A first experimental study on two-phase how patterns at a long-term, steady
microgravity condition was conducted on board the Russian Space Station "M
IR" in August 1999. Carbogal and air are used as the liquid and the gas pha
se, respectively. Bubble, slug, slug-annular transitional, and annular hows
are observed. A new region of annular how with lower liquid superficial ve
locity is discovered, and the region of the slug-annular transitional flow
is wider than that observed by experiments on board the parabolic aircraft.
The main patterns are bubble, slug-annular transitional and annular flows
based on the experiments on board MIR space station. Some influences on the
two-phase how patterns in the present experiments are discussed.