This paper studies the flow field of a new type of submersible mixer with two impellers and six blades in the wastewater treatment pool by using large-scale software, such as Pro/engineering, FLUENT 15.0 and ICEM. After that, it numerically simulates the wastewater treatment pool using the RNG k-ε turbulent model and the mobile coordinate measuring system, and analyzes the macro fluid field and flow field distribution of the sections. The fluid in the wastewater treatment pool can be propelled by the new type of mixer, and the fluid flows along the axial direction of the submersible mixer and diffuses radially. Eight water and sludge cycles are formed in the pool, and the fluid in the pool forms two high-flow region and eight low-flow regions. The velocity distribution in the pool is distributed symmetrically along the plane Z=0m and the plane X=1.75m. As the new type of mixer is installed close to the bottom of the pool, the position with the maximum velocity offsets gradually to the bottom of the pool with the increasing distance to the impeller. The new type of mixer is different from the traditional submersible mixer, in that the fluid mixed by the new one can circulate fully on both sides of the submersible mixer. Consequently, this new type of submersible mixer can mix more fluid, and there will be a smaller dead zone in the whole pool with less sludge at the bottom. This simulation method can guide the application of mixers in the practical wastewater treatment.
new type of mixer, CFD, flow filed, simulation, fluid dynamics
This work was supported by Natural Science Foundation of Jiangsu Province (Grant Nos.: BK20160521, NO.: BK20170554), Jiangsu Postdoctoral Funding Program (2018K017A) Key Development Project of Zhenjiang City (Grant Nos.: SH2017049), the National Natural Science Foundation of China (Grant Nos.: 31601676)
 Beltaos S, Rajaratnam N. (1973). Plane turbulent impinging jets. Journal of Hydraulic Research 11(1): 29-59. https://doi.org/10.1080/00221687309499789
 Bradbury LJS. (1972). The impact of an axisymmetric jet onto a normal ground. Aeroautical Quarterly 23: 141-147. https://doi.org/10.1017/S0001925900006016
 Lan ZY. (1997). Impinging jet. Beijing: Ocean press.
 Tian F, Shi WD, Chen B, Cao WD. (2010). Study on installation position of sewage treatment mixer. ASME FEDSM2010 1: 329-334. https://doi.org/10.1115/FEDSM-ICNMM2010-30988
 Dong ZY. (2005). Jet mechanics. Beijing: Science Press.
 Tian F, Shi WD, Cao WD, Zhang DS, Li W. (2008). Inner flow of new type streamline shape XCK mixer with two blades. Drainage and Irrigation Machinery 26(6): 6-9.
 Shi WD, Zhang L, Chen B, Jiang T, Zhang H. (2012). Influence of gap on pressure pulsation and radial force of centrifugal pumps. Journal of Drainage and Irrigation Machinery Engineering 30(5): 260-264.
 Guo B., Liu HL, Tan MG. (2016). Effect of circumferential setting position of diffuser in concentric volute on impeller radial thrust in centrifugal pump. Journal of Drainage and Irrigation Machinery Engineering 34(3): 204-209.
 Lee SL. (1965). Axisymmetrical turbulent swirling jet. Journal of Applied Mechanics 32(2): 258-262. https://doi.org/10.1115/1.3625793
 Wang W, Shi WD, Jiang XP. (2016). Optimization design of multistage centrifugal pump impeller by orthogonal experiment and CFD. Journal of Drainage and Irrigation Machinery Engineering 34(3): 191-197.
 Loitsyanskii LG. (1953). The propagation of a twisted jet in an unbounded space filled with the same fluid. I Prikladnaya Matetnatiza Mekhanika 17: 3-16.
 Tian F, Shi WD, Chen B. (2011). Flow Analysis and Measurement of Wastewater Treatment Mixer with Dome. China Academic Journal Electronic Publishing House 42(3): 96-99.
 Bosco F, Mollea C, Marmo L. (2018). Application of scenedesmus obliquus in the treatment of a real wastewater. Chemical Engineering Transactions 64: 475-480. https://doi.org/10.3303/CET1864080
 Sawasdee V, Pisutpaisal N. (2018). Microbial community from tannery wastewater in microbial fuel cell. Chemical Engineering Transactions 64: 397-402. https://doi.org/10.3303/CET1864067
 Donaldson C, Snedeker RS. (1971). A study of free jet impingement. Part 1: Mean properties of free and impinginq jets. J. Fluid Mech 15: 337-367.
 Tian F, Shi WD, Lu X, Chen B, Ou M. (2012). Numerical simulation of the submersible mixer with three blades. Journal of Drainage and Irrigation Machinery Engineering 30(1): 11-14.
 Tian F, Shi WD, Cao W, Chen B, Zhang D. (2009). Numerical simulation of mixer power consumptions in different ponds. Journal of Drainage and Irrigation Machinery Engineering 27(3): 140-143.
 Li WQ, Li W, Shi WD. (2016). A review of engine cooling water pump. Journal of Drainage and Irrigation Machinery Engineering 34(1): 9-17.
 Tian F, Shi WD, Jiang H. (2014). Matching criterion of submersible mixer and pool. Advances in Mechanical Engineering (4): 1-5. https://doi.org/10.1155/2014940904
 Cheng QG, Wu SF, Wu YL, Liu SH, Zhang YC. (2006) Numerical prediction of cavitating flow in a Kaplan turbine. Journal of Engineering Thermophysics 27(5): 769-771.
 Tian F, Shi WD, Jiang H, Zhang QH, (2014). A study on two-phase flow of multiple submersible mixers based on rigid-lid assumption. Advances in Mechanical Engineering (5): 1-6. https://doi.org/10.1155/2014/531234
 Xu YH, Zhang QH, Shi WD. (2016). Design of new type diffuser of plastic well pump and pulsation characteristics of internal pressure. Journal of Drainage and Irrigation Machinery Engineering 34(1): 18-25.
 Ross DG. (1978). On integral method solutions for modeling swirling jets and plumes. Appl. Sci. Res. 34(2-3): 273-298.
 Steiger MH, Bloom MH. (1962). Axially symmetric laminar free mixing with large swirl. Journal of Heat Transfer. Trans, ASME, Series C 83: 370-374. https://doi.org/10.1115/1.3684400
 Wang DX, Cao WD, Zhang YN. (2016). Effects of volute cross-section shape and impeller position on volute type axial flow pump performance. Journal of Drainage and Irrigation Machinery Engineering 34(2): 105-109.