TECHNICAL FEATURE FIGURE 7 Airflow patterns at the central plane for non-isothermal conditions with heat source near the ceiling show increasing supply airflow rates set unidirectional motion for the discharge jet and form recirculation patterns. a) 200 cfm (94.4 L/s) c) 600 cfm (283.2 L/s) downward unidirectional motion cannot sustain (Figure 10b). It shows that up to 600 cfm (283.2 L/s) supply flow rate, the centerline velocity decreases until about 70% of the distance from the diffuser where the downward jet meets the upward plume from the heat source. This reversal in the flow direction is indicated by negative values of the centerline velocity. It should be noted such point of intersection moves downward with increasing discharge velocity. When the supply airflow rate is increased to 800 cfm (377.6 L/s) such trend reverses entirely. Note in this case significant thermal gradient is established between the supply airstream and the surrounding air (Figure 6d) and the zone of high velocity detaches from the ceiling (Figure 5d). The centerline velocity starts increasing as the jet moves downward and reaches a peak value of 1.38 (38%) at a travel distance of about 67% from the diffuser. Thereafter, the centerline velocity shows sharp decline until it reaches the top of the table. This 32 ASHRAE JOURNAL ashrae.org J U N E 2 0 19 b) 400 cfm (188.8 L/s) d) 800 cfm (377.6 L/s) indicates entrainment from the surrounding air during the initial descend and loss of directionality after 67% of the travel as the cold airstream approaches the table. Similar trend in the acceleration of the centerline velocity is observed when the heat sources are located surrounding the supply diffuser (Figure 10c). Note in these situations also a significant thermal gradient is established between the supply airstream and the surrounding air (Figure 9). However, with increase in the supply airflow rate (increase in the cooling capacity) thermal gradient in the room decrease which results in reducing the acceleration of the centerline velocity (Figure 10c). In the case of 400 cfm (188.8 L/s) supply airflow rate, the peak centerline velocity reaches about 2.2 times (120%) of the initial discharge velocity at about 60% distance from the ceiling. Whereas in the cases of 600 and 800 cfm (283.2 and 377.6 L/s), the peak centerline velocity reaches abouthttps://www.ashrae.org/