Instantaneous Flow Measurement Using Thermal Type Micro Machined Flow Sensor

摘要

Constant - temperature type micro thermal flow sensors were fabricated with micromachining technologies. The sensors contained a pair of thin platinum lines. One line serves as the heating element and the other line is the temperature-compensating element. When a flow passes the sensor, the temperature difference between two platinum lines is held constant. The sensor was then installed in a pipe to measure the flow rate of the gases. The location of the sensor was investigated and numerical analysis were used to determine the flow velocity profile in the pipe. Steady flows are measured and it is cleared that the sensor can obtain high sensitivity and linearity by improving sensor design. Continuous unsteady flow generator was developed as a long time measuring dynamic characteristics of the sensor. Sinusoidal flows are measured using it and once the sensor was installed at the ideal locations, it was capable of measuring sinusoidal flow rates of up to 5 Hz with sufficient accuracy.