Research On The Flow Characteristics And Overall Removal Efficiency Optimization Of Reverse Blowing Pickup Mouth For A Light Sweeper

Sweeper,which uses the working principle of negative pressure,is a new type of city environmental protection machine. And the key to determine the dust removal performance is the dust removal efficiency of pickup mouth. According to the cooperation projects “6t dry road sweeper development and its dust removal technology research” and “16t dry-wet dualpurpose sweeper design”. It is studied that the influence of the expending zone structure size and parameters on the flow field calculation results. Finally, the optimum expending zone structure is obtained. The regression equation, which expresses the influence of Outlet diameter、Outlet inclination angle and the front baffle inclination angle on the average velocity of front narrow, is proposed. Moreover, the regression equation, which expresses the influence of reverse flow rate、pressure drop and sweeper-traveling speed on the average velocity of front narrow, is also proposed. The best structure size and operation parameters that combined with the regression equation are put forward. The followings are the results obtained in this work:The expending zone structure size and parameters about the flow field calculation of the CFD are studied with the reverse blowing pickup mouth structure. The results show that the results have implications for simulation calculation of expending zone parameters, and each parameter has its corresponding threshold. If the structure parameter is greater than the corresponding threshold, the calculation result is not affected. The flow field distribution characteristics have no distinct difference with expending zone corner or not. Expending zone that has corner can be used if high accuracy requirement is needed. While, no corner expending zone model is recommended in practical engineering, in order to reduce the amount of grid computing and shorten the calculation time.Comparative analysis results are discussed between the structure and non-structure grid of reverse blowing pickup mouth based on expending zone parameters obtained above. At the same time, the wall function has a certain effect on the internal flow calculation of the reverse blowing pickup mouth. Scalable wall functions are recommended because of the robustness on the calculation results. On this basis, simulation method of the reverse blowing pickup mouth is introduced in detail, and simulation results are validated with enterprise test data. All the steps what we have done above are to prove the feasibility of processing model. The sucking condition of solid dust particles and big particles is discussed, and the different particle size and large size dust particles object how to start moving are also calculated. The calculated results above provide theoretical references for the design of the reverse blowing pickup mouth.It is analyzed that the influence of Outlet diameter、Outlet inclination angle and the front baffle inclination angle on the average velocity of front narrow. The three structural parameters above are analyzed based on uniform design and regression analysis, and the research shows that the structure parameter has certain effect on the reverse blowing pickup mouth performance. Effects of factors on the dust removal performance are as follows: Outlet diameter has greatest influence on the dust removal performance, Outlet inclination angle has least influence and the front baffle inclination angle is medium. Effects of structure parameters interaction effects on the dust removal performance are as follows: the interaction effects between Outlet diameter and the front baffle inclination angle have the greatest impact, the interaction effects between Outlet inclination angle and the front baffle inclination angle interaction is medium, the interaction effects between Outlet diameter and Outlet inclination angle have the weak impact and it is also negligible. The structure improvement scheme is proposed based on the various parameters, and the virtual prototype is established to verify the feasibility.The improvement of dust removal performance includes the structure parameters and the operating parameters. The influence of reverse flow rate、pressure drop and sweeper-traveling speed are adjusted based on the optimum structure parameters. The three operating parameters above are analyzed based on uniform design and regression analysis, and the research shows that the operating parameter has certain effect on the reverse blowing pickup mouth performance. Effects of factors on the dust removal performance are as follows: reverse flow rate has greatest influence on the dust removal performance. Effects of operating parameters interaction effects on the dust removal performance are as follows: the interaction effects between reverse flow rate and sweeper-traveling speed have the greatest impact, the interaction effects between reverse flow rate and the pressure drop interaction is medium, the interaction effects between pressure drop and sweeper-traveling speed have the weak impact and it is also negligible. The operating improvement scheme is proposed based on the various parameters, and it is also verified the feasibility with the virtual prototype that established according to the structure improvement scheme above.Model machine is manufactured and tested in order to validate the calculation accuracy inside the internal flow field of virtual prototype and the dust removal performance. Test results and the CFD simulation results are in good agreement. It also shows that CFD optimization research technology of reverse blowing pickup mouth is a kind of effective method, and it provides a reference design for reverse blowing pickup mouth at the same time.