{"title":"Jet injection and spout formation in a fluidized bed","authors":"Hamidreza Khakpour, Navid Mostoufi, Rahmat Sotudeh-Gharebagh, Reza Zarghami","doi":"10.1016/j.ijmultiphaseflow.2024.104994","DOIUrl":null,"url":null,"abstract":"<div><p>A single jet was studied in a rectangular fluidized bed by analyzing the pressure fluctuations data to characterize the jet hydrodynamics. The bed contained with glass beads of different mean sizes (450, 650, and 920 µm) as well as pharmaceutical pellets (920 µm). The analysis of the pressure fluctuation data was performed using the power spectral density function (PSDF) and discrete wavelet transforms technique. This study investigated how the flow regime changed from a jet in a fluidized bed to a spouted regime as the gas injection velocity was increased. Increasing the mean particle size led to an increase in the minimum spouting velocity. The minimum spouting velocity for 450, 650, and 920 μm glass bead particles and for 920 μm pharmaceutical pellets were determined to be 32.47 m s<sup>-1</sup>, 38.66 m s<sup>-1</sup>, 44.78 m s<sup>-1</sup>, and 44.47 m s<sup>-1</sup>, respectively. The study also examined how the dominant frequency of the various particles and the energy percentage of scales changed with increasing injection velocities. The ratio of energy percentages of meso-scale changes as the injection velocity increases and these changes were used to estimate the minimum spouting velocity. Wavelet sub-signals analysis revealed that the Daubechies 2 (DB2) wavelet was the most effective at capturing the characteristics of the jet. Based on the Shannon entropy of the approximate coefficients, the wavelet analysis showed that 11 levels of decomposition were required. By combining the wavelet analysis and PSDF, a more detailed analysis of the meso-scale was achieved. This study provided valuable insights into the behavior of jets and spouts in fluidized beds, which can greatly contribute to the optimization of a jet in fluidized beds and spout-fluidized beds by enhancing our understanding of jet behavior in such environments.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"181 ","pages":"Article 104994"},"PeriodicalIF":3.6000,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Multiphase Flow","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0301932224002714","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MECHANICS","Score":null,"Total":0}
引用次数: 0
Abstract
A single jet was studied in a rectangular fluidized bed by analyzing the pressure fluctuations data to characterize the jet hydrodynamics. The bed contained with glass beads of different mean sizes (450, 650, and 920 µm) as well as pharmaceutical pellets (920 µm). The analysis of the pressure fluctuation data was performed using the power spectral density function (PSDF) and discrete wavelet transforms technique. This study investigated how the flow regime changed from a jet in a fluidized bed to a spouted regime as the gas injection velocity was increased. Increasing the mean particle size led to an increase in the minimum spouting velocity. The minimum spouting velocity for 450, 650, and 920 μm glass bead particles and for 920 μm pharmaceutical pellets were determined to be 32.47 m s-1, 38.66 m s-1, 44.78 m s-1, and 44.47 m s-1, respectively. The study also examined how the dominant frequency of the various particles and the energy percentage of scales changed with increasing injection velocities. The ratio of energy percentages of meso-scale changes as the injection velocity increases and these changes were used to estimate the minimum spouting velocity. Wavelet sub-signals analysis revealed that the Daubechies 2 (DB2) wavelet was the most effective at capturing the characteristics of the jet. Based on the Shannon entropy of the approximate coefficients, the wavelet analysis showed that 11 levels of decomposition were required. By combining the wavelet analysis and PSDF, a more detailed analysis of the meso-scale was achieved. This study provided valuable insights into the behavior of jets and spouts in fluidized beds, which can greatly contribute to the optimization of a jet in fluidized beds and spout-fluidized beds by enhancing our understanding of jet behavior in such environments.
期刊介绍:
The International Journal of Multiphase Flow publishes analytical, numerical and experimental articles of lasting interest. The scope of the journal includes all aspects of mass, momentum and energy exchange phenomena among different phases such as occur in disperse flows, gas–liquid and liquid–liquid flows, flows in porous media, boiling, granular flows and others.
The journal publishes full papers, brief communications and conference announcements.