AN INVESTIGATION OF MEMS-BASED TRANSDUCERS FOR BOUNDARY LAYER CONTROL

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" AN INVESTIGATION OF MEMS-BASED TRANSDUCERS FOR BOUNDARY LAYER CONTROL "

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	151619
Doc. No	:	ET23411
Main Entry	:	Sudeep M. Kumar
Title Proper	:	AN INVESTIGATION OF MEMS-BASED TRANSDUCERS FOR BOUNDARY LAYER CONTROL
Note	:	This document is digital این مدرک بصورت الکترونیکی می باشد
Abstract	:	Recent experiments and simulations have demonstrated the feasibility of active boundarylayer control in turbulent flows. Reduction of skin-fiiction drag requires the developmentof sensors, actuators and control algorithm to favorably modify the velocity profile closeto the wall. This work describes the fabrication and characterization of modular arraysof sensors and actuators for low speed Bows. These transducers provide a testbed for theevaluation and development of control strategies in a controlled environment.The sensors are arrays of hot-films that provide snapshots of the spanwise wall shearstress distribution. The active elements are thermally isolated metal resistors embeddedin polyimide diaphragms. Fabrication of modules with robust multiple backside contactsis discussed. The sensors have a frequency response of 16 kHz when operated as constanttemperature hot-film anemometers at an overheat ratio of 1.5. Individual sensors have apower consumption of about 10 m W at this overheat ratio. The sensor response in a laminarflow is nearly linear with a slope of 0.3 mV/mPa.The actuators are zero mass flux vortex generators. They are fast with millisecond risetimes, have power consumption in the milliwatt range, and incur no drag penalty whennot in operation. An actuator array consists of eight individually addressable PZT-siliconcantilevers with integrated cavities and unequal side gaps. Bulk micromachining of siliconis followed by mesoscale assembly of the piezoceramic in the fabrication process. Distur-bance velocity fields generated by an actuator in a laminar boundary layer (Urn = 5 m/s,Ree = 310) are reported- The disturbance is substantial, up to 25 of the free streamvelocity, and is concentrated in a region of about one displacement thickness from the wall.It persists far downstream - the peak disturbance.....-....,....-...,..tested for theQ1 PC1 bus cardBoth these projects mere sofixare des elopment efforts tonards contributing to dlfferentaspects of Roboucs and lZ1echatronics projects m the Controls and Roboucs Group..
Subject	:	Electericl tess
	:	برق
electronic file name	:	TL46650.pdf
Title and statement of responsibility and	:	AN INVESTIGATION OF MEMS-BASED TRANSDUCERS FOR BOUNDARY LAYER CONTROL [Thesis]