# Numerical Simulation and Optimization of the Airflow Field of a Forage Drum Mower
## 4 Results and Discussion
### Optimal Parameters and Regression Models  
In the above experiments, these three evaluation indexes are all expected to be large. The optimal combination of parameters was determined by using the integrated balance method, with consideration given to the results of range analysis and variance analysis. Factor A, i.e., the disc speed, exerts a significant effect on all three evaluation indexes, and the superior level is 3 for all three evaluation indexes. Therefore, the optimal parameter for disc speed is determined to be 2000 \(r/\text{min}\). Factor B, i.e., blade twist angle, has no significant effect on the three evaluation indexes. The optimal level of blade twist angle is 3 for the velocity of the lifting and gathering airflow, and the superior level is 1 for the velocity of the feeding airflow. After careful consideration, the optimal parameter of the \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Indexes** & **Test NO.** & **A** & **B** & **C** & **D** & \(v_{g}\)**(/m/s)** & \(v_{l}\)**(/m/s)** & \(v_{p}\)**(/m/s)** \\ \hline \multirow{9}{*}{\(v_{g}\)} & 1 & 1 & 1 & 1 & 1 & 3.024 & 3.915 & 7.3798 \\  & 2 & 1 & 2 & 2 & 2 & 3.051 & 5.3464 & 8.6026 \\  & 3 & 1 & 3 & 3 & 3 & 3.289 & 5.011 & 8.356 \\  & 4 & 2 & 1 & 2 & 3 & 4.2509 & 6.228 & 9.7953 \\  & 5 & 2 & 2 & 3 & 1 & 3.2886 & 5.9595 & 9.0892 \\  & 6 & 2 & 3 & 1 & 2 & 4.2224 & 4.5995 & 9.0434 \\  & 7 & 3 & 1 & 3 & 2 & 3.927 & 6.6839 & 11.332 \\  & 8 & 3 & 2 & 1 & 3 & 4.6207 & 5.2443 & 10.581 \\  & 9 & 3 & 3 & 2 & 1 & 4.0266 & 7.782 & 10.960 \\ \hline \multirow{9}{*}{\(v_{g}\)} & \(K_{1}\) & 3.1213 & 3.7340 & 3.9557 & 3.4464 & & \\  & \(K_{2}\) & 3.9206 & 3.6534 & 3.7762 & 3.7335 & & \\  & \(K_{3}\) & 4.1914 & 3.8460 & 3.5015 & 4.0535 & & \\  & \(R\) & 1.0701 & 0.1926 & 0.4542 & 0.6071 & & \\ \hline \multirow{9}{*}{\(v_{l}\)} & \(K_{1}\) & 4.7575 & 5.6090 & 4.5863 & 5.8855 & & \\  & \(K_{2}\) & 5.5957 & 5.5167 & 6.4521 & 5.5433 & & \\  & \(K_{3}\) & 6.5701 & 5.7975 & 5.8848 & 5.4944 & & \\  & \(R\) & 1.8126 & 0.2808 & 1.8659 & 0.3911 & & \\ \hline \multirow{9}{*}{\(v_{f}\)} & \(K_{1}\) & 8.1128 & 9.5026 & 9.0017 & 9.1433 & & \\  & \(K_{2}\) & 9.3093 & 9.4245 & 9.7862 & 9.6596 & & \\ \cline{1-1}  & \(K_{3}\) & 10.958 & 9.4534 & 9.5927 & 9.5777 & & \\ \cline{1-1}  & \(R\) & 2.8457 & 0.0781 & 0.7846 & 0.5163 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results of Orthogonal Experiments and Range Analysis. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Indexes** & **Source of Variation** & \
\begin{tabular}{c} **Sum of** \\ **Squares** \\ \end{tabular} &
\begin{tabular}{c} **Degree of** \\ **Freedom** \\ \end{tabular} & **Mean Square** & \(F\)**Values** & \(p\)**Values** \\ \hline \multirow{9}{*}{\(v_{g}\)} & Disc speed & 1.857 & 2 & 0.928 & 33.096 & 0.0293 \({}^{*}\) \\  & Disc tilt angle & 0.314 & 2 & 0.157 & 5.593 & 0.1517 \\  & Number of guide plates & 0.553 & 2 & 0.276 & 9.862 & 0.0921 \\  & Error & 0.056 & 2 & 0.028 & & \\  & Total & 128.97 & 9 & & & \\ \hline \multirow{9}{*}{\(v_{l}\)} & Disc speed & 4.937 & 2 & 2.4688 & 40.1813 & 0.0243 \({}^{*}\) \\  & Disc tilt angle & 5.489 & 2 & 2.7448 & 44.6732 & 0.0219 \({}^{*}\) \\ \cline{1-1}  & Number of guide plates & 0.272 & 2 & 0.1362 & 2.2171 & 0.3108 \\ \cline{1-1}  & Error & 0.122 & 2 & 0.0614 & & \\ \cline{1-1}  & Total & 297.217 & 9 & & & \\ \hline \multirow{9}{*}{\(v_{f}\)} & Disc speed & 12.249 & 2 & 6.124 & 1309.118 & 0.0008 \({}^{**}\) \\ \cline{1-1}  & Disc tilt angle & 1.002 & 2 & 0.501 & 107.119 & 0.0092 \({}^{**}\) \\ \cline{1-1}  & Number of guide plates & 0.462 & 2 & 0.231 & 49.380 & 0.0198 \({}^{*}\) \\ \cline{1-1}  & Error & 0.009 & 2 & 0.0047 & & \\ \cline{1-1}  & Total & 819.179 & 9 & & & \\ \hline \end{tabular} Note. \({}^{*}\) and \({}^{**}\) indicated significance at 0.05 and 0.01 levels, respectively.  
\end{table} 
Table 3: Analysis of Variance for Orthogonal Experiments. blade twist angle is determined to be 8\({}^{\circ}\).