# Pure Electric Sweeper Performance Analysis and Test Verification of Dust Extraction Port
## 5 Conclusions  
Taking the company's self-developed Ruiqing S26 pure electric sweeper as the research object, the CFD method was used to analyse the influence of the structural parameters of the dust suction port and the operating parameters of the sweeper on the dust suction effect of the sweeper, and was verified through real vehicle tests. The specific conclusions are as follows.  
1. The turbulence model is used to simulate the air flow in the dust extraction port, and physical values such as air velocity and pressure are analysed. Here, we use the air velocity at the forward air surface and the pressure at the entrance of the exhaust pipe to reflect the characteristics of the flow field; then the Euler-Lagrange method is used to analyse the trajectory of the dust particles in the dust extraction port, and then the removal efficiency is evaluated by defining an expression for the removal efficiency. The simulation results show that, for the S26 pure electric road sweeper, the air speed at the entrance increases as the negative pressure increases; in addition, the air speed near the centre of the entrance is significantly stronger than that at the edges. Similarly, the pressure at the centre of the exit increases significantly as the negative pressure increases, and the pressure at the centre of the exit is also greater than that at the edges. In the simulation of the influence of driving speed and negative pressure on the removal efficiency, the removal efficiency tends to decrease with an increase of driving speed; at the same driving speed, the greater the negative pressure provided by the fan, the greater the removal efficiency will be. The maximum removal efficiency is 85%.
2. The structural parameters of the dust suction outlet will affect its flow field characteristics, which in turn affects the operational performance of the sweeper. The size of the inclination angle directly affects the internal energy loss of the dust suction port, the best structural parameter for the inclination angle of the forward air surface is 65\({}^{\circ}\). Increasing the diameter of the pipe will reduce the along-range loss between the import and export, but too large a pipe diameter will make the increased power and losses offset each other. The best structural parameter for the outlet diameter is 160 mm.
3. By comparing the test and simulation data, it was found that the simulation variation law was basically the same as the test results. The maximum error in the simulation results was 9.5% for the outlet air pressure at different negative pressures and 9.2% for the inlet air speed at different negative pressures. The main source of the error was that the location of the measurement points in the simulation did not exactly coincide with the location of the measurement points in the test, thus causing deviations. The maximum error in the simulation results for the removal efficiency at different driving speeds and negative pressures was 6.6%. The main source of error is that the initial settings of the particle phases in the simulations do not truly reproduce the physical properties of the particles at the time of the tests. However, the maximum error in these simulations was within 10%, which is the permissible error range.  
Methodology, J.Y.; software, J.Y.; validation, J.P.; formal analysis, J.Y.; investigation, J.Y.; resources, H.A. and J.W.; data curation, J.Y.; writing--original draft preparation, J.Y.; writing--review and editing, J.P.; funding acquisition and visualisation, J.P. All authors have read and agreed to the published version of the manuscript.  
This research was funded by National Natural Foundation of China (52005004) and The Major Science and Technology Special Projects in Anhui Province under grant (201903a05020061).  
Not applicable.  
**Acknowledgments:** The authors gratefully acknowledge the financial support by National Natural Foundation of China (52005004) and The Major Science and Technology Special Projects in Anhui Province under Grant (201903a05020061).