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

Author(s):  
James L. Tangler

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.

2021 ◽  
Author(s):  
Devin F. Barcelos

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.


2021 ◽  
Author(s):  
Timothy B. Carroll

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.


2021 ◽  
Author(s):  
Devin F. Barcelos

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.


2021 ◽  
Author(s):  
Timothy B. Carroll

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.


2016 ◽  
Vol 1 (5) ◽  
pp. 4-12
Author(s):  
David P. Kuehn

This report highlights some of the major developments in the area of speech anatomy and physiology drawing from the author's own research experience during his years at the University of Iowa and the University of Illinois. He has benefited greatly from mentors including Professors James Curtis, Kenneth Moll, and Hughlett Morris at the University of Iowa and Professor Paul Lauterbur at the University of Illinois. Many colleagues have contributed to the author's work, especially Professors Jerald Moon at the University of Iowa, Bradley Sutton at the University of Illinois, Jamie Perry at East Carolina University, and Youkyung Bae at the Ohio State University. The strength of these researchers and their students bodes well for future advances in knowledge in this important area of speech science.


2011 ◽  
Vol 9 (2) ◽  
pp. 99
Author(s):  
Alex J Auseon ◽  
Albert J Kolibash ◽  
◽  

Background:Educating trainees during cardiology fellowship is a process in constant evolution, with program directors regularly adapting to increasing demands and regulations as they strive to prepare graduates for practice in today’s healthcare environment.Methods and Results:In a 10-year follow-up to a previous manuscript regarding fellowship education, we reviewed the literature regarding the most topical issues facing training programs in 2010, describing our approach at The Ohio State University.Conclusion:In the midst of challenges posed by the increasing complexity of training requirements and documentation, work hour restrictions, and the new definitions of quality and safety, we propose methods of curricula revision and collaboration that may serve as an example to other medical centers.


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