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.

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.

scholarly journals Efficacy of partial baffles for a vessel agitated by a Rushton turbine impeller

2018 ◽  
Vol 24 (3) ◽  
pp. 293-301
Author(s):  
Masanori Yoshida ◽  
Kohei Ishioka ◽  
Hiromu Ebina ◽  
Koki Oiso ◽  
Hayato Shirosaki ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Flow Velocity ◽  
Liquid Flow ◽  
Energy Transmission ◽  
Discharge Flow ◽  
Rushton Turbine ◽  
Power Characteristics ◽  
Liquid Depth ◽  
Flow Through ◽  
Turbine Impeller

For a vessel agitated by a Rushton turbine impeller, the efficacy of partial baffles was evaluated through examination of the liquid flow and impeller power characteristics. The bulk flow formed a pattern having circulation loops of different intensity and largeness depending on the baffle condition: the baffle length relative to the liquid depth for the vessel. Consequently, the liquid flow within the vessel affected the impeller power number. The characteristic circulation loops, which generally reflect the baffle efficacy, were assessed in terms of the discharge flow through the impeller and the energy transmission within the vessel based on the flow velocity profiles. The shorter length of baffles fitted partially in the upper half of the liquid phase was revealed to be effective, supported in combination by a comparable discharge flow and a successful energy transmission.

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.

Effect of Baffle Length on Power Consumption in Turbulent Mixing Vessel with Rushton Turbine Impeller

2011 ◽  
Vol 37 (2) ◽  
pp. 147-149 ◽  
Author(s):  
Yoshihito Kato ◽  
Noboru Kamei ◽  
Yutaka Tada ◽  
Azusa Nakaoka ◽  
Yuichiro Nagatsu ◽  
...  
Keyword(s):  
Power Consumption ◽  
Turbulent Mixing ◽  
Rushton Turbine ◽  
Turbine Impeller

scholarly journals The Tangential Force Affecting the Radial Baffles in a Stirred Vessel: Analysis of the Macro-instability Related Component

10.14311/450 ◽  
2003 ◽  
Vol 43 (4) ◽  
Author(s):  
P. Hasal ◽  
I. Fořt ◽  
J. Kratěna
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Tangential Force ◽  
Low Frequency ◽  
Frequency Component ◽  
Relative Magnitude ◽  
Tangential Component ◽  
Vertical Position ◽  
Total Force ◽  
Rushton Turbine

Experimental data obtained by measuring the tangential component of the force affecting radial baffles in a flat-bottomed cylindrical mixing vessel stirred with a Rushton turbine impeller is analysed. Spectral analysis of the experimental data demonstrated the presence of its macro-instability (MI) related low-frequency component embedded in the total force. Two distinct dimensionless frequencies (both directly proportional to the impeller speed of rotation N) of the occurence of the MI component were detected: a lower frequency of approximately 0.025N and a higher frequency of about 0.085N. The relative magnitude QMI of the MI-related component of the total tangential force was evaluated by a combination of proper orthogonal decomposition (POD) and spectral analysis. The values of magnitude QMI varied in the interval [rom approximately 0.05 to 0.30. The magnitude QMI takes maximum values at low Reynolds number values (in laminar and transitional regions). In the turbulent region (ReM >20000) the QMI value is low and practically constant. The dependence oj the QMI values on vertical position in the vessel is only marginal. The results suggest that the magnitude of the MI component of the force is significantly influenced by the liquid viscosity and density.

A Functional Scaling Relationship for Laminar to Turbulent Flow Regimes

2011 ◽  
Author(s):  
George Papadopoulos
Keyword(s):  
Turbulent Flow ◽  
Stokes Equations ◽  
Initial Conditions ◽  
Flow Characteristics ◽  
Flow Region ◽  
Flow Regimes ◽  
Transitional Flow ◽  
Turbulent Regime ◽  
Flow Profile ◽  
Scaling Relationship

A dimensional analysis that is based on the scaling of the two-dimensional Navier-Stokes equations is presented for correlating bulk flow characteristics arising from a variety of initial conditions. The analysis yields a functional relationship between the characteristic variable of the flow region and the Reynolds number for each of the two independent flow regimes. A linear relationship is realized for the laminar regime, while a nonlinear relationship is realized for the turbulent regime. Both relationships incorporate mass-flow profile characteristics to fully capture the effects of initial conditions on the variation of the characteristic variables. The union of these two independent relationships is formed utilizing the concept of flow intermittency to further expand into a generic scaling relationship that incorporates transitional flow effects to fully encompass solutions spanning the laminar to turbulent flow regimes. The results of the analysis are discussed within the context of several flow phenomena (e.g. pipe flow, jet flow & separated flow) resulting from various initial and boundary conditions.

scholarly journals Design of Compressor Endwall Velocity Triangles

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Kiran Auchoybur ◽  
Robert J. Miller
Keyword(s):  
Dynamic Pressure ◽  
Three Dimensional ◽  
Flow Region ◽  
Degree Of Freedom ◽  
Diffusion Limit ◽  
Local Geometry ◽  
Operating Range ◽  
Blade Row ◽  
Inlet Conditions ◽  
Separation Size

The operating range of a compressor is usually limited by the rapid growth of three-dimensional (3D) separations in the endwall flow region. In contrast, the freestream region is not usually close to its diffusion limit and has little effect on overall range. In light of these two distinct flow regions, this paper considers how velocity triangles in the endwall region should be designed to give a more balanced spanwise failure across the span of a blade row. In the first part of this paper, the sensitivity of 3D separations in a single blade row to variations in realistic multistage inlet conditions and endwall geometry is investigated. It is shown that a blade's 3D separation size is largely controlled by the dynamic pressure within the incoming endwall “repeating stage” boundary layer and not the detailed local geometry within the blade row. In the second part of this paper, the traditional design process is “flipped.” Instead of redesigning a blade's endwall geometry to cope with a particular inlet profile into the blade row, the endwall region is redesigned in the multistage environment to “tailor” the inlet profile into downstream blade rows, giving the designer a new extra degree-of-freedom. This extra degree-of-freedom is exploited to balance freestream and endwall operating range, resulting in a compressor having an increased operating range of ∼20%. If this increased operating range is traded with reduced blade count, it is shown that a design efficiency improvement of ∼0.5% can be unlocked.

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