Combined temperature and velocity field measurements in thermal fluid systems with magnetic resonance velocimetry

Abstract

Abstract A method for the combined measurement of velocity and temperature fields in water using magnetic resonance velocimetry (MRV) is presented. MRV can provide accurate volumetric, time-averaged temperature and velocity field data. However, the choice of the flow medium and other materials is limited due to the requirements placed on the magnetic properties. There are also limitations to the measurable fluid velocities and temperatures. The echo time TE, which typically defines the temperature sensitivity, is particularly important for temperature measurement in fluid flows. A longer TE means better temperature precision, but measurement errors are increased. In addition, material properties such as magnetic susceptibility and electrical conductivity are temperature-dependent and this can lead to systematic errors in the temperature results. The design of the MRV experiment must take all of these effects into account. Here, a measurement method is proposed that includes various corrective measures. The capabilities are demonstrated with two types of experiments, a pin-fin heat exchanger and a jet-in-crossflow experiment. The fluid in these systems is water with velocities of up to 1 m/s and a temperature between 20 °C and 50 °C. These experiments demonstrate the possibilities of performing quick parameter studies with MRV while achieving low measurement uncertainty and low systematic errors.