Accession Number : ADA299481

Title :   Microsensors for Turbulent Flow Diagnostics.

Descriptive Note : Final technical rept. 15 Jul 92-14 Apr 95,

Corporate Author : CALIFORNIA INST OF TECH PASADENA DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Tai, Yu-Chong

PDF Url : ADA299481

Report Date : 31 JUL 1995

Pagination or Media Count : 11

Abstract : There are two tasks in this grant. The first is to develop a micromachined miniature polysilicon hot-wire anemometers with improved spatial resolution and frequency response. The finished device was a micron sized polysilicon wire supported by free-standing gold/silicon-nitride beams. These devices have time constants as small as a few microseconds and, under constant temperature mode, an unprecedented bandwidth of 1.4 N 4Hz was achieved measured in wind tunnel. The second task is to study gaseous microchannel flows as an effort to understand the basic science of fluid mechanics when the mean free path of the gas is about the size of the channel. A micromachined microsystem was developed with a micron-sized flow channel (one micron high) and (4 or 13) distributed pressure sensors. A range of pressure drop up to 20 psi was used and nonlinear pressure distributions were for the first time, successfully obtained. It was found that surface-gas interaction plays an important role in the flow behavior in microflow systems and that new flow models have to be developed to explain the new phenomena.

Descriptors :   *TURBULENT FLOW, *PRESSURE GAGES, *ANEMOMETERS, *FLUID MECHANICS, SPATIAL DISTRIBUTION, WIRE, NONLINEAR SYSTEMS, CONSTANTS, PRESSURE DISTRIBUTION, WIND TUNNELS, FREQUENCY RESPONSE, POLYSILICONS, MEAN FREE PATH, MICROMINIATURIZATION.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE