Abstract
The present paper describes a method for the visualization of the velocity field of a high speed duct flow such that encountered in a magnetohydrodynamic (MHD) channel employing the magnetic resonance imaging (MRI) based on the echo-planar imaging (EPI) pulse sequences. It has already demonstrated by several authors that the MRI using the conventional gradient echo technique could be applicable to low speed fluid flows. However, there are no reports which discuss and apply the high speed echo planar MRI to diagnose the velocity fields of sonic speed range. The one-shot EPI is essential in this case, because a multi-shot excitation and data acquisition procedure is required in the conventional MRI, where so many shots are needed as the number of pixels consisting of the image. Then, theoretical bases were briefly reviewed and the design of the EPI pulse sequences were presented. Finally, a verification experiment was carried out using a shock driven MHD channel with the numerical result which was calculated by a 3D MHD computer code, demonstrating capability of the proposed method.
