POWER DISSIPATION AND FLOW PATTERNS IN RECIPROCATING BAFFLE-PLATE COLUMNS

Time-averaged power dissipation rates have been measured in water in a 19.4 cm diameter reciprocating plate column operating at frequencies 0.6 to 3 Hz and amplitudes 5 to 20 mm. Measurements were also taken in water in a 15 cm diameter column operated at 1 to 5.7 Hz with amplitu des 1 to 10 mm. Several different types of doughnut reciprocating plat es, fitting close to the column wall, were investigated. Power consump tion at high amplitudes agreed with the predicted values using the qua si-steady flow model, while at low amplitudes the data were more in ag reement with a recently proposed acoustic model. The measured power di ssipations were slightly affected by the spacing between adjacent plat es, and by the alignment of the holes in the case of plates with 3 hol es. Flow patterns around the reciprocating plates were also observed w ith the aid of a thin beam of light reflecting from small particles su spended in the liquid. Well-developed circulation patterns were observ ed, depending strongly on the axial spacing between the plates.