Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
36
2
2009
Effect of Inlet Conditions on Centrifugal Pump Performance
97-113
Walid
Aissa
Mechanical Power Department, Faculty of Energy Engineering, Aswan University, Aswan, Egypt
The performance of a baseline centrifugal pump was both analytically and experimentally investigated at the Fluid Lab of High Institute of Energy, South Valley University. Pressure sensors for intake and delivery pressures are fitted to the pump. These sensors, as also for the flow rate and temperature sensors are connected to the measuring unit block mounted on the basic module. Specific obstacles were mounted in a flange section which was bolted to the intake section of the centrifugal pump to simulate changes in inlet conditions of the centrifugal pump. These obstacles are perforated discs having either straight or inclined upstream surface. Comparisons of the main characteristics of the baseline (without obstacle) pump and those of pump with obstacle are made to determine the effects of changes in inlet conditions.
Analysis of Steady Laminar Blood Flow Through Arterial Stenosis
114-132
Moloy Kumar
Banerjee
Department of Mechanical Engineering, Future Institute of Engineering and Management Kolkata, India
The flow of blood through a rigid artery with different degrees of stenosis has been studied. Two different shapes (rectangular and cosine) of the stenosis are considered while the blood is modeled either as Newtonian or non-Newtonian fluid. Three different degree of stenosis, expressed in percentage, are considered representing mild to severe stenoses. The flow separates from the arterial wall at the stenosis and reattaches at a point downstream, forming a recirculating eddy. The pressure drop over the length of the artery varies for the different cases indicating the impact on the heart. A peak in the wall shear stress is observed at the location of the stenosis and zero stress points are observed where the flow separates and reattaches the wall. Results show marked differences in flow pattern and shear stress between Newtonian and non-Newtonian models. Moreover, the power-law model exhibits a different trend as compared to the Casson model in predicting the flow field and wall shear stress.
Variable Permeability Effect on Vortex Instability of Buoyancy-Induced Inclined Boundary Layer Flow in a Saturated Porous Medium
133-144
I. A.
Hassanien
Department of Mathematics, Faculty of Science, Assiut University, Assiut, Egypt
Ahmed M.
Elaiw
Department of Mathematics, Faculty of Science, Al-Azhar University, Assiut 71511, Egypt
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
A linear stability analysis has been presented for the vortex instability of free convection boundary layer flow in a saturated porous medium adjacent to an inclined non-isothermal heated plate. The variation of permeability in the vicinity of the solid boundary has been approximated by an exponential function. Velocity and temperature profiles as well as dimensionless local heat transfer rates in the form of the Nusselt number for the base flow are presented for the uniform permeability (UP) and variable permeability (VP) cases. The critical Rayleigh numbers and the associated wave numbers are obtained for both UP and VP cases. It is found that the variable permeability effect tends to augment the heat transfer rate and destabilize the flow to the vortex mode of disturbance.
Microstructure Effects on Mixed Convection Flow Over a Nonisothermal Vertical Surface
145-153
Fouad S.
Ibrahim
Department of Mathematics, University College, Umm Al-Qura University, Makkah, Saudi
Arabia; Department of Mathematics, Faculty of Science, Assiut University, Assiut, Egypt
I. A.
Hassanien
Department of Mathematics, Faculty of Science, Assiut University, Assiut, Egypt
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
A boundary layer analysis is presented to study the mixed convection flow of a micropolar fluid over a vertical non-isothermal flat plate. The transformed boundary layer equations have been solved numerically. The effects of buoyancy and micropolar parameters and Prandtl number on the velocity, angular velocity, and temperature distribution are discussed. The missing wall values of the velocity, angular velocity, and thermal functions are computed. Micropolar fluids display drag reduction and reduce surface heat transfer rate when comparing with Newtonian fluids.
Studying the Performance of Vertical Axis Wind Turbine (VAWT) Models with Blade Control Mechanism
154-165
V. P.
Kayan
Institute of Hydromechanics of National Academy of Sciences of Ukraine 8/4, Zhelyabov St., Kyiv-180, 03680, MSP, Ukraine
V. A.
Kochin
Institute of Hydromechanics of National Academy of Sciences of Ukraine 8/4, Zhelyabov St., Kyiv-180, 03680, MSP, Ukraine
O. G.
Lebid'
Institute of Hydromechanics of National Academy of Sciences of Ukraine 8/4, Zhelyabov St., Kyiv-180, 03680, MSP, Ukraine
The paper deals with determining the effect of periodic variation of blade installation angle during one turn of vertical axis wind turbine (VAWT) model on its power and momentum characteristics. Moreover, magnitude of the accompanying wind loading on the VAWT shaft is studied. The model experiment has been carried out in a hydrotray for small VAWT models. It is found that the VAWT with controlled blades is able to self-starting at quite slow incident flows. The essential increase of the torque-to-flow energy ratio is shown, along with the decrease of shaft hydrodynamic load, in comparison with VAWT model with the fixed blades.
Electrohydrodynamic Rayleigh - Taylor Instability in a Poorly Conducting Fluid Layer Bounded Above by a Nanostructured Porous Layer
166-179
N.
Rudraiah
National Research Institute for Applied Mathematics, 492/G, 7th Cross, 7th Block (West), Jayanagar, Bangalore 560 082, and UGC-DSA Centre in Fluid Mechanics, Department of Mathematics, Bangalore University, Bangalore 560 001, India
Krishna B.
Chavaraddi
UGC-Centre for Advanced Studies in Fluid Mechanics, Department of Mathematics, Bangalore University, Bangalore-560 001, India
Electrohydrodynamic Rayleigh - Talyor instability (ERTI) at the interface region between a thin poorly conducting incompressible viscous fluid saturated nanostructured porous layer and a poorly conducting fluid layer in the presence of a non-uniform electric field is investigated using linear stability analysis. A simple theory based on electrohydrodynamic approximations and Saffman slip condition is proposed. An analytical expression for dispersion relation is derived in the form of n = nb − βlνa, where n is the growth rate and βlνa is the effect of compression. It is shown that the porous lining and transverse electric field control the growth rate of ERTI depending on whether the applied electric field is opposing or aligning the direction of gravity. In particular, we found that n tends to zero for equipartition of energy (i. e., Weber number We = 1).
Three-Dimensional Free Convection Flow with Radiation in the Slip Flow Regime
180-191
The effects of radiation and sinusoidal temperature on steady three-dimensional free convection flow of a viscous, incompressible fluid through a highly porous medium along a vertical porous plate in the slip flow regime are studied. In the analysis, it is considered that the plate is subjected to a periodic suction velocity. Approximate solutions for the velocity and temperature fields are obtained by using the series expansion method for an externally cooled plate, i. e., for a Grashof number greater than zero. Expressions for the friction factor and rate of heat transfer are also derived. It is observed that suction at the plate leads to a decrease in the main flow as well as in transverse flow and serves to stabilize the temperature. The results obtained are discussed using graphs and tables.