In this paper, the lift-law method was applied to design the axial flow pump. Based on Reynolds time-averaged N-S equations and standard k turbulent model, three-dimensional air-water bubbly flow in an axial flow pump impeller was simulated. Under the condition of bubble void fraction of 5%, pressure and void fraction distributions were respectively obtained, movement of bubbles in the impeller...

Macro-mixing effects in batch and semi-batch reactors are investigated by constructing 3-dimensional models using a network of zones (NoZ) discretisation. System dynamics including volume changes due to continuous feeding are successfully predicted. Detailed flow fields are calculated from phenomenological correlations which include parameters such as reactor size and configuration, impeller ty...

The production of Schizophyllan by Schizophyllum commune and Scleroglucan by Sclerotium rolfsii is growth associated. Shear stress as a result of the impeller type and rotation speed as well as an optimum but not maximum oxygen supply are the key factors for enhanced production. Batch cultivations resulted maximum yields of 13 g L for both ß-glucans. In oxygen limited chemostats with biomass fe...

multiphase impeller stirred tank reactors enhance mixing of reacting species used in a variety of chemical industries. these reactors have been studied based on computational fluid dynamics (cfd) that can be used in the analysis, design and scale up of these reactors. most of the researches done in this area are limited to single phase reactors, and a few remaining two phase flow investigations...

The introduction of centrifugal pumps as artificial heart devices has spawned a number of interesting controls problems including magnetic levitation and motoring of a thin, gyroscopic impeller subject to significant but poorly characterized fluid couplings; parameter estimation based observation of magnetic circuits to determine impeller position; and potentially complex coordination of impell...

The flow field in a centrifugal fan is highly complex with flow reversal taking place on the suction side of impeller and diffuser vanes. Generally performance of the centrifugal fan could be enhanced by judiciously introducing splitter vanes so as to improve the diffusion process. An extensive numerical whole field analysis on the effect of splitter vanes placed in discrete regions of suspecte...

Honey bees (Apis mellifera) are remarkable fliers that regularly carry heavy loads of nectar and pollen, supported by a flight system - the wings, thorax and flight muscles - that one might assume is optimized for aerial locomotion. However, honey bees also use this system to perform other crucial tasks that are unrelated to flight. When ventilating the nest, bees grip the surface of the comb o...

Vertical turbine pumps are designed to operate with the pump shafts in tension (downthrust). Most pump and motor manufacturers caution users to not operate the vertical turbine pumps at conditions that result in “upthrust.” Upthrust conditions are usually encountered for a few seconds each time the pump is started; however, the pump should not be operated for periods longer than a few seconds i...

South African fly ash has been shown to be a useful feedstock for the synthesis of some zeolites. The present study focuses on the effect of impeller design and agitation rates on the synthesis of zeolite Na-P1 which are critical to the commercialization of this product. The effects of three impeller designs (4-flat blade, Anchor and Archimedes screw impellers) and three agitation speeds (150, ...

The simulation of the three-dimensional turbulent flow in turbomachines is currently based on the solution of the Reynolds Averaged Navier Stokes equations. A considerable computational effort usually goes to the mesh generation process due to the complexity of the impeller geometry. The use of Cartesian grids combined with a numerical technique for solving partially blocked cells is presented ...