Micromanometer for Measuring Boundary Layer Profiles

A micromanometer is described which satisfies the requirements for measuring laminar or turbulent boundary layer profiles in incompressible flow. It is a design based on the U‐tube principle and has a demonstrated accuracy of ±0.0002 in. H2O for pressure differentials less than 0.8 in. H2O and ±0.001 in. H2O for measurements in the range 0.8 to 24 in. H2O. The lag time of the instrument is small, resulting in economical use of testing time. Results of experiments to find an optimum manometer fluid and the manometer accuracy are included. Measurements of temperature effects show good correlation with theory. Typical boundary layer profiles measured with the micromanometer exhibit a high degree of consistency and lack of scatter.