Aeration of liquids in a vessel equipped with multistage impellers

1985 ◽  
Vol 50 (12) ◽  
pp. 2863-2872 ◽  
Author(s):  
Václav Machoň ◽  
Jiří Vlček
Keyword(s):  
Input Data ◽  
Power Input ◽  
Experimental Results ◽  
Simple Equation ◽  
Mechanical Power ◽  
System A ◽  
Liquid Dispersion ◽  
Liquid Depth ◽  
Turbine Impeller ◽  
Tank Diameter

The paper deals with the influence of the number of impellers and the mode of aeration on the mechanical power input in a stirred gas-liquid dispersion using two impellers on the same shaft. Gas has been supplied either under the lower impeller or under both impellers. The power input was measured in the water-air system. A six-blade turbine impeller of the Rushton type and/or impellers with six inclined blades (with downward or upward pumping effect) were used. Experimental results have been obtained for a single impeller in a tank where the depth of liquid was equal to the tank diameter, and for different combinations of two impellers located on a single shaft where the distance between the impellers was equal to the tank diameter and the liquid depth was twice this diameter. It has been found that the power input data for the two-impeller system of two turbines can be correlated adequately by a simple equation. An estimate was made of the amount of gas supplied below the lower impeller which was transported into the region of the upper impeller.

scholarly journals Power and efficiency of insect flight muscle

1985 ◽  
Vol 115 (1) ◽  
pp. 293-304 ◽  
Author(s):  
C. P. Ellington
Keyword(s):  
Power Output ◽  
Flight Muscle ◽  
Insect Flight ◽  
Power Input ◽  
Mechanical Power ◽  
Insect Flight Muscle ◽  
Muscle Properties ◽  
System A ◽  
Mechanical Power Output ◽  
Flight Muscles

The efficiency and mechanical power output of insect flight muscle have been estimated from a study of hovering flight. The maximum power output, calculated from the muscle properties, is adequate for the aerodynamic power requirements. However, the power output is insufficient to oscillate the wing mass as well unless there is good elastic storage of the inertial energy, and this is consistent with reports of elastic components in the flight system. A comparison of the mechanical power output with the metabolic power input to the flight muscles suggests that the muscle efficiency is quite low: less than 10%.

Free Level Effect on the Impeller Power Input in Baffled Tanks

1995 ◽  
Vol 60 (8) ◽  
pp. 1274-1280 ◽  
Author(s):  
Kamil Wichterle
Keyword(s):  
Reynolds Number ◽  
Power Input ◽  
Dimensionless Number ◽  
Simple Correlation ◽  
Mixture Density ◽  
Surface Aeration ◽  
Free Level ◽  
High Reynolds ◽  
Level Effect ◽  
Turbine Impeller

Analysis of extended data on turbine impeller power input in geometrically similar agitated baffled tanks shows that the power number Po is a function of Reynolds number Po = Po*(Re) until the emergence of surface aeration. Though it is usually anticipated that Po* = const in high Reynolds number region, some, whatever weak, function should be taken into consideration in more detailed analysis of the power data even here. In practice, disturbances of level and gas captured in the impeller region play also a significant role, namely in smaller tanks at higher impeller speeds. Decrease of power input can be explained by decrease of gas-liquid mixture density, or in other words by increase of efficient gas holdup eE just in the impeller region. The value eE defined by the relation Po = Po*(Re)/(1 + eE) was determined from the available data. Like other effects of the surface aeration it depends mainly on the dimensionless number Nc = (We Fr)1/4. A simple correlation eE (Nc) is suggested as a correction factor for prediction of impeller power in presence of gas capture.

Surface Aeration Threshold in Agitated Vessels

1996 ◽  
Vol 61 (5) ◽  
pp. 681-690
Author(s):  
Kamil Wichterle ◽  
Tomáš Svěrák
Keyword(s):  
Simple Model ◽  
Liquid Surface ◽  
Power Input ◽  
Power Number ◽  
Region Analysis ◽  
Surface Aeration ◽  
Liquid Dispersion ◽  
Mixing Vessels ◽  
Number Curve

Violent agitation of liquids in mixing vessels may result in the regime of surface aeration being attained when the bubbles formed at the liquid surface enter the impeller region. Analysis of data on surface aeration for different liquids in a set of geometrically similar agitated vessels is presented. Data on the just aerated state as observed visually in transparent liquids, and data for the efficient aeration as determined from the break on the power number curve are considered. A simple model is developed for correlation of the data which enables the threshold of aeration to be predicted from the value of the recirculation number Nc = Nd (ρ/σg)1/4. The possibility of interpreting various literature data for the aeration threshold and for the power input with use of Nc is demonstrated. Similar modelling rules hold also for the correlation of beginning of the efficient liquid-liquid dispersion.

scholarly journals Flagellar energetics from high-resolution imaging of beating patterns in tethered mouse sperm

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Ashwin Nandagiri ◽  
Avinash Satish Gaikwad ◽  
David L Potter ◽  
Reza Nosrati ◽  
Julio Soria ◽  
...  
Keyword(s):  
High Resolution ◽  
Power Input ◽  
Mechanical Power ◽  
Secretory Proteins ◽  
Ion Channel Regulation ◽  
Mouse Sperm ◽  
Energy Flows ◽  
Internal Dissipation ◽  
Resolution Imaging ◽  
Proper Orthogonal

We demonstrate a technique for investigating the energetics of flagella or cilia. We record the planar beating of tethered mouse sperm at high-resolution. Beating waveforms are reconstructed using Proper Orthogonal Decomposition of the centerline tangent-angle profiles. Energy conservation is employed to obtain the mechanical power exerted by the dynein motors from the observed kinematics. A large proportion of the mechanical power exerted by the dynein motors is dissipated internally by the motors themselves. There could also be significant dissipation within the passive structures of the flagellum. The total internal dissipation is considerably greater than the hydrodynamic dissipation in the aqueous medium outside. The net power input from the dynein motors in sperm from Crisp2-knockout mice is significantly smaller than in wildtype samples, indicating that ion-channel regulation by cysteine-rich secretory proteins (CRISPs) controls energy flows powering the axoneme.

scholarly journals The Roball

2002 ◽  
Vol 35 (3) ◽  
pp. 204-207 ◽  
Author(s):  
William H. Robinson
Keyword(s):  
Seismic Isolation ◽  
Inverted Pendulum ◽  
Experimental Results ◽  
Flat Plates ◽  
Isolation System ◽  
Friction Forces ◽  
New Device ◽  
System A ◽  
Full Scale Tests ◽  
User Friendly

Robinson Seismic's latest developments in seismic isolation includes a new device, the RoballTM, for seismically isolating structures during earthquakes. This advance is a new concept for seismic isolation based on the principle of the inverted pendulum. It consists of 'friction balls' or 'Roballs' moving between upper and lower spherical like cavities or flat plates. The Roballs are filled with a material which is able to provide the friction forces required to absorb the energy from numerous earthquakes while supporting the structure. The Roball technique is expected to enable light and in the future possibly heavy structures to be more economically seismically isolated. As part of a program to develop a user friendly 'seismic isolation system' a series of full-scale tests have been carried out on a number of possible designs including three approaches for vertical pressures of -1 MPa resulting in coefficients of friction of -0.1 to -0.4. In this paper we present the preliminary experimental results.

Reparo: A Fast RAID Recovery Scheme for Ultra-large SSDs

2021 ◽  
Vol 17 (3) ◽  
pp. 1-24
Author(s):  
Duwon Hong ◽  
Keonsoo Ha ◽  
Minseok Ko ◽  
Myoungjun Chun ◽  
Yoona Kim ◽  
...  
Keyword(s):  
Storage Systems ◽  
Storage System ◽  
Experimental Results ◽  
Huge Amount ◽  
Failure Characteristics ◽  
System A ◽  
Recovery Scheme ◽  
Cost Efficient ◽  
Recovery Schemes ◽  
Multi Core Processor

A recent ultra-large SSD (e.g., a 32-TB SSD) provides many benefits in building cost-efficient enterprise storage systems. Owing to its large capacity, however, when such SSDs fail in a RAID storage system, a long rebuild overhead is inevitable for RAID reconstruction that requires a huge amount of data copies among SSDs. Motivated by modern SSD failure characteristics, we propose a new recovery scheme, called reparo , for a RAID storage system with ultra-large SSDs. Unlike existing RAID recovery schemes, reparo repairs a failed SSD at the NAND die granularity without replacing it with a new SSD, thus avoiding most of the inter-SSD data copies during a RAID recovery step. When a NAND die of an SSD fails, reparo exploits a multi-core processor of the SSD controller in identifying failed LBAs from the failed NAND die and recovering data from the failed LBAs. Furthermore, reparo ensures no negative post-recovery impact on the performance and lifetime of the repaired SSD. Experimental results using 32-TB enterprise SSDs show that reparo can recover from a NAND die failure about 57 times faster than the existing rebuild method while little degradation on the SSD performance and lifetime is observed after recovery.

Study of the Vortex-Induced Vibration of the Marine Risers With the Buoyancy

2019 ◽  
Author(s):  
Lin Zhao ◽  
Hang Su ◽  
Yanju Yin
Keyword(s):  
Vibration Frequency ◽  
Cross Flow ◽  
Experimental Results ◽  
Resonance Phenomenon ◽  
Feature Points ◽  
System A ◽  
Acceleration Amplitude ◽  
Floating System ◽  
Modal Vibration ◽  
Flow Velocities

Abstract Regarding the very large top tension of ocean deep water riser which is caused by the heavy self-weight, a innovated buoyancy system is designed. This system can effectively decrease the top tension and improve the performance of the riser movement. In order to study the upper and lower part of the floating system, a specialized model test is carried out, where the acceleration, amplitude, frequency and trajectory of the interested points along the risers are investigated. It has been observed that with the increase of the current speed, both the vibration acceleration and the vibration frequency are increasing but the bare riser amplitude is decreasing. At the speed of 0.2m/s, the resonance phenomenon is observed, but the same phenomenon is not observed for the middle floating riser subjecting to different flow velocities. At the speed of 0.4 m/s, the largest amplitude is captured. Due to the response differences of the floating riser at the up and down parts of the middle floating riser, when the amplitude is increasing, the vibration frequency is decreasing, both at cross flow (CF) direction and inline flow (IL) direction. Especially the vibration behavior of the interested points is most influenced by the buoyancy. Under different models, vibration at different flow velocities is presented along bare riser, the modal vibration effects of the floating riser will decrease In addition, according to the experiment condition, Orcaflex is applied to conduct the numerical simulation to get the vibration law of the corresponding feature points and compare it with the experimental results. The results indicate that the numerical analysis reasonably match with experimental results.

scholarly journals Consequences of load carrying by birds during short flights are found to be behavioral and not energetic

2002 ◽  
Vol 283 (1) ◽  
pp. R249-R256 ◽  
Author(s):  
Robert L. Nudds ◽  
David M. Bryant
Keyword(s):  
Body Mass ◽  
Power Input ◽  
Mechanical Power ◽  
Zebra Finches ◽  
Mass Loading ◽  
Metabolic Power ◽  
Additional Mass ◽  
Reduced Body ◽  
Mechanical Power Output ◽  
Load Carrying

The doubly-labeled water technique and video were used to measure the effect of mass loading on energy expenditure and takeoff performance in zebra finches, Taeniopygia guttata, that were making routine (nonalarm) short flights. Finches that carried 27% additional mass did not expend more energy during flight than unloaded controls. Carrying additional mass, however, led to a reduced body mass and a decreased velocity during takeoffs (by 12%). Calculations of instantaneous mechanical power indicated that energy expended by unloaded and loaded finches at takeoff was similar, due to the observed decrease in velocity by mass-loaded finches and a lowering of their body mass. During routine short flights, zebra finches appear to maintain their metabolic power input and mechanical power output regardless of mass loading. Here, the costs of carrying additional mass during routine short flights were revealed to be behavioral and not energetic.

scholarly journals A Compound Current Limiter and Circuit Breaker

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 551 ◽  
Author(s):  
Amir Heidary ◽  
Hamid Radmanesh ◽  
Ali Bakhshi ◽  
Kumars Rouzbehi ◽  
Edris Pouresmaeil
Keyword(s):  
Voltage Drop ◽  
Circuit Breaker ◽  
Experimental Results ◽  
Fault Current ◽  
Fault Current Limiter ◽  
System A ◽  
Ability To Act ◽  
Compound Type ◽  
In Series ◽  
Current Limiter

The protection of sensitive loads against voltage drop is a concern for the power system. A fast fault current limiter and circuit breaker can be a solution for rapid voltage recovery of sensitive loads. This paper proposes a compound type of current limiter and circuit breaker (CLCB) which can limit fault current and fast break to adjust voltage sags at the protected buses. In addition, it can act as a circuit breaker to open the faulty line. The proposed CLCB is based on a series L-C resonance, which contains a resonant transformer and a series capacitor bank. Moreover, the CLCB includes two anti-parallel power electronic switches (a diode and an IGBT) connected in series with bus couplers. In order to perform an analysis of CLCB performance, the proposed structure was simulated using MATLAB. In addition, an experimental prototype was built, tested, and the experimental results were reported. Comparisons show that experimental results were in fair agreement with the simulation results and confirm CLCB’s ability to act as a fault current limiter and a circuit breaker.

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