Design and Performance of a Horizontal, Axial-Flow Water Circulator

Abstract

An axial-flow water circulator was developed for use in channel catfish, Ictalurus punctatus, culture ponds. The circulator design incorporated a series of 0.76-m diameter fan blades housed within a belled inlet duct 0.92 m in diameter and 1.22 m in length. Power was provided by a 2.24-kW gear motor. Power demand and discharge rates were established using all combinations of the following design variables: impeller type-three blades set at 30' angle or six blades set at 25' angle; impeller speed-90, 120, 144, and 180 rpm; number of impellers in series-1, 2, 3, or 4. The highest discharge rate of 63 m3/minute was established using four six-blade impellers operating at 144 rpm. A maximum discharge rate per unit of power input (efficiency) of 91.4 m3/minute-kW was obtained using two three-blade impellers operating at 90 rpm. Circulator efficiency decreased with increasing discharge rates as described by the model Y = 12888.8X-1.68315, where Y = m3/minute-kW and X = m3/minute. Field tests conducted in 1.62-ha channel catfish production ponds demonstrated the ability of the circulator to increase water movement in all areas of the ponds and to reduce the frequency and total duration of required emergency aeration by 39.3% and 54.6%, respectively. Net production of channel catfish in ponds outfitted with the water circulator (6,683 kg/ha, n = 3) was not different (P > 0.05) than production in control ponds (6,205 kg/ha, n = 3).