Void fraction distributions of inert gas jets across a single cylinder with non-wetting surface in liquid sodium

Abstract

Little work on the void fraction behaviors along structural materials with poor-wettability for liquid metals has been performed. In the present study, void fraction behaviors around a single cylinder with non-wetting surface condition were quantitatively discussed by using a gas jet-cylinder system where the impinging jet flow, the boundary layer flow, the separation flow, and the wake flow appear. One cylinder with a non-wetting surface and two cylinders with a wetting surface were used to vary the wettability for liquid sodium, and void fraction distributions were measured around the cylinders. In the case of wetting condition, void fraction distributions around the cylinder decrease clearly in the backward region of the cylinder, and liquid-rich region is formed due to bubble separation from the cylinder surface. On the other hand, under non-wetting condition, because of two-phase flow without bubble separation on the cylinder surface, void fraction distributions show almost steady values around the cylinder compared to those with wetting surface. The void behaviors on a non-wetting surface were also confirmed by a visualization experiment conducted in water. The observed differences can be basically attributed to the work of adhesion required for liquid-solid interfacial separation.

Visualization on the behavior of inert gas jets impinging on a single glass tube submerged in liquid sodium

“…On the other hand, in the backward region, the temporally averaged area average void fraction, a a , of 0.54 was found to agree well with the time average void fraction, a t , of 0.56 as measured by the probe. As explained in our previous paper, both the gas and liquid phases at the non-wettable surface are smoothly released from the backward region to the wake region [8]. Therefore, the good agreement between the two values in the backward stagnation region is reasonable.…”

“…The diameter of the nozzle-hole, which was formed using a drill, was 3.5 mm, and the distance between the nozzle exit and the forward stagnation point of the glass tube was 25 mm. These dimensions are the same as those in the previous study, and are selected for the simultaneous visualization of gas-jet behaviors in water from the nozzle head to the wake area near the back side of the cylinder [8]. In the present study, simultaneous visualization of the gas-jet behaviors in sodium from the nozzle hole to the outer surface of the forward side of the cylinder with a sufficient spatial resolution is required.…”

“…In the present study, only the test section shown in Figure 1 was replaced in the previous experimental equipment [8]. The new test section of the stainlesssteel vessel has an inner diameter of 80 mm and a height of 700 mm.…”

“…Images of the gas jet behavior were captured by a high-speed camera at a frame rate of 2000 fps (Fastcam-512PCI model 32K; Photron Ltd.) connected to the endoscope. Three conductivity probes for void fraction measurement used in the previous paper were placed around the glass tube [8]. The liquid sodium and argon gas temperatures were both maintained at 1208C.…”

Numerical Methods for Compressible Multiphase Flow with Sodium-Water Chemical Reaction

“…The calculated pressure was compared to the experimental data. Kudo et al (6) carried out the experiment on the argon gas jet in the water pool and measured the void fraction around the rod installed above the gas inlet nozzle. Their experiment was chosen as one of the validation problem for the multiphase flow model.…”