# CFD Analysis and Validation of a Foreign Material Winnowing Machine for Pepper Harvester
## 4 Conclusions  
The present study measured terminal velocities of chili pepper fruits, branches, and leaves of two species. Aerodynamic analysis of winnower was conducted to develop a foreign material winnowing machine to be used after harvesting chili peppers. The performance of the winnower designed through the analysis was validated by conducting a CFD analysis and using a winnower test device. For terminal velocity measurement, species Jeokyoung and AR Legend suitable for mechanical harvesting were used as test samples. An aerodynamic analysis was conducted for chili pepper fruits and chili pepper branches freely falling into a collection tank at different wind speeds. The analysis result showed that chili pepper fruits were collected into the collection tank at a wind speed lower than 17.5 m/s and that chili pepper branches and chili pepper leaves were separated at speeds higher than 12.5 m/s. A winnower was designed using the analysis result. Results of a CFD analysis and a winnower test device were compared to evaluate the rotating speed and the performance of 0-, 3-, and 5-guide at the discharge port. Although the CFD analysis showed that discharged wind speeds were higher than those of the winnower test device by 0 to 2.4 m/s, it was thought to be an effective validation due to the simplification of the design model. As a result of comparing the CFD analysis of the winnower developed in the present study and the performance of the test device, the 3-guide and 5-guide conditions were found to be suitable with a rotating speed of 1800 RPM and a rotating speed of 2000 RPM. However, with the 5-guide, since the winnowing machine generates internal noise and vibration, the guide type must be selected, taking into account the 3-guide or the 5-guide when it is applied to a chili pepper harvester. The winnowing machine developed in this study can be verified through terminal velocity, aerodynamic analysis, CFD flow analysis, testing equipment, and then applied to the chili pepper harvester to reduce the additional workforce in the separation of foreign substances after mechanical harvesting. Therefore, the conditions analyzed in the present study must be verified through additional field tests after applying them to foreign material separation units of chili pepper harvesters.  
Conceptualization, S.-Y.S. and Y.C.; Experiments and data analyses, S.-Y.S. and D.-C.K.; Methodology, M.-H.K.; Writing--original draft preparation, S.-Y.S. and Y.C.; Project administration, Y.C.; Writing--review and editing, Y.C., D.-C.K. and M.-H.K. All authors have read and agreed to the published version of the manuscript.  
This work was supported by a grant (716001-7) of the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, and Forestry (IPET) through the Agriculture, Food, and Rural Affairs Convergence Technologies Program for Educating Creative Global Leader Program funded by the Ministry of Agriculture, Food, and Rural Affairs (MAFRA), Republic of Korea. It was also supported by a grant (NRF-2021R1G1A1012778) of the National Research Foundation of Korea (NRF) funded by the Korean government (MSIT, Ministry of Science and ICT). This research was supported by \"Research Base Construction Fund Support Program\" funded by Jeonbuk National University in 2022.  
Not applicable.  
The authors declare no conflict of interest.