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Abdus Samad
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Abdus Samad
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Abdus Samad
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Samad, A.
Samad, Abdus
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80 results
Now showing 1 - 10 of 80
- PublicationDesign optimization of a marine current turbine having winglet on blade(01-11-2021)
;Kunasekaran, Murali ;Rhee, Shin Hyung ;Venkatesan, NithyaWinglets on a turbine blade can modify flow features and improve a marine current turbine (MCT). In this work, to maximize the power coefficient (CP) and torque (T), cant angle (α), and height (h) of a winglet of an MCT were modified. The problem was solved using a high-fidelity solver code Fluent 2019R2 containing Reynolds-Averaged Navier–Stokes (RANS) equations. The flow domain meshed with tetrahedral elements. Nine different designs were produced to fill the design space for optimization. A set of low fidelity models such as second-order regression, kriging, and neural network models were used to approximate the high-fidelity results. The optimal designs further validated with the high-fidelity simulated results. The optimal design, increased CP by 7% for α = 33.2o and h = 2.04% of the turbine radius, reduced the recirculation zone at the trailing edge, increased the pressure gradient, and reduced the tip vortex. - PublicationComputational and experimental study of sand entrapment in a hydrocyclone during desanding operations in oil fields: Consequences for leakage and separation efficiency(01-01-2019)
;Khalde, Chirag M.; In the oil and gas industry, upstream and downstream hydrocyclones are used extensively to separate heavy or dense particles from the formation water/reservoir fluids. These hydrocyclones, after a long period of operation, can fail as a result of wear-initiated leakage, thereby needing maintenance or replacement. A detailed investigation of this failure was carried out using computational fluid dynamics (CFD). One-way and two-way coupling of a discrete phase model was used along with the Reynolds stress turbulence model (RSM). Experimental studies were conducted to understand the flow dynamics within the hydrocyclone and to validate the computational model. Key findings, such as bifurcation of the inlet flow, local acceleration of fluid within the hydrocyclone, the impact of the sand drain pipe on fractional efficiency, and the impact of multiple particle sizes and density interactions on the degree of particle entrapment, are discussed in detail. The approach and results presented in this work provide useful insights and a systematic basis for improving the service life and separation efficiency of the hydrocyclone. - PublicationNature-inspired design of a turbine blade harnessing wave energy(01-08-2020)
;Kumar, P. MadhanA bidirectional turbine used in an oscillating water column device extracts wave energy from oscillating airflow. To improve its power output, a concept of static extended trailing edge found in the wings of owl and merganser was adopted. The static extended trailing edge with 0–10% of chord length (C) was analyzed for different flow coefficients via Reynolds-averaged Navier–Stokes equation-based computational fluid dynamics (CFD) analysis. ANSYS-CFX 15.0 was used to simulate the flow. Grid convergence index was calculated to obtain optimum mesh, and numerical validation was done with experimental results. The static extended trailing edge with 5%C enhanced relative mean torque by 23.4% and, reduced relative mean efficiency by 5.4%, before stall condition. The modification increased pressure difference between the suction side and the pressure side and enhanced torque. The increased pressure drop reduced the efficiency. A further longer static extended trailing edge showed poorer stall characteristics. - PublicationIntroducing Gurney flap to Wells turbine blade and performance analysis with OpenFOAM(01-09-2019)
;Kumar, P. MadhanA Gurney flap (GF) placed at pressure side of the trailing edge of an airfoil and perpendicular to the chord line enhances lift in aircraft wings, helicopter rotors, and wind turbines, etc. In this article, the GF concept was introduced for Wells turbine blade used to harvest wave energy with special consideration as the blades are having symmetric airfoil and faces bidirectional flow. Hence, the flap was extended to both pressure and suction sides of the trailing edge (TE) to maintain blade symmetry, and the turbine performance was evaluated using opensource computational fluid dynamics code OpenFOAM 4.0. Different GF-lengths (0.5–3% chord length) were considered, and the performance parameters such as non-dimensional torque, pressure drop and efficiency were evaluated. The GF blades produced a counter-rotating vortex pair behind the TE which modified the TE Kutta condition and increased the circulation and lift. In addition, the GF blades increased the blade loading and enhanced the torque generated. However, the increased pressure drop lead to decrement in efficiency. - PublicationExperimental Investigation of a Bidirectional Impulse Turbine for Oscillating Flows at Various Resistive Loads(01-01-2021)
;Ravikumar, Suchithra ;Anandanarayanan, R. ;George, Aravind ;Pattanaik, Biren ;Dudhgaonkar, Prasad Vinayak ;Jalihal, PurnimaA bidirectional impulse turbine is a self-rectifying air turbine used in an oscillating water column wave energy converters. Most of the study on bidirectional impulse turbines involves steady-state performance analysis; however, the performance under oscillating airflow conditions is necessary to understand its behavior. The objective of this study is to experimentally analyze an optimized and numerically investigated bidirectional impulse turbine with fixed guide vane subjected to oscillating airflow conditions. A bidirectional airflow test facility developed at Indian Institute of Technology Madras, Chennai, India is employed to determine the aerodynamic characterization of the turbine and the dynamics involved in each of the coupling stages. The test rig consists of a piston chamber assembly, which provides different airflow rates by varying the stroke length (SL) and cycle time. Emphasis is made on the pressure and flow rate coefficients of the turbine, turbine-generator coupling, and power developed for different input conditions. The operating range of the turbine is mapped for four different frequencies and three SLs. Different electrical loading and the power output were analyzed for accelerations and decelerations of inflow and outflow. The preliminary dynamic characterization of the turbine with respect to nondimentionalized pressure coefficient and flow coefficient was determined for inflow and outflow. The power output is found to be in strong correlation with the flow rate and angular rotation of the rotor. The turbine analyzed in the experimental test rig will be proceeded with real sea testing on the Indian coast by the National Institute of Ocean Technology, Chennai, India. - PublicationDESIGN AND MIXING PERFORMANCE OF PASSIVE MICROMIXERS: A CRITICAL REVIEW(01-01-2023)
;Husain, Afzal ;Khan, Asharul Islam ;Raza, Wasim ;Al-Rawahi, Nabeel ;Al-Azri, NasserThis study extracts and reports notable findings on passive micromixers by conducting an exhaustive review of designs, their features, and mixing performance. The study has covered the relevant articles on passive micromixers published from 2010 to 2020. The analysis of filtered and selected articles sums up passive micromixers into four categories: designed inlets, designed mixing-channel, lamination-based, and flow obstacles-based. The prominent mixing channel categories identified in the study are split-and-recombine (SAR), convergent-divergent (C-D), and mixed (SAR, C-D, and others). Moreover, differences in mixing channel designs, number of inlets, and evaluation methods have been used in comparing the mixing performance of passive micromixers. The SAR and the obstacles-based micromixers were found to outperform the others. The designs covered in the present review show significant improvements in the mixing index. However, these studies were conducted in an isolated environment, and most of the time, their fabrication and device integration issues were ignored. The assortment and critical analysis of micromixers based on their design features and flow parameters will be helpful to researchers interested in designing new passive micromixers for microfluidic applications. - PublicationLeakage flow correlation of a progressive cavity pump delivering shear thinning non-Newtonian fluids(01-01-2017)
;Mrinal, K. R.The majority of the complex fluids in petroleum engineering applications are shear thinning non-Newtonian. The industry pumps non-Newtonian fluids by progressive cavity pumps (PCPs) are being used for pumping non-Newtonian fluids in the petroleum industry from the past few years. In this work, an experimental setup was developed and the objective is to study the performance of a PCP delivering shear thinning non-Newtonian fluids and the effect of speed, slurry viscosity and differential pressure on the leakage and volumetric efficiency of the pump. The fluids were prepared by mixing bentonite, water and 0.06% of Na2CO3 to maintain pH level at 8.5-9.5, and the mixture produced are shear thinning non-Newtonian fluid. It was observed that the pump efficiency increases with the increase in viscosity, which reduces the pump leakage. At a higher speed, the pump leakage was lower and volumetric efficiency was higher while increased differential pressure caused an increase in leakage and a decrease in volumetric efficiency. Using the experimental results, a polynomial regression model was developed to predict the leakage of the pump. The correlation development approach can be implemented in the other type of pumps and can cut down experimental expenses. - PublicationHigh performance ocean energy harvesting turbine design-A new casing treatment scheme(15-06-2015)
;Halder, Paresh; ;Kim, Jin HyukChoi, Young SeokDelaying a stall improves the performance of any turbomachinery system. TC (tip clearance), which is used in a bi-directional flow Wells turbine of an ocean wave energy device, changes the flow pattern on the turbine blade suction surface, while changing or modifying the TC zone can help obtaining a delayed stall. In the present work, a new tip grooving scheme is introduced and the performance is compared for different tip groove depths and TCs of a Wells turbine. The performance is defined in terms of wider operating range or stall delay, power production and efficiency. The problem was solved by a numerical analysis technique. A multi-block meshing scheme was employed to generate structured and hexahedral elements in the computational domain and the flow was solved in ANSYS CFX® v14.5 by solving Reynolds-averaged Navier Stokes equations. It was found that the grooves improve the turbine operating range and power production as compared to those of the turbine without a groove. The groove depth of 3% of the chord length produced highest power and widest operating range. Using the circumferential groove, 26% increase in turbine power output for a particular operating point is achieved. - PublicationWave energy harvesting turbine: Effect of hub-to-tip profile modification(01-01-2018)
;Madhan Kumar, P. ;Halder, Paresh; Rhee, Shin HyungThe present paper investigates the leading edge (LE) undulations of a Wells turbine blade through numerical analysis. The aspiration for this modification came from humpback whales, which have uneven protrusions at the LE of their pectoral flippers. The flippers help whales to maneuver during swimming. The work is performed by using three-dimensional steady, incompressible Reynolds Averaged Navier-Stokes (RANS) equations with turbulent closer model. The LE of the turbine blades is modified with undulations of three different amplitudes: 1mm, 2.5mm, and 4mm. The results show that the undulation changes the turbine performance. The amplitude 2.5mm gives the peak performance. The comparison between blades with different amplitudes and the reference blade has been discussed throughout this study. - PublicationPerformance analysis of a multiple micro-jet impingements cooling model(01-01-2016)
;Husain, A. ;Al-Azri, N. A.; Kim, K. Y.The present study investigates the thermal performance of a multiple micro-jet impingements model for electronics cooling. The fluid flow and heat transport characteristics were investigated for steady incompressible laminar flow by solving three-dimensional (3D) Navier-Stokes equations. Several parallel and staggered micro-jet configurations (ie. inline 2 × 2, 3 × 3 and 4 × 4 jets, and staggered five-jet and 13-jet arrays with the jet diameter to the channel height ratios from 0.25-0.5) were analyzed at various flow rates for the maximum temperature rise, pressure drop, heat-transfer coefficient, thermal resistance, and pumping power characteristics. The parametric investigation was carried out based on the number of jets and the jet diameters at various mass flow rates and jet Reynolds numbers. Temperature uniformity and coefficient of performance were evaluated to find out the trade-off among the various designs investigated in the present study. The maximum temperature rise and the pressure drop decreased with an increase in the number of jets except in the case of staggered five-jet array. A higher temperature uniformity was observed at higher flow rates with a decrease in the coefficient of performance. The performance parameters, such as thermal resistance and pumping power, showed a conflicting nature with respect to design variables (viz. jet diameter to stand-off ratio and interjet spacing or number of jets) at various Reynolds numbers within the laminar regime.