1997 Fiscal Year Final Research Report Summary
Basic Study on Active-Feedback Control of Non-Linear Heat and Fluid Flow
| Project/Area Number |
08455102
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KASAGI Nobuhide The University of Tokyo, School of Engineering, Professor, 大学院・工学系研究科, 教授 (80107531)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Yuji The University of Tokyo, School of Engineering, Lecturer, 大学院・工学系研究科, 講師 (80222066)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Turbulent Transport Phenomena / Active Control / Optimal Control Theory / Neural Network / Actuator / MEMS / Solid Particle / Coherent Structure |
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| Research Abstract |
In pursuit of an effective active feedback control methodology for heat and fluid flow, control theories and control devices were studied extensively. The following conclusions can be derived :
A suboptimal control theory is applied to the numarically-simulated channel flow with a spanwise virtual body force field as a control input. The suboptimal control achieves a significant turbulent drag reduction with fairly small control, when compared with simple feedback law.
A simple oscillatory mode of wall deformation is tested in a turbulent channel with a flexible wall by using direct numerical simulation. The substantial influences are observed in the mean flow properties as well as instantaneous flow structures. The turbulent structures are found to be dependent on the scales of the wall deformation at both their enhanced and damped phases.
The optimal control algorithm based on neural network (NN) was found to be effective for controlling the heat conduction and the Burgers equations. The present method is also applied to the management of velocity fluctuations downstream of a cylinder successfully.
An array of twelve sets of flap actuators was developed so as to control the kinematics of the near-wall quasi-streamwise vortical structures. The effect of periodic motion of the actuators on the turbulent statistics was found to affect the spanwise velocity component selectively.
A prototype electromagnetic flap actuator was developed with photo lithography. The dynamic characteristics of the flap predicted by models were in reasonable agreement with experimental results. A group of flap mounted on the circular nozzle lip can manipulate significantly the vortex shedding phenomena of an axisymmetric jet.
Dynamics of particles in wall turbulence was examined by using a series of DNS and laboratory experiments. The effect of particle on heat transfer phenomena was also studied.
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