Experimental and Computational Studies to Understand the Role of Flow Curvature Effects on the Aerodynamic Performance of a MAV-Scale Cycloidal Rotor in Forward Flight

Author(s):  
Moble Benedict ◽  
Tejaswi Jarugumilli ◽  
Vinod Lakshminarayan ◽  
Inderjit Chopra
2020 ◽  
Vol 10 (2) ◽  
pp. 168-176
Author(s):  
Krishnasamy Gopinath ◽  
Nagarajan Subbiah ◽  
Muthusamy Karthikeyan

Background: Syzygium densiflorum Wall. ex Wight & Arn (Myrtaceae) has been traditionally used by the local tribes of the Nilgiris, Tamil Nadu, India, for the treatment of diabetes. Objective: This study aimed to isolate the major phytoconstituents from the S. densiflorum fruits and to perform computational studies for chemical reactivity and biological activity of the isolated compound. Materials and Methods: Two different compounds were isolated from ethanolic extract of S. densiflorum fruits and purified using HPLC. The structures of the compounds were elucidated on the basis of their 1H NMR, 13C NMR, 1H-1H COSY, HMBC, HRESIMS, and FT-IR data. Further, the chemical reactivity of the compounds was analyzed by density functional theory calculations and its therapeutic role in diabetic management was examined by comparing the structure of isolated compounds with previously reported bioactive compounds. Results: Of the two compounds ((6,6 & 1-kestopentaose (1) and 6-(hydroxymethyl)-3-[3,4,5- trihydroxy- 6-[(3,4,5-trihydroxyoxan-2-yl)oxymethyl]oxan-2-yl]oxyoxane-2,4,5-triol)(2)). β-glucosidase, β-galactosidase, α-glucosidase and β-amylase inhibition activity of the compounds were predicted by structure activity relationship. Conclusion: Structure-activity relationship analysis was performed to predict the therapeutic role of isolated compounds. These computational studies may be performed to minimize the efforts to determine the therapeutic role of natural compounds.


Author(s):  
Alessandro Bianchini ◽  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari

The assessment of robust CFD techniques is casting new light on the aerodynamics of airfoils rotating around an axis orthogonal to flow direction, with particular reference to flow curvature effects and stall mechanisms. In particular, Darrieus wind turbines’ designers are taking profit from these new discovers to improve the aerodynamic design of the rotors, in view of an increase of the overall efficiency and a reduction of the structural stresses on the blades. A controversial design parameter for Darrieus turbines, especially in case of small-size rotors, is represented by the location of the blade-spoke connection along the chord. The most common solution is indeed to place the connection at approximately airfoil’s quarter chord, i.e. where the pressure center is commonly located for low incidence angles. In some cases, however, the blade is connected at middle chord due to symmetry or aesthetic reasons. In some small turbines, innovative designs have even disregarded this parameter. Even if one can argue that the blade connection point is about to have some aerodynamic effects on the turbine’s performance, the real impact of this important design parameter is often not fully understood. The present study makes use of extensive CFD simulations on a literature case study, using a NACA 0021 airfoil, to assess the influence of the blade-spoke connection point. In particular, the differences in terms of power coefficient curve of the turbine, optimal tip-speed ratio, torque profiles and stresses on the connection are analyzed and discussed. Detailed flow analyses are also shown for azimuthal positions of particular interest. Results on the selected case study showed that the middle-chord blade-spoke connection point seems to guarantee a higher performance of the rotor, even if additional solicitation is applied to the connection itself. It is further shown that the same performance can indeed be obtained with the airfoil attached at quarter chord and properly pitched. By doing so, the stresses are contained and the performance is maximized.


2018 ◽  
Vol 117 ◽  
pp. 279-289 ◽  
Author(s):  
Hyo-Jung Lee ◽  
Hong-Goo Lee ◽  
Yong-Bin Kwon ◽  
Ju-Young Kim ◽  
Yun-Seok Rhee ◽  
...  

Author(s):  
Francesco Balduzzi ◽  
Alessandro Bianchini ◽  
Riccardo Maleci ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari

Darrieus wind turbines are experiencing a renewed interest in the wind energy scenario, in particular whenever small and medium-size installations are considered. In these contexts, the average wind speeds are generally quite low due to scale effects and therefore the most exploited design choices for the turbines are the H-shape configuration, as the entire blade can take advantage of the maximum rotational radius, and high chord to radius ratios, in order to ensure suitable Reynolds numbers on the airfoils. By doing so, the aerodynamic effects induced by the motion of the airfoils in a curved flowpath become more evident and the airfoils themselves have to be designed to compensate these phenomena if conventional design tools based on the BEM theory are used. In this study, fully unsteady 2D simulations were exploited to analyze a three-bladed H-Darrieus wind turbine in order to define the real flow structure and its effects on the turbine performance; in detail, the influence of both the virtual camber and the virtual incidence were investigated. CFD results were supported by experimental data collected on full-scale models reproducing two different airfoil mountings. Finally, the proper design criteria to compensate these phenomena are proposed and their benefits on a conventional simulation with a BEM approach are discussed.


2018 ◽  
Vol 8 (14) ◽  
pp. 3638-3648 ◽  
Author(s):  
Oscar F. González-Belman ◽  
J. Oscar C. Jiménez-Halla ◽  
Fady Nahra ◽  
Catherine S. J. Cazin ◽  
Albert Poater

Computational studies on homo- and heterobimetallic group 11 metal-NHC complexes were carried out, providing insights into the catalysed-hydrophenoxylation of alkynes.


2019 ◽  
Vol 880 ◽  
pp. 723-742 ◽  
Author(s):  
Luke R. Smith ◽  
Yong Su Jung ◽  
James D. Baeder ◽  
Anya R. Jones

The physics of a rotary wing in forward flight are highly complex, particularly when flow separation is involved. The purpose of this work is to assess the role of three-dimensional (3-D) vortex dynamics, with a focus on Coriolis forces, in the evolution of vortices in the reverse flow region of a rotating wing. High-fidelity numerical simulations were performed to recreate the flow about a representative rotating wing in forward flight. A vorticity transport analysis was performed to quantify and compare the magnitudes of 2-D flow physics, vortex tilting and Coriolis effects in the resulting flow fields. Three-dimensional vortex dynamics was found to have a very small impact on the growth and behaviour of vortices in the reverse flow region; in fact, the rate of vortex growth was successfully modelled using a simple 2-D vortex method. The small role of 3-D physics was attributed to the Coriolis and vortex tilting terms being approximately equal and opposite to one another. This ultimately lead to vortex behaviour that more closely resembled a surging wing as opposed to a conventional rotating wing, a feature unique to the reverse flow region.


Sign in / Sign up

Export Citation Format

Share Document