Control of Centrifugal Instability in Vortex-Surface Interaction

2015 ◽  
Author(s):  
Vaibhav Kumar ◽  
Nandeesh Hiremath ◽  
Dhwanil Shukla ◽  
Nikolaus Thorrell ◽  
Narayanan Komerath
Keyword(s):  
Flow Control ◽  
Delta Wing ◽  
Active Flow Control ◽  
Angle Of Attack ◽  
Surface Flow ◽  
Near Surface ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Centrifugal Instability ◽  
Active Flow

The interaction of a rotating conical flow with a solid surface generates a centrifugal instability. This occurs in the flow over the wings of certain types of aircraft at high angles of attack. Efforts at our laboratory have detected such structures using near-surface flow diagnostics, and shown that they can be effectively alleviated using passive flow control near the surface. Their alleviation removes the narrowband spectral peak at the nominal location of vertical fins on these aircraft. This paper explores the substitution of active flow control techniques that remain conformal to the surface and are only powered during high angle of attack operation. The occurrence of the phenomenon and its 15-dB alleviation with geometric fences are shown on a rounded-edge 42-degree swept, cropped delta wing at 25 degrees angle of attack. The feasibility and power requirements for the plasma actuator are estimated in this paper. The generation of counter-rotating vortices using a double dielectric barrier discharge actuator is demonstrated.

Active and Passive Flow Control of an Incompressible Axisymmetric Jet

2008 ◽  
Author(s):  
Nagendra Karthik Depuru Mohan ◽  
David Greenblatt ◽  
Christian Navid Nayeri ◽  
Christian Oliver Paschereit ◽  
Panchapakesan Nagangudy Ramamurthi
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Central Portion ◽  
Jet Stream ◽  
Streamwise Vortices ◽  
Passive Flow Control ◽  
Axisymmetric Jet ◽  
Passive Flow ◽  
Negative Pressures ◽  
Active Flow

An experimental investigation was carried out to compare active and passive flow control of an incompressible axisymmetric jet. For active flow control, the lip of the circular jet was equipped with a single small flap deflected away from the jet stream at an angle of 30°. The flap incorporated a flow control slot through which steady suction and oscillatory suction were implemented. For passive flow control, the lip of the circular jet was equipped with a single small triangular tab deflected into the jet stream at an angle of 30°. Both the flap and triangular tab chord lengths were one sixth of the jet diameter. The momentum of jet increased in the case of active flow control by entraining ambient fluid, whereas momentum decreased in the case of passive flow control. The effect of steady suction saturated for volumetric suction coefficient values greater than approximately 0.82%. The strength of the streamwise vortices generated by active flow control flaps were greater than those generated by the passive triangular tab. Steady suction produced positive pressures just downstream of the flow control slot in the central portion of the flap and negative pressures at the flap edges. Oscillatory suction was highly dependent on dimensionless frequency (F+) based on flap-length; the pressures on the central portion of the flap increased for F+≤0.11 and then decreased for greater F+; finally attaining negative pressures at F+ = 0.44. The increase in jet momentum, combined with the generation of strong streamwise vortices makes a strong case for improvements in propulsion efficiency and jet noise reduction.

scholarly journals Drag reduction by combination of flow control using inlet disturbance body and plasma actuator on cylinder model

2019 ◽  
Vol 13 (1) ◽  
pp. 4503-4511
Author(s):  
Budiarso . ◽  
Harinaldi . ◽  
E. A. Kosasih ◽  
R. F. Karim ◽  
J. Julian
Keyword(s):  
Reynolds Number ◽  
Flow Control ◽  
Active Flow Control ◽  
Plasma Actuators ◽  
Test Model ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Reduction Coefficient ◽  
Flow Past A Cylinder ◽  
Active Flow

Flow past a cylinder is one of the things that is very applicable in everyday life. But behind those facts, there is a problem in it namely the drag force which is adverse and needs to be reduced. This research was conducted to find solutions to reduce drag by using a mix of passive flow control of inlet disturbance body and active flow control from plasma actuators. This research uses a test model in the form of a cylinder of a diameter of 120 mm with Reynolds Number 15000, 41000, 62000 and was expected to reduce drag after a given combination of flow control. From the results shown, either inlet disturbance of body and plasma actuators as well as a combination of both the flow of control is capable of performing the reduction coefficient of drag up to 70,22% on a variation of the Reynolds Number 62000.

scholarly journals Conceptual Design of a Novel Unmanned Ground Effect Vehicle (UGEV) and Flow Control Integration Study

Drones ◽  
2022 ◽  
Vol 6 (1) ◽  
pp. 25
Author(s):  
Charalampos Papadopoulos ◽  
Dimitrios Mitridis ◽  
Kyros Yakinthos
Keyword(s):  
Flow Control ◽  
Conceptual Design ◽  
Active Flow Control ◽  
Ground Effect ◽  
Passive Flow Control ◽  
Control Techniques ◽  
Passive Flow ◽  
Conceptual Design Phase ◽  
Wide Range ◽  
Active Flow

In this study, the conceptual design of an unmanned ground effect vehicle (UGEV), based on in-house analytical tools and CFD calculations, followed by flow control studies, is presented. Ground effect vehicles can operate, in a more efficient way, over calm closed seas, taking advantage of the aerodynamic interaction between the ground and the vehicle. The proposed UGEV features a useful payload capacity of 300 kg and a maximum range of 300 km cruising at 100 kt. Regarding the aerodynamic layout, a platform which combines the basic geometry characteristics of the blended wing body (BWB), and box wing (BXW) configurations is introduced. This hybrid layout aims to incorporate the most promising features from both configurations, while it enables the UGEV to operate under adverse flight conditions of the atmospheric boundary layer of the earth. In order to enhance the performance characteristics of the platform, both passive and active flow control techniques are studied and incorporated into the conceptual design phase of the vehicle. For the passive flow control techniques, the adaptation of tubercles and wing fences is evaluated. Regarding the active flow control techniques, a wide range of morphing technologies is investigated based on performance and integration criteria. Finally, stability studies are conducted for the proposed platform.

Active Flow Control on a Nonslender Delta Wing

2008 ◽  
Vol 45 (6) ◽  
pp. 2100-2110 ◽  
Author(s):  
N. M. Williams ◽  
Z. Wang ◽  
I. Gursul
Keyword(s):  
Flow Control ◽  
Delta Wing ◽  
Active Flow Control ◽  
Active Flow

Computational analysis of the aerodynamic performance of a jet-flap airfoil in transonic flow

2012 ◽  
Vol 226 (6) ◽  
pp. 664-678 ◽  
Author(s):  
V Mantič-Lugo ◽  
G Doulgeris ◽  
A Gohardani ◽  
R Singh
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Angle Of Attack ◽  
Aircraft Design ◽  
Civil Aviation ◽  
Commercial Aircraft ◽  
Angle Variation ◽  
Distributed Propulsion ◽  
Lift And Drag ◽  
Active Flow

The needed shift in next generation aircraft design is expected to bring novel concepts for civil aviation as the jet-flap wing. The aircraft efficiency improvements with the jet-flap wing directs its use for future aircraft designs reinforced by the tendency for more synergistic systems as active flow control, boundary layer ingestion and distributed propulsion, making the jet-flap wing a very suitable option for the latter concept. The analysis carried out in this paper is aimed at the application of the jet-flap wing concept for manoeuvrability and cruise efficiency improvement of an airliner. A 2D computational model of a jet-flapped transonic airfoil is developed in order to assess the jet-flap wing technology for a commercial aircraft at cruise conditions. This paper provides an insight into the parameters that affect the performance of a jet-flap under various flight conditions. To do this, a general parametrical analysis is performed, studying numerically the influences of main flow parameters like Mach number, Reynolds number, angle of attack, jet deflection angle and jet thickness. Changes in pressure distribution and flow circulation around the airfoil yield strong modifications in lift and drag due to jet angle variation. Improvements are encountered in the performance of an airfoil with a jet-flap system compared with a standard airfoil with no jet. Enhancements in lift and reduction in drag, as well as an increase of the lift-to-drag ratio is possible with a proper combination of the jet deflection and the angle of attack of the airfoil. In summary, this paper shows the conditions under which the benefits of the jet-flapped wing, for lift enhancement and manoeuvrability as an active flow control are promising.

Influence of Active Flow Control on Blunt-Edged VFE-2 Delta Wing model

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
I. Madan ◽  
N. Tajudin ◽  
M. Said ◽  
S. Mat ◽  
N. Othman ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Flow Control ◽  
Delta Wing ◽  
Active Flow Control ◽  
Leading Edge ◽  
Control Technique ◽  
Primary Vortex ◽  
Flow Topology ◽  
Main Observation ◽  
Active Flow

This paper highlights the flow topology above blunt-edged delta wing of VFE-2 configuration when an active flow control technique called ‘blower’ is applied in the leading edge of the wing. The flow topology above blunt-edged delta wing is very complex, disorganised and unresolved compared to sharp-edged wing. For the sharp leading-edged wing, the onset of the primary vortex is fixed at the apex of the wing and develops along the entire wing towards the trailing edge. However, the onset of the primary vortex is no longer fixed at the apex of the wing for the blunt-edged case. The onset of the primary vortex develops at a certain chord-wise position and it moved upstream or downstream depending on Reynolds number, angle of attack, Mach number and the leading-edge bluntness. An active flow control namely ‘blower’ technique has been applied in the leading edge of the wing in order to investigate the upstream/downstream progression of the primary vortex. This research has been carried out in order to determine either the flow on blunt-edged delta wing would behave as the flow above sharp-edged delta wing if any active flow control is applied. The experiments were performed at Reynolds number of 0.5×106, 1.0×106 and 2.0×106 corresponding to 9 m/s, 18 m/s and 36 m/s in UTM Low Speed wind Tunnel based on the mean aerodynamic chord of the wing. The results obtained from this research have shown that the blower technique has significant effects on the flow topology above blunt-edged delta wing. The main observation from this study was that the primary vortex has been shifted 20% upstream when the blower technique is applied. Another main observation was the ability of this flow control to delay the formation of the vortex breakdown.

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