## 3 Results and Discussion  
### Individual Sprinklers  
Individual RSPSs distributed most water around the sprinkler (Figure 5a-c), and the application intensity declined gradually from the center to the edge of the circular wetted area. However, individual FSPSs distributed most water in a ring-shaped region, centered on the location of the sprinkler, and the applied water volumes around the sprinkler were lower than in the ring-shaped region (Figure 5d-f). The low application area of the FSPS was increased with the increase in nozzle diameter. There was almost no applied water over the area where sprinkler located in the case of the 6.76-mm nozzle. Figure 5: Water distribution characteristics of individual rotating spray plate sprinklers (RSPSs) and fixed spray plate sprinklers (FSPSs). The figures in different columns and rows indicate different sprinkler types (RSPS and FSPS) and nozzle diameters (2.78, 4.76, and 6.75 mm): RSPS—2.78 (**a**), RSPS—4.76 (**b**), RSPS—6.75 (**c**), FSPS—2.78 (**d**), FSPS—4.76 (**e**) and FSPS—6.75 (**f**). The sprinklers also showed different radial water distribution characteristics: RSPSs showed single-peak patterns, while FSPSs showed double-peak patterns (Figure 6). With an increase of nozzle diameter, the double-peak patterns of the FSPS's radial water distribution became more obvious. Thus, the water distributions of FSPSs and RSPSs showed differing water distribution characteristics. It could be seen that the locations of intensively applied area for FSPSs were about 2, 3.5 and 4 m away from sprinklers for 2.78-, 4.76-, and 6.75-mm nozzles respectively. It is noteworthy that a significantly high of application rate appeared within the range about \(\pm\)2.75 m away from the RSPS (Figure 6a, blue line), when the 6.75-mm nozzle was installed. The wetted radii for RSPSs and FSPSs ranged from 4.88 to 7.05 m and from 5.02 to 6.85 m, respectively. The wetted radii of RSPSs and FSPSs were both enlarged significantly with an increase in nozzle diameter (Figures 5 and 6; Table 5). For the 4.76- and 6.75-mm nozzle diameters, the wetted radii of RSPSs were higher than those of FSPSs. The wetted radii of RSPSs were slightly lower than previous results [49], while those of FSPSs were slightly higher than previous results [20; 30]. These could be attributed to different sprinkler height and pressure [50], which could influence the wetted radii. These differing water distribution characteristics between RSPSs and FSPSs were attributable primarily to the different structures of the spray plates (Table 2). The blue spray plate used for the FSPS has 36 grooves with unique shape, angle and deepness, however the brown spray plate used for the RSPS has 12 grooves with multiple shapes, angles, and depth (Table 2), including the specialty of rotatability [20; 49]. Thus the RSPS could generate multiple streams. This should be beneficial for the water distribution. Besides, the brown spray plate used in current experiments had deeper grooves than the blue spray plate. Our results are also in accord with [PERSON] et al. who reported that the deeper grooves in spray plate could bring longer wetted radii [20]. The obtained results were also consistent with findings based on radial features of FSPS [20; 21] and RSPS [31]. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Sprinkler**} & \multicolumn{3}{c}{**Wetted Radius (m)**} \\ \cline{2-4}  & **2.78-mm-Diameter Nozzle** & **4.76-mm-Diameter Nozzle** & **6.75-mm-Diameter Nozzle** \\ \hline RSPS & 4.88 \(\pm\) 0.22\(a\) & 6.40 \(\pm\) 0.11\(b\) & 7.05 \(\pm\) 0.09\(c\) \\ FSPS & 5.02 \(\pm\) 0.06\(a\) & 6.33 \(\pm\) 0.07\(b\) & 6.85 \(\pm\) 0.15\(c\) \\ \hline \hline \end{tabular} Note: Lowercase in differences represents significant different level among nozzle diameters (\(P<\) 0.05).  
\end{table} 
Table 5: Wetted radii of rotating spray plate sprinklers (RSPSs) and fixed spray plate sprinklers (FSPSs) with nozzles of differing diameters installed.