The more the bubble close to the free surface, the narrower the bottom jet develops crosswise, and the larger the pressure gradient, the rising velocity and the height of the bottom jet is upwards.
This paper reports some experimental results on variation of voidage in bed materials, bubble size and bubble rising velocity etc along the height of the bed.
To predict the rising velocity of hydrogen gas and the influencing factors, a suitable working fluid was determined for experimental simulation on the vold fraction of hydrogen in a neutron moderator.