Transition Trajectory Optimization for a Tiltwing VTOL Aircraft with Leading-Edge Fluid Injection Active Flow Control

2022 ◽  
Author(s):  
Leo Panish ◽  
Marko Bacic
Keyword(s):  
Flow Control ◽  
Trajectory Optimization ◽  
Active Flow Control ◽  
Leading Edge ◽  
Fluid Injection ◽  
Active Flow ◽  
Vtol Aircraft ◽  
Transition Trajectory

Comparison of Two Active Flow Control Mechanisms of Pure Blowing and Pure Suction on a Pitching NACA0012 Airfoil at Reynolds Number of 1 × 106

2018 ◽  
Author(s):  
Ehsan Asgari ◽  
Mehran Tadjfar
Keyword(s):  
Reynolds Number ◽  
Flow Control ◽  
Active Flow Control ◽  
Hysteresis Loops ◽  
Leading Edge ◽  
Control Mechanisms ◽  
Airfoil Surface ◽  
Naca0012 Airfoil ◽  
Maximum Angle ◽  
Active Flow

In this study, we have applied and compared two active flow control (AFC) mechanisms on a pitching NACA0012 airfoil at Reynolds number of 1 × 106 using 2-D computational fluid dynamics (CFD). These mechanisms are continuous blowing and suction which are applied separately on the airfoil which pitches around its quarter-chord in a sinusoidal motion. The location for suction and blowing was determined in our previous study based on the formation of a counter clock-wise vortex near the leading-edge. In our current study, we have compared the effectiveness of pure blowing and pure suction in suppressing the dynamic stall vortex (DSV) which is the main contributor to the drag increase, particularly near the maximum angle of attack (AOA) and in early downstroke motion. The blowing/suction slot is considered as a dent on the airfoil surface which enables the AFC to perform in a tangential manner. This configuration would allow blowing jet to penetrate further downstream and was shown to be more effective compared to a cross-flow orientation. We have compared the two aforementioned mechanisms in terms of hysteresis loops of lift and drag coefficients and have demonstrated the dynamics of flow in controlled and uncontrolled situations.

Organization of Cylinder Wake Using a Splitter-Plate Active Flow Control

2010 ◽  
Author(s):  
Chris Weiland ◽  
Pavlos Vlachos
Keyword(s):  
Circular Cylinder ◽  
Flow Control ◽  
Strouhal Number ◽  
Active Flow Control ◽  
Leading Edge ◽  
Splitter Plate ◽  
Cylinder Wake ◽  
Time Resolved ◽  
Image Velocimetry ◽  
Active Flow

Time Resolved Digital Particle Image Velocimetry (TRDPIV) was used in conjunction with spectral analysis to study the effects of Leading Edge Blowing (LEB) flow control on the near-wake of a circular cylinder. The airfoil was placed 1.9 circular cylinder diameters downstream, effectively acting as a splitter plate. Spectral measurements of the TRDPIV results indicated that the presence of the airfoil decreased the Strouhal number from 0.19 to 0.12 as anticipated. When activated the LEB jet organized the circular cylinder wake, effectively neutralizing the effect of the splitter plate and modifying the wake so as to return the Strouhal number to 0.19. Thus the circular cylinder wake returned to its normal shedding frequency, even in the presence of the airfoil. Evidence presented in this study supports the notion that the LEB jet directly excites the circular cylinder shear layers causing instability, roll up, and subsequent vortex shedding.

Numerical Investigation of an Elastomer-Piezo-Adaptive Blade for Active Flow Control of a Nonsteady Flow Field Using Fluid–Structure Interaction Simulations

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Tien Dat Phan ◽  
Patrick Springer ◽  
Robert Liebich
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Leading Edge ◽  
Material Behavior ◽  
Fluid Structure ◽  
Numerical Investigations ◽  
Pulsed Detonation ◽  
Stator Blade ◽  
Suitable Concept ◽  
Active Flow

In order to prevent critical effects due to pulsed detonation propulsion, e.g., incidence fluctuations, an elastomer-piezo-adaptive stator blade with a deformable front part is developed. Numerical investigations with respect to the interaction of fluid and structure including the piezoelectric properties and the hyperelastic material behavior of an elastomer membrane are conducted in order to investigate the concept of the elastomer-piezo-adaptive blade for developing the best suitable concept for subsequent experiments with a stator cascade in a wind tunnel. Results of numerical investigations of the structure-dynamic and fluid mechanical behavior of the elastomer-piezo-adaptive blade by using a novel fluid–structure-piezoelectric-elastomer-interaction simulation (FSPEI simulation) show that the latent danger of a laminar flow separation at the leading edge at incidence fluctuations can be prevented by using an adaptive blade. Therefore, the potential of the concept of the elastomer-piezo-adaptive blade for active flow control is verified. Furthermore, it is essential to consider the interactions between fluid and structure of the transient FSPEI simulations, since not only the deformation of the adaptive blade affects the flow around the blade, the flow has a significant effect on the dynamic behavior of the adaptive blade, as well.

scholarly journals Numerical study on the steady suction active flow control of hydrofoil in the profile of the blended-wing-body underwater glider

2021 ◽  
Vol 39 (4) ◽  
pp. 801-809
Author(s):  
Xiaoxu Du ◽  
Lianying Zhang
Keyword(s):  
Flow Control ◽  
Numerical Study ◽  
Active Flow Control ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Flow State ◽  
Underwater Glider ◽  
Blended Wing Body ◽  
Active Flow

The hydrodynamic performance of the blended-wing-body underwater glider can be improved by opening a hole on the surface and applying the steady suction active flow control. In order to explore the influence law and mechanism of the steady suction active flow control on the lift and drag performance of the hydrofoil, which is the profile of the blended-wing-body underwater glider, based on the computational fluid dynamics (CFD) method and SST k-ω turbulence model, the steady suction active flow control of hydrofoil under different conditions is studied, which include three suction factors: suction angle, suction position and suction ratio, as well as three different flow states: no stall, critical stall and over stall. Then the influence mechanism in over stall flow state is further analyzed. The results show that the flow separation state of NACA0015 hydrofoil can be effectively restrained and the flow field distribution around it can be improved by a reasonable steady suction, so as to the lift-drag performance of NACA0015 hydrofoil is improved. The effect of increasing lift and reducing drag of steady suction is best at 90° suction angle and symmetrical about 90° suction angle, and it is better when the steady suction position is closer to the leading edge of the hydrofoil. In addition, with the increase of the suction ratio, the influence of steady suction on the lift coefficient and drag coefficient of hydrofoil is greater.

Active flow control concepts and application opportunities

2017 ◽  
Vol 89 (5) ◽  
pp. 725-729 ◽  
Author(s):  
Heribert Bieler
Keyword(s):  
Flow Control ◽  
Skin Friction ◽  
High Speed ◽  
Active Flow Control ◽  
Leading Edge ◽  
Design Activity ◽  
Content Type ◽  
Low Speed ◽  
Significant Step ◽  
Active Flow

Purpose Aerodynamics drives the aircraft performance and, thus, influences fuel consumption and environmental compatibility. Further, optimization of aerodynamic shapes is an ongoing design activity in industrial offices; this will lead to incremental improvements. More significant step changes in performance are not expected from pure passive shape design. However, active flow control is a key technology, which has the potential to realize a drastic step change in performance. Flow control targets two major goals: low speed performance enhancements mainly for start and landing phase via control of separation and drag reduction at high speed conditions via skin friction and shock wave control. Design/methodology/approach This paper highlights flow control concepts and Airbus involvements for both items. To mature flow control systematically, local applications of separation control technology are of major importance for Airbus. In parallel, but at lower maturity level, investigations are ongoing to reduce the turbulent skin friction at cruise. A popular concept to delay separation at low speed conditions is the implementation of jet actuation control systems flush mounted to the wall of aerodynamic components. Findings In 2006, DLR (in collaboration with universities Berlin, Braunschweig and industrial partner Airbus) started to study active flow control for separation delay towards application. Based on basic proof of concepts (achieved in national projects), further flow control hardware developments and wind tunnel and lab testing took place in European funded projects. Originality/value Significant lift enhancements were realized via flow control applied to the wing leading edge and the flap.

Design and cost analysis of integration of fluidic oscillator into a flap structure

2017 ◽  
Vol 232 (16) ◽  
pp. 2978-2988 ◽  
Author(s):  
J Li ◽  
J Colton
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Leading Edge ◽  
Control Technology ◽  
Fluidic Oscillator ◽  
Transport Aircraft ◽  
High Production ◽  
Manufacturing Assembly ◽  
The Cost ◽  
Active Flow

Integration of active flow control technology into civil transport aircraft is a highly desired objective due to the potential reductions in part count, weight, and recurring manufacturing costs. This study develops an optimal design for integrating a fluidic oscillator into the leading-edge of a trailing-edge flap structure on a civil transport aircraft. The design incorporates design specifications set by members of the aerospace industry, robust design methodologies, and simulation studies to create three separate designs that can be mass-produced. An analysis of the manufacturing, assembly, material, and weight reveals the cost of the design with respect to its production rate, which ranges from about $4090 per aircraft for low-production volumes to about $2600 per aircraft for high-production volumes. As a result, this study provides a basis for the design of manufacturing and assembly techniques to integrate active flow control technology into civil transport aircraft.

Active Flow Control for Reduction of Fluctuating Aerodynamic Forces of a Blunt Trailing Edge Airfoil

2009 ◽  
Author(s):  
Arash Naghib Lahouti ◽  
Horia Hangan
Keyword(s):  
Flow Control ◽  
Numerical Simulations ◽  
Control Mechanism ◽  
Active Flow Control ◽  
Three Dimensional ◽  
Leading Edge ◽  
Aerodynamic Forces ◽  
Trailing Edge ◽  
Blunt Trailing Edge ◽  
Active Flow

Vortex shedding from the base of two dimensional bluff bodies is accompanied by three dimensional wake instabilities. These instabilities manifest as streamwise and vertical vorticity components which occur at a certain spanwise wavelength. The spanwise wavelength of the instabilities (λz) depends on several parameters, including profile geometry and Reynolds number. The present study aims to determine λz for a blunt trailing edge airfoil, which is comprised of an elliptical leading edge, followed by a rectangular section. Results of numerical simulations of flow around the airfoil at Re(d) = 500, 800, 1200, and 17,000, and flow visualization at Re(d) = 2200 indicate that λz has an average value of 2.2d. An active flow control mechanism based on the three dimensional wake instabilities is proposed, to attenuate the fluctuating aerodynamic forces of the airfoil. The mechanism is comprised of trailing edge injection ports distributed across the span, with a spacing equal to λz. Injection of a secondary flow leads to excitation of the three dimensional instabilities and disorganization of the von Ka´rma´n vortex street. Numerical simulations at Re(d) = 500 and 17,000 indicate that the flow control mechanism can attenuate the fluctuating aerodynamic forces significantly, and reduce mean drag using a relatively small injection mass flow rate.

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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