Flow Resistance Experiments in HTS Cable Form

High-temperature superconducting cables have application in the Navy for power cables as well as degaussing cables. The current interest is in using a gaseous cryogen circulated by means of a cryogenic fan as the cooling media for the HTS conductor. Flow through this style of cable is through an eccentrically situated corrugated annular region. Correlations do not currently exist for this arrangement since it is not a simple configuration. Experiments were carried out to measure pressure drop with varied flow rate of air and nitrogen through 10-m sections of tubing. A variety of tubing configurations was used including smooth tube, eccentric smooth annulus, and eccentric corrugated annulus with HTS wire bundle forming the inner filling material. A method was developed for comparing the relative flow resistance of tubing configuration, which included determining an effective hydraulic diameter based on observed data set fit to the Darcy-Weisbach equation and the Colebrook equation. The effective hydraulic diameter allowed for easy comparison of flow impedance for all configurations regardless of specific flow conditions.