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Aeration performance of a 500 mm diameter double-hub paddle wheel aerator was tested in a brick masonry tank of 5.9×2.9×1.6 m3. The prime objective of the present study is to evaluate the aeration performance of double-hub paddle wheels at different dynamic conditions. The results showed that the oxygen transfer simulation curve for double hub almost matched that of a single-hub paddle wheel. However, the power consumption simulation curve for double hub distinctly deviated from that of a single-hub paddle wheel due to the fact that if geometric and process conditions remain the same, a double-hub paddle wheel consumes more power than a single hub. Hence, a separate power consumption simulation equation was developed for a double-hub paddle wheel. The optimum dynamic condition producing maximum standard aeration efficiency is also presented along with a sample calculation. [ABSTRACT FROM AUTHOR]

Aeration experiments, based on dimensional analysis, were conducted in brick masonry tanks of dimensions 2.9×2.9×1.6 m3 and 5.9×2.9×1.6 m3 to study the design characteristics of a single hub paddle wheel aerator. A generalized equation has been developed to estimate the optimum volume of water to be aerated at a given paddle wheel diameter (d) and speed (N). A simulation equation with E [nondimensional number characterizing standard aeration efficiency (SAE)] and P* (nondimensional number characterizing power input per unit volume) provided a correlation better than that with E and F (Froude number) and E and R (Reynolds number) only. A simplified generalized equation correlating E and P* was developed which can be used to predict aeration efficiency for P*<=6.56. Similarly, a simulation equation with Ne [(power number)(nondimensional number charcterizing power consumption)] and P* provided a correlation better than that with Ne and F and Ne and R only. The optimum dynamic condition at which maximum SAE is produced has also been presented. All the above results are valid subject to 1.47<=P*<=15.54. [ABSTRACT FROM AUTHOR]