Thesis
The Role of Humidity and Stokes Number for Aggregation in Particle-Laden Jet Flow and an Investigation of Entrainment for Submerged Gas Jets
Washington State University
Master of Science (MS), Washington State University
2023
DOI:
https://doi.org/10.7273/000005276
Abstract
Ash transport and deposition from volcanic eruptions can pose significant hazards to human health and infrastructure. Particle size plays an important role in modeling efforts to predict ash fall because large particles fall faster than small particles and deposit closer to the vent exit. Aggregation, or the formation of individual particles into clusters, can greatly impact ash particle size. This study investigates the influence of humidity and Stokes number on aggregation within a particle-laden jet flow. These factors have been previously shown to be relevant to aggregation in prior studies, but have not been studied extensively within jet flow. To address this, a vertical air jet was seeded with hollow glass and nickel particles at typical mass loadings of ϕ =1.1±0.5%. Aggregates were examined over a range of Reynolds numbers (Re=5500-11000), Stokes numbers (St=1.0-9.4), and relative humidities (RH=40-75%). The median size of collected nickel particles at St = 9.4 and RH = 75% increased by 50% from lower humidity trials at RH = 40 - 60%, while the hollow glass particles at St = 1.0 did not show sensitivity to humidity from RH = 40-75%.
Separately, submarine volcanic eruptions can exhibit vastly different behavior than sub-aerial eruptions. The entrainment of water into these submerged gas jets is a critical factor in predicting their behavior. A preliminary analysis of entrainment for an air jet submerged in water is conducted, over a range of Reynolds numbers (Re=500-1500) and nozzle diameters (d = 1/8-1/4”). On average, increasing the Reynolds number by 75% decreased the mass entrainment coefficient (Ce) 30% over these flow conditions. Doubling the nozzle diameter from 1/8” to 1/4” and holding the Reynolds number constant yielded a decrease of ∼17% in Ce. The limitations of the current apparatus are discussed, and suggestions for future experimental designs are given.
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Details
- Title
- The Role of Humidity and Stokes Number for Aggregation in Particle-Laden Jet Flow and an Investigation of Entrainment for Submerged Gas Jets
- Creators
- Peter A. Newman
- Contributors
- Stephen A. Solovitz (Advisor)Hua Tan (Committee Member)Linda Chen (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Engineering and Computer Science (VANC), School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 93
- Identifiers
- 99901019534401842
- Language
- English
- Resource Type
- Thesis