Configurable flow control mechanisms for fault-tolerant routing

1995 ◽  
Vol 23 (2) ◽  
pp. 220-229 ◽  
Author(s):  
Binh Vien Dao ◽  
Jose Duato ◽  
Sudhakar Yalamanchili
Keyword(s):  
Flow Control ◽  
Fault Tolerant ◽  
Control Mechanisms

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.

scholarly journals AT-DIFC + : Toward Adaptive and Trust-Aware Decentralized Information Flow Control

2020 ◽  
Vol 15 (4) ◽  
pp. 1-35
Author(s):  
Charilaos Skandylas ◽  
Narges Khakpour ◽  
Jesper Andersson
Keyword(s):  
Flow Control ◽  
Information Flow ◽  
Decentralized Control ◽  
Software Systems ◽  
Control Mechanisms ◽  
Information Flow Control ◽  
Decentralized System ◽  
Additional Information ◽  
Reference Implementation ◽  
And Performance

Modern software systems and their corresponding architectures are increasingly decentralized, distributed, and dynamic. As a consequence, decentralized mechanisms are required to ensure security in such architectures. Decentralized Information Flow Control (DIFC) is a mechanism to control information flow in distributed systems. This article presents and discusses several improvements to an adaptive decentralized information flow approach that incorporates trust for decentralized systems to provide security. Adaptive Trust-Aware Decentralized Information Flow (AT-DIFC + ) combines decentralized information flow control mechanisms, trust-based methods, and decentralized control architectures to control and enforce information flow in an open, decentralized system. We strengthen our approach against newly discovered attacks and provide additional information about its reconfiguration, decentralized control architectures, and reference implementation. We evaluate the effectiveness and performance of AT-DIFC + on two case studies and perform additional experiments and to gauge the mitigations’ effectiveness against the identified attacks.

Exploratory Studies on the Control of High-Speed Flows With Magnetogasdynamics

2002 ◽  
Author(s):  
Datta V. Gaitonde
Keyword(s):  
Flow Control ◽  
High Speed ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Control Mechanisms ◽  
Ground Testing ◽  
Simulation Efficiency ◽  
The Status ◽  
Physical Phenomena ◽  
Insight Into

Magnetogasdynamics (MGD) has the potential to lift many of the constraints presently inhibiting sustained hypersonic flight and affordable access to space. Given the difficulty of ground-testing under the expected harsh conditions, numerical methods can provide insight into the physical phenomena, and thus complement experimental investigations in the development of future concepts. This paper describes the status of an effort to develop a high-fidelity, fully three-dimensional method to explore MGD flow control in complex configurations. The theoretical model includes several non-ideal effects and takes recourse to a blend of first principles and phenomenological approaches to enhance simulation efficiency. Boundary conditions are summarized and sample verification exercises are presented. Exploratory calculations on a reentry vehicle and flow-through scramjet flowpath with MGD-bypass demonstrate the versatility of the approach and yield insight into dominant flow control mechanisms.

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