A design methodology for rotors of small multirotor vehicles

A model is presented for the aerodynamic performance prediction of fixed-pitch rotors for small unmanned aerial vehicles. The method uses a blade element momentum theory based approach that is formulated specifically for small rotors operating in hover and edgewise flight. In order to validate the model, a rotor test stand is used to measure the performance of a commercially available rotor for several inflow angles and advance ratios. The predictions agree with measurements for operating conditions excluding conditions with suspected vortex ring state. The model is incorporated into a numerical optimization scheme to demonstrate its potential as a design tool. Designs are presented that minimize the power loading for single- and multi-point operating conditions. The optimized designs have hyperbolic twist distributions, higher solidities, and operate at lower tip-speeds than existing designs. A potential flow based model is also presented to predict the wake interactions between multiple rotors in configuration.

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

10.32920/ryerson.14654919 ◽

2021 ◽

Author(s):

Devin F. Barcelos

Keyword(s):

Performance Prediction ◽

Potential Flow ◽

Higher Order ◽

Theory Approach ◽

Flow Method ◽

Momentum Theory ◽

Radial Loading ◽

Rotational Direction ◽

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.

Geometrical Design of a Rotor Blade for a Small Scale Horizontal Axis Wind Turbine

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.c5036.098319 ◽

2019 ◽

Vol 8 (3) ◽

pp. 3390-3400

Keyword(s):

Wind Turbine ◽

Rotor Blade ◽

Operating Conditions ◽

Horizontal Axis ◽

Small Scale ◽

Horizontal Axis Wind Turbine ◽

Geometrical Properties ◽

Momentum Theory ◽

Bem Theory ◽

In the present study, Blade Element Momentum theory (BEMT) has been implemented to heuristically design a rotor blade for a 2kW Fixed Pitch Fixed Speed (FPFS) Small Scale Horizontal Axis Wind Turbine (SSHAWT). Critical geometrical properties viz. Sectional Chord ci and Twist distribution θTi for the idealized, optimized and linearized blades are analytically determined for various operating conditions. Results obtained from BEM theory demonstrate that the average sectional chord ci and twist distribution θTi of the idealized blade are 20.42% and 14.08% more in comparison with optimized blade. Additionally, the employment of linearization technique further reduced the sectional chord ci and twist distribution θTi of the idealized blade by 17.9% and 14% respectively, thus achieving a viable blade bounded by the limits of economic and manufacturing constraints. Finally, the study also reveals that the iteratively reducing blade geometry has an influential effect on the solidity of the blade that in turn affects the performance of the wind turbine.

The Nebulous Art of Using Wind-Tunnel Airfoil Data for Predicting Rotor Performance

ASME 2002 Wind Energy Symposium ◽

10.1115/wind2002-40 ◽

2002 ◽

Cited By ~ 8

Author(s):

James L. Tangler

Keyword(s):

Performance Prediction ◽

Ohio State University ◽

Prediction Methods ◽

Data Sets ◽

State University ◽

Colorado State University ◽

Momentum Theory ◽

Lifting Surface ◽

University Of Technology ◽

The objective of this study was threefold: to evaluate different two-dimensional S809 airfoil data sets in the prediction of rotor performance; to compare blade-element momentum rotor predicted results to lifting-surface, prescribed-wake results; and to compare the NASA Ames combined experiment rotor measured data with the two different performance prediction methods. The S809 airfoil data sets evaluated included those from Delft University of Technology, Ohio State University, and Colorado State University. The performance prediction comparison with NASA Ames data documents shortcomings of these performance prediction methods and recommends the use of the lifting-surface, prescribed-wake method over blade-element momentum theory for future analytical improvements.

Tidal Turbine Blades: Design and Dynamic Loads Estimation Using CFD and Blade Element Momentum Theory

Volume 5: Ocean Space Utilization; Ocean Renewable Energy ◽

10.1115/omae2011-49740 ◽

2011 ◽

Cited By ~ 2

Author(s):

Ce´line Faudot ◽

Ole G. Dahlhaug

Keyword(s):

Wind Turbines ◽

Operating Conditions ◽

Dynamic Loads ◽

Power Coefficient ◽

Scaled Model ◽

Momentum Theory ◽

Stage Of Development ◽

Tidal Turbine ◽

The interest in tidal power is constantly increasing thanks to its high predictability, the huge potential of tides and the actual need for renewable energy. It explains the emergence of many tidal turbine designs, especially in Europe, often inspired from wind turbines. All of them are at a more or less early stage of development. But because of the high density of water, environmental drag forces are very large compared with wind turbines of the same capacity. Therefore the knowledge acquired by the wind industry is certainly qualitatively useful, but it has to be reconsidered to be applicable to tidal turbines. The aim of the project presented in this paper is to create a 1 MW reference tidal turbine, whose small-scaled model has been tested in the towing tank of Marintek laboratory (Trondheim, Norway). The tests focused on dynamic loads, which are an important reason of failure, and thus will help tidal turbine designers in their work by gaining valuable experience in turbine performance in various operating conditions. The chosen turbine has a horizontal axis and two blades, which have been designed using the blade element momentum theory for a diameter of 20m. This paper states the project issues and the method used to design the blades, from the hydrodynamic properties of the hydrofoils to the computational fluid dynamic analysis. The tests on the small scaled model makes it possible to validate the concept and a comparison between efficiencies obtained analytically, experimentally and with CFD computation has been performed in this paper. The maximum power coefficient experimentally obtained is 0.427, i.e. 1.4% higher than the power coefficient obtained numerically. The blade element momentum theory is then used to estimate the loads on each blade when the rotor is subjected to regular waves of many heights and periods, with the intention of ranking the parameters of importance and introducing a fatigue analysis.

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

10.32920/ryerson.14654919.v1 ◽

2021 ◽

Author(s):

Devin F. Barcelos

Keyword(s):

Performance Prediction ◽

Potential Flow ◽

Higher Order ◽

Theory Approach ◽

Flow Method ◽

Momentum Theory ◽

Radial Loading ◽

Rotational Direction ◽

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.

Dynamic inflow model for a Floating Horizontal Axis Wind Turbine in surge motion

10.5194/wes-2021-34 ◽

2021 ◽

Author(s):

Carlos Ferreira ◽

Wei Yu ◽

Arianna Salla ◽

Axelle Vire

Keyword(s):

Vortex Ring ◽

Turbulent Wake ◽

Rotor Wake ◽

Momentum Theory ◽

Wake Interaction ◽

Actuator Disc ◽

Vortex Ring State ◽

Wake State ◽

Abstract. Floating Offshore Wind Turbines may experience large surge motions which, when faster than the local wind speed, cause rotor-wake interaction. Previous research hypothesised that this phenomena can result in a turbulent wake state or even a vortex ring state, invalidating the Actuator Disc Momentum Theory and the use of the Blade Element Momentum Theory. We challenge this hypothesis and demonstrate that the Actuator Disc Momentum Theory is valid and accurate in predicting the induction at the actuator in surge, even for large and fast motions. To achieve this, we derive a dynamic inflow model which mimics the vorticity-velocity system and the effect of the motion. The predictions of the model are compared against results from other authors and from a semi-free wake vortex-ring model. The results show that the surge motion and rotor-wake interaction do not cause a turbulent wake state or vortex ring state, and that the application of Actuator Disc Momentum Theory and Blade Element Momentum Theory is valid and accurate, when correctly applied in an inertial reference frame. The results show excellent agreement in all cases. The proposed dynamic inflow model includes an adaptation for highly loaded flow and it is accurate and simple enough to be easily implemented in most Blade Element Momentum models.

Volume 2: Thermal Management; Data Centers and Energy Efficient Electronic Systems ◽

Prediction of Hot Aisle Partition Airflow Boundary Conditions

10.1115/ipack2013-73049 ◽

2013 ◽

Author(s):

Zhihang Song ◽

Bruce T. Murray ◽

Bahgat Sammakia

Keyword(s):

Boundary Conditions ◽

Data Center ◽

Computation Time ◽

Design Tool ◽

Operating Conditions ◽

Ann Model ◽

Flow Rates ◽

Level Model ◽

Optimization Methodology ◽

Artificial Neural Network Ann

The integration of a simulation-based Artificial Neural Network (ANN) with a Genetic Algorithm (GA) has been explored as a real-time design tool for data center thermal management. The computation time for the ANN-GA approach is significantly smaller compared to a fully CFD-based optimization methodology for predicting data center operating conditions. However, difficulties remain when applying the ANN model for predicting operating conditions for configurations outside of the geometry used for the training set. One potential remedy is to partition the room layout into a finite number of characteristic zones, for which the ANN-GA model readily applies. Here, a multiple hot aisle/cold aisle data center configuration was analyzed using the commercial software FloTHERM. The CFD results are used to characterize the flow rates at the inter-zonal partitions. Based on specific reduced subsets of desired treatment quantities from the CFD results, such as CRAC and server rack air flow rates, the approach was applied for two different CRAC configurations and various levels of CRAC and server rack flow rates. Utilizing the compact inter-zonal boundary conditions, good agreement for the airflow and temperature distributions is achieved between predictions from the CFD computations for the entire room configuration and the reduced order zone-level model for different operating conditions and room layouts.

Analysis of Aerodynamic Loads on Wind Turbine Blades Based on Blade Element Momentum Theory and Machine Learning

10.1109/auteee52864.2021.9668745 ◽

2021 ◽

Author(s):

Yuhang Guo

Keyword(s):

Machine Learning ◽

Wind Turbine ◽

Turbine Blades ◽

Wind Turbine Blades ◽

Aerodynamic Loads ◽

Momentum Theory ◽

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

Journal of Energy Resources Technology ◽

10.1115/1.4052774 ◽

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 ◽

Momentum Theory ◽

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.