Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 131 for “"impeller"”.
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Scaling of impeller response to impeller-diffuser interactions in centrifugal compressors
… has been conducted to quantify the effect of impeller-diffuser interaction on changes in impeller performance. An assessment is made of the hypothesis that the nondimensional parameter characterizing impeller performance change due to interaction is the ratio of the radial gap between the …
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Impeller-diffuser interaction in centrifugal compressors
… simulation, to define the effect of impeller-diffuser interaction on the performance of a centrifugal compressor stage. The principal finding from the study was that the most influential aspect of this unsteady interaction was the effect on impeller tip leakage flow . In particular, …
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Impeller loss reduction in multi-stage centrifugal compressors
Loss generation features for the first stage impeller in a multistage centrifugal compressor are examined using three-dimensional RANS computations. The calculations were carried out for a baseline configuration and for seven other impeller configurations, with the constraints of constant mass flow …
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Effects of impeller-diffuser interaction on centrifugal compressor performance
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003.
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Impact of tip clearance flow on centrifugal pump impeller performance
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003.
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The effects of tank size and impeller type on turbulent flocculation
… and (2.7 ft)$\sp3$ ($\approx$560L) with two impeller types (Rushton turbine and A310 fluid foil impeller) were evaluated experimentally using a laser Doppler velocimeter and numerically using a computational fluid dynamic software called FIDAP. The results of both the experimental and …
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Modeling of flow in impeller stirred tanks using computational fluids dynamics
The efficiency of mixing processes in impeller agitated tanks depends highly on the hydrodynamics. Computational fluids dynamics (CFD) provides a method of predicting the complex flow structures in stirred tanks. As with any approximate numerical method, CFD methods are subject to errors due to …
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CFD analysis and redesign of centrifugal impeller flows for rocket pumps
The analysis and redesign of a centrifugal impeller for a rocket pump is presented in this thesis. A baseline impeller was designed by Rocketdyne for the NASA Marshall Pump Consortium. Initially, the objective was to reduce the circumferential exit flow distortion of the baseline impeller. Later in …
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Characterization of unsteady loading due to impeller-diffuser interaction in centrifugal compressors
… are used to characterize the unsteady impeller blade loading due to imipeller-diffuser interaction in centrifugal compressor stages. The capability of simulations are assessed by comparing results against unsteady pressure and velocity measurements in the vaneless space. Simulations are …
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Experimental determination of solids suspension with angled impeller in a pharmaceutical mixing vessel
Angled-mounted impellers are commonly used in a number of pharmaceutical industry applications, from laboratory reactors to full-scale tanks. In these systems, the impeller is not centrally and vertically mounted, as in most stirred vessels, but it enters the vessel, and is therefore immersed in …
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Power dissipation and power correlations for a retreatblade impeller under different baffling conditions
… a torispherical tank bottom and a retreat curve impeller with low impeller clearance from the vessel bottom. The power, P, dissipated by the impeller is a critical process parameter to mixing processes to achieve the desired mixing effect, especially since the power per unit volume, P/V, directly …
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Forced response of a centrifugal compressor stage due to the impeller-diffuser interaction
… compressor stage can be dominated by of the impeller-diffuser interaction. The energy of the unsteady field, under certain aerodynamic and structural conditions, is capable of forcing the rotating impeller blades to vibrate excessively to the point of failure, better known as a high cycle …
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Effects of Tip Clearance and Surface Roughness on Small-Scale Turbopump Impeller Performance
Centimeter-scale turbopump impellers typically used in liquid rocket engines of small launch vehicles suffer from reduced performance due to manufacturing challenges and nonuniform geometric scaling. This thesis aims to characterize the impact of impeller blade tip clearance and surface roughness …
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Computational study of 3D turbulent flow in a tandem inducer/impeller rocket pump rotor
… study of the flow in a tandem inducer/impeller rocket pump has been performed using a 3D elliptic flow program including viscous effects. The axial inducer has four blades and the centrifugal impeller has eight main blades and sixteen splitter blades. The purpose of this thesis is to …
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Experimental and CFD–PBM investigation of an agitated bioreactor using a dual helical ribbon impeller
… close-clearance mixers (screw, helical, anchor impellers) increase biogas production, the information about hydrodynamic characteristics and flow field generated by these types of agitators is inadequate. Although hydrodynamics and the rheology of sludge have been studied in the past, more …
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The Integration of a Mixed-Flow Impeller with a Crossover Diffuser into the CAT250TJ Engine
… While traditional MGT engines employ centrifugal impellers, this thesis investigates an alternative approach: implementing a mixed-flow impeller with a crossover diffuser into the CAT250TJ MGT engine. Over the past 15 years, compressor design research at Stellenbosch University has focused …
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The role of impeller outflow conditions on the performance and stability of airfoil vaned radial diffusers
… thesis quantifies the relative importance of the impeller outflow angle, Mach number, non-uniformity and unsteadiness on diffuser performance, through diffuser experiments in a compressor stage and in a swirling flow test rig combined with steady and unsteady Reynolds-Averaged Navier Stokes …
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Experimental investigation of mixing time in a stirred, torispherical-bottomed tank equipped with a retreat-blade impeller
… are typically equipped with a retreat-blade impeller placed close to the bottom of the tank a single baffle mounted from the top. The mixing performance of such reactors has not received significant attention in the literature, despite their ubiquitous presence in the pharmaceutical industry. …
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Dissolution of different commercial aspirin tablets using a novel off-center paddle impeller (OPI) dissolution testing system
… 2, termed "OPI" System for "off-center paddle impeller," in which the impeller is placed 8 mm off center in the vessel is tested to determine its sensitivity to differentiate between the dissolution profiles of differently formulated and manufactured tablets. Dissolution tests are conducted …
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