Optical Mass Gauging System for Measuring Liquid Levels in a Reduced-Gravity Environment

摘要

A compact and rugged fiber-coupled liquid volume sensor designed for flight on a sounding rocket platform isnpresented. The sensor consists of a Mach–Zehnder interferometer capable of measuring the amount of liquidncontained in a tank under any gravitational conditions, including a microgravity environment, by detecting smallnchanges in the index of refraction of the gas contained within a sensing region. By monitoring changes in theninterference fringe pattern as the systemundergoes a small compression provided by a piston, the ullage volume of antank can be directlymeasured, allowing for a determination of the liquid volume.To demonstrate the technique, datanare acquired using two tanks containing different volumes of liquid,which are representative of the levels of liquid inna tank at different time periods during a mission. The two tanks are independently exposed to the measurementnapparatus, allowing for a determination of the liquid level in each. In a laboratory test of the unit, a liquid level ofn11:2 u0001 3:7 ml was measured, comparing favorably with the actual liquid volume level of 10.5 ml.