THE MEASUREMENT OF FLUID FLOW USING NUCLEAR MAGNETIC RESONANCE AND RELAXATION.
Abstract
A theoretical study was performed to determine the potential use of nuclear magnetic resonance (NMR) and relaxation for the measurement of fluid flow. The objective of the study was to relate the amplitude of the nuclear magnetization to the fluid velocity in circular pipes. Bloch's equations were used in deriving the absorption/dispersion signals and the relaxation (free-induction) signal for moving fluids. The fluid velocity was related to the nuclear magnetization by equating time with the ratio of pipe length to velocity. Effects of the profile for both laminar and turbulent flow were included. Results included the following: The absorption and dispersion components are attenuated nonlinearly by the fluid velocity and are dependent on the type of flow. In general the same is true for free-induction magnetization. However, when a 90 deg d-c pulse of short time duration is used to rotate the nuclei, the free-induction magnetization becomes a linear function of velocity and insensitive to the flow profile. With the above result, a theoretical design of a free-induction, flow sensor was developed to be insensitive to the flow profile and the fluid parameters. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1970
- Accession Number
- AD0706348
Entities
People
- Henry Keith Whitesel