scholarly journals Power Input of High-Speed Rotary Impellers

10.14311/280 ◽  
2001 ◽  
Vol 41 (6) ◽  
Author(s):  
K. R. Beshay ◽  
J. Kratěna ◽  
I. Fořt ◽  
O. Brůha
Keyword(s):  
Pitch Angle ◽  
High Speed ◽  
Power Input ◽  
Cylindrical Vessel ◽  
Turbulent Regime ◽  
Power Dependence ◽  
Rushton Turbine ◽  
Weak Influence ◽  
Turbine Impeller ◽  
Blade Pitch Angle

This paper presents the results of an experimental investigation of the power input of pitched blade impellers and standard Rushton turbine impellers in a cylindrical vessel provided with four radial baffles at its wall under a turbulent regime of flow of an agitated liquid. The influence of the geometry of the pitched blade impellers (pitch angle, number of blades) and the off-bottom impeller clearance of both high-speed impellers tested on the impeller power input is determined in two sizes of the cylindrical vessel (0.3 m and 0.8 m diameter of vessel). A strain gauge torquemeter is used in the small vessel and a phase shift mechanical torquemeter is used in the large vessel. All results of the experiments correspond to the condition that the Reynolds number modified for the impeller exceeds ten thousand. The results of this study show that the significant influence of the separating disk thickness of the turbine impeller corresponds fairly well to the empirical equations presented in the literature. Both the influence of the number of impeller blades and the blade pitch angle of the pitched blade impeller were expressed quantitatively by means of the power dependence of the recently published correlations: the higher the pitch angle and the number of blades, the higher the values of the impeller power input. Finally, it follows from results of this study that the impeller off-bottom clearance has a weak influence on the power input of the Rushton turbine impeller, but with decreasing impeller off-bottom clearance the power input of the pitched blade impeller increases significantly.

Energetic efficiency of two impellers on the same shaft in a cylindrical baffled vessel of high height/diameter ratio

1989 ◽  
Vol 54 (9) ◽  
pp. 2345-2356 ◽  
Author(s):  
Ivan Fořt ◽  
Jiří Hájek ◽  
Václav Machoň
Keyword(s):  
High Speed ◽  
Power Input ◽  
Vessel Diameter ◽  
Diameter Ratio ◽  
Energetic Efficiency ◽  
Turbulent Regime ◽  
Inclined Plane ◽  
Pumping Effect ◽  
Charge Flow ◽  
Turbine Impeller

The paper deals with the experimental study of the indicating particle circulation and the impeller power input in a liquid mechanically agitated with two high-speed impellers (combination of the standard turbine impeller and the six inclined (at 45°) plane blades impeller) on the same shaft in a slender vessel (its height is equal double of the vessel diameter) equipped with four radial baffles at its walls under the turbulent regime of agitated charge flow. By the visual method of the indicating particle it is examined its circulation in the lower part of the system pumping effect of the lower impeller), its circulation in the upper part of the system (pumping effect of the upper impeller), and the exchangeable circulation between the upper and lower part of the system and vice versa. The impeller power input is ascertained from the measured current electricity in the anchor of the direct current driving motor. It follows from the calculated energetic efficiency (the ratio of the cube of the sum of the impeller flow rate numbers and the sum of the impeller power numbers) of the investigated combinations of impellers that the highest value of this quantity is exhibited for two standard turbine impellers on the same shaft and for a combination of the lower standard turbine impeller and the upper impeller with inclined plane blades pumping upwards; slightly less value of the impeller energetic efficiency appears for the combination of two impellers with six inclined plane blades, the upper one pumps liquid upwards and the lower one downwards. For all the configurations the vertical distance of impellers on the same shaft has to be longer than the vessel diameter.

BLENDING CHARACTERISTICS OF HIGH-SPEED ROTARY IMPELLERS

2013 ◽  
Vol 34 (4) ◽  
pp. 427-434 ◽  
Author(s):  
Ivan Fořt ◽  
Pavel Seichter ◽  
Luboš Pešl ◽  
František Rieger ◽  
Tomáš Jirout
Keyword(s):  
Turbulent Flow ◽  
Flow Regime ◽  
High Speed ◽  
Large Scale ◽  
Energy Savings ◽  
Axial Flow ◽  
Power Input ◽  
Maximum Energy ◽  
Cylindrical Vessel ◽  
Turbulent Flow Regime

Abstract This paper presents a comparison of the blending efficiency of eight high-speed rotary impellers in a fully baffled cylindrical vessel under the turbulent flow regime of agitated charge. Results of carried out experiments (blending time and impeller power input) confirm that the down pumping axial flow impellers exhibit better blending efficiency than the high-speed rotary impellers with prevailing radial discharge flow. It follows from presented results that, especially for large scale industrial realisations, the axial flow impellers with profiled blades bring maximum energy savings in comparison with the standard impellers with inclined flat blades (pitched blade impellers).

Heat and momentum transfer in the wall region of a cylindrical vessel mixed by a turbine impeller

1979 ◽  
Vol 44 (3) ◽  
pp. 684-699 ◽  
Author(s):  
Ivan Fořt ◽  
Jiří Placek ◽  
Frederyk Strek ◽  
Zdislaw Jaworski ◽  
Joana Karcz
Keyword(s):  
Momentum Transfer ◽  
Cylindrical Vessel ◽  
Temperature Fields ◽  
Wall Region ◽  
Turbulent Heat ◽  
Turbulent Regime ◽  
Region Flow ◽  
Velocity And Temperature Fields ◽  
Heat And Momentum Transfer ◽  
Turbine Impeller

Velocity and temperature fields have been described in the wall region of a cylindrical vessel equipped with radial baffles mixed by a standard six-blade disc turbine impeller under the turbulent regime of the flow in a homogeneous Newtonian charge. The results of experiments offer conclusions regarding the mechanism of the turbulent flow in individual subregions of the wall region together with the method of description of the flow in these regions as a sequence of impinging wall turbulent streams. Based on the theory of analogy the results on the turbulent heat and momentum transfer have been compared and confirm validity of the Chilton-Colburn analogy in which the characteristic quantities for the calculation of the local friction factor are parameters of the wall region flow - the characteristic velocity and the characteristic thickness of the wall region.

Design and Testing of a New Small Wind Turbine Blade

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Qiyue Song ◽  
William David Lubitz
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Pitch Angle ◽  
High Speed ◽  
Wind Turbine Blade ◽  
Horizontal Axis Wind Turbine ◽  
Small Wind Turbine ◽  
High Winds ◽  
Design And Testing ◽  
Blade Pitch Angle

A small wind turbine blade was designed using blade element momentum (BEM) method for a three bladed, fixed pitch 1 kW horizontal axis wind turbine. The new blades were fabricated, fit to a Bergey XL 1.0 turbine, and tested using a vehicle-based platform at the original designed pitch angle, plus with 5 deg and 9 deg of additional pitch. The new blades had better aerodynamic performance than the original Bergey XL 1.0 blades at high speed, but in some cases at lower speeds the original blades performed better. The results demonstrated that selecting the blade pitch angle on a rotor is a tradeoff between starting performance and power output in high winds. The BEM simulations were evaluated against the test data and demonstrated that the BEM simulations predicted the rotor performance with reasonable accuracy.

Investigation of the flow patterns and power requirements in agitated systems: effects of the design of baffles and vessel base

2020 ◽  
Vol 18 (9) ◽  
Author(s):  
Mohammed Foukrach ◽  
Houari Ameur
Keyword(s):  
Power Consumption ◽  
Power Input ◽  
Vessel Diameter ◽  
Flow Patterns ◽  
Cylindrical Vessel ◽  
Rushton Turbine ◽  
Conical Shape

AbstractThe flow patterns and power consumption of a six-blade Rushton turbine (RT) in a cylindrical vessel are characterized in this paper. We focus on the effects of the shape of the vessel base by studying two cases: a conical and a dished shape. In addition, the effects of the height of the vessel base (h2) are explored and four cases are considered, namely: h2/D = 1/10, 1/6, 1/5 and 1/3 (D: vessel diameter). In the second part of our investigation, a new design of baffles (a triangular-shaped baffle) is suggested and a comparison is made between the performance of the standard and the triangular baffles. The main findings revealed that the conical shape of the vessel base provides a slight enhancement in the axial circulation at almost the same power input for the dished bottomed vessel. For Re < 2 × 104, the power required by both types of baffles is the same; however, above this value of Re, a reduction by about 4% in power consumption is given by the standard baffles. Also, and for all shapes of baffles and vessel bases, a reduction in power consumption may be obtained by increasing the height of the vessel base.

scholarly journals Study of the Discharge Stream from a Standard Rushton turbine impeller

10.14311/600 ◽  
2004 ◽  
Vol 44 (4) ◽  
Author(s):  
J. Kratěna ◽  
I. Fořt
Keyword(s):  
Velocity Field ◽  
Experimental Studies ◽  
Turbulent Energy ◽  
High Rate ◽  
Turbulent Regime ◽  
Mean Velocity ◽  
Special Flow ◽  
Rushton Turbine ◽  
The Mean ◽  
Turbine Impeller

The discharge stream from a standard Rushton turbine impeller exhibits special flow properties different from the characteristics of the velocity field in other parts of the volume of an agitated liquid in a cylindrical baffled vessel, e.g. two prevailing components of the mean velocity (radial and tangential), high rate of turbulent energy dissipation and anisotropy of turbulence in this region. At the same time, the discharge stream plays an important role in mixing operations, above all in liquid-liquid and gas-liquid systems.This paper deals with theoretical and experimental studies of the velocity field and flow of angular momentum in a discharge stream from a standard Rushton turbine impeller in a cylindrical baffled flat bottomed vessel under turbulent regime of flow of an agitated liquid with emphasis on describing the ensemble averaged values over the whole interval of the tangential coordinate around the vessel perimeter.

scholarly journals Dynamic Effect of Discharge Flow of a Rushton Turbine Impeller on a Radial Baffle

10.14311/198 ◽  
2001 ◽  
Vol 41 (1) ◽  
Author(s):  
J. Kratěna ◽  
I. Fořt ◽  
O. Brůha
Keyword(s):  
Dynamic Pressure ◽  
Dynamic Effect ◽  
Flow Region ◽  
Tangential Component ◽  
Turbulent Regime ◽  
Torsional Moment ◽  
Discharge Flow ◽  
Rushton Turbine ◽  
Dynamic Relation ◽  
Turbine Impeller

This paper presents an analysis of the mutual dynamic relation between the impeller discharge flow of a standard Rushton turbine impeller and a standard radial baffle at the wall of a cylindrical mixing vessel under turbulent regime of flow of an agitated liquid. A portion of the torsional moment of the baffle corresponding to the region of the force interaction of the impeller discharge stream and the baffle is calculated under the assumption of constant angular momentum in the flow region between the impeller and the baffles. This theoretically obtained quantity is compared with the torsional moment of the baffles calculated from the experimentally determined distribution of the peripheral (tangential) component of dynamic pressure along the height of the radial baffle in pilot plant mixing equipment. It follows from the results of our calculations that for both investigated impeller off-bottom clearances the theoretically determined transferred torsional moment of the baffles in the area of interference between the impeller discharge flow and the baffles agrees fairly well with experimentally determined data and, moreover, that more than 2/3 of the transferred torsional moment of the baffles as a whole is located in the above mentioned interference area.

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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