Location
Rolla, Missouri
Session Dates
11 Jun 1999 - 17 Jun 1999
Keywords and Phrases
Area Ratio; Flow Ratio; Entrainment; Momentum; Energy; Pressure; Jet Mixing Length; Mixing Velocity; Performance; Losses; Efficiency
Abstract
Jet fans or ductless fans have been analyzed using momentum and energy considerations. This analysis is necessary for the mechanisms of mixing between the jet primary flow and the secondary or induced stream to be understood. In each case it is possible to predict performance in terms of pressure, flow ratios and hence the percentage mechanical efficiency of the whole system using equations derived from momentum and energy principles. The analysis given is suitable for situations where jet fans are utilized as area boosters in a mine ventilation system and in longitudinal vehicular tunnel ventilation. The energy and momentum equations serve as important tools for the analysis and consider all losses in the system. The derivations identified a range of flow ratios of the induced flow to the jet flow which can be used to design effective ventilation systems incorporating jet fans. Each flow ratio (n) is associated with an optimum area ratio (µ) of the jet fan outlet to tunnel, or airway area, for maximum induction or entrainment of the secondary flow. It can be shown that there is an optimum set of conditions for jet fan performance which are explained in detail in the paper.
Department(s)
Mining Engineering
Meeting Name
8th U.S. Mine Ventilation Symposium
Publisher
University of Missouri--Rolla
Document Version
Final Version
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Mutama, Kuda R. and Hall, Allan E., "Theoretical Analysis of Jet Fan Performance Using Momentum and Energy Considerations" (1999). U.S. Mine Ventilation Symposium. 2.
https://scholarsmine.mst.edu/usmvs/8usmvs/8usmvs-theme13/2
Theoretical Analysis of Jet Fan Performance Using Momentum and Energy Considerations
Rolla, Missouri
Jet fans or ductless fans have been analyzed using momentum and energy considerations. This analysis is necessary for the mechanisms of mixing between the jet primary flow and the secondary or induced stream to be understood. In each case it is possible to predict performance in terms of pressure, flow ratios and hence the percentage mechanical efficiency of the whole system using equations derived from momentum and energy principles. The analysis given is suitable for situations where jet fans are utilized as area boosters in a mine ventilation system and in longitudinal vehicular tunnel ventilation. The energy and momentum equations serve as important tools for the analysis and consider all losses in the system. The derivations identified a range of flow ratios of the induced flow to the jet flow which can be used to design effective ventilation systems incorporating jet fans. Each flow ratio (n) is associated with an optimum area ratio (µ) of the jet fan outlet to tunnel, or airway area, for maximum induction or entrainment of the secondary flow. It can be shown that there is an optimum set of conditions for jet fan performance which are explained in detail in the paper.
