Design and Optimization of a Ducted Marine Current Savonius Turbine for Gun-Barrel Passage, Fiji

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Jai Nendran Goundar ◽  
M. Rafiuddin Ahmed ◽  
Young-Ho Lee
Keyword(s):  
Flow Characteristics ◽  
Maximum Efficiency ◽  
Speed Ratio ◽  
Water Stream ◽  
Freestream Velocity ◽  
Design And Optimization ◽  
Gun Barrel ◽  
Marine Current ◽  
Ducted Turbine ◽  
Shaft Power

Marine current energy is a reliable and clean source of energy. Many marine current turbines have been designed and developed over the years. Placement of an appropriately designed duct or shroud around the turbine significantly improves the turbine performance. In the present work, a ducted Savonius turbine (DST) is designed and optimized and its performance analysis carried out. The components of DSTs are simple and easily available and can be manufactured in developing countries like Fiji. A scaled-down model of 1/20 of a DST was fabricated and tested in a water stream at a velocity of 0.6 m/s and the results were used to validate the results from a commercial computational fluid dynamics (CFD) code ANSYS-cfx. Finally, a full-scale DST was modeled to study the flow characteristics in the turbine and the performance characteristics. The maximum efficiency of the turbine is around 50% at the tip speed ratio (TSR) of 3.5 and the maximum shaft power obtained is 10 kW at the rated speed of 1.15 m/s and around 65 kW at a freestream velocity of 2.15 m/s. The stress distribution on the ducted turbine was also obtained.

Design and Performance Testing of a Ducted Savonius Turbine for Marine Current Energy Extraction

2013 ◽  
Author(s):  
Jai N. Goundar ◽  
Deepak Prasad ◽  
Mohammed Rafiuddin Ahmed
Keyword(s):  
Flow Characteristics ◽  
Performance Testing ◽  
Maximum Efficiency ◽  
Speed Ratio ◽  
Stream Velocity ◽  
Water Stream ◽  
Ansys Cfx ◽  
Marine Current ◽  
And Performance ◽  
Current Energy

Marine current energy is a reliable and clean source of energy. Several marine current turbines have been developed over the years, most of the turbines perform well at velocities over 2 m/s and need to be installed at depths of 20–40 m. Placing an appropriately designed duct or shroud around the turbine significantly improves the turbine’s performance. Ducted Savonius turbines can operate at low depths, since large clearance is not required because turbulent flow has little effect on the performance of the Savonius rotor. Ducted Savonius turbine has simple components and can be easily fabricated in Pacific Island Countries (PIC) and other places that do not have advanced manufacturing industries. A ducted Savonius turbine was designed for a location in Fiji, to operate at a rated marine current speed of 1.15 m/s and cut in speed of 0.2 m/s. The model of ducted Savonius turbine, scaled down to 1/20, was fabricated and tested in a water stream with a velocity of 0.6 m/s and was validated with commercial Computational Fluid Dynamics (CFD) code ANSYS-CFX. Finally, a full scale numerical model was constructed to study the flow characteristics and compute the performance. The area ratio of the duct of 2.5:1 (inlet to turbine section) shows significant increase in kinetic energy and an improved turbine performance. The maximum efficiency of the turbine is around 50% at a tip speed ratio (TSR) of 3.5 and the maximum power produced is 10 kW at the rated speed of 1.15 m/s and 63.4 kW at a free-stream velocity of 2.15 m/s.

scholarly journals Performance Investigation of the Immersed Depth Effects on a Water Wheel Using Experimental and Numerical Analyses

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 982 ◽  
Author(s):  
Mengshang Zhao ◽  
Yuan Zheng ◽  
Chunxia Yang ◽  
Yuquan Zhang ◽  
Qinghong Tang
Keyword(s):  
Water Level ◽  
Volume Fraction ◽  
Flow Characteristics ◽  
Maximum Error ◽  
Radius Ratio ◽  
Maximum Efficiency ◽  
Water Volume ◽  
Speed Ratio ◽  
Water Wheel ◽  
Water Volume Fraction

The purpose of this research is to study the effect of different immersed depths on water wheel performance and flow characteristics using numerical simulations. The results indicate that the simulation methods are consistent with experiments with a maximum error less than 5%. Under the same rotational speeds, the efficiency is much higher and the fluctuation amplitude of the torque is much smaller as the immersed radius ratio increases, and until an immersed radius ratio of 82.76%, the wheel shows the best performance, achieving a maximum efficiency of 18.05% at a tip-speed ratio (TSR) of 0.1984. The average difference in water level increases as the immersed radius ratio increases until 82.76%. The water area is much wider and the water volume fraction shows more intense change at the inlet stage at a deep immersed depth. At an immersed radius ratio of 82.76%, some air intrudes into the water at the inlet stage, coupled with a dramatic change in the water volume fraction that would make the flow more complex. Furthermore, eddies are found to gradually generate in a single flow channel nearly at the same time, except for an immersed depth of 1.2 m. However, eddies generate in two flow channels and can develop initial vortexes earlier than other cases because of the elevation of the upstream water level at an immersed radius ratio of 82.76%.

Design and optimization of bump (compression surface) for diverterless supersonic inlet

2021 ◽  
pp. 095441002110029
Author(s):  
Irsalan Arif ◽  
Hassan Iftikhar ◽  
Ali Javed
Keyword(s):  
Fitness Function ◽  
Supersonic Jet ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Least Square ◽  
Pressure Recovery ◽  
Design Parameters ◽  
Inlet System ◽  
Design And Optimization ◽  
Supersonic Inlet

In this article design and optimization scheme of a three-dimensional bump surface for a supersonic aircraft is presented. A baseline bump and inlet duct with forward cowl lip is initially modeled in accordance with an existing bump configuration on a supersonic jet aircraft. Various design parameters for bump surface of diverterless supersonic inlet systems are identified, and design space is established using sensitivity analysis to identify the uncertainty associated with each design parameter by the one-factor-at-a-time approach. Subsequently, the designed configurations are selected by performing a three-level design of experiments using the Box–Behnken method and the numerical simulations. Surrogate modeling is carried out by the least square regression method to identify the fitness function, and optimization is performed using genetic algorithm based on pressure recovery as the objective function. The resultant optimized bump configuration demonstrates significant improvement in pressure recovery and flow characteristics as compared to baseline configuration at both supersonic and subsonic flow conditions and at design and off-design conditions. The proposed design and optimization methodology can be applied for optimizing the bump surface design of any diverterless supersonic inlet system for maximizing the intake performance.

Hydrodynamic Design and Analysis of Horizontal Axis Marine Current Turbines With Lifting Line and Panel Methods

2011 ◽  
Author(s):  
J. Baltazar ◽  
J. Machado ◽  
J. A. C. Falca˜o de Campos
Keyword(s):  
Computational Models ◽  
Design Procedure ◽  
Horizontal Axis ◽  
Complete Analysis ◽  
Speed Ratio ◽  
Integral Boundary ◽  
Power Extraction ◽  
Marine Current ◽  
Lifting Line ◽  
Blade Geometry

This paper presents the computational models used by the authors at MARETEC/IST for hydrodynamic design and analysis of horizontal axis marine current turbines. The models combine a lifting line method for the optimization of the turbine blade geometry and an Integral Boundary Element Method (IBEM) for the hydrodynamic analysis. The classical lifting line optimization is used to determine the optimum blade circulation distribution for maximum power extraction. Blade geometry is determined with simplified cavitation requirements and limitations due to mechanical strength. The application of the design procedure is illustrated for a two-bladed 300 kW marine current turbine with a diameter of 11 meters. The effects of design tip-speed-ratio and the influence of blade section foils on power and cavitation inception are discussed. A more complete analysis may be carried out with an IBEM in steady and unsteady flow conditions. The IBEM has been extended to include wake alignment. The results are compared with experimental performance data available in the literature.

scholarly journals Sustainable Power Generation by Tidal Current Turbine in Straits of Malacca

2018 ◽  
Vol 198 ◽  
pp. 04004
Author(s):  
P. T. Ghazvinei ◽  
H.H. Darvishi ◽  
A. Bhatia
Keyword(s):  
Tidal Current ◽  
Energy Resource ◽  
Flow Characteristics ◽  
Tidal Power ◽  
Tropical Country ◽  
Marine Current ◽  
Tidal Current Turbine ◽  
Straits Of Malacca ◽  
Sustainable Power ◽  
Current Turbine

Marine current power is a significant energy resource which is yet to be exploited for efficient energy production. Malaysia, being a tropical country is rich in renewable sources and tidal power is one of them. In Malaysia, Straits of Malacca is a potential site to establish a tidal current turbine. In the current study, the potential sites of the Straits of Malacca are discussed. A detailed review about the generator suitable for the Straits of Malacca with the associated challenges has also been discussed. Furthermore, the suitable solution for such challenges is proposed. The role of simulation in choosing an appropriate site and generator has also been reviewed. The focus of the study is to propose a generator suitable for the flow characteristics of the Straits of Malacca.

Aerodynamic Performance of an Elliptical-Bladed Savonius Rotor Under the Influence of Number of Blades and Shaft

2017 ◽  
Author(s):  
Nur Alom ◽  
Nitish Kumar ◽  
Ujjwal K. Saha
Keyword(s):  
Flow Characteristics ◽  
Rotor Blades ◽  
Experimental Investigations ◽  
Speed Ratio ◽  
Ansys Fluent ◽  
Savonius Rotor ◽  
Velocity Magnitude ◽  
Augmentation Techniques ◽  
Influencing Parameters ◽  
Overlap Ratio

In the past, various influencing parameters of the conventional semicircular-bladed Savonius rotor such as overlap ratio, aspect ratio, number of rotor blades have been optimized through numerical and experimental investigations to improve its performance. Furthermore, the rotor performance under the influence of various blade profiles, shaft, endplates, and augmentation techniques has also been studied. Recent rudimentary studies with an elliptical-bladed Savonius rotor have demonstrated its potential to harness the wind energy more efficiently; however, its influencing parameters have not been thoroughly studied and therefore they need to be optimized to arrive at a suitable design configuration. In view of this, the objective of the present investigation is to optimize the number of elliptical blades on the rotor and then to find the influence of shaft with the optimized number of blades on the rotor performance. For this, 2D unsteady simulation is carried out with different combinations of blades, and after having optimized the number of blades, the influence of shaft on the rotor performance is studied. The continuity, unsteady Reynolds-Averaged Navier-Stokes (RANS) equations, and two equation eddy viscosity SST (Shear Stress transport) k-ω model are solved by using the commercial FVM based solver ANSYS Fluent. The torque and power coefficients are calculated as a function of tip speed ratio (TSR) and at rotating conditions. The total pressure, velocity magnitude, turbulence intensity and streamline patterns are obtained and analyzed to arrive at the intended objective. The numerical investigation demonstrates an improved flow characteristics and performance coefficients of the 2-elliptical-bladed profile without shaft.

Augmented Diffuser for Horizontal Axis Marine Current Turbine

2016 ◽  
Vol 7 (1) ◽  
pp. 235 ◽  
Author(s):  
Aly Hassan Elbatran ◽  
Omar Yaakob ◽  
Yasser Ahmed ◽  
Firdaus Abdallah
Keyword(s):  
Tidal Current ◽  
Renewable Energy Sources ◽  
Research Work ◽  
Horizontal Axis ◽  
Offshore Wind ◽  
Water Current ◽  
Maximum Efficiency ◽  
Marine Current Turbine ◽  
Marine Current ◽  
Current Turbine

<span>The potential of renewable energy sources is enormous as they can make a major contribution to the future of energy needs. The ocean has a great potential to become a practical and predictable energy source compared to other energy resources such as solar, wind, and nuclear. It offers different sources of energy which can be utilized namely wave, tidal, offshore wind, thermal, and tidal current. Among these sources, marine tidal current has major advantages such as higher power availability and predictability. The main objective of this research work is to design and develop a horizontal axis marine current turbine (HAMCT) that suitable for operating within Malaysian ocean, which has low speed current (0.5 – 1 m/s average). A prototype of augmented diffuser 4-bladed HAMCT applying NACA 0014 was proposed in the current study. The turbine model has 0.666 m diameter, and it was designed to produce as much as power from flowing water current. Model was constructed and tested at Marine Technology Center (MTC) in three conditions, namely, free tow testing, ducted tow testing, and ducted diffuser tow testing in order to predict the power and efficiency of the turbine system. The results showed that the application of duct was significant to concentrate the flow and diffuser arrangement was effective when it was placed behind of the rotor in this condition of low water current speed. The maximum efficiency Cp obtained in the current system was 0.58.</span>

Heat Transfer Computations for Turbine Blade Airfoils

1996 ◽  
Author(s):  
Jamel Slimani ◽  
Pascale Kulisa
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Separation Bubble ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Equation Model ◽  
Computational Time ◽  
Design And Optimization ◽  
Wall Flows ◽  
Turbine Blade Design

The design and optimization of turbine blades subjected to high temperature flows require the prediction of aerodynamic and thermal flow characteristics. A computation of aerothermal viscous flow model has been developed suitable for the turbine blade design process. The computational time must be reduced to allow intensive use in an industrial framework. The physical model is based on a compressible boundary layer approach, and the turbulence is a one-equation model. Special attention has been paid to the influence of wall curvature on the turbulence modelling. Tests were performed on convex wall flows to validate the turbulence model. Turbine blade configurations were then computed. These tests include most difficulties that can be encountered in practice : laminar-turbulent transition, separation bubble, strong accelerations, shock wave. Satisfactory predictions of the wall heat transfer are observed.

Performance improvement and flow field investigation in hydraulic torque converter based on a new design of segmented blades

2020 ◽  
Vol 234 (8) ◽  
pp. 2162-2175
Author(s):  
Chunbao Liu ◽  
Konghua Yang ◽  
Jing Li ◽  
Zhixuan Xu ◽  
Tongjian Wang
Keyword(s):  
Turbine Blade ◽  
Fuel Economy ◽  
Transient Flow ◽  
Torque Converter ◽  
Transmission Efficiency ◽  
Maximum Efficiency ◽  
Speed Ratio ◽  
Start Up ◽  
Computational Fluid Dynamics Analysis ◽  
Hydraulic Torque Converter

Hydraulic torque converter is of lower efficiency in the powertrain, particularly at low speed ratio, which is crucial for vehicles due to its ability of torque multiplication. Therefore, torque converters should be taken into account with both higher start-up acceleration and transmission efficiency. Inspired by the fact that the multi-airfoils of the aircraft can improve the lift, a new design of segmented turbine blade in torque converter is presented to improve the transmission efficiency and start-up acceleration. To ensure reproducibility and popularization, the camber line and shape of blades are extracted to obtain the expression in the Cartesian coordinate system. A scale-resolving simulation setting, large eddy simulation with kinetic energy transport, and refined hexahedron meshes, which were verified by our studies, are applied to simulate the three-dimensional transient flow numerically. According to the results of computational fluid dynamics analysis, the new design eliminated the ultra-high vorticity of the near-wall boundary layer to reduce the flow loss, which further improves fuel economy. The pressure difference in the segmented turbine blade is significantly higher than that of the original model, causing the improvement of powertrain performance. As a result, the torque ratio and nominal torque increase by 6.7% and 7.7%, respectively, at stalling speed ratio; meanwhile, the maximum efficiency increases by 1.1%. This research, using a new design of segmented blades, has many advantages, such as high starting torque ratio, large adjusting range, and greater fuel economy, and shows great potential to apply in the manufacturing process.

Evolution of a Cavitating Bubble in a Nonuniform Pressure Field

2007 ◽  
Author(s):  
Vladimir A. Knyazev ◽  
Vladimir A. Soldatov ◽  
Upendra Singh Rohatgi
Keyword(s):  
Volume Content ◽  
Cavitation Erosion ◽  
Flow Characteristics ◽  
Major Effect ◽  
Wall Layer ◽  
Maximum Efficiency ◽  
Mode Of Operation ◽  
Direct Modeling ◽  
Established Fact ◽  
Made In

The cavitation erosion problem is not a new one; however, it is still important and even becomes more pressing. This is associated with requirements to justify and extend service life of power-generating plants while obviously seeking the maximum efficiency. Currently semiempirical correlation relations are typically used in pump designing for prediction of modes of operation that may be hazardous in terms of development of cavitation erosion [1, 2]. It appears, however, that a progress can be made in this field by introducing numerical modeling of flow with direct modeling of the cavitation erosion process. This optimism is based on an established fact that the major effect of erosion damage is observed in the mode of operation between the “NPSH-incipient” mode (mode of activation of vapor-phase formation centers) and the “NPSH-3%” mode (mode where a noticeable vapor volume content is produced in the near-wall layer), i.e. in the mode of operation where the vapor volume content is small and its effect on flow characteristics can be neglected.

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