Numerical Investigation of an Experimental Ocean Current Turbine Based on Blade Element Momentum Theory (BEM)

2021 ◽  
Author(s):  
S. Sadeqi ◽  
S. Rouhi ◽  
N. Xiros ◽  
E. Aktosun ◽  
J. VanZwieten ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Ocean Currents ◽  
Ocean Current ◽  
Test Model ◽  
Small Current ◽  
Power Estimate ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Current Turbine ◽  
Blade Element

Abstract Ocean currents are one of the alternative sources of green, sustainable, and renewable energy that could generate low-cost electric power without any pollution due to the burning of fossil fuels. Due to the density of the water, ocean currents can produce a significant amount of energy even with a very small current velocity field. In this study, a comprehensive performance analysis of 3-blade horizontal-axis Ocean Current Turbine (OCT) is shown to achieve optimal rpm (revolutions per minute) to match environmental conditions in order to harvest the maximum possible energy from OCT in ocean currents. Our approach is to use Blade Element Momentum (BEM) theory in order to estimate hydrodynamic loads for the turbine; specifically, the design of the OCT blades is based on a FX77-W121 type airfoil. We use JavaFoil to analyze and determine hydrodynamic lift and drag coefficients with respect different angles of attack for the hydrofoil profiles in seawater. After validation of blade design characteristics and obtaining the local coefficients of each hydrofoil cross-sections, we transfer them to our in-house-developed Blade Element Momentum Theory (BEM) code in order to achieve the estimation of performance analysis of the OCT in order to get maximum power and ideal torque and thrust. This performance analysis with BEM model of the OCT is an important step for further analysis due to having different incoming flow speeds in actual time-varying sea conditions. Indeed, the OCT will encounter different incoming ocean current speeds during operation. Therefore, this approach is used to get an accurate brake power estimate of the OCT in different operational current speeds. In addition, this performance analysis of the OCT is going to be utilized in designing and developing a test model for the physical towing tank experiment for later investigation.

Wind Tunnel Tests of a Model Small-scale Horizontal-axis Wind Turbine Developed from Blade Element Momentum Theory

2021 ◽  
pp. 1-16
Author(s):  
Ojing Siram ◽  
Niranjan Sahoo ◽  
Ujjwal K. Saha
Keyword(s):  
Wind Tunnel ◽  
Horizontal Axis ◽  
Superior Performance ◽  
Speed Ratio ◽  
Small Scale ◽  
Blade Design ◽  
Horizontal Axis Wind Turbine ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Blade Element

Abstract The small-scale horizontal-axis wind turbines (SHAWTs) have emerged as the promising alternative energy resource for the off-grid electrical power generation. These turbines primarily operate at low Reynolds number, low wind speed, and low tip speed ratio conditions. Under such circumstances, the airfoil selection and blade design of a SHAWT becomes a challenging task. The present work puts forward the necessary steps starting from the aerofoil selection to the blade design and analysis by means of blade element momentum theory (BEMT) for the development of four model rotors composed of E216, SG6043, NACA63415, and NACA0012 airfoils. This analysis shows the superior performance of the model rotor with E216 airfoil in comparison to other three models. However, the subsequent wind tunnel study with the E216 model, a marginal drop in its performance due to mechanical losses has been observed.

scholarly journals Aerodynamic analysis of multirotor vehicles using a higher-order potential flow method

2021 ◽  
Author(s):  
Devin F. Barcelos
Keyword(s):  
Performance Prediction ◽  
Potential Flow ◽  
Higher Order ◽  
Theory Approach ◽  
Blade Element Momentum Theory ◽  
Flow Method ◽  
Momentum Theory ◽  
Radial Loading ◽  
Rotational Direction ◽  
Blade Element

A higher-order potential flow method is adapted for the aerodynamic performance prediction of small rotors used in multirotor unmanned aerial vehicles. The method uses elements of distributed vorticity which results in numerical robustness with both a prescribed and relaxed wake representation. The radial loading and wake shapes of a rotor in hover were compared to experiment to show strong agreement for three disk loadings. The advancing flight performance prediction of a single rotor was compared to a single rotor was compared to a blade element momentum theory based approach and to experiment. Comparison showed good thrust and power agreement with experiment across a range of advance ratios and angles of attack. Prediction in descending flights showed improvements in comparison to the blade element momentum theory approach. The model was extended to a quadrotorm configuration showing the differences associated to vehicle orientation and rotor rotational direction.

scholarly journals A Study in Aerodynamic Optimization of UAV Helicopter Rotor- Blades Planform in Vertical Motion

AVIA ◽  
2021 ◽  
Vol 2 (1) ◽  
Author(s):  
M F Afthon ◽  
M A Moelyadi
Keyword(s):  
Cfd Simulation ◽  
Twist Angle ◽  
Vertical Motion ◽  
Vertical Movement ◽  
Rotor Blades ◽  
Aerodynamic Optimization ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Design Variables ◽  
Blade Element

According to the objectivity of UAV helicopter, endurance is a valuable performance. To increase the endurance, we need to decrease the helicopter required power. Within the research scope in vertical movement only, 5 parameters of blades planform design were considered as design variables. They are root chord of the blades, taper location, taper ratio, pitch angle, and tip twist angle. Optimization was done using own developed genetic algorithm codes with built-in blade element momentum theory (BEMT) as a performance calculator. It was chosen due to its ability to estimate rotor performance quickly. Several CFD simulation were done to reduce the error of blade element momentum theory calculation. Using constant adjustment methods, BEMT can predict thrust and power with a difference with respect to CFD of 3.8% and 8.2% respectively. The optimization result gives the optimum blades design with improving almost 11% in efficiency which came out from 9.4% reduction in power required which is good for helicopter performance.

Iterative Blade Element Momentum Theory for Predicting Coaxial Rotor Performance in Hover

2020 ◽  
Vol 65 (4) ◽  
pp. 1-12
Author(s):  
Seongkyu Lee ◽  
Maxime Dassonville
Keyword(s):  
Figure Of Merit ◽  
Measurement Data ◽  
Separation Distance ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Coaxial Rotor ◽  
Aerodynamic Properties ◽  
Induced Velocity ◽  
Empirical Constants ◽  
Blade Element

This paper presents a new blade element momentum theory (BEMT) for a coaxial rotor in hover. The new BEMT iteratively solves the upper and lower rotor induced velocities to account for the mutual rotor-to-rotor interaction. The upper rotor induced velocity is affected by the lower rotor thrust and induced velocity, whereas the lower rotor induced velocity is affected by the upper rotor thrust and induced velocity. Two empirical constants are included in each rotor calculation. This new BEMT provides the performance of each rotor as a function of the rotor separation distance. The new BEMT is validated with measurement data for two coaxial rotor experiments. The first experiment validates the thrust to power coefficients at a given separation distance. The second experiment validates each rotor's figure of merit, thrust, power, interference loss factors, etc. as a function of the rotor separation distance. It is shown that the BEMT captures the trends and magnitudes of the performance as a function of the rotor separation distance compared to the measurement data. Detailed radial distributions of aerodynamic properties are also presented at several separation distances.

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