Dispersion characteristics of typical non-spherical particles in a high-speed round jet

HUANG Wenshi; WU Yuxin; FENG Lele; ZHANG Man; ZHANG Yang

doi:10.16511/j.cnki.qhdxxb.2020.25.015

PDF(1295 KB)

Journal of Tsinghua University(Science and Technology) ›› 2020, Vol. 60 ›› Issue (6) : 485-492. DOI: 10.16511/j.cnki.qhdxxb.2020.25.015

SPECIAL SECTION: FUNDAMENTAL AND APPLICATION OF MULTIPHASE FLOW IN ENERGY

Dispersion characteristics of typical non-spherical particles in a high-speed round jet

{{article.zuoZhe_EN}}

Author information +

History +

Abstract

Moderate and intense low-oxygen dilution (MILD) combustion is appealing due to its uniform heat flux profile and low NO_x emissions. The new generation of MILD coal combustion burners use high-speed jets with strong turbulent mixing. The dispersion of the coal particles in the high-speed jet is a key issue in such systems. There are many studies of the dispersion of spherical particles in particle-laden jets in the literature. However, the dispersion of fossil fuel particles, which are typically not spherical, differs from that of spherical particles, so the dispersion characteristics of these non-spherical particles in high-speed jets still deserves further study. This study used glass beads, glass powder and pulverized coal as the solid phase in a high-speed two-phase round jet for a wide range of Reynolds numbers. The particle concentrations, velocities and turbulent kinetic energy distributions were measured for various particle sphericities, sizes and jet velocities using laser phase-Doppler anemometry (PDA). The results show that the concentration, velocity and turbulent kinetic energy distribution characteristics of non-spherical particles are similar to those of smaller spherical particles. However, the non-spherical particle dispersion cannot be accurately characterized by just the Stokes number since the lift can strongly affect the particle dispersion. Non-spherical particles are more easily dispersed than spherical particles, mainly due to a significant increase in the radial turbulent kinetic energy. Increasing the jet velocity promotes the shear layer growth and radial dispersion of the particles and more strongly influences the non-spherical particle dispersion than the particle size or sphericity.

Key words

particle-laden flow / high-speed jet / particle dispersion / sphericity

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

HUANG Wenshi, WU Yuxin, FENG Lele, ZHANG Man, ZHANG Yang. Dispersion characteristics of typical non-spherical particles in a high-speed round jet[J]. Journal of Tsinghua University(Science and Technology). 2020, 60(6): 485-492 https://doi.org/10.16511/j.cnki.qhdxxb.2020.25.015

References

[1] GALLETTI C, PARENTE A, TOGNOTTI L. Numerical and experimental investigation of an MILD combustion burner[J]. Combustion and Flame, 2007, 151(4):649-664.
[2] LI P F, MI J C, DALLY B B, et al. Progress and recent trend in MILD combustion[J]. Science China Technological Sciences, 2011, 54(2):255-269.
[3] ZHANG H, YUE G X, LU J F, et al. Development of high temperature air combustion technology in pulverized fossil fuel fired boilers[J]. Proceedings of the Combustion Institute, 2007, 31(2):2779-2785.
[4] WANG F F, LI P F, MI J C, et al. A refined global reaction mechanism for modeling coal combustion under moderate or intense low-oxygen dilution condition[J]. Energy, 2018, 157:764-777.
[5] AHN S, TANNO K, WATANABE H. Numerical analysis of particle dispersion and combustion characteristics on a piloted coaxial pulverized coal jet flame[J]. Applied Thermal Engineering, 2017, 124:1194-1202.
[6] CHEN Z C, LI Z Q, WANG F Q, et al. Gas/particle flow characteristics of a centrally fuel rich swirl coal combustion burner[J]. Fuel, 2008, 87(10-11):2102-2110.
[7] 崔金雷, 王希麟, 容易. 颗粒在气固两相圆湍射流近场截面对气相的影响[J]. 清华大学学报(自然科学版), 2005, 45(8):1088-1090. CUI J L, WANG X L, RONG Y. Particle effect on the gas phase in a near field cross section in gas-solid round turbulent jets[J]. Journal of Tsinghua University (Science and Technology), 2005, 45(8):1088-1090. (in Chinese)
[8] 燕小芬, 王希麟. 不同材料颗粒对两相湍射流场的调制规律[J]. 清华大学学报(自然科学版), 2007, 47(8):1375-1379. YAN X F, WANG X L. Effect of different material particle on the modulation of two-phase turbulent jets[J]. Journal of Tsinghua University (Science and Technology), 2007, 47(8):1375-1379. (in Chinese)
[9] FLECKHAUS D, HISHIDA K, MAEDA M. Effect of laden solid particles on the turbulent flow structure of a round free jet[J]. Experiments in Fluids, 1987, 5(5):323-333.
[10] 罗坤, 樊建人, 郑水华, 等. 圆湍射流中的拟序结构和颗粒弥散[J]. 化工学报, 2006, 57(6):1329-1333. LUO K, FAN J R, ZHENG S H, et al. Coherent structures and particle dispersion in a turbulent round jet[J]. CIESC Journal, 2006, 57(6):1329-1333. (in Chinese)
[11] 崔金雷, 王希麟, 容易. 气固两相圆湍射流颗粒对气相流动的影响[J]. 工程热物理学报, 2005, 26(6):974-976. CUI J L, WANG X L, RONG Y. Influence of the dispersed phase on the gas phase in gas-particle turbulent jets[J]. Journal of Engineering Thermophysics, 2005, 26(6):974-976. (in Chinese)
[12] 白建基, 郑水华, 樊建人, 等. Reynolds数对气固两相圆湍射流影响的实验研究[J]. 浙江大学学报(工学报), 2006, 40(3):433-437. BAI J J, ZHENG S H, FAN J R, et al. Experiment study on effects of Reynolds number on gas-particle turbulent round jet[J]. Journal of Zhejiang University (Engineering Science), 2006, 40(3):433-437. (in Chinese)
[13] LAU T C W, NATHAN G J. The effect of Stokes number on particle velocity and concentration distributions in a well-characterised, turbulent, co-flowing two-phase jet[J]. Journal of Fluid Mechanics, 2016, 809:72-110.
[14] 周华辉, 许建良, 李伟锋, 等. 稠密气固两相同轴射流颗粒弥散特性[J]. 化工学报, 2009, 60(2):332-337. ZHOU H H, XU J L, LI W F, et al. Particle dispersion characteristics of dense gas-solids two-phase coaxial jets[J]. CIESC Journal, 2009, 60(2):332-337. (in Chinese)
[15] ZHANG W, TAINAKA K, AHN S, et al. Experimental and numerical investigation of effects of particle shape and size distribution on particles' dispersion in a coaxial jet flow[J]. Advanced Powder Technology, 2018, 29(10):2322-2330.
[16] 由长福, 祁海鹰, 徐旭常. 气固两相流动中非球形颗粒所受曳力的数值研究[J]. 化工学报, 2003, 54(2):188-191. YOU C F, QI H Y, XU X C. Numerical simulation of drag force on non-spherical particle in gas-particle two-phase flow[J]. CIESC Journal, 2003, 54(2):188-191. (in Chinese)
[17] HARTMAN M, TRNKA O, SVOBODA K. Free settling of nonspherical particles[J]. Industrial & Engineering Chemistry Research, 1994, 33(8):1979-1983.
[18] KNOLL M, GERHARDTER H, PRIELER R, et al. Particle classification and drag coefficients of irregularly-shaped combustion residues with various size and shape[J]. Powder Technology, 2019, 345:405-414.
[19] NJOBUENWU D O, FAIRWEATHER M. Dynamics of single, non-spherical ellipsoidal particles in a turbulent channel flow[J]. Chemical Engineering Science, 2015, 123:265-282.
[20] HÅKANSSON K M O, KVICK M, LUNDELL F, et al. Measurement of width and intensity of particle streaks in turbulent flows[J]. Experiments in Fluids, 2013, 54(6):1555.
[21] 冯乐乐, 王景玉, 吴玉新, 等. 颗粒特性对撞击分离器性能影响的实验与数值研究[J]. 化工学报, 2018, 69(8):3348-3355. FENG L L, WANG J Y, WU Y X, et al. Experimental and numerical investigation on effect of particle characteristics on performance of plate-type impact separator[J]. CIESC Journal, 2018, 69(8):3348-3355. (in Chinese)
[22] 邱建荣, 马毓义. 用PDA测量两相湍流流场时固体粒子的选择[J]. 气动实验与测量控制, 1994, 8(1):54-59. QIU J R, MA Y Y. Choice of solid particles during measuring gas-solid two-phase turbulent flow field with particle dynamic analyzer[J]. Aerodynamic Experiment and Measurement & Control, 1994, 8(1):54-59. (in Chinese)
[23] 刘虎. PDA接收方式和参数对气固两相流场测量影响的研究[D]. 哈尔滨:哈尔滨工业大学, 2006. LIU H. Study on the influences of the reception mode and parameters of PDA on the measure of gas-solid flow field[D]. Harbin:Harbin Institute of Technology, 2006. (in Chinese)
[24] BACHALO W D, HOUSER M J. Phase/Doppler spray analyzer for simultaneous measurements of drop size and velocity distributions[J]. Optical Engineering, 1984, 23(5):583-590.
[25] CROWE C T, GORE R A, TROUTT T R. Particle dispersion by coherent structures in free shear flows[J]. Particulate Science and Technology, 1985, 3(3-4):149-158.
[26] 王兵, 张会强, 王希麟, 等. 湍流分离流动中的颗粒弥散机制[J]. 清华大学学报(自然科学版), 2003, 43(11):1507-1510. WANG B, ZHANG H Q, WANG X L, et al. Particle dispersion mechanism in turbulent separated flow[J]. Journal of Tsinghua University (Science and Technology), 2003, 43(11):1507-1510. (in Chinese)
[27] HAIDER A, LEVENSPIEL O. Drag coefficient and terminal velocity of spherical and nonspherical particles[J]. Powder Technology, 1989, 58(1):63-70.
[28] LAU T C W, NATHAN G J. Influence of Stokes number on the velocity and concentration distributions in particle-laden jets[J]. Journal of Fluid Mechanics, 2014, 757(6):432-457.
[29] LEE BLACK D, MCQUAY M Q. Laser-based particle measurements of spherical and nonspherical particles[J]. International Journal of Multiphase Flow, 2001, 27(8):1333-1362.
[30] ZHANG W, WATANABE H, KITAGAWA T. Numerical investigation of effects of particle shape on dispersion in an isotropic turbulent flow[J]. Advanced Powder Technology, 2018, 29(9):2048-2060.