study of a Pyrolysis Plant Compressor With Heavy Wall Erosion From Metal Particle Impact
Authors: Omri Riadh , Semel Matthias , Delgado Antonio , Russwurm Hans J. 
Published: October 2017

In a pyrolysis plant, a mounted centrifugal compressor takes heavy damage because of erosion originating from metal particle mixed with the inlet air flow impacting its blades and volute walls. In a first step, the original impeller design as well as other centrifugal compressor designs are studied to identify the design parameters which influence the erosion distribution, shape and magnitude. It has been concluded that the first impact plays an important role in defining the particles trajectories and the erosion on the walls.
A novel impeller design method based on particle trajectories after a controlled first impact is introduced.
The new setup is simulated via CFD coupled with Finnie erosion model to assess the damage. This design is improved in a further step. Adequate simulation setups such as interfaces, boundary conditions and particle coupling methods with carrier fluid are introduced.
This study focuses on predicting the particle trajectory within the impeller to reduce the impacts on blade walls and thus reducing the erosion rate. For all designs, the analysis is conducted in the same stage operating point, this point is defined at a predefined volume flow VF [kg/m3] and total-to-static pressure Δp[Pa] as is recommended for the pyrolysis facility including the compressor. Simulations are conducted in a steady state with compressible air at high static temperature going to 530°C. For CFD calculations the software in use is CFX of the ANSYS Group. All mesh used is structured and produced by TurboGrid for the blade rows and with Icem for inlet, outlet and volute.
The final compressor design contain the design recommendation for hub form and outlet flow angle.
Separation Kinetics of Oil/Water Emulsions Stabilized by Nanoparticles
Authors: Gavrielatos Ilias , Dabirian Ramin , Mohan Ram S. , Shoham Ovadia 
Published: October 2017

A state-of-the-art, Portable Dispersion Characterization Rig (P-DCR) is used to investigate the effect of nanoparticles on oil-water emulsion formation and stabilization. Mineral oil and distilled water are used as the test fluids and separation profiles are obtained from the experiments using a sophisticated software. Spherical silica nanoparticles of average primary particle size of 20 nm were selected as the emulsifying agent, since silica is commonly found in the produced fluids. Nanoparticles of different wettabilities were used to investigate their effect on separation kinetics of solid stabilized emulsions in terms of solid particle concentration, wettability, initial dispersion phase, water-cut, and shearing time.
In one series of experiments the emulsions were prepared with intermediate-wet nanoparticles. Both simple water-in-oil (W/O), as well as multiple oil-in-water-in-oil (O/W/O) emulsions were observed. Faster separation occurred when the particles were initially dispersed in oil. Increased nanoparticle concentration, as well as shearing time typically resulted in slower emulsion separation rates.
Another series of experiments was performed with hydrophobic and hydrophilic nanoparticles. Very fast separation rates were observed when using hydrophilic silica nanoparticles and 25% water-cut regardless of solid concentration. However, when the water-cut was increased to 50% and 75% very stable emulsions were produced. Emulsions prepared using hydrophobic particles were the most stable across all water-cuts. For the case of 25% water-cut, no water coalescence was observed for a wide range of oil-wet nanoparticle concentrations. Oil creaming was promoted as the concentration of solids decreased, and the emulsions remained oil continuous and highly resistant to water coalescence even for very low solid concentration (100 ppm), resulting in a dispersed phase volume fraction as high as 93%. The effect of nanoparticles on the properties of pure fluids, namely, density, viscosity and surface/interfacial tension is also reported.
The main findings of the study include the following: Nanoparticles, even at low concentrations, can significantly decrease separation rates of oil and water emulsions. The Portable Dispersion Characterization Rig (P-DCR) is recommended as an effective way to measure emulsion stability in the field.
Calculation Model Based Design-Point Gas Generator Performance Adaptation Method
Authors: Li Shiyao , Li Zhenlin , Huang Ning 
Published: October 2017

Accurate performance simulation can provide operating parameters and performance parameters for the gas turbine’s optimization, maintenance, and fault diagnosis. However, the components maps necessary for performance simulation are not publically available. In addition, the same type of gas turbine has slightly different component operating characteristics due to components′ variations in status and assembly tolerance. These causes bring real difficulties to the research of performance simulation.
In order to obtain accurate components characteristics and performance simulation results, the original or generic components maps should be modified by the scaling factors. In the process of calculating scaling factors, the simulation model is applied repeatedly to determine the engine’s actual performance parameters until the simulated gas path thermal parameters are compatible with the actual measureable data.
This paper introduces a new adaptation method and substitutes the calculation model with the simulation model in the adaptation process. It directly calculates the mass flow rate, isentropic efficiency, and pressure ratio of compressor and turbine based on measureable parameters such as gas path temperature, pressure, fuel component and mass flow rate. Moreover, this paper introduces the virtual gas generator model that enhances the applicability of calculation model based performance adaptation method on gas generators with different structures.
This method has been applied to GE PGT25+ gas generator (single-spool) and RR RB211-24G gas generator (double-spool). Compared with the simulation model used in adaptation process, performance calculation model is much simpler and less time consuming.
Pressure Oscillations in Piva Hydro Power Plant Draft Tube: Case Studies
Authors: Giljen Z. 
Published: October 2017

In this paper performed the analysis and comparison the measured values of pressure oscillations in the draft tube of Francis units obtained in tests from 1976 and 2009. HPP “Piva” has been operating since 1976. In July 1976, September 1976 and in October 1976, performed tests on Francis units HPP “Piva”, at different levels of head water elevations, reason for which measurements are repeated complexity of the observed problems, the excessive pressures oscillations in the unit’s draft tube. Also during 2009 performed measurements the pressure oscillations on the rim of the draft tube and at turbine head cover Francis units HPP “Piva”, as a supervising engineer I worked on these measurements.
During 1976, team from Litostroj-Ljubljana performed the measurements and recording of pressures oscillations in the middle of draft tube (in direction of the unit’s axis), at 0.25 Ds distance from the draft tube’s rim, and at the mere rim of the draft tube. The most unfavourable results were obtained, on the measuring point at 0.25 Ds from the rim the draft tube. In order improve the performances of Francis turbines installed in the HPP “Piva” units, it is very important thoroughly investigate and eliminate the causes of increased pressure oscillations in the draft tube HPP “Piva” units.
Large Eddy Simulation of a Helical Coil Steam Generator Test Section
Authors: Lai Jonathan K. , Merzari Elia , Delgado Marilyn , Lee Samuel J. , Lee Saya , Hassan Yassin A. 
Published: October 2017

The helical coil steam generator (HCSG) is a compact heat exchanger that can have high heat transfer even when the pressure drop is low. This makes it advantageous in small modular reactors and high-temperature reactor designs. In order to investigate the fluid phenomena around these helical banked tubes, a test section was built at Texas A&M University to represent flow across two half-rods within HCSG. This study focuses on the validation of large eddy simulation (LES) for this particular geometry. Pressure tap and particle image velocimetry (PIV) measurements have been recorded at an inlet Reynolds number of 8643, and both mean and fluctuating data is compared with the numerical results.
The highly scalable spectral-element code Nek5000 has been used to produce the LES calculations. First, simulations of varying polynomial order expansions are made to determine the spatial resolution required to capture the turbulent scales. Then, simulations with different inlet conditions are compared with experimental data. The pressure drop shows good agreement with pressure tap measurements while velocity shows similar characteristics with PIV. Furthermore, the components of the Reynolds stresses and modes from proper orthogonal decomposition have been developed to validate the physics captured.
Consistent Evaluation of Wear Coefficients From the Experiments for Use in CFD Simulations
Authors: Pagalthivarthi Krishnan V. , Furlan John M. , Visintainer Robert J. 
Published: October 2017

Coriolis and impact wear testers are commonly used in the slurry industry to determine the sliding and impact wear coefficients (respectively) for a given combination of slurry and wear substrate material. In these experiments, the mass loss of wear specimens, and the easily-measured bulk concentration, flow rate and angle of the impact wedge are correlated to determine estimates of wear coefficients. In CFD-based wear prediction in slurry pump casings and impellers, these experimentally determined coefficients are used in combination with such near-wall computed quantities as particle concentration, velocity, and angle of impact, with a potential inconsistency between the bulk quantities of the wear experiments and the local CFD-based flow field.
This paper uses finite element CFD to obtain the slurry flow field in the Coriolis and impact wear testers. The ratio of the wear-related bulk quantities to the local quantities is evaluated for both impact and sliding wear. It is observed that this ratio for the impact wear coefficient is of the order of 2.0 for the flow conditions studied. In the Coriolis wear tester experiment, it turns out fortuitously that for certain operating conditions, the wear coefficient determined using bulk flow quantities would be nearly the same as the wear coefficient determined using local quantities.
Improvement of Suction Performance Using Splitter Impeller and Inducer
Authors: Hayashi K. , Konno S. , Hayakawa M. , Kawata Y. 
Published: October 2017

Suction performance is one of the most important characteristics of the industrial pump to keep the pump capability against the cavitation under the low suction pressure condition. Inducers have been developed to improve the suction performance of pumps. They are used for rocket turbo pumps and recently for many industrial applications. It is one of the competitiveness of the industrial pumps to downsize the scale with higher rotational speed by adopting inducer.
The authors had proved that pump with splitter impeller with inducer can further improve the suction performance. The splitter impeller was specially designed to be resistant to the cavitation choke. The other very important requirement for the pump against cavitation is that it does not occur cavitation surge. The cavitation surge arises at the partial flow rate of the pump. In contrast to this the suction performance become better at the partial flow rate. So the precise compromise is necessary to satisfy these requirements.
This paper presents the experimental and CFD results to improve and optimize the suction performance without generating cavitation surge. The many design and combination of splitter impeller and inducer are tested to get the better performance. The test results of pumps with different inlet flow coefficient are compared not only suction performance but also the onset of cavitation surge.
Visualization of Internal Flow Field of Propeller Fan
Authors: Onishi Takaya , Sato H. , Hayakawa M. , Kawata Y. 
Published: October 2017

Propeller fans are required not only to have high performance but also to be extremely quiet. The internal flow field of ventilation propeller fans is even more complicated because they usually have a very peculiar configuration with protruding blades upstream. Thus, many kinds of internal vortices yield which cause noise and their cause and countermeasures are needed to be clarified.
The purposes of this paper are to visualize the internal flow of the propeller fan from the static and rotating frame of reference. The internal flow visualization measured from the static frame gives approximately the scale of the tip vortex. The visualization from the rotating coordinate system yields a better understanding of the flow phenomena occurring at the specific blade. The experiment is implemented by using a small camera mounted on the shaft of the fan and rotated it to capture the behavior of the vortices using a laser light sheet to irradiate the blade surface. Hence, the flow field of the specific blade could be understood to some extent. The visualized results are compared with the CFD results and these results show a similar tendency about the generation point and developing process of the tip vortex. In addition, it is found that the noise measurement result is relevant to the effect of tip vortex from the visualization result.
Traceable Flow Rate Measurements With a Very Low Uncertainty Using Laser Doppler Anemometry
Authors: Juling Markus , Steinbock Jonas , Weissenbrunner Andreas 
Published: October 2017

Precise volume flow rate measurements are very important for various industrial applications. Here, one problem is that the service conditions of a flow meter used in the field differ significantly from the conditions present during calibration. The working conditions such as the pressure, the temperature and the flow profile greatly increase the uncertainty of the flow rate measurement.
To address this problem, a new laser-optical flow rate standard (LFS) was developed at the Physikalisch-Technische Bundesanstalt (PTB) that allows flow meters to be calibrated on site, thus greatly reducing the uncertainty of the flow rate measurement.
For the LFS, the velocity profile within the pipe is measured with laser Doppler anemometry (LDA). The profile is then integrated to calculate the volume flow rate. Various improvements to LDA have made it possible to measure the flow rate with an uncertainty of less than 0.15 % (k = 2).
A comparison of the LFS with the primary standard for thermal energy at PTB, which has an uncertainty of less than 0.04 % (k = 2), revealed a maximum deviation of 0.07 % for Reynolds numbers from 105 to 106, thus verifying the uncertainty of the LFS.
Noise Reduction Measures for an Axial Fan
Authors: Swienty Andreas , Palamarchuk Evgenii , Abou Ackl Raja , Thamsen Paul Uwe 
Published: October 2017

The aim of this work is to investigate how a reduction of the noise emissions can be achieved by means of an irregular arrangement of the blades of the fan impeller and an additional blade skewing.
For this purpose a fan impeller with a defined operating point is designed. Preliminary investigations have shown that a volumetric flow rate of 18 m3/h at a pressure of 200 Pa is required for cooling. Due to structural restrictions, only one axial impeller with a diameter of 68 mm can be used. The rotational speed of the electric motor is 10000 rpm. In a further step, the influences of the blade skewing and irregular arrangement of the blades are examined. These impellers are manufactured in a rapid prototyping process, which is a cost-effective and fast process. Thus, various variants can be examined to find the most suitable impeller. The study of the impellers is divided into two phases. Firstly, the fluid mechanical data of the impeller is measured. For this purpose, a chamber test stand is used to measure the characteristic curves of fan impellers. Thus, on the one hand, it can be examined whether the designed impeller reaches the operating point and, on the other hand, the influence of the noise reduction measures on the characteristic curves can also be evaluated. It is, of course, not desired that the noise reduction measures result in a deterioration of the pressure increase or in the volumetric flow rate. In the second phase, the noise generation of the impeller is measured in an installed state on an acoustic test stand. For this purpose, the impellers are installed in the electric motor and then acoustically examined in enveloping surface method according to DIN 45635.
It can be seen that the sound load can be reduced by 5.6 dB by a sufficient design of the impeller compared to a reference impeller. The further measures taken, such as the irregular arrangement of the blades and the blade skewing, have shown a further improvement of 1.6 dB. The influence of the implemented measures on the characteristic curve lies in a small area. It is measured that the pressure increase has fallen due to the irregular arrangement of the blades and the blade skewing by 10 Pa with a constant remaining flow rate.