Showing papers on "Impeller published in 2001"

Numerical Study of Pressure Fluctuations Caused by Impeller-Diffuser Interaction in a Diffuser Pump Stage

Abstract: Two-dimensional and three-dimensional, unsteady state Reynolds-averaged Navier-Stokes (RANS) equations with standard k-e turbulence models were solved within an entire stage of a diffuser pump to investigate pressure fluctuations due to the interaction between impeller and diffuser vanes. A complete solution of transient flows due to the interaction between components in the whole pump without approximating the blade count ratio of impeller to diffuser was obtained by employing an Arbitrary Sliding Mesh. The unsteady numerical results were compared with experimental data and values calculated by the singularity method

The flow structure during onset and developed states of rotating stall within a vaned diffuser of a centrifugal pump

Abstract: Particle Image Velocimetry (PIV) and pressure fluctuation measurements are used for investigating the onset and development of rotating stall within a centrifugal pump having a vaned diffuser. The experiments are performed in a facility that enables measurements between the diffuser vanes, within part of the impeller, in the gap between them and in the volute. The diffuser is also instrumented with pressure transducers that track the circumferential motion of rotating stall in the stator. The timing of low-pass-filtered pressure signals are also used for triggering the acquisition of PIV images. The data include detailed velocity distributions, instantaneous and phase-averaged, at different blade orientations and stall phases, as well as auto- and cross-spectra of pressure fluctuations measured simultaneously in neighboring vane passages. The cross-spectra show that the stall propagation rate is 0.93 Hz, 6.2 percent of the impeller speed, and that the stall travels from the passages located on the exit side of the volute toward the beginning side, crossing the tongue region in the same direction as the impeller, where it diminishes. Under stall conditions the flow in the diffuser passage alternates between outward jetting, when the low-pass-filtered pressure is high, to a reverse flow, when the filtered pressure is low. Being below design conditions, there is a consistent high-speed leakage flow in the gap between the impeller and the diffuser from the exit side to the beginning of the volute. Separation of this leakage flow from the diffuser vane causes the onset of the stall. The magnitude of the leakage and the velocity distribution in the gap depend on the orientation of the impeller blade. Conversely, the flow in a stalled diffuser passage and the occurrence of stall do not vary significantly with blade orientation. With decreasing flow-rate the magnitudes of leakage and reverse flow within a stalled diffuser passage increase, and the stall-cell size extends from one to two diffuser passages. @DOI: 10.1115/1.1374213#

Water-cooled system and method for cooling electronic components

Abstract: A water-cooled system and method for cooling electronic components. The system includes a surface. At least one electronic component is coupled to the surface, the at least one electronic component including an integrated circuit. A closed-loop fluidic circuit is coupled to the surface for removing heat from the integrated circuit. The closed-loop fluidic circuit includes a heat exchanger. A blower is coupled to the surface, the blower having a first port, a second port, and an impeller that rotates around an axis. The blower is oriented such that the axis is perpendicular to the surface and non-intersecting with the heat exchanger, wherein the blower moves air through the heat exchanger.

Double-ended blower and volutes therefor

Abstract: A variable speed blower for Continuous Positive Airway Pressure (CPAP) ventilation of patients includes two impellers in the gas flow path that cooperatively pressurize gas to desired pressure and flow characteristics. Thus, the blower can provide faster pressure response and desired flow characteristics over a narrower range of motor speeds, resulting in greater reliability and less acoustic noise.

Numerical and experimental investigation of a centrifugal compressor with an inducer casing bleed system

Abstract: State-of-the-art centrifugal compressors for turbocharger applications are required to provide broad compressor maps, high pressure ratios and high efficiency levels. Usually these requirements are perceived as contradictory and represent challenging design targets. Various techniques for map width enhancements have been reported since the early 1980s. ABB Turbo Systems Limited has adopted a simple bleed system for internal flow recirculation to a high flowrate, high efficiency, pressure ratio 4.2 centrifugal compressor stage. After initial test runs had proved the effectiveness of the bleed system, computational fluid dynamics (CFD) calculations were performed in order to gain insight into the flow pattern in both the compressor stage and the bleed system. The simulations explain the effectiveness by comparing them with simulations without the bleed channel. Selected streamline and iso-surface plots show the effect of the bleed channel flow on the main flow through the impeller. Four more variant...

An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

Abstract: Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to successfully control these events. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to simultaneously capture transient velocity and pressure measurements in the non-stationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique which is ideally suited for studying transient flow phenomena in high speed turbomachinery and has been used previously to successfully map the stable operating point flow field in the diffuser of a high speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

Trailing Vortices of Rushton Turbine: PIV Measurements and CFD Simulations with Snapshot Approach

Abstract: Understanding fluid dynamic characteristics of trailing vortices behind impeller blades and the capability to computationally simulate these vortices is essential for reliable design and scale-up of stirred reactors. In this paper, trailing vortices behind the blades of a standard Rushton turbine were studied using particle image velocimetry (PIV). Angle resolved and angle averaged flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail. A computational snapshot approach of Ranade and Dommeti was extended and used to simulate flow generated by the Rushton turbine in baffled stirred vessels. The approach was implemented using the commercial CFD code, FLUENT (of Fluent Inc, USA). Two turbulence models, namely, standard k – ɛ model and renormalization group version (RNG) of k – ɛ model were used for simulating the flow in stirred vessels. Predicted results were compared with the angle resolved PIV measurements to examine whether the computational model captures the flow structures around impeller blades. Predicted results were also compared with the angle averaged PIV data. Predicted gross flow characteristics like pumping number were also compared with the present and previously published experimental data. The results and conclusions drawn from this study will have important implications for extending the applicability of CFD models for simulating flow near impeller blades.

Power consumption, mixing time and homogenisation energy in dual-impeller agitated gas–liquid reactors

Abstract: The study relates to the power consumption, mixing time and mixing efficiency defined as the product of the mixing time and the power consumption in a non standard vessel equipped with various axial and mixed dual-impeller configurations. The effects of the rotational speed, gas flow rate, impeller type and diameter are investigated. The mixing mechanisms are found strongly dependent on flow patterns, impeller type and diameter. Dimensionless correlations are proposed to predict power consumption and the mixing time beyond complete dispersion regime.

The effect of size, location and pumping direction of pitched blade turbine impellers on flow patterns: lda measurements and cfd predictions

Abstract: A combined LDA-CFD (MRF method) study has been undertaken of the turbulent flow associated with two sizes of 6-bladed 45° pitch blade turbine at three clearances, either pumping up or down. Good quantitative agreement for mean velocity vectors has been obtained but that for RMS values was poor. The mean discharge angle is more vertical: (a) for the smaller impeller at all clearances; (b) for both sizes when an impeller approaches a surface towards which it is pumping.

Unified Treatment of Flow Instabilities of Turbomachines

Abstract: The relationship among four flow instabilities of turbomachines, namely, surge, rotating stall, cavitation surge, and rotating cavitation, is elucidated, using a unified or common model for their analysis. The simplest unifying model was employed in the analysis to focus on the characteristic features of each instability. Moreover, the concentration is on the stability criteria, and hence, the amplitudes are assumed small. Of course, the instabilities often grow to amplitudes comparable with the average value of the flow variable. Flows upstream and downstream of the impeller were assumed to be one dimensional for surge and cavitation surge and to be two dimensional for rotating stall and rotating cavitation, respectively. Viscous effects were taken into consideration in the form of cascade loss. Impeller blade geometry was incorporated in the assumption that the flow is perfectly guided. The peripheral wavelength of the disturbance was assumed to be much larger than the blade pitch.

Refrigerant-cooled system and method for cooling electronic components

Abstract: A system and method of using refrigerant for cooling electronic components is presented. The system includes a surface. At least one electronic component is coupled to the surface, the at least one electronic component including an integrated circuit. A closed-loop refrigeration circuit is coupled to the surface for removing heat generated by the integrated circuit. The closed-loop refrigeration circuit includes a condenser. A blower is coupled to the surface, the blower having a first port, a second port, and an impeller that rotates around an axis. The blower is oriented such that the axis is perpendicular to the surface and non-intersecting with the condenser, wherein the blower moves air across the condenser.

Impeller Geometry Effect on Velocity and Solids Suspension

Abstract: The effect of varying impeller geometrical parameters, including impeller type, number of impeller blades, blade pitch angle and blade thickness, on the turbulent velocity fields in mixing tanks has been studied through LDV measurements. Pitch bladed turbines and disc turbines were used in the experiments. It was found that universal time-mean velocity profiles exist for both pitch bladed turbines and disc turbines. Flow number correlations based on power number for both pitch bladed turbines and disc turbines are presented. It was found that there is a link between impeller pumping capacity and the S parameter in the Zwietering correlation, and this can be expressed as NQ × S = K, where NQ is the impeller flow number and K is a non-dimensional constant independent of the solid/liquid material property and impeller geometry.

Rotor and bearing system for electrically assisted turbocharger

Abstract: A turbocharger having an electric motor for assisting spin up of the rotor employs a shaft carrying the turbine and compressor impeller with a unitary pinned semi-floating bearing supporting the shaft and a spacer collar carrying the electric motor magnet. The unitary bearing has integral thrust faces engaging a hub of the turbine wheel and the spacer collar. A reduced diameter of the shaft received in the spacer collar allows the collar to engage a greater diameter bearing land allowing the attachment of the compressor impeller with a nut on the shaft extending through a bore in the impeller to firmly engage the impeller, spacer collar and bearing land of the shaft to fix the rotor length. The pinned semi-floating bearing with integral thrust faces provides enhanced reaction moments for negative spring forces created by the electric motor in operation and the additional length of the rotor created by the motor.

Molten metal pump with protected inlet

Abstract: An inlet protector or guard that prevents jamming and clogging of a molten metal pump. The guard includes a flat surface having a central opening that accepts a shaft of the molten metal pump. A wall extends from the periphery of the flat surface along a longitudinal axis of the shaft. The wall is sized to fit within an inlet opening of the pump. The wall includes a plurality of openings, forming an inlet through which molten metal can enter a base of the pump. The plurality of openings are small enough to prevent solid particles that are larger than a distance between an impeller of the pump and a pump chamber from entering the pump and large enough to prevent the pump from clogging.

Heat sink-equipped cooling apparatus

Abstract: A heat sink-equipped cooling apparatus capable of exhibiting increased cooling performance and durability and being reduced in dimensions in a radial direction thereof. A heat sink includes a radiation fin unit including a plurality of radiation fins arranged so as to surround a virtual central line while keeping a center thereof aligned with the central line. A cooling fan includes an impeller including a plurality of blades and rotated through a motor. The cooling fan is mounted on the heat sink in such a manner that the impeller is positioned above the radiation fin unit of the heat sink. The radiation fins each are inclined with respect to a virtual vertical plane so as to form a predetermined inclination angle θ therebetween.

Magnetically levitated pump and controlling circuit

Abstract: An impeller has one surface with a soft magnetic member arranged closer to an inner diameter thereof, opposite an electromagnet, the impeller is provided with a permanent magnet arranged closer to an outer diameter thereof, opposite a permanent magnet of a rotor, and the impeller has the other surface provided with a ferromagnetic body, opposite a permanent magnet of a casing, thereby magnetically levitating the impeller, and allowing a motor stator to rotate a motor rotor to rotate the impeller.

Methods, systems and devices relating to implantable fluid pumps

Abstract: An implantable pump system including an external driver. The implantable pump is driven by the external driver during normal operation but may also operate on a-battery. The external driver is used to drive the pump with the mechanical energy of the impeller also being used to charge the battery. The external driver is also useful during emergency situations to directly drive the pump if the battery or internal coils should fail. The pump is also preferably implanted in a subpectoral location outside the patient's rib cage.

Blower impeller apparatus with pivotable blades

Abstract: Blower designs for vented enclosures include an impeller having a plurality of blades. The impeller includes a plurality of blades pivotably coupled to an impeller body. The blades pivot to enable operation in one of a closed and an open state. Air flow between blades is substantially restricted when the blades are in the closed state. Air flow between the blades is permitted when the blades are in an open state. In one embodiment, the pivotable couplings are spring loaded to maintain the blades in the closed state when the impeller rotational speed is below a threshold range. The blades pivot to the open state when the rotational speed exceeds the threshold range.

An Ultradurable and Compact Rotary Blood Pump with a Magnetically Suspended Impeller in the Radial Direction

Abstract: A magnetically suspended centrifugal blood pump has been developed with a self-bearing motor for long-term ventricular assist systems. The rotor of the self-bearing motor is not only actively suspended in the radial direction, but also is rotated by an electromagnetic field. The pump has a long lifetime because there are no mechanical parts such as seals and motor bearings. An outer rotor mechanism was adopted for the self-bearing motor. The stator was constructed in the central space of the motor. The rotor shaped thin ring was set at the circumferential space of the stator. Six vanes were extended from the upper surface of the rotor toward the center of the pump to construct an open-type impeller. The outer diameter and the height of the impeller are 63 mm and 34 mm, respectively. The magnetic bearing method and the servomotor mechanism were adopted to levitate and rotate the rotor. Radial movements of the rotor and rotation are controlled actively by using electromagnets in the stator. Axial movement and tilt of the rotor are restricted by passive stability to simplify the control. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was used to examine basic performance of the pump. Maximum flow rate and pressure head were 8 L/min and 200 mm Hg, respectively. Maximum amplitude of radial displacement of the impeller was 0.15 mm. The impeller could be suspended completely without touching the casing wall during the entire pumping process. Power consumption of the pump was only 9.5 W to produce a flow rate of 5 L/min against a pressure head of 100 mm Hg. We conclude that the pump has sufficient performance for the implantable ventricular assist system.

Toroidal vortex vacuum cleaner centrifugal dust separator

Abstract: Disclosed is an improved vacuum cleaning apparatus utilizing a self-sustained vortex flow in a centrifugal separator More specifically, vortex flow is maintained via pressure differentials allowing the ejection of dust and other particles without bags, filters, or liquid baths Furthermore, the impeller inside of the separator serves the dual purpose of moving air through the system as well as creating a cylindrical vortex fluid flow providing an efficient and simple configuration Also disclosed herein is a complete toroidal vortex vacuum cleaner in which a toroidal vortex nozzle is used in conjunction with the centrifugal separator The vacuum cleaner exhibits recirculating airflow that not only prevents unseparated dust from escaping into the atmosphere, but also conserves the kinetic energy of the flowing air The present invention excels in producing clean air of a better quality more efficiently, more quietly, and more simply than the prior art

A Numerical Investigation on the Volute/Diffuser Interaction Due to the Axial Distortion at the Impeller Exit

Abstract: A numerical simulation is performed on a single-stage centrifugal compressor using the commercially available CFD software, CFX-TASCflow. The steady flow is obtained by circumferentially averaging the exit fluxes of the impeller. Three runs are made at the design condition and off-design conditions. The predicted performance is in agreement with experimental data. The flow details inside the stationary components are investigated, resulting in a flow model describing the volute/diffuser interaction at design and off-design conditions

Pump for molten materials with suspended solids

Abstract: A molten material pump includes an impeller housed within a base member of the pump. A plurality of grooves are defined in a peripheral sidewall of the impeller for either drawing a molten material into the base member's chamber or pushing molten material out of the base member's chamber. The impeller is rotated by a rotatable shaft connected to an upper surface of the impeller. The rotatable shaft includes a non-circular shaped lower end dimensioned to be received within a cooperating opening in the impeller. The molten material pump further includes a connecting assembly for interconnecting components of the molten material pump. The connecting assembly includes a first mounting member attached to a first pump component that is dimensioned to be fitted within a cooperating recess of a second mounting member attached to a second pump component. In another embodiment of the invention, a stub shaft connects an upper shaft portion of the shaft to the impeller. The stub shaft includes a universal joint that is not rigidly connected to the upper shaft portion. In addition, the universal shaft is configured to allow the stub shaft and impeller to pivot. A floating deflector block weighs on an upper sealing block of the pump for enhancing the seal at the pump's bearing surfaces.

Pump with electrodynamically supported impeller

Abstract: A pump includes an impeller, a stator, and a plurality of permanent magnets forming bearing poles coupled to a selected one of the stator or the impeller. The pump further includes a plurality of shorted coils coupled to the other of the stator and the impeller. The plurality of bearing poles and shorted coils co-operate to form an electrodynamic bearing during rotation of the impeller. The electrodynamic bearing supports the impeller either axially or radially during operation of the pump. Currents induced into each coil by a single bearing pole or by a plurality of bearing poles substantially simultaneously produce an electrodynamically generated magnetic field that repels the inducing bearing pole(s) when the impeller is rotating.

Fundamental Analysis on Rotor-Stator Interaction in a Diffuser Pump by Vortex Method

Abstract: A two-dimensional unsteady flow was calculated within a whole stage of a diffuser pump to investigate pressure fluctuations due to the interaction between impeller and diffuser vanes by using the vortex method, in which vortices shedding from solid boundary were determined by the basic governing equation. The Petrov-Galerkin Method was applied to yield the solutions that satisfy the boundary conditions in an integral sense, and it improved the stability and accuracy of the numerical solutions greatly. A new scheme was also proposed to improve the unsteady pressure evaluation by a boundary integration method in the rotor-stator interaction problem. Moreover, for a more realistic prediction of the pressure fluctuations, the inlet flow was supposed to change with time so that pumping system may balance. The calculated time-varying flow rate, total hydraulic head rise and pressure fluctuations in the vaned diffuser passage, were compared with the measured and calculated ones by other methods

Apparatus and methods for thermoelectric heating and cooling

Abstract: A thermoelectric device adaptable for heating and for cooling a fluid such as air. The device includes at least one thermoelectric module and at least one rotating heat sink that transfer heat between the thermoelectric module(s) and the fluid. The heat sink(s) are mounted on a shaft and include a plurality of thermally conductive impeller blades. The thermoelectric module(s) rotate with the heat sink(s) about the shaft. Because the thermoelectric module(s) are in direct contact with the thermally conductive impeller, heat is transferred more efficiently into and out of the thermoelectric device. Because the impeller blades also act as heat sinks, fewer components are needed than with conventional devices.

Two-Equation Turbulence Modeling for Impeller Stirred Tanks

Abstract: In this study, the predictive performance of six different two-equation turbulence models on the flow in an unbaffled stirred tank has been investigated. These models include the low Reynolds number k-e model of Rodi, W., and Mansour, N.N., Low Reynolds Number k-e Modeling With the Aid of Direct Simulation Data, J. Fluid Mech., Vol. 250, pp. 509-529, the high and low Reynolds number k-ω models of Wilson, D.C., 1993, Turbulence Modeling for CFD, DCW Industries, La Canada, CA., the RNG k-e model, and modified k-ω and k-e models which incorporate a correction for streamline curvature and swirl. Model results are compared with experimental laser Doppler velocimetry (LDV) data for the turbulent velocity field in an unbaffled tank with a single paddle impeller. An overall qualitative agreement has been found between the experimental and numerical results with poor predictions observed in some parts of the tank. Discrepancies in model predictions are observed in the anisotropic regions of the flow such as near the impeller shaft and in the impeller discharge region where the model overpredicts the radial velocity component. These results are discussed and a strategy for improving two-equation models for application to impeller stirred tanks is proposed.