Buoyancy-driven exchange flow through double openings with having multi flow patterns

Buoyancy-driven helium-air exchange flow through double Small openings was investigated. The double openings with rectangular cross section were settl ed side by side, in order to evaluate the interaction between the flows thr ough the double openings. In the exchange flow experiment, the exchange flo w rate and the flow pattern around the openings were simultaneously measure d. Two flow patterns were formed even in the same boundary condition, i.e., (a) uncaptured flow pattern with larger exchange flow rate, and (b) captur ed flow pattern with smaller exchange flow rate. The entrainment effect cau sed the two flow patterns. In order to clarify the mechanism, characteristi cs of the entrainment were evaluated in the forced flow experiment. Only th e flow pattern (b) was observed in the forced flow experiment. The relation ship between the entrainment ratio alpha and flow rate q was measured for t he flow pattern (b), resulting in the entrainment characteristic curve. A n ew correlation for the exchange flow rate was proposed with considering the entrainment. With applying the obtained entrainment characteristic curve t o the correlation, the exchange flow rate was predicted. It agreed with the measured value better than the conventional prediction without considerati on of the entrainment.