A STUDY OF THE MEAN-FLOW CHARACTERISTICS OF GAS-SOLID SUSPENSIONS. Technical Report No. 101-ME-F

Technical Report · Sat Feb 01 04:00:00 EST 1964

OSTI ID:4066714

Peskin, R L; Dwyer, H A

A study of gas mean velocity profiles and solid mean velocity profile was undertaken for a horizontal suspension of small particles suspended in turbulent air. Small pitot tubes were used to measure air velocity profiles, and small fiber optic instruments were developed for solids velocity profile measurements. An analysis was made of the effect of the solids motion on the mean gas velocity, the laminar sublayer structure, and the shear stress at the wall. An evaluation of the slip velocity of solids was made, and the contribution of the solids motion to overall dissipation was computed. The flow system was a horizontal 3 inch by 3 inch channel in which the mass flow of solids and gas were set independently and held fixed. The system is capable of flowing in excess of 15 pounds of solids per pound of air at over 100 feet per second. However, this study is restricted to flows of less than 4 pounds of solids per pound of air. Fiber optics of 240 micron diameter were used to measure solids mass flow rate locally, and solids density was measured locally by a special light attenuation meter. Both probes were small enough to probe into high shear stress region of the flow. The effect of solids motion on the gas velocity profile could be described by dividing the usual u/V* versus log yV*/ nu graph into four regions determined by size, spacing, and particle material density. The effect of solids on the mean gas velocity depended on whether the solids caused primarily inertial, viscous, and/or small perturbation forces in thp laminar sublayer. The inertial disturbances cause a destruction of the laminar sublayer and increased wall shear stress. The viscous disturbances increased the size of the laminar sublayer and reduced shear stress. The small perturbation disturbances had no effect on wall shear stress. In the case of small perturbation effects, the dissipation due to solids motion was caused primarily by the mean slip velocity and local fluctuating velocities of the turbulent motion. The lower overall friction factor for the small perturbation regime as measured and reported in the literature can be explained with the help of this analysis. (auth)

• Research Organization: Rutgers Univ., New Brunswick, N.J. Coll. of Engineering
• NSA Number: NSA-18-016176
• OSTI ID: 4066714
• Report Number(s): NYO-2930-1
• Country of Publication: United States
• Language: English

Related Subjects

ABSORPTION
AIR
CONFIGURATION
DENSITY
DIAGRAMS
ENGINEERING
FIBERS
FLUID FLOW
FRICTION
GASES
LAYERS
LIGHT
MEASURED VALUES
MOTION
OPTICAL SYSTEMS
PARTICLES
SHEAR
SLIP
SOLIDS
STRESSES
SURFACES
SUSPENSIONS
TENSILE PROPERTIES
TUBES
TURBULENCE
VARIATIONS
VELOCITY
VISCOSITY