scholarly journals Investigation on the Nonconstant Behavior of a Vortex Flow Meter with Narrow Gauge Pipe via Conducting Measurements and Numerical Simulations

1970 ◽  
Vol 61 (3) ◽  
pp. 247
Author(s):  
Bence Fenyvesi ◽  
Csaba Horváth
Keyword(s):  
Numerical Simulations ◽  
Cross Sections ◽  
Flow Measurement ◽  
Vortex Flow ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Diagnostic Investigation ◽  
Number Range ◽  
Wide Range ◽  
The Given

Vortex shedding flowmeters can be used for a wide range of flow measurement applications with various kinds of fluids. The critical point in applying this method comes from the assumption that the Strouhal number is constant for the given Reynolds number range. In some cases – typically regarding flowmeters with narrow gauge pipes –, this assumption is only partially met, thus limiting the widespread use of these instruments in certain industrial appliances. The paper presents a diagnostic investigation on the effects of this nonconstant behavior. The method elaborated in this report can be applied to vortex flowmeters with narrow gauge pipes. In these instruments – usually due to the narrow cross-sections of the gauge pipe – measurement possibilities are limited, thus it is not possible for the user to determine the effects of the nonconstant behavior. To conduct these investigations, a calibration rig was designed and assembled. The presented diagnostic method combines measurements and numerical simulations. The results of the investigations can be used in the data processing phase, in order to reduce the uncertainty of the volume flow rate measured by vortex flowmeters.

Prediction of Coolant Pressure and Volume Flow Rate in the Gundrilling Process

2003 ◽  
Vol 125 (4) ◽  
pp. 696-702 ◽  
Author(s):  
Jinhyuk Jung ◽  
Jun Ni
Keyword(s):  
General Practice ◽  
Hydraulic Resistance ◽  
Flow Rate ◽  
Cross Sections ◽  
Fluid Model ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Influential Factor ◽  
Saturation Point ◽  
Hole Bottom

Coolant volume flow rate and pressure critically affect the chip evacuation in the gundrilling process. A predictive fluid model was developed to estimate coolant volume flow rate and pressure, which considered the whole gundrill system of coolant channels as a system of circular and non-circular cross-sections of fluid channels and gundrill geometry. Major contributions to the findings of the following important facts were made through experiments as well as modeling. First, the generation of swarfs in the coolant transport did not create a noticeable hydraulic resistance no matter whether swarfs were carbon steel or aluminum. Second, the size of the coolant holes of the head is not necessarily the most influential factor for determining coolant volume flow rate as believed in general practice. Last, hydraulic resistance by the clearance area of the hole bottom becomes negligible when its size reaches a saturation point.

scholarly journals Simulation of Air Motion in Human Lungs during Breathing. Dynamics of Liquid Droplet Precipitation in the Case of Medicine Drug Aerosols

2021 ◽  
Vol 16 (2) ◽  
pp. 422-438
Author(s):  
A.E. Medvedev ◽  
P.S. Golysheva
Keyword(s):  
Respiratory Tract ◽  
Numerical Simulations ◽  
Cross Sections ◽  
Liquid Droplet ◽  
Air Flow ◽  
Bronchial Tree ◽  
Lung Pathology ◽  
Human Lungs ◽  
Wide Range ◽  
Medical Drug

The paper deals with numerical simulation of the air flow in the full human bronchial tree. In their previous studies, the authors developed an analytical model of the full human bronchial tree and a method of stage-by-stage computation of the respiratory tract. A possibility of using the proposed method for a wide range of problems of numerical simulations of the air flow in human lungs is analyzed. The following situations are considered: 1) steady inspiration (with different flow rates of air) for circular and “starry” cross sections of bronchi (“starry” cross sections models some lung pathology); 2) steady expiration; 3) unsteady inspiration; 4) precipitation of medical drug aerosol droplets in human bronchi. The results predicted by the proposed method are compared with results of other researchers and found to be in good agreement. In contrast to previous investigations, the air flow in the full (down to alveoli) bronchial tree is studied for the first time. It is shown that expiration requires a greater pressure difference (approximately by 30%) than inspiration. Numerical simulations of precipitation of medical drug aerosol droplets in the human respiratory tract show that aerosol droplets generated by a standard nebulizer do not reach the alveoli (the droplets settle down in the lower regions of the bronchi).

scholarly journals Understanding Dissolution Rates via Continuous Flow Systems with Physiologically Relevant Metal Ion Saturation in Lysosome

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 311 ◽  
Author(s):  
Johannes Keller ◽  
Willie Peijnenburg ◽  
Kai Werle ◽  
Robert Landsiedel ◽  
Wendel Wohlleben
Keyword(s):  
Flow Rate ◽  
Continuous Flow ◽  
Metal Ion ◽  
Volume Flow Rate ◽  
Particle Surface ◽  
Volume Flow ◽  
High Similarity ◽  
Dissolution Rates ◽  
Wide Range ◽  
Flow Systems

Dissolution rates of nanomaterials can be decisive for acute in vivo toxicity (via the released ions) and for biopersistence (of the remaining particles). Continuous flow systems (CFSs) can screen for both aspects, but operational parameters need to be adjusted to the specific physiological compartment, including local metal ion saturation. CFSs have two adjustable parameters: the volume flow-rate and the initial particle loading. Here we explore the pulmonary lysosomal dissolution of nanomaterials containing the metals Al, Ba, Zn, Cu over a wide range of volume flow-rates in a single experiment. We identify the ratio of particle surface area (SA) per volume flow-rate (SA/V) as critical parameter that superimposes all dissolution rates of the same material. Three complementary benchmark materials—ZnO (quick dissolution), TiO2 (very slow dissolution), and BaSO4 (partial dissolution)—consistently identify the SA/V range of 0.01 to 0.03 h/μm as predictive for lysosomal pulmonary biodissolution. We then apply the identified method to compare against non-nanoforms of the same substances and test aluminosilicates. For BaSO4 and TiO2, we find high similarity of the dissolution rates of their respective nanoform and non-nanoform, governed by the local ion solubility limit at relevant SA/V ranges. For aluminosilicates, we find high similarity of the dissolution rates of two Kaolin nanoforms but significant dissimilarity against Bentonite despite the similar composition.

Design and Performance Assessments of a Partial Admission Axial Turbine Using Supercritical Carbon Dioxide

2016 ◽  
Author(s):  
Young-Seok Kang ◽  
Jae-Sung Huh ◽  
Junhyun Cho ◽  
Hyungki Shin ◽  
Young-Jin Baik
Keyword(s):  
Numerical Simulations ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Aerodynamic Design ◽  
Turbine Stage ◽  
Axial Turbine ◽  
Rotating Speed ◽  
Cubic Equation ◽  
Partial Admission

Power density of a super-critical carbon dioxide cycle is very high due to its fluid-like density. For this reason, generally size of turbines are very compact compared to that of the air Brayton cycle. However, such an advantage sometimes becomes a challenge for aerodynamic design, because low volume flow rate of the turbine requires design point at a very low specific speed. One of the solution for the challenge is to design a turbine stage as a partial admission stage in which flow enters the turbine nozzle over only a portion of its annulus. Then it secures a sufficient turbine inlet area, even though performance degradation should be taken in to account. In this study, aerodynamic design of an axial turbine has been carried out and its performance has been assessed with numerical simulations. One of design requirements for the axial turbine was to minimize rotor inlet and outlet pressure difference to avoid potential axial thrust. In spite of a small amount of expansion ratio in the turbine stage, the absolute pressure difference could cause severe damage to rotor dynamic system and require complicated bearing system. For this reason, in this study, the turbine was designed as impulse type axial turbine with partial admission. Required rotating speed and resultant low volume flow rate restricted mean diameter and blade height at the stage inlet. The final design has a very low aspect ratio, less than unity. The number of nozzle and rotor are 12 and 34, respectively. The rotating speed of the rotor is 45,000 rpm. The ratio of nozzle arc to blade pitch is approximately 3, which determines efficiency deterioration due to the partial admission. During the numerical simulations, to implement real gas property, Redlich-Kwong-Aungier cubic equation was used. As the turbine operating point is far from its critical point, the Redlich-Kwong-Aungier cubic equation showed a good agreement with real supercritical gas property. To assess full and partial admission turbine performance, steady state numerical simulations have been performed. The full annulus CFD domain was constructed for the partial admission stage. At the design condition, there was 15% isentropic efficiency drop in case of the partial admission stage relative to the full admission stage. Also similar amount of power output penalty was investigated from the partial admission case. As the nozzle was choked at the design condition, the mass flow rate was conserved regardless of the admission type. Then in the flowing region, design velocity triangle in front of the rotor well established, while additional loss was generated along the circumferential direction over non flowing region.

scholarly journals Mixing Performance of a Cross-Channel Split-and-Recombine Micro-Mixer Combined with Mixing Cell

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 685
Author(s):  
Makhsuda Juraeva ◽  
Dong Jin Kang
Keyword(s):  
Molecular Diffusion ◽  
Numerical Study ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Mixing Enhancement ◽  
Mixing Performance ◽  
Two Fluids ◽  
Dean Vortex ◽  
Wide Range ◽  
Micro Mixer

A new cross-channel split-and-recombine (CC-SAR) micro-mixer was proposed, and its performance was demonstrated numerically. A numerical study was carried out over a wide range of volume flow rates from 3.1 μL/min to 826.8 μL/min. The corresponding Reynolds number ranges from 0.3 to 80. The present micro-mixer consists of four mixing units. Each mixing unit is constructed by combining one split-and-recombine (SAR) unit with a mixing cell. The mixing performance was analyzed in terms of the degree of mixing and relative mixing cost. All numerical results show that the present micro-mixer performs better than other micro-mixers based on SARs over a wide range of volume flow rate. The mixing enhancement is realized by a particular motion of vortex flow: the Dean vortex in the circular sub-channel and another vortex inside the mixing cell. The two vortex flows are generated on the different planes perpendicular to each other. They cause the two fluids to change their relative position as the fluids flow into the circular sub-channel of the SAR, eventually promoting violent mixing. High vorticity in the mixing cell elongates the flow interface between two fluids, and promotes mixing in the flow regime of molecular diffusion dominance.

scholarly journals The intermediate Rossby number range and two-dimensional–three-dimensional transfers in rotating decaying homogeneous turbulence

2007 ◽  
Vol 587 ◽  
pp. 139-161 ◽  
Author(s):  
LYDIA BOUROUIBA ◽  
PETER BARTELLO
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Domain Size ◽  
Homogeneous Turbulence ◽  
Finite Domain ◽  
Rossby Number ◽  
Computational Domain ◽  
Two Dimensional ◽  
Number Range ◽  
Wide Range

Rotating homogeneous turbulence in a finite domain is studied using numerical simulations, with a particular emphasis on the interactions between the wave and zero-frequency modes. Numerical simulations of decaying homogeneous turbulence subject to a wide range ofbackground rotation rates are presented. The effect of rotation is examined in two finiteperiodic domains in order to test the effect of the size of the computational domain on the results obtained, thereby testing the accurate sampling of near-resonant interactions.We observe a non-monotonic tendency when Rossby number Ro is varied from large values to the small-Ro limit, which is robust to the change of domain size. Three rotation regimes are identified and discussed: the large-, the intermediate-, and the small-Ro regimes. The intermediate-Ro regime is characterized by a positive transfer of energy from wave modes to vortices. The three-dimensional to two-dimensional transfer reaches an initial maximum for Ro ≈ 0.2 and it is associated with a maximum skewness of vertical vorticity in favour of positive vortices. This maximum is also reached at Ro ≈ 0.2. In the intermediate range an overall reduction of vertical energy transfer is observed. Additional characteristic horizontal and vertical scales of this particular rotation regime are presented and discussed.

Flow Induced by a Two Stage Electrohydrodynamic Gas Pump in a Square Channel

2020 ◽  
Author(s):  
A. K. M. Monayem H. Mazumder ◽  
Grace S. Trombley ◽  
Brendon G. Cusinio
Keyword(s):  
Velocity Profile ◽  
Cross Sections ◽  
Volume Flow Rate ◽  
Forced Flow ◽  
Tube Length ◽  
Two Stage ◽  
Maximum Enhancement ◽  
Square Channel ◽  
Parabolic Velocity Profile ◽  
Wide Range

Abstract In this study, fluid flow induced by a two stage electrohydrodynamic (EHD) gas pump in a square channel has been evaluated by experimental measurement and numerical simulations. This study is implemented for a two stage EHD gas pump with three emitting electrode configurations: 8, 24, and 56 respectively to seek the relation between the number of stages and emitting electrodes. The EHD pump is evaluated for a wide range of operating voltages starting from 20 kV up to 28 kV for further improvement in its performance over a single stage. To achieve the maximum enhancement, the emitting electrodes of the EHD gas pump are flush mounted on the channel walls so that the corona wind produced directly disturbs the boundary layer thickness and improves the heat transfer. This is leading to a higher velocity near the channel walls and resulting in an inverted parabolic velocity profile at the center of the channel, which is opposite to the fully developed velocity profile of a forced flow. Velocities are measured at three cross-sections along the tube length and then integrated to obtain the volume flow rate. The results show that EHD technique has a great potential for many engineering applications.

Limitations of a pulsed Doppler velocimeter for blood flow measurement in small vessels

1993 ◽  
Vol 75 (6) ◽  
pp. 2745-2754 ◽  
Author(s):  
A. W. Quail ◽  
D. B. Cottee ◽  
S. W. White
Keyword(s):  
Blood Flow ◽  
Doppler Shift ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Pulsed Doppler ◽  
Small Vessels ◽  
Flow Disturbances ◽  
Wide Range ◽  
Blood Flow Velocities ◽  
Flow Velocities

The performance of a new and simplified flow probe construction and the Iowa 545C-4 pulsed Doppler velocimeter was evaluated for measurement of blood flow over several months in small arteries of awake animals. Calibrations were performed over a wide range of intraluminal pressures and physiological flow velocities. Pressure-dependent differences in slope of the Doppler shift-volume flow relationship were detected in some probes. Signal strength was maintained at hematocrits > 10%. Distortion of pulsed Doppler signal peaks occurred in the conscious rabbit at peak aortic velocities, at which Reynold's number for turbulence was exceeded and the Doppler shift surpassed the Nyquist limit of 31.25 kHz for the velocimeter. Although the Doppler shift-volume flow relationship is linear at < 5 kHz, in some cases at higher Doppler shifts and blood flow velocities the relationship may become nonlinear, thus causing the volume flow rate to be underestimated by up to 38%. The cause of this phenomenon may be "aliasing" and/or the consequence of the range control capability of the velocimeter selectively sampling changing velocity profiles and flow disturbances in the central stream at higher velocities.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

Slip And Hall Effects On The Flow Of A Hyperbolic Tangent Fluid Through Porous Medium In A Planar Channel With Peristalsis

GIS Business ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 383-394
Author(s):  
K. Shalini ◽  
K.Rajasekhar
Keyword(s):  
Porous Medium ◽  
Pressure Gradient ◽  
Volume Flow Rate ◽  
Perturbation Technique ◽  
Volume Flow ◽  
Planar Channel ◽  
Hyperbolic Tangent ◽  
Closed Form Solutions ◽  
Long Wavelength ◽  
Hall Effects

In this paper, the effect of Slip and Hall effects on the flow of Hyperbolic tangent fluid through a porous medium in a planar channel with peristalsis under the assumption of long wavelength is investigated. A Closed form solutions are obtained for axial velocity and pressure gradient by employing perturbation technique. The effects of various emerging parameters on the pressure gradient, time averaged volume flow rate and frictional force are discussed with the aid of graphs.

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