Real Time Measurement for High Frequency Pulsating Flow Rate in a Pipe

1990 ◽  
Vol 112 (4) ◽  
pp. 762-768 ◽  
Author(s):  
Tong Zhao ◽  
K. Sanada ◽  
A. Kitagawa ◽  
T. Takenaka
Keyword(s):  
Flow Rate ◽  
High Frequency ◽  
Time Measurement ◽  
Differential Pressure ◽  
Pulsating Flow ◽  
Electronic Circuits ◽  
Flow Rates ◽  
Real Time Measurement ◽  
Wide Range ◽  
Transformation Methods

Two kinds of analog transformation methods for the measurement of high frequency pulsating flow rates in pipe flow are investigated. By use of the methods, the high frequency pulsating flow rates can be obtained by feeding differential pressure or centerline velocity to analog electronic circuits. First, the frequency characteristics of the electronic circuits for the measurement are examined by experiments. Then a criterion for determining the measurement distance of the differential pressure is derived analytically in order to ensure the required accuracy of the measurement when the flow rate is obtained from the differential pressure signal. Both methods are experimented with over a wide range of frequency. The results show that both methods are not only simple and practical, but also very accurate for the measurement of high frequency pulsating flow rates.

Theoretical, Numerical, and Experimental Study on an Unsteady Venturi Flowmeter for Incompressible Flows

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Izuru Kambayashi ◽  
Donghyuk Kang ◽  
Naoki Nishimura
Keyword(s):  
Flow Rate ◽  
Dynamic Characteristics ◽  
Energy Equation ◽  
Incompressible Flows ◽  
Euler Method ◽  
Pulsating Flow ◽  
Systematic Research ◽  
Flow Rates ◽  
Wide Range ◽  
Venturi Flowmeter

Abstract To examine the dynamic characteristics of turbomachinery and cavitation, the pulsating flow rates should be evaluated. As it is difficult to measure these pulsating flow rates quantitatively, systematic research has not been conducted on the dynamic characteristics of turbomachinery and cavitation. In this paper, an unsteady energy equation for a venturi tube has been proposed to measure pulsating flow rates. The pulsating flow rates were calculated using two methods based on the unsteady energy equation for incompressible flows. The first method calculated a pulsating flow rate by using the Euler method. The second one calculated the complex amplitude of a pulsating flow rate using a transfer function derived from the linearized unsteady energy equation. We analytically examined the order of magnitude for unsteady terms. The results indicated that the unknown unsteady loss was much smaller than the unsteady momentum. In the experiment, pulsating flows were generated by a reciprocating piston, and the given pulsating flow was measured using a hot wire anemometer. The pulsating flow rates evaluated by using the proposed methods were validated via numerical simulation and experiment. In particular, the influence of amplitudes on the evaluation of pulsating flow rates was numerically examined. Therefore, the nonlinear effect could be evaluated by using the proposed method, and the time-averaged loss coefficient was enough to evaluate the pulsating flow rate coefficient. The proposed unsteady venturi flowmeter can be applied to a wide range of research fields, such as analyzing dynamic characteristics of flows.

Subsynchronous Vibration Patterns Under Reduced Oil Supply Flow Rates

2017 ◽  
Author(s):  
B. R. Nichols ◽  
R. L. Fittro ◽  
C. P. Goyne
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Operating Conditions ◽  
System Stability ◽  
Supporting Evidence ◽  
Test Rig ◽  
Flow Rates ◽  
Oil Supply ◽  
Bending Mode ◽  
Wide Range

Many high-speed, rotating machines across a wide range of industrial applications depend on fluid film bearings to provide both static support of the rotor and to introduce stabilizing damping forces into the system through a developed hydrodynamic film wedge. Reduced oil supply flow rate to the bearings can cause cavitation, or a lack of a fully developed film layer, at the leading edge of the bearing pads. Reducing oil flow has the well-documented effects of higher bearing operating temperatures and decreased power losses due to shear forces. While machine efficiency may be improved with reduced lubricant flow, little experimental data on its effects on system stability and performance can be found in the literature. This study looks at overall system performance of a test rig operating under reduced oil supply flow rates by observing steady-state bearing performance indicators and baseline vibrational response of the shaft. The test rig used in this study was designed to be dynamically similar to a high-speed industrial compressor. It consists of a 1.55 m long, flexible rotor supported by two tilting pad bearings with a nominal diameter of 70 mm and a span of 1.2 m. The first bending mode is located at approximately 5,000 rpm. The tiling-pad bearings consist of five pads in a vintage, flooded bearing housing with a length to diameter ratio of 0.75, preload of 0.3, and a load-between-pad configuration. Tests were conducted over a number of operating speeds, ranging from 8,000 to 12,000 rpm, and bearing loads, while systematically reducing the oil supply flow rates provided to the bearings under each condition. For nearly all operating conditions, a low amplitude, broadband subsynchronous vibration pattern was observed in the frequency domain from approximately 0–75 Hz. When the test rig was operated at running speeds above its first bending mode, a distinctive subsynchronous peak emerged from the broadband pattern at approximately half of the running speed and at the first bending mode of the shaft. This vibration signature is often considered a classic sign of rotordynamic instability attributed to oil whip and shaft whirl phenomena. For low and moderate load conditions, the amplitude of this 0.5x subsynchronous peak increased with decreasing oil supply flow rate at all operating speeds. Under the high load condition, the subsynchronous peak was largely attenuated. A discussion on the possible sources of this subsynchronous vibration including self-excited instability and pad flutter forced vibration is provided with supporting evidence from thermoelastohydrodynamic (TEHD) bearing modeling results. Implications of reduced oil supply flow rate on system stability and operational limits are also discussed.

Determinants of flow across isolated gastroduodenal junctions of cats and rabbits

1983 ◽  
Vol 245 (2) ◽  
pp. G257-G264 ◽  
Author(s):  
K. Schulze-Delrieu ◽  
J. P. Wall
Keyword(s):  
Flow Rate ◽  
High Yield ◽  
Pressure Waves ◽  
Base Line ◽  
Tonic Activity ◽  
Flow Rates ◽  
Wide Range ◽  
Line Flow ◽  
Pressure Resistance ◽  
Unidirectional Valve

The resistance generated by the gastroduodenal junction was measured in isolated cat and rabbit preparations. Cannulas were tied into the antrum and duodenum. Yield pressures were determined by increasing the pressure in one of the cannulas until flow occurred. The junctional segment of the cat maintained a high yield pressure. Yield pressures were similar in the antroduodenal and the duodenogastric direction (12.5 +/- 5.7 vs. 14.8 5.8 cmH2O) and increased on both sides to the same degree following exposure of the preparation to 100 mM [K+] and to 10(-6) M carbachol. These experimental manipulations also led to the occurrence of pressure waves in the antral cannula. Yield pressures were diminished but not abolished by exposure of the preparation to 0 [Ca2+] solution or 10(-6) M isoproterenol. Junctional segments from the rabbit did not maintain a yield pressure. Resistance across the junctional segment of both species was also measured by channeling the outflow of one of the cannulas to a flowmeter. Over a wide range of pressures, flow rates across the junctional segment of the rabbit exceeded those across the junctional segment of the cat. Carbachol and 100 mM [K+] decreased the base-line flow and increased the amplitude of intermittent decreases of flow. Isoproterenol and 0 [Ca2+] had opposite effects. Inflation of a balloon decreased the flow rate across the rabbit but not the cat junctional segment. Flow rates across the junctional segment did not differ in the antroduodenal and duodenogastric direction. The gastroduodenal junction does not act as an unidirectional valve. Pyloric resistance relates to the structure of the pyloric segment and to phasic and tonic activity of its musculature.

Influence of milk flow rate and streak canal length on new intramammary infection in dairy cows

1991 ◽  
Vol 58 (4) ◽  
pp. 383-388 ◽  
Author(s):  
Robert J. Grindal ◽  
Andrew W. Walton ◽  
J. Eric Hillerton
Keyword(s):  
Flow Rate ◽  
Peak Flow ◽  
Peak Flow Rate ◽  
Secondary Importance ◽  
Flow Rates ◽  
Intramammary Infection ◽  
Susceptibility To Infection ◽  
Milk Flow ◽  
Wide Range ◽  
Mastitis Control

SummaryEighteen cows with a wide range of quarter peak flow rates (0·35–2·22 kg/min) were inoculated with Streptococcus agalactiae and Str. dysgalactiae 4 mm into each streak canal every 3 d for 12 d. Thirty of the 72 quarters developed intramammary infection. Mean peak flow rate and length of streak canal of those quarters that became infected were 1·26 ± 0·08 kg/min (mean ± SEM) and 11·47 ± 0·41 mm respectively, compared with 1·01 ± 0·05 kg/min and 12·05 ± 0·35 mm for those that remained uninfected. Logistic regression analysis showed that the probability of infection increased significantly with the increase in peak flow rate (P = O·O1). The influence of streak canal length on new infection, after allowing for the effect of peak flow rate, was not significant at the 5% level (P = 0·07), suggesting that there may be an inverse relationship between teat duct length and infection, but that it is of secondary importance to peak flow rate. If increased mass of milk distends the teat duct by raising intramammary pressure, then quarter susceptibility to infection is further compromised. These results strongly suggest that the benefits of reduced infection from mastitis control, achieved despite dramatic increases in milk flow rate and milk yield, are significantly underestimated.

scholarly journals Computational study of a radial flow turbine operates under various pulsating flow shapes and amplitudes

2021 ◽  
pp. 1-24
Author(s):  
Ahmed Rezk ◽  
Sidharath Sharma ◽  
S.M. Barrans ◽  
Abul Kalam Hossain ◽  
P. Samuel Lee ◽  
...  
Keyword(s):  
Mass Flow ◽  
Radial Flow ◽  
Pulsating Flow ◽  
Gradual Change ◽  
Maximum Mass ◽  
Flow Rates ◽  
Flow Accumulation ◽  
Wide Range ◽  
Mass Flow Rates ◽  
The Impact

Abstract Radial flow turbines are extensively used in turbocharging technology due to their unique capability of handling a wide range of exhaust gas flow. The pulsating flow nature of the internal combustion engine exhaust gases causes unsteady operation of the turbine stage. This paper presents the impact of the pulsating flow of various characteristics on the performance of a radial flow turbine. A three-dimensional computational fluid dynamic model was coupled with a one-dimensional engine model to study the realistic pulsating flow. Applying square wave pulsating flow showed the highest degree of unsteadiness corresponding to 92.6% maximum mass flow accumulation due to the consecutive sudden changes of the mass flow rates over the entire pulse. Although saw-tooth showed a maximum mass flow accumulation value of 88.9%, the mass flow rates entailed gradual change resulted in the least overall mass flow accumulation over the entire pulse. These two extremes constrained the anticipated performance of the radial flow turbine operates under realistic pulsating flow. Such constraints could develop an operating envelop to predict the performance and optimize radial flow turbines' power extraction under pulsating flow conditions.

scholarly journals At what flow rate does aortic valve gradient become severely elevated? Implications for guideline recommendations on aortic valve area cutoffs

2021 ◽  
Author(s):  
Wilbert Aronow ◽  
Ayesha Salahuddin ◽  
Daniel Spevack
Keyword(s):  
Aortic Valve ◽  
Linear Regression ◽  
Aortic Stenosis ◽  
Flow Rate ◽  
Aortic Valve Area ◽  
Flow Rates ◽  
Wide Range ◽  
The Relationship ◽  
Valve Area

IntroductionSince many patients with AVA < 1.0 cm2 do not manifest a mAVG > 40 mmHg, we sought to determine the AVA at which mAVG tends to exceed 40 mmHg in a sample of subjects with varied transvalvular flow rates.Material and methodsWe selected 200 subjects with an AVA< 1.0 cm2. The sample was selected to include subjects with a varied mean systolic flow (MSF) rates. Linear regression was performed to determine the relationship between MSF and mAVG. Since this relationship varied by AVA, the regression was stratified by AVA (critical <0.6 cm2, severe 0.6-0.79 cm2 , moderately severe 0.8-0.99 cm2)ResultsThe study sample was 79 ± 12 years-old and was 60% female. The MSF rate at which mAVG tended to exceed 40 mmHg was 120 ml/s for critical AVA, 183 ml/s for severe AVA and 257 ml/s for moderately severe AVA. Those with moderately severe AVA rarely (8%) had a mAVG > 40 mmHg at a wide range of MSF. In contrast, those with severe AVA typically (75%) had mAVG > 40 mmHg when MSF was normal (>200 ml/s). Those with critical AVA frequently (44%) had mAVG > 40 mmHg, even when MSF was reduced.ConclusionsAVA > 0.8 cm2 was rarely associated with mAVG > 40 mmHg, even when transvalvular flow rate was normal. Consideration should therefore be given to either raising the cutoff AVA or lowering the mAVG at which aortic stenosis is considered severe.

Optimization of the process of reproducing units of mass and volume of liquid in a stream, mass and volumetric flow rates of liquid for calibration units with weighing devices

2020 ◽  
pp. 60-64
Author(s):  
R. A. Korneev ◽  
A. R. Tukhvatullin ◽  
V. A. Fafurin ◽  
R. R. Nigmatullin ◽  
A. V. Shchelchkov
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Storage Tank ◽  
Experimental Studies ◽  
Working Fluid ◽  
Time Interval ◽  
Flow Rates ◽  
Wide Range ◽  
Flow Switch

The publication presents an experimental method for estimating the minimum time interval for filling a storage tank with a working fluid with a fixed geometry of the nozzle of the flow switch of the calibration plant when playing units of mass and volume of fluid in the flow, mass and volumetric flow rates of the fluid. Experimental studies were performed in a wide range of mass flow rate 11,10–83,26 kg/s (40–300 t/h) with repeated static weighing of the working fluid. The flow switch is made with a fixed geometry of the flow part of the nozzle exit, which is typical for a large number of calibration units in use in our country with weighing devices. The graphical dependences of the mass flow rate on the time of filling the storage capacity obtained from the research results are the basis for optimizing the process of reproducing units of mass and volume of liquid in the flow, mass and volumetric flow rates of the liquid for calibration plants with weighing devices. These graphical dependencies made it possible to formulate recommendations on the reasonable choice of the minimum interval for filling the storage tank with working fluid in the studied range of mass flow rate. Optimization has been tested and can be extended to calibration units with weighing devices from various manufacturers with individual design and operating parameters.

scholarly journals Effect of Flow Rate and Filter Efficiency on Indoor PM2.5 in Ventilation and Filtration Control

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1061 ◽  
Author(s):  
Ji-Hye Kim ◽  
Myoung-Souk Yeo
Keyword(s):  
Flow Rate ◽  
High Efficiency ◽  
Residential Buildings ◽  
Critical Role ◽  
Particle Model ◽  
Flow Rates ◽  
Filter Efficiency ◽  
Wide Range ◽  
Low Efficiency ◽  
Indoor Pm2.5

Ventilation and filtration control play a critical role in determining indoor PM2.5 (particles less than 2.5 μm in aerodynamic diameter) concentrations of outdoor or indoor origin in residential environments. The objective of this study was to investigate the combined effects of flow rates and filter efficiency on indoor PM2.5 concentrations of residential buildings in Seoul, Korea. Using a particle model based on a mass–balance equation, parametric analysis was performed to examine indoor PM2.5 concentrations according to flow rates and filter efficiency under a wide range of outdoor concentrations and indoor generations. Results showed that ventilation control equipped with a medium–efficiency filter was as effective as that with a high-efficiency filter under normal outdoor concentration and high indoor generation rate conditions. It is not recommended to apply a low-efficiency filter because indoor concentration increases rapidly as outdoor PM2.5 increases when ventilation flow rate is high. For filtration control, it is important to increase both flow rate and filter efficiency in order to improve indoor PM2.5 concentration.

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