Influence of Tubercle Modifications on the Performance of Marine Vertical Axis Propellers

2021 ◽  
pp. 1-10
Author(s):  
Mohamed R. Shouman ◽  
Mohamed M. Helal
Keyword(s):  
Cfd Simulation ◽  
Leading Edge ◽  
Vertical Axis ◽  
Ansys Fluent ◽  
Thrust Coefficient ◽  
Marine Propellers ◽  
Marine Propulsion ◽  
Complete Procedure ◽  
Propeller Blades ◽  
High Level

Even though past efforts in computational fluid dynamics (CFD) simulations have shown great progress in the implementation of tubercles into aero-foils and turbines blades, incorporating these tubercles into marine vertical axis propellers is still comparatively less well understood. In general, the performance of marine propellers is highly related to the pressure and velocity distributions over the propeller blades. Since the presence of tubercles’ serrations in the blade leading edge can vary these distributions over the blade, the performance of the propellers can be enhanced. In this article, tubercle modifications are investigated in marine vertical axis propellers through the use of CFD simulation. To achieve this purpose, a complete procedure of CFD simulation using ANSYS FLUENT 16 is proposed. Obtained CFD results are validated using direct comparison with the previous analytical studies. Obtained performance characteristics of the modified vertical axis propeller are assessed against the available characteristics of the baseline one. The CFD results are found in a good agreement with the analytical ones. Moreover, the results demonstrate the improvement of the obtained performance of the modified vertical axis propeller compared to the baseline one in terms of increased thrust coefficient and higher efficiency over the considered range of advance ratio. Introduction Shallow waters, rivers, and seas; the presence of obstacles; the complexity of water routes; and the territorial orography require the availability of effective maneuverability to enhance marine propulsion compared to the traditional rudder-propeller system (Pasetto1 2013). In this context, the vertical axis propellers (VAP) can be a real and valid alternative to the rudder-propeller system (Chen 2007), allowing the ships to navigate in an effective way also in the difficult routing and in shallow water conditions (Carlton 2007). The VAP provides the ability to sail vessels in all sea conditions effectively. It maintains the ability to direct the thrust to 360° and, consequently, provides a better performance in terms of maneuverability, stop and crash maneuvers and higher efficiency. It is therefore necessary for all kinds of vessels requiring high level of maneuverability in congested waterways to be equipped with VAPs for ease, safety, and immediate response.

Simulation Study on the Performance of Vertical Axis Wind Turbine

2013 ◽  
Vol 465-466 ◽  
pp. 270-274 ◽  
Author(s):  
N. Afzanizam Samiran ◽  
A.A. Wahab ◽  
Mohd Sofian ◽  
N. Rosly
Keyword(s):  
Output Power ◽  
Flow Characteristic ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Navier Stokes ◽  
Vertical Axis Wind Turbine ◽  
Ansys Fluent ◽  
Savonius Rotor ◽  
Torque Coefficient

The present study considered the design improvement of Savonius rotor, in order to increase the efficiency of output power. An investigation was conducted to study the effect of geometrical configuration on the performance of the rotor in terms of coefficient of torque, coefficient of power and power output. Modification of conventional geometry has been designed by combining the effect of number of blades and shielding method. CFD simulation was conducted to analyze the flow characteristic and calculate the torque coefficient of all the rotor configurations. The continuity and Reynolds Averaged Navier-Stokes (RANS) equations and realizable k-ε epsilon turbulence model are numerically solved by commercial software Ansys-Fluent 14.0. The results obtained by transient and steady method for the conventional two bladed Savonius rotor are in agreement with those obtained experimentally by other authors and this indicates that the methods can be successfully applied for such analysis. The modified 3 and 4 bladed rotors with hybrid shielding method gave the highest maximum power coefficient which 0.37 at TSR 0.5 and output power exceed 4 watts with rotor dimensions of 0.2m width and 0.2m height. This blade configuration also is the best configuration by several percentages compared to the other model from the previous study

Aerodynamic and aeroacoustic performance investigations on modified H-rotor Darrieus wind turbine

2021 ◽  
pp. 0309524X2110039
Author(s):  
Amgad Dessoky ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
3D Models ◽  
Power Coefficient ◽  
Design Parameters ◽  
Second Phase ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes

The present paper investigates the aerodynamic and aeroacoustic characteristics of the H-rotor Darrieus vertical axis wind turbine (VAWT) combined with very promising energy conversion and steering technology; a fixed guide-vanes. The main scope of the current work is to enhance the aerodynamic performance and assess the noise production accomplished with such enhancement. The studies are carried out in two phases; the first phase is a parametric 2D CFD simulation employing the unsteady Reynolds-averaged Navier-Stokes (URANS) approach to optimize the design parameters of the guide-vanes. The second phase is a 3D CFD simulation of the full turbine using a higher-order numerical scheme and a hybrid RANS/LES (DDES) method. The guide-vanes show a superior power augmentation, about 42% increase in the power coefficient at λ = 2.75, with a slightly noisy operation and completely change the signal directivity. A remarkable difference in power coefficient is observed between 2D and 3D models at the high-speed ratios stems from the 3D effect. As a result, a 3D simulation of the capped Darrieus turbine is carried out, and then a noise assessment of such configuration is assessed. The results show a 20% increase in power coefficient by using the cap, without significant change in the noise signal.

scholarly journals The study of the numerical diffusion in computational calculation

2020 ◽  
Vol 310 ◽  
pp. 00039
Author(s):  
Kamila Kotrasova ◽  
Vladimira Michalcova
Keyword(s):  
Heat Transfer ◽  
Differential Equation ◽  
Numerical Simulation ◽  
Continuity Equation ◽  
Cfd Simulation ◽  
Flow Process ◽  
Ansys Fluent ◽  
Numerical Diffusion ◽  
Mesh Density ◽  
Computational Calculation

The numerical simulation of flow process and heat transfer phenomena demands the solution of continuous differential equation and energy-conservation equations coupled with the continuity equation. The choosing of computation parameters in numerical simulation of computation domain have influence on accuracy of obtained results. The choose parameters, as mesh density, mesh type and computation procedures, for the numerical diffusion of computation domain were analysed and compared. The CFD simulation in ANSYS – Fluent was used for numerical simulation of 3D stational temperature flow of the computation domain.

A Preliminary Study of the Blade Erosion for a Wind Turbine Operating in a Dusty Environment

2016 ◽  
Author(s):  
Ahmed Hossam El-Din ◽  
Aya Diab
Keyword(s):  
Leading Edge ◽  
Particle Collision ◽  
Turbine Engines ◽  
Surface Erosion ◽  
Coal Slurry ◽  
Predictive Tool ◽  
Ansys Fluent ◽  
Flow Parameters ◽  
Discrete Phase Modeling ◽  
Discrete Phase

The process of surface erosion due to particle collision has been the focus of a number of investigations with regards to gas turbine engines, aircraft, reentry missiles, pipelines carrying coal slurry, etc. Recently, increased interest in wind energy by countries in the Saharan regions of the Middle East and North Africa (MENA) brings about some concern about leading edge erosion of wind turbines operating under such dusty conditions. Leading edge erosion can have a detrimental impact on the extracted energy as it changes the blade surface roughness causing premature/unpredictable separation. Though erosion may not be easily avoided; it may be mitigated via using airfoil families characterized by low roughness sensitivity. In this paper, a model of an airfoil erosion subjected to sand blasting is developed using the discrete phase modeling capability in ANSYS-FLUENT along with the DNV erosion model. The effect of various flow parameters, such as angle of attack, and particle size, on the extent of erosion is investigated for a number of airfoil designs. The developed model is used as a predictive tool to assess the power deterioration of eroded wind blades.

scholarly journals Effect of Pitch Parameters on Aerodynamic Forces of a Straight-Bladed Vertical Axis Wind Turbine with Inclined Pitch Axes

2021 ◽  
Vol 11 (3) ◽  
pp. 1033
Author(s):  
Jia Guo ◽  
Timing Qu ◽  
Liping Lei
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Incline Angle ◽  
Asymmetric Distribution ◽  
Vertical Axis Wind Turbine ◽  
Power Performance ◽  
Aerodynamic Forces ◽  
Ansys Fluent ◽  
Pitch Regulation

Pitch regulation plays a significant role in improving power performance and achieving output control in wind turbines. The present study focuses on a novel, pitch-regulated vertical axis wind turbine (VAWT) with inclined pitch axes. The effect of two pitch parameters (the fold angle and the incline angle) on the instantaneous aerodynamic forces and overall performance of a straight-bladed VAWT under a tip-speed ratio of 4 is investigated using an actuator line model, achieved in ANSYS Fluent software and validated by previous experimental results. The results demonstrate that the fold angle has an apparent influence on the angles of attack and forces of the blades, as well as the power output of the wind turbine. It is helpful to further study the dynamic pitch regulation and adaptable passive pitch regulation of VAWTs. Incline angles away from 90° lead to the asymmetric distribution of aerodynamic forces along the blade span, which results in an expected reduction of loads on the main shaft and the tower of VAWTs.

Numerical Study on Control of Sunroof Buffeting

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
K. Vijaykumar ◽  
S. Poonkodi ◽  
A.T. Sriram
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Dominant Frequency ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Flow Modification ◽  
Numerical Result ◽  
Modification Technique ◽  
Commercial Solver

Sunroof has become one of the essential features of a luxury car, and it provides natural air circulation and good illumination into the car. But the primary problem associated with it is the buffeting noise which causes discomfort to the passengers. Though adequate studies were carried out on sunroof buffeting, efficient control techniques are needed to be developed from fundamental mechanism. To reduce the buffeting noise, flow modifications at the entrance of the sunroof is considered in this study. The internal portion of the car with sunroof is simplified into a shear driven open cavity, and two-dimensional numerical simulations are carried out using commercial solver, ANSYS Fluent. Reynolds averaged Navier-Stokes equation is used with the realizable k-? turbulence model. The unsteady numerical result obtained in this study is validated with the available experimental results for the dominant frequency. The prediction is good agreement with experiment. Flow modification technique is proposed to control the sunroof buffeting by implementing geometric modifications. A hump has been placed near the leading edge of the cavity which resulted in significant reduction of pressure oscillations. Parametric studies have been performed by varying the height of hump and the distance of hump from the leading edge. There is no prominent difference when the height of the hump is varied. As the distance of the hump from the leading edge is reduced, the sound pressure level decreases.

Geometric Modeling of a Propeller Turbine Runner Using ANSYS BladeGen, Meshing Using ANSYS TurboGrid and Fluid Dynamic Simulation Using ANSYS Fluent

2016 ◽  
Vol 842 ◽  
pp. 164-177 ◽  
Author(s):  
Indra Djodikusumo ◽  
I. Nengah Diasta ◽  
Iwan Sanjaya Awaluddin
Keyword(s):  
Geometric Modeling ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Thickness Distribution ◽  
Ansys Fluent ◽  
Implementation Phase ◽  
Runner Blade ◽  
Modeling Process ◽  
Turbine Runner ◽  
Preparation Phase

This paper aims to demonstrate how to model, mesh and simulate a hydraulic propeller turbine runner based on the geometrical specification of the runner blade. Modeling process is divided into preparation and implementation phase. Preparation phase illustrates how to develop stream surfaces and passages, how to create and transform meanline and how to create an rtzt file. The profile in rtzt file has a certain fix thickness which has to be altered later. Implementation phase describes operations necessary in creating a propeller runner model in ANSYS BladeGen which consist of importing rtzt file, modifying the trailing edge properties and altering profile thickness distribution to that of 4 digits NACA airfoil standard. Grid is generated in ANSYS TurboGrid utilizing ATM Optimized topology. CFD simulation is done using the ANSYS Fluent with pressure inlet and pressure outlet boundary conditions and k-ε turbulence model. Hydraulic efficiency of the runner is calculated utilizing Turbo Topology module in ANSYS Fluent. The authors will share the advantages that may be obtained by using ANSYS BladeGen compared with the use of general CAD Systems.

Performance Modeling of Ducted Vertical Axis Turbine Using Computational Fluid Dynamics

2013 ◽  
Vol 47 (4) ◽  
pp. 36-44 ◽  
Author(s):  
Prasun Chatterjee ◽  
Raymond N. Laoulache
Keyword(s):  
Performance Modeling ◽  
Flow Direction ◽  
Computational Cost ◽  
Vertical Axis ◽  
Area Ratio ◽  
Diameter Ratio ◽  
Turbulent Model ◽  
Ansys Fluent ◽  
Second Order In Time ◽  
Vertical Axis Turbine

AbstractVertical axis turbines (VATs) excel over horizontal axis turbines in their independent flow direction. VATs that operate in an enclosure, e.g., a diffuser shroud, are reported to generate more power than unducted VATs. A diffuser-shrouded, high solidity of 36.67%, three-blade VAT with NACA 633-018 airfoil section is modeled in 2-D using the commercial software ANSYS-FLUENT®. Incompressible, unsteady, segregated, implicit, and second order in time and space solver is implemented in association with the Spalart-Allmaras turbulent model with a reasonable computational cost. The computational results are assessed against experimental data for unducted VAT at low tip speed ratios between 1 and 2 for further numerical analysis on diffuser models. Different diffuser designs are investigated using suitable nozzle size, area ratio, length-to-diameter ratio and angles between the diffuser inner surfaces. The numerical model shows that, for a specific diffuser design, the ducted VAT performance coefficient can be augmented by almost 90% over its unducted counterpart.

Performance on an Adaptive Automated Team Tracking Task with Human and Computer Teammates

1997 ◽  
Vol 41 (1) ◽  
pp. 551-555 ◽  
Author(s):  
Kristin Krahl ◽  
Mark W. Scerbo
Keyword(s):  
Adaptive Systems ◽  
High Performance ◽  
Vertical Axis ◽  
Tracking Task ◽  
Superior Performance ◽  
Performance Skills ◽  
Group Assignment ◽  
Pursuit Tracking ◽  
Human Participants ◽  
High Level

The present study examined team performance on an adaptive pursuit tracking task with human-human and human-computer teams. The participants were randomly assigned to one of three team conditions where their partner was either a computer novice, computer expert, or human. Participants began the experiment with control over either the horizontal or vertical axis, but had the option of taking control of their teammate's axis if they achieved superior performance on the previous trial. A control condition was also run where a single participant controlled both axes. Performance was assessed by RMSE scores over 100 trials. The results showed that performance along the horizontal axis improved over the session regardless of the experimental condition, but the degree of improvement was dependent upon group assignment. Individuals working alone or paired with an expert computer maintained a high level of performance throughout the experiment. Those paired with a computer-novice or another human performed poorly initially, but eventually reached the level of those in the other conditions. The results showed that team training can be as effective as individual training, but that the quality of training is moderated by the skill level of one's teammate. Moreover, these findings suggest that task partitioning of high performance skills between a human and a computer is not only possible but may be considered a viable option in the design of adaptive systems.

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