scholarly journals Study of the Blending Efficiency of Pitched Blade Impellers

10.14311/276 ◽  
2001 ◽  
Vol 41 (6) ◽  
Author(s):  
I. Fořt ◽  
T. Jirout ◽  
F. Rieger ◽  
R. Allner ◽  
R. Sperling
Keyword(s):  
Pitch Angle ◽  
Theoretical Data ◽  
Vessel Diameter ◽  
Diameter Ratio ◽  
Energetic Efficiency ◽  
Turbulent Regime ◽  
Conductivity Method ◽  
Homogenization Time ◽  
Miscible Liquids ◽  
The Given

This paper presents an analysis of the blending efficiency of pitched blade impellers under a turbulent regime of flow of an agitated low viscous liquid. The conductivity method is used to determine of the blending (homogenization) time of miscible liquids in pilot plant mixing equipment with standard radial baffles. For the given homogeneity degree (98 %) a three-blade pitched blade impeller is tested with various off-bottom clearances, vessel/ impeller diameter ratios and various impeller pitch angles. The experimental results show in accordance with theoretical data from the literature, that the greatest effect on the dimensionless blending time is exhibited by the vessel/ impeller diameter ratio and the impeller pitch angle. The number of total circulations necessary for reaching the chosen homogeneity degree depends on the impeller pitch angle and amounts more than three. Finally, the energetic efficiency of the blending process is calculated. The results of this study show, that the highest energetic efficiency of the three-blade pitched blade impeller appears for the pitch angle a = 24°, the impeller/vessel diameter ratio T/D = 2 and the impeller off-bottom clearance h/D = 1.

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.

scholarly journals Study of Pumping Capacity of Pitched Blade Impellers

10.14311/380 ◽  
2002 ◽  
Vol 42 (4) ◽  
Author(s):  
I. Fořt ◽  
T. Jirout ◽  
R. Sperling ◽  
S. Jambere ◽  
F. Rieger
Keyword(s):  
Laser Doppler Anemometry ◽  
Radial Profile ◽  
Axial Flow ◽  
Power Input ◽  
Vessel Diameter ◽  
Energetic Efficiency ◽  
Turbulent Regime ◽  
Flat Bottom ◽  
Mean Velocity ◽  
Liquid Suspensions

A study was made of the pumping capacity of pitched blade impellers in a cylindrical pilot plant vessel with four standard radial baffles at the wall under a turbulent regime of flow. The pumping capacity was calculated from the radial profile of the axial flow, under the assumption of axial symmetry of the discharge flow. The mean velocity was measured using laser Doppler anemometry in a transparent vessel of diameter T = 400 mm, provided with a standard dished bottom. Three and six blade pitched blade impellers (the pitch angle varied within the interval a Îá24°; 45°ń) of impeller/vessel diameter ratio D/T = 0.36, as well as a three blade pitched blade impeller with folded blades of the same diameter, were tested. The calculated results were compared with the results of experiments mentioned in the literature, above all in cylindrical vessels with a flat bottom. Both arrangements of the agitated system were described by the impeller energetic efficiency, i.e, a criterion including in dimensionless form both the impeller energy consumption (impeller power input) and the impeller pumping effect (impeller pumping capacity). It follows from the results obtained with various geometrical configurations that the energetic efficiency of pitched blade impellers is significantly lower for configurations suitable for mixing solid-liquid suspensions (low impeller off bottom clearances) than for blending miscible liquids in mixing (higher impeller off bottom clearances).

Hydraulic characteristics of turbine impeller

1982 ◽  
Vol 47 (2) ◽  
pp. 421-429 ◽  
Author(s):  
Ivan Fořt ◽  
Jana Malá
Keyword(s):  
Mechanical Energy ◽  
Volumetric Flow Rate ◽  
Vessel Diameter ◽  
Diameter Ratio ◽  
Turbulent Regime ◽  
Hydraulic Efficiency ◽  
Hydraulic Characteristics ◽  
Total Head ◽  
Turbine Impeller

The study concentrates on the determination of hydraulic characteristics (volumetric flow rate, power output, hydraulic efficiency and total head) of a standard, six-blade turbine impeller in a flat-bottomed cylindrical vessel provided with radial baffles at a turbulent regime of agitated liquid. The investigated characteristics are determined by means of a macroscopic balance of mechanical energy of the impeller region expressed in a dimensionless form. The results show that all the hydraulic characteristics investigated, with the exception of the dimensionless impeller total head, are independent of the impeller-to-vessel diameter ratio. The hydraulic efficiency of a standard turbine impeller is about 40%.

Experimental Investigation of Pressure Drop Characteristics of Viscous Fluid Flow Through Small Diameter Orifices

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Lalit Kumar Bohra ◽  
Leo M. Mincks ◽  
Srinivas Garimella
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Viscous Fluid ◽  
Euler Number ◽  
Small Diameter ◽  
Reynolds Numbers ◽  
Diameter Ratio ◽  
Operating Conditions ◽  
Turbulent Regime ◽  
Pressure Drops

Abstract An experimental study on the flow of a highly viscous fluid through small diameter orifices was conducted. Pressure drops were measured for each of nine orifices, including orifices of nominal diameter 0.5, 1, and 3 mm and three different orifice thicknesses, over wide ranges of flow rates and temperatures. The fluid under consideration exhibits steep dependence of the properties (changes of several orders of magnitude) as a function of temperature and pressure and is also non-Newtonian at the lower temperatures. At small values of Reynolds number, an increase in aspect ratio (length/diameter ratio of the orifice) causes an increase in Euler number. It was also found that at extremely low Reynolds numbers, the Euler number was very strongly influenced by the Reynolds number, while the dependence becomes weaker as the Reynolds number increases toward the turbulent regime, and the Euler number tends to assume a constant value determined by the aspect ratio and the diameter ratio. A two-region (based on Reynolds number) model was developed to predict Euler number as a function of diameter ratio, aspect ratio, viscosity ratio, and generalized Reynolds number. It is shown that for such a highly viscous fluid with some non-Newtonian behavior, accounting for the shear rate through the generalized Reynolds number results in a considerable improvement in the predictive capabilities of the model. Over the laminar, transition, and turbulent regions, the model predicts 86% of the data within ±25% for the geometry and operating conditions investigated in this study.

Gas flooding of an inclined blade impeller

1991 ◽  
Vol 56 (3) ◽  
pp. 636-645 ◽  
Author(s):  
Václav Machoň ◽  
Ivan Fořt ◽  
Eva Antošová ◽  
Bohumil Španihel ◽  
Vladimír Kudrna
Keyword(s):  
Relative Size ◽  
Power Input ◽  
Vessel Diameter ◽  
Turbulent Regime ◽  
Gas Flooding ◽  
Rotating Impeller ◽  
Balance Of Forces ◽  
Phase Water ◽  
Input Ratio ◽  
Good Agreement

The conditions are studied in the paper of flooding the six plane blade impeller with blades inclined at the angle of 45° of relative size d/D = 1/3 and relative distance from the bottom of cylindrical vessel H2/D = 1/3 equipped at the wall with four radial baffles of width b/D = 0.1 at the relative vessel filling H/D = 1. The flooding conditions are determined experimentally from the course of dependence of the power input ratio of gassed and ungassed impeller on the flow rate number of air blown into the liquid phase (water) in the vessel. Theoretically, the conditions of the impeller flooding, when it is no more able to disperse air blown into the charge, are determined from balance of forces in the liquid flow leaving the region of rotating impeller acting on the bubbles of rising gas under the turbulent regime of charge flow. The results of the blade impeller frequency of revolutions determined theoretically at its flooding were found to be in good agreement with the experimentally determined values of the frequency of revolutions investigated obtained in the model equipment with vessel diameter D = 290 mm.

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.

Design of New Attitude Measuring Method of Non-Spinning Projectile Based on Magnetic Sensors

2012 ◽  
Vol 226-228 ◽  
pp. 1825-1828 ◽  
Author(s):  
Chao Xiang ◽  
Xiong Zhu Bu ◽  
Ya Ping Zhu
Keyword(s):  
Measurement Error ◽  
Pitch Angle ◽  
Simulation Experiment ◽  
Measuring Method ◽  
Magnetic Sensors ◽  
Ratio Method ◽  
Mathematical Relationship ◽  
Characteristic Ratio ◽  
Spinning Projectile ◽  
The Given

Because of the requirement of accurate measurement of projectile’s flying characteristics and limitations of the traditional attitude measuring methods, a new method based on three pairwise-orthogonal magnetic sensors only is presented for non-spinning projectiles. The characteristic ratio theory proposed in our earlier work is described in detail. In order to get the pitch angle with this theory, the mathematical relationship between magnetic sensors output and the theoretical extreme value is derived in this paper. Based on this relation, the extremum ratio method is expanded to be used in non-spinning projectiles. The measurement error of the attitude measuring method is also analyzed in theoy. At last, the simulation of the method is achieved under the given conditions to prove its effectiveness. The simulation experiment results indicate that the method is feasible and the calculating errors of the attitude angles are within ±1°.

Effects of type and number of impellers and liquid viscosity on the power characteristics of mechanically agitated gas—liquid systems

2007 ◽  
Vol 61 (1) ◽  
Author(s):  
R. Adamiak ◽  
J. Karcz
Keyword(s):  
Fluid Flow ◽  
Power Consumption ◽  
High Speed ◽  
Vessel Diameter ◽  
Turbulent Regime ◽  
Relative Power ◽  
Liquid Viscosity ◽  
Power Characteristics ◽  
Liquid Systems ◽  
Inner Diameter

AbstractEffect of the type and number of high-speed impellers installed on a common shaft on the power characteristics was investigated in water and glucose solutions of different concentration. Different configurations of the Rushton or Smith turbines, pitched blade turbines, propeller, and A 315 impeller were tested. Measurements of power consumption were carried out within the transitional and turbulent regime of the fluid flow using the strain gauge method. Baffled agitated vessels with inner diameter of 0.288 m and 0.634 m were used for the experiments. Liquid height in the vessels was equal to the vessel diameter or it was twice higher. The relative power consumption was compared for different configurations of the impellers.

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