Showing papers on "Impeller published in 1998"

Sealless rotary blood pump

Abstract: An implantable rotary sealless blood pump is provided. The pump includes a housing having an inlet tube on one end and an impeller casing on the other end. A rotor is mounted for rotation within the housing, with the rotor having an elongated shaft portion and an impeller attached to the shaft portion. The impeller is located within the impeller casing. Radial magnetic bearings are carried by the shaft portion and radial magnetic bearings are carried by the housing for maintaining the shaft portion of the rotor within the inlet tube of the housing. A rotor motor includes a plurality of permanent magnets carried by the impeller and a motor stator including an electrically conductive coil located within the housing. A ring of back iron is carried by the impeller to aid in completing a flux return path for the permanent magnets. A plurality of hydrodynamic thrust bearings are located outside of the axis of rotation of the rotor. The impeller uses large axially thick blade sectors with narrow blood channels extending through the impeller, to minimize hemolysis and to increase the working surface of the blades.

Turbulence properties of the impeller stream of a Rushton turbine

Abstract: The structure of the flow in a vessel stirred by a Rushton turbine was investigated using laser Doppler anemometry measurement techniques. The time and length scales of turbulence were determined and used to estimate the dissipation rate of turbulence energy. The levels of turbulence energy and dissipation are high near the turbine and decrease rapidly with increasing distance from the turbine blades. The turbulence in the impeller stream is mostly anisotropic close to the blades. The results are compared with the findings of earlier investigations, and their implications for computational fluid dynamics (CFD) predictions of the flows are discussed.

Rotary pump with hydrodynamically suspended impeller

Abstract: This invention relates to rotary pumps adapted, but not exclusively, for use as artificial hearts or ventricular assist devices and, in particular, discloses in preferred forms a seal-less shaft-less pump featuring open or closed (shrouded) impeller blades with the edges of the blades used as hydrodynamic thrust bearings and with electromagnetic torque provided by the interaction between magnets embedded in the blades and a rotating current pattern generated in coils fixed relative to the pump housing.

Assessment of Sliding Mesh CFD Predictions and LDA Measurements of the Flow in a Tank Stirred by a Rushton Impeller

Abstract: LDA measurements and CFD predictions of the flow in a vessel stirred by a Rushton impeller are reported. The predictions employed a rotating mesh around the impeller and a stationary mesh in the remainder of the vessel. The experimental and numerical results are compared and discussed. It is shown that the mean velocity field is well reproduced quantitatively by the CFD model; the turbulence field is well predicted qualitatively across the whole vessel and quantitatively in the bulk flow region but differences between experiment and calculation are found near the impeller blades. Both the measurement and prediction methods are assessed.

Trailing vortices around a 45° pitched‐blade impeller

Abstract: The trailing vortex system near impeller blades has been identified as the major flow mechanism responsible for mixing and dispersion in stirred vessels, and high turbulence levels in the vortices have an important impact on such phenomena as drop breakup and cell damage in bioreactors. Numerical computations of the flows require more detailed information on the velocity characteristics generated by different impeller designs than is available in the literature. The study on the mean flow and turbulence structure generated by a pitched-blade turbine with four 45° inclined blades found that single trailing vortex is formed around each turbine blade. The vortex axis spread out radially by less than 0.0015 T and was inclined at 20° to the horizontal plane. The vortices merged into the bulk flow structure at around 135° behind each blade. Periodicity of the mean flow due to the crossing of the individual blades and high levels of kinetic energy of turbulence (k) are contained within a radial distance of around r/T=0.23 from the axis and a vertical distance of z/T=0.07-0.46 from the bottom of the vessel. The k levels decay to nearly-uniform and low values outside this region. The results are compared with earlier investigations, and their implications for mixing processes and CFD predictions of the flows are discussed. The data identify flow regions accurately where intense turbulence is present and thus give useful indications for the optimization of mixing processes.

System for generating electricity in a vehicle

Abstract: A wind-powered system for generating electricity in a vehicle or other power consumption unit generally having a multi-stage impeller system for driving an electric generator/alternator, an improved air channel, and an improved start-up/back-up air compressor. The multi-stage impeller system includes high-speed impellers and low-speed impellers for efficient energy conversion throughout the entire range of a vehicle's operating speeds or forward motion. The improved start-up/back-up air compressor discharges air directly to the multi-stage impellers, abolishing the need for heavy air accumulators. The improved air channel includes a specially formed air scoop/vortex, a wind tube/tunnel and a heating element to increase the velocity of the air passing therethrough.

Dependence of penicillium chrysogenum growth, morphology, vacuolation, and productivity in fed-batch fermentations on impeller type and agitation intensity

Abstract: The influence of the agitation conditions on the growth, morphology, vacuolation, and productivity of Penicillium chrysogenum has been examined in 6 L fed-batch fermentations. A standard Rushton turbine, a four-bladed paddle, and a six-bladed pitched blade impeller were compared. Power inputs per unit volume of liquid, P/VL, ranged from 0.35 to 7.4 kW/m3. The same fermentation protocol was used in each fermentation, including holding the dissolved oxygen concentration above 40% air saturation by gas blending. The mean projected area (for all dispersed types, including clumps) and the clump roughness were used to characterize the morphology. Consideration of clumps was vital as these were the predominant morphological form. For a given impeller, the batch-phase specific growth rates and the overall biomass concentrations increased with agitation intensity. Higher fragmentation at higher speeds was assumed to have promoted growth through increased formation of new growing tips. The mean projected area increased during the rapid growth phase followed by a sharp decrease to a relatively constant value dependent on the agitation conditions. The higher the speed, the lower the projected area for a given impeller type. The proportion by volume of hyphal vacuoles and empty regions decreased with speed, possibly due to fragmentation in the vacuolated regions. The specific penicillin production rate was generally higher with lower impeller speed for a given impeller type. The highest value of penicillin production as well as its rate was obtained using the Rushton turbine impeller at the lowest speed. At given P/VL, changes in morphology, specific growth rate, and specific penicillin production rate depended on impeller geometry. The morphological data could be correlated with either tip speed or the "energy dissipation/circulation function," but a reasonable correlation of the specific growth rate and specific production rate was only possible with the latter. Copyright 1998 John Wiley & Sons, Inc.

Pump motor having fluid cooling system

Abstract: A brushless water pump motor includes a pump housing having an impeller chamber with an impeller disposed therein, and a motor assembly coupled at a first end thereof to the pump housing. The motor assembly includes a stator assembly having laminations and windings, the stator having an interior portion defining a rotor chamber in which a rotor assembly is disposed. There is a partition structure provided between the rotor assembly and the stator assembly for isolating the stator assembly from the rotor chamber, and the partition structure has a wall in communication with the rotor chamber. The pump/motor assembly further includes a hollow shaft in communication with the rotor chamber, such that the rotor assembly and impeller are mounted on the hollow shaft. A bearing structure is operatively associated with the hollow portion of the shaft for supporting the shaft for rotational movement. The pump motor further includes an electronic control unit coupled to a second end of the motor assembly and has an upper surface in communication with the rotor chamber. A fluid flow path structure is arranged to permit fluid to pass from a high pressure portion of the impeller chamber to enter the rotor chamber to submerge the rotor assembly in the fluid and fluid may contact the upper surface of the electronic control unit to cool the electronic control unit. By contacting the wall of the partition structure, the fluid cools the laminations and windings, and by entering the hollow portion of the shaft, the fluid cools the bearing structure.

Determination of correlations to predict the minimum agitation speed for complete solid suspension in agitated vessels

Abstract: Experiments were conducted to determine the effects of impeller clearance, impeller diameter, and other operating variables on the minimum agitation speed for off-bottom solid suspension in agitated vessels, Njs, for disc turbines (DTs) and flat-blade turbines (FBTs). Only data for which the impellers produced recirculation flows above and below the impeller (the so-called “double-eight” flow pattern) were considered. Regression equations for Njs were obtained, in which explicit terms for impeller clearance and vessel diameter-to-impeller diameter ratio (T/D) were included. Modified Zwietering equations (Zwietering, 1958) were also obtained, in which Zwietering's parameter S was mathematically expressed as a function of vessel diameter-to-impeller clearance ratio and T/D ratio. When used together with the correlations of Armenante and Uehara Nagamine (1998) for impellers close to the vessel bottom, the equations presented here can be used to calculate Njs for DTs and FBTs for any typical impeller clearance.

The influence of tank size and impeller geometry on turbulent flocculation : I. Experimental

Abstract: The effects of tank size and impeller geometry on the particle size distribution after 30 min of flocculation at constant characteristic average velocity gradient, Gm, were studied Flocculation was performed in three square tanks 5-, 28-, and 560-L volume with Rushton turbines and A310 fluid foil impellers The floc size was recorded in situ using a photographic technique, and the resulting photographs were analyzed with an image analysis system The results show that the cumulative particle size distribution shifts to a smaller particle size range with increasing tank size, regardless of impeller type A similar shift in the cumulative particle size distribution was observed when the impeller type was switched from the A310 fluid foil to the Rushton turbine, regardless of tank size The volume mean floc size, floc standard deviation, and maximum stable floc size were found to be controlled by the turbulence intensity in the impeller discharge zone and not by Gm Key words: Tank size; impeller g

Development of design methods of a centrifugal blood pump with in vitro tests, flow visualization, and computational fluid dynamics: results in hemolysis tests.

Abstract: There are few established engineering guidelines aimed at reducing hemolysis for the design of centrifugal blood pumps. In this study, a fluid dynamic approach was applied to investigate hemolysis in centrifugal pumps. Three different strategies were integrated to examine the relationship between hemolysis and flow patterns. Hemolytic performances were evaluated in in vitro tests and compared with the flow patterns analyzed by flow visualization and computational fluid dynamic (CFD). Then our group tried to establish engineering guidelines to reduce hemolysis in the development of centrifugal blood pumps. The commercially available Nikkiso centrifugal blood pump (HPM-15) was used as a standard, and the dimensions of 2 types of gaps between the impeller and the casing, the axial and the radial gap, were varied. Four impellers with different vane outlet angles were also prepared and tested. Representative results of the hemolysis tests were as follows: The axial gaps of 0.5, 1.0, and 1.5 mm resulted in normalized index of hemolysis (NIH) values of 0.0028, 0.0013 and 0.0008 g/100 L, respectively. The radial gaps of 0.5 and 1.5 mm resulted in NIH values of 0.0012 and 0.0008 g/100 L, respectively. The backward type vane and the standard one resulted in NIH values of 0.0013 and 0.0002 g/100 L, respectively. These results revealed that small gaps led to more hemolysis and that the backward type vane caused more hemolysis. Therefore, the design parameters of centrifugal blood pumps could affect their hemolytic performances. In flow visualization tests, vortices around the impeller outer tip and tongue region were observed, and their patterns varied with the dimensions of the gaps. CFD analysis also predicted high shear stress consistent with the results of the hemolysis tests. Further investigation of the regional flow patterns is needed to discuss the cause of the hemolysis in centrifugal blood pumps.

Motor-driven blower and method of manufacturing impeller for motor-driven blower

Abstract: Reduction of air resistance which acts on the conventional motor-driven blower is limited because crushed protrusions are formed on the surface of the plate of the impeller of the conventional motor-driven blower, and this air resistance is a significant impediment to an increase of the operating speed of the motor-driven blower. Thus, an impeller is provided which comprises a front plate having a suction opening, a back plate disposed opposite to the front plate, and a plurality of blades disposed between the front plate and the back plate. At least either the front plate or the back plate is formed integrally with the blades.

Heat exchanging pump motor for usage within a recirculating water system

Abstract: A pump which is designed to be mounted within a recirculating water system where a portion of the recirculating water is diverted and caused to flow through the pump with this recirculating water to absorb heat that is produced during the operation of the motor. The heated diverted water is then added back to the recirculating water system. The pump includes an electric motor which is mounted within a motor housing and is completely enclosed therein. An electrically insulative mounting arrangement mounts the motor relative to the motor housing preventing the conductance of electricity therebetween. The motor housing is filled with oil thereby submerging of the electric motor in oil. The motor housing is enclosed within a seal plate. Surrounding the motor housing is an annular chamber through which the liquid is caused to flow. A baffle arrangement is located within the annular chamber to direct the flow of the liquid so that all area across the surface of the pump housing has liquid flowing thereacross. The heat that is produced in the operation of the motor is absorbed by the oil which in turn is conducted through the motor housing to be absorbed by the diverted liquid prior to being added back into the recirculating liquid system. The impeller is mounted in conjunction with a wear ring which functions to properly align the impeller.

Impeller assembly with asymmetric concave blades

Abstract: An impeller assembly (10) for agitating a fluid (31) contained in a vessel (30) and dispersing a gas introduced therein. The impeller assembly (10) includes an impeller having a plurality of generally radially extending blades (16). Each of the blades (16) includes diverging upper and lower sheet-like portions having generally radially extending leading edges. The upper and lower portions are joined to form a generally V-shaped cross-section with a trailing vertex. The width of the upper portion of each blade (16) is greater than the width of the lower portion of the blade such that the upper portion leading edge extends forwardly of the lower portion leading edge, thus producing an upper portion overhang to capture and disperse rising gas bubbles (34). The impeller assembly (10) further comprises a drive assembly (17) for rotating the impeller assembly (10).

Two-stage centrifugal compressor

Abstract: A low pressure-side first-stage compressor impeller and a high pressure-side second-stage compressor impeller are mounted respectively on opposite ends of a rotation shaft. A rotor of an electric motor for driving the two impellers is formed at a central portion of the rotation shaft. A stator of the motor is held by a motor casing. The motor casing, a first-stage compressor casing, which cooperates with the first-stage compressor impeller to form a first-stage compressor, and a second-stage compressor casing, which cooperates with the second-stage compressor impeller to form a second-stage compressor, are cast into an integral construction. This integral casing is further formed integrally with an intermediate cooler, disposed downstream of the first-stage compressor, and a discharge cooler disposed downstream of the second-stage compressor. The intermediate cooler and the discharge cooler are disposed below the motor casing in generally parallel relation to the rotation shaft, and the main portions of the two-stage centrifugal compressor are combined into a compact, generally rectangular parallelepiped configuration.

Gas-liquid venturi mixer

Abstract: An apparatus and method are provided for mixing gas and liquid. An impeller is rotatably mounted inside a draft tube having a constricted section. Rotation of the impeller draws liquid down through the constricted portion of the draft tube. A gas delivery system introduces gas under the surface of the liquid downstream from the constricted portion of the draft tube to entrain the gas in the liquid by a venturi effect. The impeller creates a turbulent gas-liquid mixing zone and also projects liquid radially into the gas as it enters the draft tube. The gas-liquid venturi mixer is particularly suitable for treating industrial and municipal waste water, as well as various other liquids. Gases such as air, oxygen, hydrogen, and the like are efficiently dissolved in such liquids during operation of the gas-liquid venturi mixer.

Combined variable-speed drive and speed reducer for pumps and fans

Abstract: A variable speed drive for fans and pumps. An impeller is connected to a primary motor and an auxiliary motor/generator through a transmission. The transmission includes an epicyclic gearing system. The primary motor is run at constant speed. The auxiliary motor/generator is driven at variable speeds to control the speed of the impeller. The device may be used to retrofit an existing pump or fan system.

Mixing system for dispersion of gas into liquid media

Abstract: In order to sparge gas into a liquid or liquid suspension in a tank wherein a principally axial flow pattern downwardly towards the bottom of the tank and then upwardly along the side wall of the tank returning axially downward is established by an axial flow impeller, a disc of a diameter less than the diameter of the impeller is spaced axially therefrom in the direction of the outlet flow towards the bottom of the tank from the impeller so as to turn the axial flow, radially, thereby establishing a pressure gradient which prevents the collection of gas released by a sparge between the disc and the bottom of the tank and flooding of the impeller. The gas is released in the axial flow from the tip region of the impeller thereby facilitating the shearing of the gas into fine bubbles promoting mass transfer of the gaseous phase into the liquid phase in the tank. Since flooding is inhibited, as much as six times the volume of gas (gas rate) can be handled as may be the case without the disc.

Thrust bearing for multistage centrifugal pumps

Abstract: A pump has a thrust bearing has a casing with an inlet port and a discharge port. A shaft is positioned within the pump. A thrust bearing is coupled to the shaft. A pressure alterable bearing cavity is located within the casing. The pressure alterable cavity allows the axial thrust on the shaft from the impellers to be counteracted. The thrust bearing has an annular seal coupled with respect to the casing disc is coupled to the shaft and positioned adjacent the seal. The seal and the disc have a gap therebetween. A feedback pipe couples the bearing cavity to the inlet port. As the axial thrust acting on the shaft changes, the gap between the seal and the disc also changes. The changing of the gap changes the pressure within the bearing cavity. The disc and thus the shaft are repositioned in response to the change in the bearing cavity pressure change.

Power consumption in agitated vessels provided with multiple-disk turbines

Abstract: The power dissipated by one-, two-, or three-disk turbines (Rushton type) in stirred vessels was experimentally determined under turbulent conditions. The power dissipated by each individual impeller (in single- or multiple-impeller configurations) and the total power consumption were measured by means of strain gauges mounted on the shaft and were reported as individual or total power numbers. Results were obtained for different combinations of number of impellers, off-bottom clearance of the lowest impeller, and spacing among impellers. These variables were found to play a very important role in the power drawn by individual impellers and, hence, the total power consumption. The impeller closest to the vessel bottom generally consumed significantly less power than the other impeller(s). This was especially true for combinations of low impeller clearances and small impeller spacing. Proximity of two impellers also lowered their power consumption. Only when the impellers were significantly spaced apart an...

Prediction of Air-Water Two-Phase Flow Performance of a Centrifugal Pump Based on One-Dimensional Two-Fluid Model

Abstract: To predict the performance of centrifugal pumps under air-water two-phase flow conditions, a consistent one-dimensional two-fluid model with fluid viscosity and air-phase compressibility in a rotating impeller is proposed by considering energy changes in the transitional flow from the rotating impeller to the stationary volute casing. The two-fluid model is numerically solved for the case of a radial-flow pump after various constitutive equations are applied

Reduced-noise ducted flow hair dryer with multiple impellers and ambient air inlets

Abstract: An axial flow hair dryer comprises a generally circular main housing with a transitional portion that smoothly reduces the housing diameter to an outlet. A first fan stage in the main housing generates an axial air flow through the housing. An outer duct has two axial extensions secured to the housing near the beginning of the transitional portion, and the housing air outlet introduces air exiting the housing into the outer duct. The housing and the outer duct form two additional ambient air intakes extending between the axial extensions in a smooth arc toward the main housing outlet. A second fan stage includes a second axial flow impeller in the outer duct for generating air flow through the ambient air intake. The second axial flow impeller includes inner and outer blades separated by an annular shroud that forms an extension of the main housing flow passage. A guide duct in the outer duct forms a further extension of the extended air flow passage, and the guide duct includes stator vanes at its outlet. A handle depending from the main housing holds a motor and a flex shaft connects the motor to a drive shaft that carries both fan stages. Resistance heating wires in the main housing heat the air flowing through the hair dryer.

Analysis of the Flow in Vaneless Diffusers With Large Width-to-Radius Ratios

Abstract: The flow in vaneless diffusers with large width-to-radius ratios is analyzed by using three-dimensional boundary-layer theory. The variations of the wall shear angle in the layer and the separation radius of the turbulent boundary layer versus various parameters are calculated and compared with experimental data. The effect of the separation point on the performance of vaneless diffusers and the mechanism of rotating stall are discussed. It is concluded that when the flow rate becomes very low, the reverse flow zone on the diffuser walls extends toward the entry region of diffusers. When the rotating jet-wake flow with varying total pressure passes through the reverse flow region near the impeller outlet, rotating stall is generated. The influences of the radius ratio on the reverse flow occurrence as well as on the overall performance are also discussed