Analog VLSI for active drag reduction

Citation

Gupta, Vidyabhusan (1997) Analog VLSI for active drag reduction. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/3zas-5z34. https://resolver.caltech.edu/CaltechETD:etd-01102008-132037

Abstract

In today's cost conscious air transportation industry, fuel costs are a substantial economic concern. Drag reduction is an important way to increase fuel efficiency which reduces these costs. Even 1% reduction in drag can translate into estimated savings of tens of millions of dollars in annual fuel costs. Fluid mechanicists believe that microscopic vortex pairs impinging on the surface play an important role in turbulent transport that may cause large skin friction drag. The microscopic nature and unpredictable appearance of these structures has limited practical approaches to their control. With the advent of micromachining technology providing the ability to build mechanical structures with microscopic dimensions, the tools finally exist with which to detect and control the vortex structures. These sensors and actuators require control circuitry between them in order to build a complete system. We propose an analog VLSI system that can process information along a surface in a moving fluid with the goal of controlling actuators to minimize the surface shear stress. We obtain the information from the surface by using microsensors which measure the surface shear stress. The actuators interact with the fluid by moving up and down in an attempt to diminish the impact of the drag-inducing structures in the fluid. We have designed and fabricated an analog control system. We have tested the system in several different experiments to verify its effectiveness in providing a control signal that energizes an actuator. We also have studied the methodology for creating a completely integrated wafer-scale system.

Thesis Files