Heat Transfer > MRV
Magnetic Resonance Velocimetry (MRV)
Magnetic resonance velocimetry (MRV) is a non-invasive technique that uses healthcare MRI scanners to measure 3D flow fields in complex geometries. It is based on the nuclear magnetic resonance phenomenon. The nuclear magnetic resonance of hydrogen protons develops a precession motion with a fixed frequency when exposed to an external magnetic field. In this state each spin can interact with electromagnetic fields that excite the spins and provoke a measureable reaction. The technique is capable of measuring the three components of the mean velocity field without flow tracers or optical windows. 3 components of velocity can be measured in full 3D volumes with sub-millimeter resolution, within a few hours. Figure below depicts a flow model about to enter the MRI scanner.
A flow model about to enter the MRI scanner
Using the MRV technique, our research team plans to measure various flow patterns in gas turbine internal cooling passages. Figures below (Siekman et al. 2014) show an example of flow through a pin bank, which is often found near the trailing edge of blades (refer to Internal Cooling). Until now, investigation of the convective cooling flow inside the blade has been limited. For this reason, usually only the internal heat transfer coefficient is measured, and the blade is developed with sufficient safety factor. Through the usage of MRV, we will attempt to discover the various characteristics of internal cooling flow (such as recirculation zones) and apply the knowledge to blade design.
(a) The pin bank model (b) MRV visualization of pin bank flow pattern
