# Performance Development of Fluidic Oscillator Nozzle for Cleaning Autonomous-Driving Sensors
## 4 Conclusions  
This study determined the main design factors of the sweeping angle and frequency of the autonomous-driving sensor-cleaning nozzle through unsteady-state flow analysis. The sweeping angle and frequency were compared based on design factors. We optimized the sweeping angle and frequency through simulation and experiment by combining models that showed excellent performance. The following conclusions were drawn. 1. Results of analyzing the pressure condition as a variable in the base model showed that the frequency doubled as the inlet pressure increased from 1.5 to 5.0 bar. However, the pressure variation had a minor effect on the sweeping angle. The inlet pressure was considered as the major factor affecting the frequency. 2. The highest sweeping angle was 70\({}^{\circ}\) for R6, and the highest frequency was 333 Hz for R8. Therefore, it was difficult to analyze the effect because the frequency performance improvement of the radius of outlet models compared to the base model was less than 3%. Excellent performance improvement was obtained at approximately 30% increment in the sweeping angle of the R6 model. It is believed that the radius variable in these outlets has a major effect on the sweeping angle. 3. Analysis of giving the radius variable to the outlet curvature showed that the highest sweeping angle was 63.5\({}^{\circ}\) in RC10, and the frequency was almost constant. Therefore, as the radius variable at the outlet decreases, the sweeping angle tends to increase. Compared to that of the base model, the sweeping angle of RC10 increased by 15%, showing excellent performance improvement. It is believed that the radius variable in this outlet curvature has a major effect on the sweeping angle. 4. Additional analysis was performed using the radius variables of the outlet and outlet curvature with the highest sweeping angle for each design variable. The highest sweeping angle was 75\({}^{\circ}\) for R8+RC10, and the frequency was almost constant. Compared to that of the base model, the angle of R8+RC10 increased by 39%, confirming excellent performance improvement. It is believed that the radius variable in this outlet curvature has an excellent effect on the sweeping angle. 5. To improve the accuracy of the analysis and confirm the physical phenomenon, models combining the radius variables of the outlet and outlet curvature were produced and tested. Comparing the experimental and analysis results, the error rate for the sweeping angle was within about 6%, which was close to the analysis; however, the error rate for the frequency was approximately 15%. In the case of frequency error, the values were different due to surface treatment and processing errors. Therefore, autonomous-driving sensor-cleaning nozzles must be manufactured with high accuracy. Figure 18: Error rate of simulation and experiment. (**a**) Frequency. (**b**) Sweeping angle. **Author Contributions:** Software, J.-H.C.; Validation, C.-H.K. ; Investigation, C.-H.K. ; Writing--original draft, C.-H.K. and J.-H.C.; Writing--review & editing, S.-Y.P. ; Supervision, S.-Y.P. ; Project administration, S.-Y.P. All authors have read and agreed to the published version of the manuscript. This research was supported by the Regional Innovation Strategy (RIS) through the (National Research Foundation of Korea NRF) grant funded by the Ministry of Education (2021 RIS-004) and by the Korea Basic Science Institute (National research Facilities and Equipment Center) grant funded by the Ministry of Education (2020R1A6C101A187). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The data that support the findings of this study will be available from the corresponding author upon reasonable request. The data are not publicly available due to privacy. **Conflicts of Interest:** Author [PERSON] was employed by the company Soosan CSM.