The power input of screw rotors and agitators: The power input of screw agitator with a draught tube

1989 ◽  
Vol 54 (6) ◽  
pp. 1589-1598
Author(s):  
František Rieger
Keyword(s):  
Power Input ◽  
Draught Tube ◽  
Screw Rotors

The power input has been measured of 52 various geometries of the screw agitator with a draught tube. The obtained results have been correlated by a relation derived for the power input of screw rotors in the previous paper.

Power input of screw rotors and agitators: Theory of calculation of power input of screw rotors

1989 ◽  
Vol 54 (6) ◽  
pp. 1575-1588 ◽  
Author(s):  
František Rieger
Keyword(s):  
Power Input ◽  
Screw Rotors

A method has been proposed of the calculation of screw rotors. The calculation starts from the equation for the power input for the flow between two plates corrected by correction coefficients.

Process characteristics of screw impellers with a draught tube for Newtonian liquids. The power input

1981 ◽  
Vol 46 (9) ◽  
pp. 2007-2020 ◽  
Author(s):  
Pavel Seichter ◽  
Jiří Dohnal ◽  
František Rieger
Keyword(s):  
Reynolds Number ◽  
Experimental Verification ◽  
Power Input ◽  
Creeping Flow ◽  
Total Power ◽  
Geometrical Parameters ◽  
Draught Tube ◽  
Process Characteristics ◽  
Wide Range ◽  
Newtonian Liquids

An expression has been proposed for the power input of a screw impeller with a draught tube in the creeping flow regime based on the analogy with extruder screws. Experimental verification has confirmed practical utility of the expression in a wide range of geometrical parameters of the impeller and for the Reynolds number for mixing below 20. The total power input of the impeller is expressed as a sum of the input inducing the drag flow and the input to create the pressure flow. The former of the inputs may be deduced from the theory of extruders while an empirical approach based on experiment has been used to formulate an expression for the latter.

A review of high-power magnetoplasmodynamic electric propulsion designs and studies of RSC Energia

2020 ◽  
pp. 112-133
Author(s):  
Victor V. SINYAVSKIY
Keyword(s):  
Service Life ◽  
Electric Power ◽  
High Power ◽  
Electric Propulsion ◽  
Nuclear Power ◽  
Materials Science ◽  
Low Voltage ◽  
Power Input ◽  
Design Bureau ◽  
Rocket Propulsion

At the initiative of S.P.Korolev, in 1959, Special Design Bureau No.1 (now RSC Energia) established the High-temperature Power Engineering and Electric Propulsion Center which was tasked with development of nuclear electric propulsion for heavy interplanetary vehicles. Selected as the source of electric power was a nuclear power unit based on a thermionic converter reactor, and selected as the engine was a stationary low-voltage magnetoplasmodynamic (MPD) high-power (0.5–1.0 MW) thruster which had thousands of hours of service life. The paper presents the results of extensive efforts in research, development, design, materials science experiments, and tests on the MPD-thruster, including the results of development and 500-hours life tests of an MPD-thruster with a 500-600 kW electric power input that used lithium propellant. The world’s first lithium 17 kW MPD-thruster was built and successfully tested in space. The paper points out that to this day nobody has surpassed the then achievements of RSC Energia neither in thruster output during long steady-state operation, nor in performance and service life. Key words: Martian expeditionary vehicle, nuclear electric rocket propulsion system, electric rocket thruster, magnetoplasmodynamic thruster, lithium, cathode, anode, barium, electric propulsion tests in space.

Process characteristics of screw impellers with a draught tube for Newtonian liquids. Time of homogenization

1981 ◽  
Vol 46 (9) ◽  
pp. 2032-2042 ◽  
Author(s):  
Pavel Seichter
Keyword(s):  
Flow Regime ◽  
Creeping Flow ◽  
Energy Requirements ◽  
Dimensionless Time ◽  
Mixing Times ◽  
Conductivity Method ◽  
Draught Tube ◽  
Process Characteristics ◽  
Newtonian Liquids

A conductivity method has been used to assess the homogenization efficiency of screw impellers with draught tubes. The value of the criterion of homochronousness, i.e. the dimensionless time of homogenization, in the creeping flow regime of Newtonian liquids is dependent on the geometrical simplexes of the mixing system. In particular, on the ratio of diameters of the vessel and the impeller and on the ratio of the screw lead to the impeller diameter. Expression have been proposed to calculate the mixing times. Efficiency has been examined of individual configurations of screw impellers. The lowest energy requirements for homogenization have been found for the system with the ratio D/d = 2.

Process characteristics of screw impellers with a draught tube for Newtonian liquids. Pumping capacity of the impeller

1981 ◽  
Vol 46 (9) ◽  
pp. 2021-2031 ◽  
Author(s):  
Pavel Seichter
Keyword(s):  
Viscous Liquid ◽  
Energy Criterion ◽  
Velocity Profiles ◽  
Newtonian Liquid ◽  
Creeping Flow ◽  
Geometrical Arrangement ◽  
Draught Tube ◽  
Process Characteristics ◽  
Newtonian Liquids

Velocity profiles and pumping capacity have been determined using a thermistor anemometer in a vessel equipped with a screw impeller. In region of the creeping flow of a Newtonian liquid, i.e. for Re <15, the dimensionless pumping capacity is dependent on the geometrical arrangement of the mixing system. The efficiency was assessed of individual configuration from the value energy criterion expressing the dimensionless power requirements for recirculation of a highly viscous liquid in a vessel equipped with a screw impeller.

The pumping characteristics of screw rotors. I. The theory of calculation of the pumping capacity of screw rotors

1987 ◽  
Vol 52 (2) ◽  
pp. 357-371 ◽  
Author(s):  
František Rieger
Keyword(s):  
Present State ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Screw Rotor ◽  
Screw Rotors

This paper summarizes the present state of the theory of calculation of the pumping capacity of screw rotors. The calculation starts from the equation for the volumetric flow rate of the flow between two unconfined plates modified by correction coefficients obtained from the relationships for the flow rate in simpler geometrical configurations to which the screw rotor may be, under certain circumstances, reduced.

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.

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