Numerical Study of the Active Control of Underexpanded Jets

2014 ◽  
Author(s):  
Kalyan Goparaju ◽  
Datta V. Gaitonde ◽  
Mei Zhuang
Keyword(s):  
Active Control ◽  
Numerical Study ◽  
Underexpanded Jets

Numerical study of active control by piezoelectric materials for fluid–structure interaction problems

2018 ◽  
Vol 435 ◽  
pp. 23-35 ◽  
Author(s):  
Shigeki Kaneko ◽  
Giwon Hong ◽  
Naoto Mitsume ◽  
Tomonori Yamada ◽  
Shinobu Yoshimura
Keyword(s):  
Active Control ◽  
Numerical Study ◽  
Piezoelectric Materials ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Structure Interaction

Active control of fan noise from high-bypass ratio aeroengines: a numerical study

2001 ◽  
Vol 105 (1053) ◽  
pp. 627-631
Author(s):  
P. Traub ◽  
F. Kennepohl ◽  
K. Heinig
Keyword(s):  
Active Control ◽  
Numerical Study ◽  
Active Noise Control ◽  
Sound Field ◽  
Primary Objective ◽  
Scale Model ◽  
Research Centre ◽  
Infinite Length ◽  
Circular Duct ◽  
Bypass Ratio

Abstract Under the national research project, dubbed Turbotech II, in which MTU Aero Engines, DLR Institute of Propulsion Technology and EADS Corporate Research Centre participate, active noise control (ANC) has been tested with a scale model fan of one metre diameter for a high bypass ratio aeroengine. MTU’s task in this project was to develop a computer code to predict the sound field in the intake duct of the fan-rig by the use of active control. The primary objective of the numerical study was to specify numbers of actuators (loudspeakers) and error sensors (microphones) and their positioning to control the harmonic sound power, radiated upstream to the duct intake. The computer model is based on the geometry of an annular or circular duct of rigid walls and infinite length, containing a subsonic axial uniform flow. The modal amplitudes of the primary sound field are input data. The actuators are modelled by acoustic monopoles. Two control algorithms have been used for achieving the control objective. The first consists simply in the reduction of the in-duct mean squared pressures. The second, so called modal control, is designed to cancel dominant modes selectively. Numerical results are presented using a typical configuration of wall mounted actuators and error sensors in the form of a number of rings uniformly distributed along the length of the intake duct. Guidelines have also been derived to design a favourable configuration of actuators and sensors. The findings of the numerical study are compared with the results of the ANC tests.

scholarly journals Numerical Study on Nonlinear Semiactive Control of Steel-Concrete Hybrid Structures Using MR Dampers

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Long-He Xu ◽  
Zhong-Xian Li ◽  
Yang Lv
Keyword(s):  
Active Control ◽  
Numerical Study ◽  
Material Model ◽  
Relative Displacement ◽  
Hybrid Structure ◽  
Semiactive Control ◽  
Building Structures ◽  
Seismic Safety ◽  
Analysis And Design ◽  
Mr Dampers

Controlling the damage process, avoiding the global collapse, and increasing the seismic safety of the super high-rise building structures are of great significance to the casualties’ reduction and seismic losses mitigation. In this paper, a semiactive control platform based on magnetorheological (MR) dampers comprising the Bouc-Wen model, the semi-active control law, and the shear wall damage criteria and steel damage material model is developed in LS-DYNA program, based on the data transferring between the main program and the control platform; it can realize the purpose of integrated modeling, analysis, and design of the nonlinear semi-active control system. The nonlinear seismic control effectiveness is verified by the numerical example of a 15-story steel-concrete hybrid structure; the results indicate that the control platform and the numerical method are stable and fast, the relative displacement, shear force, and damage of the steel-concrete structure are largely reduced using the optimal designed MR dampers, and the deformations and shear forces of the concrete tube and frame are better consorted by the control devices.

609 Numerical Study of Active Control of Oblique Waves in a transitional boundary layer

2001 ◽  
Vol 2001 (0) ◽  
pp. 91
Author(s):  
Koichi SHIBAMOTO ◽  
Kiyoshi MORITA ◽  
Masato MOTOKI ◽  
Seiichiro IZAWA ◽  
Yu FUKUNISHI
Keyword(s):  
Boundary Layer ◽  
Active Control ◽  
Numerical Study ◽  
Oblique Waves ◽  
Transitional Boundary Layer

scholarly journals Active Control of Contact Force for a Pantograph-Catenary System

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Jiqiang Wang
Keyword(s):  
Active Control ◽  
Contact Force ◽  
High Speed ◽  
Large Scale ◽  
Vibration Suppression ◽  
Numerical Study ◽  
Primary Objective ◽  
Geometric Framework ◽  
High Speed Trains ◽  
Catenary System

The performance of the high speed trains depends critically on the quality of the contact in the pantograph-catenary interaction. Maintaining a constant contact force needs taking special measures and one of the methods is to utilize active control to optimize the contact force. A number of active control methods have been proposed in the past decade. However, the primary objective of these methods has been to reduce the variation of the contact force in the pantograph-catenary system, ignoring the effects of locomotive vibrations on pantograph-catenary dynamics. Motivated by the problems in active control of vibration in large scale structures, the author has developed a geometric framework specifically targeting the remote vibration suppression problem based only on local control action. It is the intention of the paper to demonstrate its potential in the active control of the pantograph-catenary interaction, aiming to minimize the variation of the contact force while simultaneously suppressing the vibration disturbance from the train. A numerical study is provided through the application to a simplified pantograph-catenary model.

Numerical Study of Active Control of Interior Noise in a Structural-Acoustic Enclosure

2011 ◽  
Vol 486 ◽  
pp. 103-106
Author(s):  
Ming Gang Zhu ◽  
Guo Yong Jin ◽  
Na Feng
Keyword(s):  
Control System ◽  
Active Control ◽  
Lead Zirconate Titanate ◽  
Numerical Study ◽  
Sound Field ◽  
Lead Zirconate ◽  
Interior Noise ◽  
Placement Problem ◽  
Total Potential ◽  
Flexible Plates

This paper is concerned with the numerical study of active control of interior noise induced by the flexible plates in a coupled enclosure. A cabin-like enclosure with four acoustically rigid walls and two flexible plates is considered. Two types of actuators are used, i.e. acoustic actuators and distributed lead zirconate titanate piezoelectric (PZT) actuators instead of point force actuators. With the control system designed to globally reduce the sound field, different control configurations are considered, including the structural actuator on the incident panel, actuator on the receiving panel, acoustic actuator on the cavity, and their combinations. The effectiveness and performance of the control system corresponding to each configuration are studied numerically, and desirable placement problem of structural actuators in terms of total potential energy reduction are of particular interest.

ACTIVE CONTROL OF A MACHINE SUSPENSION SYSTEM SUPPORTED ON A CYLINDRICAL SHELL

2013 ◽  
Vol 21 (03) ◽  
pp. 1350012
Author(s):  
X. LIU ◽  
G. JIN ◽  
Y. WANG ◽  
Y. SHI ◽  
X. FENG
Keyword(s):  
Cylindrical Shell ◽  
Numerical Simulations ◽  
Active Control ◽  
Numerical Study ◽  
Control Strategies ◽  
Acoustic Power ◽  
Suspension System ◽  
Sound Power ◽  
Control Force ◽  
Power Minimization

A numerical study on the active control of a machine suspension system supported on a cylindrical shell aiming to reduce the sound radiation is presented in this paper. In this system, a rigid-body machine is supported on a simply-supported elastic cylindrical shell through four active isolators. A theoretical model is employed and four types of active control strategies including kinetic energy minimization strategy, power flow minimization strategy, squared acceleration minimization strategy and acoustic power minimization strategy are considered, with corresponding active control force obtained by linear quadratic optimal method. Numerical simulations are conducted and detailed results were presented. Active control performance under these four control strategies is compared and analyzed in terms of radiated sound power, and the effect of the number of active actuators is discussed by numerical analysis. The results show that acoustic power minimization strategy has the best performance to reduce the sound power radiated from supporting shell in general. Through numerical simulations, some comprehensive design principles of active control system are discussed at the end.

Numerical Study of the Implementation of an Active Control Turbocharger on Automotive Diesel Engines

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
J. Galindo ◽  
V. Dolz ◽  
A. Tiseira ◽  
R. Gozalbo
Keyword(s):  
Active Control ◽  
Numerical Study ◽  
Operating Point ◽  
Variable Geometry ◽  
One Dimensional ◽  
Engine Efficiency ◽  
Gas Dynamic ◽  
Operating Points ◽  
Engine Operating Point ◽  
Average Position

Active control turbocharger (ACT) has been proposed as a way to improve turbocharger performance under highly pulsating exhaust flows. This technique implies that the variable geometry mechanism in the turbine is used to optimize its position as a function of the instantaneous mass flow during the engine cycle. Tests presented in the literature showed promising results in a pulsating gas-stand. In this work, a modeling study has been conducted at different engine conditions aimed to quantify the gain in on-engine conditions and to develop a strategy to integrate the ACT system within the engine. Different ways of changing the displacement of the variable mechanism have been analyzed by means of a one-dimensional gas dynamic model. The simulations have been carried out at constant engine operating points defined by fixed air-to-fuel ratio for different mechanism displacement functions around an average position that guarantees the desired amount of intake air. The benefits in overall engine efficiency are lower to those predicted in the literature. It can be concluded that it is not possible to use the ACT system to optimize the turbine operating point and at the same time to control the engine operating point.

Genetic Algorithm Based Optimum Semi-Active Control of Building Frames Using Limited Number of Magneto-Rheological Dampers and Sensors

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Vishisht Bhaiya ◽  
S. D. Bharti ◽  
M. K. Shrimali ◽  
T. K. Datta
Keyword(s):  
Genetic Algorithm ◽  
Active Control ◽  
Optimization Problem ◽  
Numerical Study ◽  
Accurate Estimation ◽  
Computationally Efficient ◽  
Linear Quadratic ◽  
Building Frames ◽  
Mr Dampers ◽  
Magneto Rheological

Optimum semi-active control with a limited number of magneto-rheological (MR) dampers and measurement sensors has certain requirements. Most important of them is the accurate estimation of control forces developed in the MR dampers from the observations made in the structure. Therefore, the observation strategy should form an integral part of the optimization problem. The existing literature on the subject does not address this issue properly. The paper presents a computationally efficient optimization scheme for semi-active control of partially observed building frames using a limited number of MR dampers and sensors for earthquakes. The control scheme duly incorporates the locations of measurement sensors as variables into the genetic algorithm (GA) based optimization problem. A ten-storied building frame is taken as an illustrative example. The optimum control strategy utilizes two well-known control laws, namely, the linear quadratic Gaussian (LQG) with clipped optimal control and the bang-bang control to find the time histories of voltage to be applied to the MR dampers. The results of the numerical study show that the proposed scheme of sensor placement provides the optimum reduction of response with more computational efficiency. Second, optimal locations of sensors vary with the response quantities to be controlled, the nature of earthquake, and the control algorithm. Third, optimal locations of MR dampers are invariant of the response quantities to be controlled and the nature of earthquake.

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