Enhancing the Aerodynamic Performance of Stepped Airfoils

Enhancing the Aerodynamic Performance of Stepped Airfoils
Author: Ranganadhan Voona
Publisher:
Total Pages: 0
Release: 2012
Genre: Aerofoils
ISBN:
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"The main objective of this research was to investigate the lift and drag characteristics of a stepped airfoil with backward facing steps; apply active flow control technique to enhance the aerodynamic performance of stepped airfoils and examine the possibility of using such airfoils on Unmanned Aerial Vehicles (UAV's). A step was introduced at mid-chord, with a depth of 50% of the airfoil thickness at mid-chord position extending till the trailing edge of a NACA 4415 airfoil. Computational studies were conducted with the use of passive flow control constituting the activation of step and active flow control with the use of air injecting jets placed in the step cavity of the NACA 4415 airfoil with a goal of enhancing the aerodynamic performance. The jet angle and jet momentum coefficient were varied independently to identify the best setting for optimizing the aerodynamic performance of the stepped airfoil. Experimental studies of a scaled wing model with the same airfoil were conducted in a wind tunnel for a range of Reynolds numbers to validate some of the numerical results obtained for the cases of base and stepped airfoils. The results produced show that as much as 37% increase in C1 and as much as 12% increase in L/D ratios over conventional airfoil values could be obtained using stepped airfoils and further enhancement could be made with the employment of jets placed in the step cavities. The case study conducted as a part of this research focuses on the UAV RQ-2 Pioneer employing a stepped airfoil configuration by comparing its aerodynamic characteristics with the conventional NACA 4415 airfoil originally used on this aircraft. The primary objective of the case study was to identify and outline a step schedule for the flight envelope of the UAV Pioneer using a stepped airfoil configuration while applying active flow control to obtain enhanced aerodynamic performance over conventional NACA 4415 airfoil originally used and hence improve the flight performance characteristics like Range and Endurance of the aircraft"--Abstract, leaf iii

Enhancing the Aerodynamic Performance of Stepped Airfoils

Enhancing the Aerodynamic Performance of Stepped Airfoils
Author: Ranganadhan Voona
Publisher:
Total Pages: 0
Release: 2012-10-26
Genre: Aerofoils
ISBN: 9783659266003
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"The main objective of this research was to investigate the lift and drag characteristics of a stepped airfoil with backward facing steps; apply active flow control technique to enhance the aerodynamic performance of stepped airfoils and examine the possibility of using such airfoils on Unmanned Aerial Vehicles (UAV's). A step was introduced at mid-chord, with a depth of 50% of the airfoil thickness at mid-chord position extending till the trailing edge of a NACA 4415 airfoil. Computational studies were conducted with the use of passive flow control constituting the activation of step and active flow control with the use of air injecting jets placed in the step cavity of the NACA 4415 airfoil with a goal of enhancing the aerodynamic performance. The jet angle and jet momentum coefficient were varied independently to identify the best setting for optimizing the aerodynamic performance of the stepped airfoil. Experimental studies of a scaled wing model with the same airfoil were conducted in a wind tunnel for a range of Reynolds numbers to validate some of the numerical results obtained for the cases of base and stepped airfoils. The results produced show that as much as 37% increase in C1 and as much as 12% increase in L/D ratios over conventional airfoil values could be obtained using stepped airfoils and further enhancement could be made with the employment of jets placed in the step cavities. The case study conducted as a part of this research focuses on the UAV RQ-2 Pioneer employing a stepped airfoil configuration by comparing its aerodynamic characteristics with the conventional NACA 4415 airfoil originally used on this aircraft. The primary objective of the case study was to identify and outline a step schedule for the flight envelope of the UAV Pioneer using a stepped airfoil configuration while applying active flow control to obtain enhanced aerodynamic performance over conventional NACA 4415 airfoil originally used and hence improve the flight performance characteristics like Range and Endurance of the aircraft"--Abstract, p. iii

Experimental Investigation of Moving Surfaces for Boundary Layer and Circulation Control of Airfoils and Wings

Experimental Investigation of Moving Surfaces for Boundary Layer and Circulation Control of Airfoils and Wings
Author: Robert Vets
Publisher:
Total Pages: 180
Release: 2015
Genre:
ISBN:
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An experimental study was conducted to assess the application of a moving surface to affect boundary layers and circulation around airfoils for the purpose of altering and enhancing aerodynamic performance of finite wings at moderate Reynolds numbers. The moving surface was established by a wide, lightweight, nylon belt that enveloped a wing's symmetric airfoil profile articulated via a friction drive cylinder such that the direction of the upper surface was in the direction of the free stream. A water tunnel visualization study accompanied wind tunnel testing at the University of Washington, Kirsten Wind Tunnel of finite wings. An experimental study was conducted to assess the application of a moving surface to affect boundary layers and circulation around airfoils for the purpose of altering and enhancing aerodynamic performance of finite wings at moderate Reynolds numbers. The moving surface was established by a wide, lightweight, nylon belt that enveloped a wing's symmetric airfoil profile articulated via a friction drive cylinder such that the direction of the upper surface was in the direction of the free stream. A water tunnel visualization study accompanied wind tunnel testing at the University of Washington, Kirsten Wind Tunnel of finite wings. The defining non-dimensional parameter for the system is the ratio of the surface velocity to the free stream velocity, u/U. Results show a general increase in lift with increasing u/U. The endurance parameter served as an additional metric for the system's performance. Examining the results of the endurance parameter shows general increase in endurance and lift with the moving surface activated. Peak performance in terms of increased endurance along with increased lift occurs at or slightly above u/U = 1. Water tunnel visualization showed a marked difference in the downwash for velocity ratios greater than 1, supporting the measured data. Reynolds numbers for this investigation were 1.9E5 and 4.3E5, relevant to the class of fixed wing, Tier-1, Unmanned Aerial Vehicles (UAV).

Advanced Wind Turbines

Advanced Wind Turbines
Author: Teik-cheng Lim
Publisher: World Scientific
Total Pages: 538
Release: 2023-09-13
Genre: Technology & Engineering
ISBN: 9811272506
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How can non-windy places make use of wind power for electricity generation? Advanced Wind Turbines provides detailed information that is of great practical importance to wind turbine practitioners from small and congested city-states, where the lack of vast land and high wind speed render the conventional wind turbine less effective. It introduces the non-conventional Darrieus and Savonius wind turbines, as well as their hybrid version, covering basic concepts, computational modelling and recent advances in experimental optimization.What about those who prefer wind turbines in faraway oceans to take advantage of high wind speed, or who come from countries with a lack of shallow seabed? Floating offshore wind turbines are also discussed, and the dynamics of floating vis-à-vis grounded wind turbines are thoroughly expounded upon to aid practitioners in achieving more accurate performance modelling. This is a work of paramount usefulness for areas which have long wanted to jump on the renewable energy bandwagon, but have thus far been hampered by their natural geographical limitations.