Programa de Cómputo para Estimar el Rendimiento de una Hélice Empleando una Corrección por Número de Mach a la Teoría Combinada

2021 ◽  
Vol 2 (5) ◽  
pp. 6739-6753
Author(s):  
Tiburcio Fernández Roque ◽  
Braulio Vera García ◽  
José Arturo Correa Arredondo ◽  
Jorge Sandoval Lezama ◽  
Alejandro Mejía Carmona
Keyword(s):  
Mach Number ◽  
Experimental Results ◽  
Aerodynamic Coefficients ◽  
Aerodynamic Coefficient ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Empirical Correction ◽  
Para Determinar ◽  
Bem Theory ◽  
Blade Element

En este trabajo se propone una corrección empírica por número de Mach a la teoría combinada para hélices y se describe el programa de cómputo desarrollado para determinar el comportamiento de la misma. El programa requiere como datos de entrada la geometría de la hélice y los coeficientes aerodinámicos en función del número de Mach de los perfiles de la pala de la hélice. Éste calcula los coeficientes aerodinámicos y las velocidades inducidas de cada elemento de pala empleando la teoría combinada, corrige los coeficientes aerodinámicos por efecto de compresibilidad y calcula la eficiencia, así como los coeficientes de tracción y de potencia de la hélice para diferentes velocidades de avance y, finalmente, los presenta en forma gráfica. Se observa que los resultados obtenidos con la teoría combinada corregida por número de Mach fueron satisfactorios ya que se aproximan más a los resultados experimentales que la teoría combinada simple.   This work proposes an empirical correction by Mach number to the BEM (Blade-Element Momentum) Theory for propellers and describes the software developed to determine the behavior of it. The input for the software is the geometry of the propeller and the aerodynamic coefficient in function of the Mach number for the airfoils used for the propeller chosen. The software calculates the aerodynamic coefficients and the induced velocities at each station of the blade of the propeller using the BEM theory, then corrects these coefficients by the effect of compressibility and calculates the efficiency, the traction and power coefficients for a range of forward velocities, and finally presents a graph with the results obtained. We can observe that the results obtain are satisfactory comparing with the experimental results and obtaining lower difference error by this method than with the simple BEM theory.

Vertical Autorotation of a Single-Winged Samara

1991 ◽  
Vol 58 (4) ◽  
pp. 1064-1071 ◽  
Author(s):  
A. Rosen ◽  
D. Seter
Keyword(s):  
Theoretical Model ◽  
Experimental Results ◽  
Experimental Setup ◽  
Dynamic Effects ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Mode Of Operation ◽  
Rotary Wings ◽  
Rotary Wing ◽  
Blade Element

A derivation of a theoretical model for the vertical autorotation of a samara wing is presented. The dynamic effects are treated in an accurate manner. The aerodynamic effects are calculated by using the blade element/momentum theory. Because of basic differences between the mode of operation of a samara wing and other rotary wings, the model differs from existing rotary wing models. An experimental setup, aimed at verifying the theoretical model, is also described. Comparison between theoretical and experimental results are presented.

A New Multi-Objective Evolutionary Algorithm for Optimizing the Aerodynamic Design of HAWT Rotor

2014 ◽  
Author(s):  
Ekhlas M. Alfayyadh ◽  
Sadeq H. Bakhy ◽  
Yasir M. Shkara
Keyword(s):  
Genetic Algorithm ◽  
Aerodynamic Performance ◽  
Power Coefficient ◽  
Aerodynamic Design ◽  
Thrust Coefficient ◽  
Blade Element Momentum Theory ◽  
Multi Objective ◽  
Momentum Theory ◽  
Bem Theory ◽  
Blade Element

This paper presents a new multi-objective evolutionary algorithm (MOEA) for optimum aerodynamic design of horizontal-axis wind turbines (HAWT). The design problem is set to find the blade shape such that optimizing multi-objective at different airfoil profiles. Combined Blade Element Momentum (BEM) theory and two different algorithms (Genetic (GA) and Enumeration) are used. Flow around subsonic airfoils is analyzed using XFOIL software. WINDMEL III wind turbine is selected to improve its aerodynamic performance with different airfoil profiles technique of National Renewable Energy Laboratory (NREL) family. Employing Genetic Algorithm embodied in Blade Element Momentum theory to calculate power, thrust and starting torque coefficients that are the fitness function. Another method, Enumeration method, is used to enhance evolutionary method results. The optimum solution acquired from combination of Genetic Algorithm and Blade Element Momentum theory of three blades configuration increased power coefficient by (25.8 %) and thrust coefficient by (16.6%). Enumeration method results increased power coefficient by (13.8%), while thrust coefficient decreased by (0.2%) from the original design. In general, the evolutionary method of combined GA and BEM theory with different airfoil profiles technique improved the turbine aerodynamic performance, and the results are in good agreement with other published papers.

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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