scholarly journals Open-Loop and Closed-Loop Trailing-Edge Separation Control on a Natural Laminar Flow Airfoil

2016 ◽  
Author(s):  
Rohit Gupta ◽  
Phillip J. Ansell
Keyword(s):  
Laminar Flow ◽  
Closed Loop ◽  
Open Loop ◽  
Separation Control ◽  
Trailing Edge ◽  
Natural Laminar Flow ◽  
Edge Separation

Closed-Loop Feedback Control of Flow Over a Flapped Airfoil at High Angles of Attack Using Identified NARMAX Model

2012 ◽  
Author(s):  
Sohaib Obeid ◽  
Ratneshwar Jha ◽  
Goodarz Ahmadi
Keyword(s):  
Feedback Control ◽  
Closed Loop ◽  
Active Flow Control ◽  
Leading Edge ◽  
Open Loop ◽  
Synthetic Jet ◽  
Trailing Edge ◽  
Loop Feedback ◽  
Closed Loop Feedback ◽  
High Angles Of Attack

This study investigates closed-loop feedback control system design aimed at reduction of turbulent flow separation over a NACA 0015 airfoil having 30% integral type trailing edge flap and equipped with leading-edge and trailing edge synthetic jet actuators (SJAs). The multiple-input single-output controller employs system identification techniques based on Nonlinear Auto Regressive Moving Average with eXogenous inputs (NARMAX) method to model nonlinear dynamics of the flow. RANS FLUENT simulations for 2-D airfoil are used besides an analytical modeling for the set of synthetic actuators. The resulting closed loop response using NARMAX tracks the desired pressure value and significant improvement in the transient response over the open-loop system at high angles of attack is realized. Improvements in aerodynamic efficiency and maximum lift values through active flow control would lead to better performance characteristics of airplanes.

scholarly journals Exploitation of a Multifunctional Twistable Wing Trailing-Edge for Performance Improvement of a Turboprop 90-Seats Regional Aircraft

Aerospace ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 122 ◽  
Author(s):  
Francesco Rea ◽  
Francesco Amoroso ◽  
Rosario Pecora ◽  
Frederic Moens
Keyword(s):  
Laminar Flow ◽  
High Speed ◽  
Limit Load ◽  
Trailing Edge ◽  
Aircraft Wings ◽  
Actuation System ◽  
Load Carrying ◽  
Aircraft Performance ◽  
Wing Chord ◽  
Natural Laminar Flow

Modern transport aircraft wings have reached near-peak levels of energy-efficiency and there is still margin for further relevant improvements. A promising strategy for improving aircraft efficiency is to change the shape of the aircraft wing in flight in order to maximize its aerodynamic performance under all operative conditions. In the present work, this has been developed in the framework of the Clean Sky 2 (REG-IADP) European research project, where the authors focused on the design of a multifunctional twistable trailing-edge for a Natural Laminar Flow (NLF) wing. A multifunctional wing trailing-edge is used to improve aircraft performance during climb and off-design cruise conditions in response to variations in speed, altitude and other flight parameters. The investigation domain of the novel full-scale device covers 5.15 m along the wing span and the 10% of the local wing chord. Concerning the wing trailing-edge, the preliminary structural and kinematic design process of the actuation system is completely addressed: three rotary brushless motors (placed in root, central and tip sections) are required to activate the inner mechanisms enabling different trailing-edge morphing modes. The structural layout of the thin-walled closed-section composite trailing-edge represents a promising concept, meeting both the conflicting requirements of load-carrying capability and shape adaptivity. Actuation system performances and aeroelastic deformations, considering both operative aerodynamic and limit load conditions, prove the potential of the proposed structural concept to be energy efficient and lightweight for real aircraft implementation. Finally, the performance assessment of the outer natural laminar flow (NLF) wing retrofitted with the multifunctional trailing-edge is performed by high-fidelity aerodynamic analyses. For such an NLF wing, this device can improve airplane aerodynamic efficiency during high speed climb conditions.

A Novel Process for the Manufacture of Extended Laminar Flow Lipskins

2013 ◽  
Vol 549 ◽  
pp. 3-12
Author(s):  
Alan G. Leacock
Keyword(s):  
Laminar Flow ◽  
External Surface ◽  
Next Generation ◽  
Production Rates ◽  
Trailing Edge ◽  
Processing Methods ◽  
Improve Efficiency ◽  
Edge Current ◽  
Natural Laminar Flow

To reduce drag and improve efficiency, the next generation of aircraft will increasingly utilise laminar flow technologies. Of particular interest is the use of natural laminar flow in nacelle designs. A key element to achieving natural laminar flow is the elimination of joints on the external surface of the nacelle through the rearward extension of the lipskin trailing edge. Current processing methods are limited in their ability to produce these extended lipskins while meeting production rates, cost targets and the requirements of the natural laminar flow designs. A novel process for the production of extended natural laminar flow lipskins is presented along with a series of pre-production trials. The efficacy of the process is clearly demonstrated.

Flow-separation-control system operating in feedback closed loop

2019 ◽  
Vol 91 (3) ◽  
pp. 498-508
Author(s):  
Wienczyslaw Stalewski ◽  
Andrzej Krzysiak
Keyword(s):  
Flow Separation ◽  
Closed Loop ◽  
Pressure Sensors ◽  
The Self ◽  
Experimental Investigations ◽  
Separation Control ◽  
Trailing Edge ◽  
High Lift ◽  
Content Type ◽  
Flow Separation Control

Purpose The purpose of this study is to develop the concept of self-adapting system which would be able to control a flow on the wing-high-lift system and protect the flow against strong separation. Design/methodology/approach The self-adapting system has been developed based on computational approach. The computational studies have been conducted using the URANS solver. The experimental investigations have been conducted to verify the computational results. Findings The developed solution is controlled by closed-loop-control (CLC) system. As flow actuators, the main-wing trailing-edge nozzles are proposed. Based on signals received from the pressure sensors located at the flap trailing edge, the CLC algorithm changes the amount of air blown from the nozzles. The results of computational simulations confirmed good effectiveness and reliability of the developed system. These results have been partially confirmed by experimental investigations. Research limitations/implications The presented research on an improvement of the effectiveness of high-lift systems of modern aircraft was conducted on the relatively lower level of the technology readiness. However, despite this limitation, the results of presented studies can provide a basis for developing innovative self-adaptive aerodynamic systems that potentially may be implemented in future aircrafts. Practical implications The studies on autonomous flow-separation control systems, operating in a closed feedback loop, are a great hope for significant advances in modern aeronautical engineering, also in the UAV area. The results of the presented studies can provide a basis for developing innovative self-adaptive aerodynamic systems at a higher level of technological readiness. Originality/value The presented approach is especially original and valuable in relation to the innovative concept of high-lift system supported by air-jets blown form the main-wing-trailing-edge nozzles; the effective and reliable flow sensors are the pressure sensors located at the flap trailing edge, and the effective and robust algorithm controlling the self-adapting aerodynamic system – original especially in respect to a strategy of deactivation of flow actuators.

On closed-loop equilibrium strategies for mean-field stochastic linear quadratic problems

2020 ◽  
Vol 26 ◽  
pp. 41
Author(s):  
Tianxiao Wang
Keyword(s):  
Optimal Control ◽  
Closed Loop ◽  
Optimal Control Problems ◽  
Mean Field ◽  
Open Loop ◽  
Time Inconsistency ◽  
Control Problems ◽  
Linear Quadratic ◽  
Linear Quadratic Optimal Control ◽  
Equilibrium Strategies

This article is concerned with linear quadratic optimal control problems of mean-field stochastic differential equations (MF-SDE) with deterministic coefficients. To treat the time inconsistency of the optimal control problems, linear closed-loop equilibrium strategies are introduced and characterized by variational approach. Our developed methodology drops the delicate convergence procedures in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. When the MF-SDE reduces to SDE, our Riccati system coincides with the analogue in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. However, these two systems are in general different from each other due to the conditional mean-field terms in the MF-SDE. Eventually, the comparisons with pre-committed optimal strategies, open-loop equilibrium strategies are given in details.

Comparison of Dc-Dc SEPIC, CUK and Flyback Converters Based LED Drivers

2020 ◽  
pp. 99-107
Author(s):  
Erdal Sehirli
Keyword(s):  
Integrated Circuit ◽  
Closed Loop ◽  
Input Voltage ◽  
Open Loop ◽  
Current Sensor ◽  
Switching Frequency ◽  
Led Driver ◽  
Advantages And Disadvantages ◽  
Led Drivers ◽  
Conduction Mode

This paper presents the comparison of LED driver topologies that include SEPIC, CUK and FLYBACK DC-DC converters. Both topologies are designed for 8W power and operated in discontinuous conduction mode (DCM) with 88 kHz switching frequency. Furthermore, inductors of SEPIC and CUK converters are wounded as coupled. Applications are realized by using SG3524 integrated circuit for open loop and PIC16F877 microcontroller for closed loop. Besides, ACS712 current sensor used to limit maximum LED current for closed loop applications. Finally, SEPIC, CUK and FLYBACK DC-DC LED drivers are compared with respect to LED current, LED voltage, input voltage and current. Also, advantages and disadvantages of all topologies are concluded.

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