A Capacitance Densitometer for Determination of the Transient Densities of Cryogenic Liquids
Amandus H. Sharbaugh, M. W. Lippitt · ARS journal · 1961
In the operation and testing of rocket engines using liquid propellants, it is desirable to measure continuously the density of the flowing liquid under transient conditions where the changing temperature and pressure cause small, but important, density changes. This report describes a novel method for doing this by measuring the electrical capacitance of a calibrated concentric-cylinder capacitor which is inserted into the feed system of the rocket engine. Test results with liquid oxygen show tha t this capacitance densitometer will indicate changes in density to about ±0.2% accuracy and absolute values of density may be measured with an error of about ± 1 % .