Flow of liquid in a cylindrical vessel with a turbine impeller and radial baffles

1982 ◽  
Vol 47 (1) ◽  
pp. 226-239 ◽  
Author(s):  
Ivan Fořt ◽  
Ahmed Obeid ◽  
Vítězslav Březina
Keyword(s):  
Theoretical Model ◽  
Flow Pattern ◽  
Analytical Description ◽  
Cylindrical Vessel ◽  
Newtonian Liquid ◽  
Mean Velocity ◽  
Hot Film ◽  
System Geometry ◽  
Turbine Impeller

The study describes a theoretical model of flow pattern of a newtonian liquid in a flat-bottomed cylindrical vessel with radial baffles at wall agitated by a standard six-blade disc turbine impeller, under turbulent flow. The model, comprising the description of the field of main mean velocity components and of Stokes stream function in the system, is identified by experimental determination of velocity field by means of Pilot direction tubes and hot-film anemometer. The resulting analytical description of the flow pattern in the vessel corresponds well to that found experimentally. Knowing three parameters derived from the velocity profile of the stream streaking from the impeller, the description depends only on the system geometry.

The flow of liquid in a stream from the standard turbine impeller

1979 ◽  
Vol 44 (3) ◽  
pp. 700-710 ◽  
Author(s):  
Ivan Fořt ◽  
Hans-Otto Möckel ◽  
Jan Drbohlav ◽  
Miroslav Hrach
Keyword(s):  
Reynolds Number ◽  
Kinematic Viscosity ◽  
Momentum Flux ◽  
Relative Size ◽  
Mean Velocity ◽  
Axial Profile ◽  
The Mean ◽  
Hot Film ◽  
Turbine Impeller

Profiles of the mean velocity have been analyzed in the stream streaking from the region of rotating standard six-blade disc turbine impeller. The profiles were obtained experimentally using a hot film thermoanemometer probe. The results of the analysis is the determination of the effect of relative size of the impeller and vessel and the kinematic viscosity of the charge on three parameters of the axial profile of the mean velocity in the examined stream. No significant change of the parameter of width of the examined stream and the momentum flux in the stream has been found in the range of parameters d/D ##m <0.25; 0.50> and the Reynolds number for mixing ReM ##m <2.90 . 101; 1 . 105>. However, a significant influence has been found of ReM (at negligible effect of d/D) on the size of the hypothetical source of motion - the radius of the tangential cylindrical jet - a. The proposed phenomenological model of the turbulent stream in region of turbine impeller has been found adequate for values of ReM exceeding 1.0 . 103.

DETERMINATION OF THE DISTRIBUTION FUNCTION OF THE TIME BETWEEN FAILURES OF A WEAPON MODEL WITHOUT TAKING INTO ACCOUNT THE ENEMY’S FIRE IMPACT

2019 ◽  
pp. 39-45
Author(s):  
M. Sliusarenko ◽  
O. Semenenko ◽  
T. Akinina ◽  
O. Zaritsky ◽  
V. Ivanov
Keyword(s):  
Distribution Function ◽  
Analytical Description ◽  
Time To Failure ◽  
Missile Defense ◽  
Incorrect Choice ◽  
Military Equipment ◽  
Time Between Failures ◽  
The Military ◽  
Fire Impact

In the article, based on the analysis of the requirements for the readiness of weapons and military equipment during combat use and the reliability of their operation in the course of combat operations, it was discovered that one of the reasons that causes a discrepancy between the declared failures and real ones may be the incorrect choice and justification of the time distribution function up to the refusal of military means. As a rule, during the development of these tools, the function of distribution of time to failure is chosen by analogy with similar patterns of weapons and military equipment. In the theory of reliability, special attention is given to choosing the function of time-breaking non-response (failures or failures). Therefore, the article deals with the questions of evaluating the effectiveness of functioning of complex systems and methods of modeling the processes of their functioning, taking into account the laws of the distribution of random variables. The discrepancy between the declared irregularity of the military apparatus and the fact that is actually observed in the troops can be explained by the incorrectly accepted hypothesis about the distribution of time to failure. Therefore, the article analyzes the order of the justification of such a function without taking into account the enemy's fire impact and the proposed variant of determining the function of distribution of the time of work until the refusal of the model of military equipment. The article also cites the reasons for the discrepancy between the claimed missile defense equipment and what is actually observed in the troops. The proposed mathematical model of faultlessness, which at stages of designing and design will allow to set requirements to the model of technology with the help of analytical description. The sequence of calculations of non-failure indexes based on the use of Weibull distribution is substantiated.

Energy dissipation rate in a baffled vessel with pitched blade turbine impeller

1991 ◽  
Vol 56 (9) ◽  
pp. 1856-1867 ◽  
Author(s):  
Zdzisław Jaworski ◽  
Ivan Fořt
Keyword(s):  
Energy Dissipation ◽  
Cross Sections ◽  
Mechanical Energy ◽  
Vessel Diameter ◽  
Energy Dissipation Rate ◽  
Mean Velocity ◽  
Agitated Vessel ◽  
Radial Profiles ◽  
Pitched Blade Turbine ◽  
Turbine Impeller

Mechanical energy dissipation was investigated in a cylindrical, flat bottomed vessel with four radial baffles and the pitched blade turbine impeller of varied size. This study was based upon the experimental data on the hydrodynamics of the turbulent flow of water in an agitated vessel. They were gained by means of the three-holes Pitot tube technique for three impeller-to-vessel diameter ratio d/D = 1/3, 1/4 and 1/5. The experimental results obtained for two levels below and two levels above the impeller were used in the present study. Radial profiles of the mean velocity components, static and total pressures were presented for one of the levels. Local contribution to the axial transport of the agitated charge and energy was presented. Using the assumption of the axial symmetry of the flow field the volumetric flow rates were determined for the four horizontal cross-sections. Regions of positive and negative values of the total pressure of the liquid were indicated. Energy dissipation rates in various regions of the agitated vessel were estimated in the range from 0.2 to 6.0 of the average value for the whole vessel. Hydraulic impeller efficiency amounting to about 68% was obtained. The mechanical energy transferred by the impellers is dissipated in the following ways: 54% in the space below the impeller, 32% in the impeller region, 14% in the remaining part of the agitated liquid.

scholarly journals New Equation for Predicting Pipe Friction Coefficients Using the Statistical Based Entropy Concepts

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 611
Author(s):  
Yeon-Woong Choe ◽  
Sang-Bo Sim ◽  
Yeon-Moon Choo
Keyword(s):  
Friction Coefficient ◽  
Accurate Determination ◽  
Mean Velocity ◽  
Friction Coefficients ◽  
Flow Discharge ◽  
Comparison Results ◽  
Flow Loss ◽  
Key Variables ◽  
New Equation

In general, this new equation is significant for designing and operating a pipeline to predict flow discharge. In order to predict the flow discharge, accurate determination of the flow loss due to pipe friction is very important. However, existing pipe friction coefficient equations have difficulties in obtaining key variables or those only applicable to pipes with specific conditions. Thus, this study develops a new equation for predicting pipe friction coefficients using statistically based entropy concepts, which are currently being used in various fields. The parameters in the proposed equation can be easily obtained and are easy to estimate. Existing formulas for calculating pipe friction coefficient requires the friction head loss and Reynolds number. Unlike existing formulas, the proposed equation only requires pipe specifications, entropy value and average velocity. The developed equation can predict the friction coefficient by using the well-known entropy, the mean velocity and the pipe specifications. The comparison results with the Nikuradse’s experimental data show that the R2 and RMSE values were 0.998 and 0.000366 in smooth pipe, and 0.979 to 0.994 or 0.000399 to 0.000436 in rough pipe, and the discrepancy ratio analysis results show that the accuracy of both results in smooth and rough pipes is very close to zero. The proposed equation will enable the easier estimation of flow rates.

D-C Network-Analyzer Determination of Fluid-Flow Pattern in a Centrifugal Impeller

1947 ◽  
Vol 14 (2) ◽  
pp. A113-A118
Author(s):  
C. Concordia ◽  
G. K. Carter
Keyword(s):  
Fluid Flow ◽  
Flow Pattern ◽  
Arbitrary Shape ◽  
Centrifugal Impeller ◽  
Network Analyzer ◽  
Two Dimensional ◽  
Special Shape ◽  
Electrical Method ◽  
Incompressible Ideal Fluid

Abstract The objects of this paper are, first, to describe an electrical method of determining the flow pattern for the flow of an incompressible ideal fluid through a two-dimensional centrifugal impeller, and second, to present the results obtained for a particular impeller. The method can be and has been applied to impellers with blades of arbitrary shape, as distinguished from analytical methods which can be applied directly only to blades of special shape (1).

scholarly journals Determination of Long Horizontal Borehole Height in Roofs and its Application to Gas Drainage

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2647
Author(s):  
Gang Wang ◽  
Cheng Fan ◽  
Hao Xu ◽  
Xuelin Liu ◽  
Rui Wang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Fracture Zone ◽  
Coalbed Methane ◽  
High Efficiency ◽  
Gas Drainage ◽  
Methane Drainage ◽  
Working Face ◽  
Variation Characteristics

Accurately determining the height of the gas-guiding fracture zone in the overlying strata of the goaf is the key to find the height of the long horizontal borehole in the roof. In order to determine the height, in this study we chose the 6306 working face of Tangkou Coal Mine in China as a research example and used both the theoretical model and discrete element method (DEM) numerical simulation to find the height of the gas-guiding fracture zone and applied the height to drill a long horizontal borehole in the roof of the 6303 working face. Furthermore, the borehole was utilized to deep into the roof for coalbed methane drainage and the results were compared with conventional gas drainage measures from other aspects. The height of the gas-guiding fracture zone was found to be 48.57 m in theoretical model based on the bulk coefficient and the void ratio and to be 51.19 m in the DEM numerical simulation according to the temporal and spatial variation characteristics of porosity. Taking both the results of theoretical analysis and numerical simulation into consideration, we determined that gas-guiding fracture zone is 49.88 m high and applied it to drill a long horizontal borehole deep into the roof in the 6303 working face field. Compared with conventional gas drainage measures, we found that the long horizontal borehole has the high stability, high efficiency and strong adaptability for methane drainage.

Determination of Technological Forces in the Incremental Forming Process

2013 ◽  
Vol 371 ◽  
pp. 133-137
Author(s):  
Radu Eugen Breaz ◽  
Melania Tera ◽  
Octavian Bologa ◽  
Sever Gabriel Racz
Keyword(s):  
Image Processing ◽  
Theoretical Model ◽  
Data Acquisition ◽  
Incremental Forming ◽  
Single Point ◽  
Cnc Milling ◽  
Forming Process ◽  
Feed Drive ◽  
Cnc Milling Machine

The paper presents a joint theoretical and experimental approach to determine the technological forces within the asymmetric single point incremental forming ASPIF process, based upon a theoretical model, image processing and data acquisition. The first step of this approach was to develop a theoretical model of the forces within the process, based upon the model of a mechanical feed drive of a CNC milling machine. By means of this model, relationships between the resistant torque at the motor spindle level and the technological force on the movement axis could be determined. Using an image processing method, which allowed the user to extract information within the machines operator panel and analytical relationships, the technological forces were determined. The results were compared with the measured values, obtained by means of a data acquisition system.

An Analytical Description of the Magnetic Conductance Across an Isolated Defect Region in a 1D-Ferromagnetic Lead

SPIN ◽  
2019 ◽  
Vol 09 (01) ◽  
pp. 1950005 ◽  
Author(s):  
Adel Belayadi ◽  
Boualem Bourahla ◽  
Ahmed Mougari
Keyword(s):  
Contact Region ◽  
Analytical Description ◽  
Quantum Scattering ◽  
Defect Region ◽  
Model Calculations ◽  
Adopted Model ◽  
Field Matching ◽  
Ferromagnetic Lead ◽  
Transmission And Reflection

We illustrate in this contribution the determination of the magnetic conductance across a nanocontact region defined by an isolated defect region joined between two mono-atomic leads ferromagnetically ordered. The system is described by the Heisenberg interaction. Additionally, to deal with the lack of symmetry across the contact region defined by the isolated defect, we involve the phase field matching approach. Furthermore, to compute the quantum conductance, we define the quantum scattering of the transmission and reflection probabilities within the framework of Landauer–Büttiker formalism. Based on these approaches, we present an analytical expression of the magnetic conductance. The obtained analytical results based on our adopted procedures confirm the known results adopted for perfect infinite leads (no defect). Our model calculations can be applied numerically when we deal with doping across the defect region. The adopted model could be also used numerically to deal with the impurity configurations that one might encounter in real systems.

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