653 power draw and dampens local turbulence (Arbiter et al., 1969; Chapman et al., 1983; Warmoeskerken et al., 1984), while also reducing impeller pumping capacity and fluid velocities (Brayant & Sadeghzadeh, 1979; Nienow, 1997; Nelson et al., 2009). These effects hinder particle suspension, leading to higher Njs values at increased Jg. The relationship is non-linear: Njs rises with Jg, but the rate of increase diminishes at higher gas velocities. Although increasing Jg consistently elevated Njs, the magnitude of this effect depended strongly on the baffling arrangement (Figure 3). Operation with a stator generates hydrodynamic conditions characterized by higher turbulence and lower mean flow, making particle suspension more difficult compared to baffles. As a result, the rotor suspension performance is more sensitive to increasing Jg. Conversely, when baffles are used, suspension is more easily achieved, and the system becomes less sensitive to aeration rate. Thus, the impact of Jg on Njs is smaller in the baffled configuration. Figure 3 – Impact of Jg on mean Njs for stator (0) and baffles (1) arrangements 3.2 Effect of baffling and airflow rate on the specific power draw (Pjs) A statistical regression model was developed to understand the significance of the studied variables on the specific power draw at Njs (Pjs). The derived model is shown in Equation 2. The Pjs model has an adjusted R2 of 99.91% (Table 4). Pjs = 617.1 + 1306.7 Jg - 291.5 Baffling - 77.5 Jg2 - 1048.9 Baffling*Jg (2) Table 4 – Metrics of the Pjs regression model Indicator Value R2 (%) 99.95 R2 adjusted (%) 99.91 Standard Error (W/m3) 21.1 Observations 10
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