Pyrolysis and Boundary Layer Combustion of a Non-Charring Solid Plate Under Forced Flow

2003 ◽  
Author(s):  
Ramagopal Ananth ◽  
Patricia A. Tatem ◽  
Chuka C. Ndubizu
Keyword(s):  
Boundary Layer ◽  
Forced Flow ◽  
Solid Plate

scholarly journals Soot Volume Fraction Profiles in Forced-Combusting Boundary Layers

1983 ◽  
Vol 105 (1) ◽  
pp. 159-165 ◽  
Author(s):  
R. A. Beier ◽  
P. J. Pagni
Keyword(s):  
Boundary Layer ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Volume Fraction ◽  
Liquid Hydrocarbon ◽  
Forced Flow ◽  
Volume Fractions ◽  
Ambient Oxygen ◽  
Mass Fractions

A multiwavelength laser transmission technique is used to determine soot volume fraction fields and aproximate particle size distributions in a forced flow combusting boundary layer. Measurements are made in diffusion flames of polymethylmethacrylate (PMMA) and five liquid hydrocarbon fuels (n-heptane, iso-octane, cyclohexane, cyclohexene, and toluene) with ambient oxygen mass fractions in the range of 0.23 ≲ Y0∞ ≲ 0.50. Soot is observed in a region between the pyrolyzing fuel surface and the flame zone. Soot volume fraction increases monotonically with Y0∞, e.g., n-heptane and PMMA are similar with soot volume fractions, fν, ranging from fν ∼ 5 × 10−7 at Y0∞ = 0.23 to fν ∼ 5 × 10−6 at Y0∞ = 0.50. For an oxygen mass fraction the same as air, Y0∞ = 0.23, soot volume fractions are approximately the same as values previously reported in pool fires and a free combusting boundary layer. However, the shape of the fν profile changes with more soot near the flame in forced flow than in free flow due to the different y-velocity fields in these two systems. For all fuels tested, a most probable particle radius is between 20 nm and 80 nm, and does not appear to change substantially with location, fuel, or oxygen mass fraction.

Mathematical Modelling of Hydromagnetic Convection from a Rotating Sphere with Impulsive Motion and Buoyancy Effects

2006 ◽  
Vol 11 (3) ◽  
pp. 227-245 ◽  
Author(s):  
O. Anwar Bég ◽  
H. S. Takhar ◽  
G. Nath ◽  
A. J. Chamkha
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Boundary Layer ◽  
Chemical Engineering ◽  
Numerical Solutions ◽  
Forced Flow ◽  
Impulsive Motion ◽  
Rotating Sphere ◽  
Linear Partial Differential Equations ◽  
Layer Flow

The convective heat transfer on a rotating sphere in the presence of magnetic field, buoyancy forces and impulsive motion is examined theoretically and numerically in this paper. We apply a boundary layer model comprising the balance equations for x and y direction translational momentum and heat transfer, and solve these coupled non-linear partial differential equations using Blottner’s finite-difference method [1]. The numerical solutions are benchmarked with the earlier study by Lee [2] on laminar boundary layer flow over rotating bodies in forced flow and found to be in excellent agreement. The effects of magnetic field, buoyancy parameter, Prandtl number and thermal conductivity parameter on translational velocities and temperature and other variables (shear stress etc) are presented graphically and discussed at length. The problem finds applications in chemical engineering technologies, aerodynamics and planetary astrophysics.

Conjugated Heat Transfer in a Laminar Boundary Layer With Heat Source at the Wall

1982 ◽  
Vol 104 (1) ◽  
pp. 90-95 ◽  
Author(s):  
A. Brosh ◽  
D. Degani ◽  
S. Zalmanovich
Keyword(s):  
Boundary Layer ◽  
Heat Conduction ◽  
Heat Source ◽  
Flow Direction ◽  
Boundary Layer Separation ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Line Heat Source ◽  
Solid Plate ◽  
Conjugated Heat Transfer

This work presents the solution of the temperature field in a two-dimensional laminar incompressible flow over a conducting solid plate with a line heat source located at the fluid-solid interface perpendicular to the flow direction. A numerical scheme was used to obtain the temperature profiles as a function of the source strength, and of the properties of the fluid and the solid. The heat conduction and forced convection in the fluid and the heat conduction in the solid were solved for the case of moderate temperature rise, where the assumption of constant properties applies. The model enables the improvement of an instrument for the detection of boundary layer separation. It was found that for the actual parameters of the separation detector, a distance of 4 to 24 mm between the sensors gives an indication of 70 percent of the maximum temperature difference.

Nonsimilar Boundary-Layer Heat Transfer of a Rotating Cone in Forced Flow

1967 ◽  
Vol 89 (2) ◽  
pp. 139-145 ◽  
Author(s):  
J. C. Y. Koh ◽  
J. F. Price
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Numerical Solutions ◽  
Cone Angle ◽  
Rotating Disk ◽  
Forced Flow ◽  
Degenerate Problem ◽  
Prandtl Numbers ◽  
Half Cone ◽  
Half Cone Angle

The nonsimilar boundary-layer flow and heat transfer of a cone rotating in a forced-flow field are investigated. Numerical solutions are shown for a half-cone angle of 53.5 deg with parameters (vw/ue)2 ranging from 0 to 20, and with Prandtl numbers from 0.2 to 10. With a half-cone angle of 90 deg (so that one has a rotating disk), the degenerate problem is solved in the same manner.

Mesoscale meteorological conditions in Dronning Maud Land, Antarctica, during summer: the momentum budget of the boundary layer

2000 ◽  
Vol 12 (2) ◽  
pp. 229-242 ◽  
Author(s):  
Richard Bintanja
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Time Of Day ◽  
Meteorological Conditions ◽  
Forced Flow ◽  
Research Station ◽  
General Description ◽  
Momentum Budget ◽  
Synoptic Conditions ◽  
Dronning Maud Land

The momentum budget of the boundary layer flew near the Swedish research station Svea in the mountainous region of western Dronning Maud Land, Antarctica, is evaluated using detailed concurrent observations of surface meteorological variables, high-resolution boundary layer profiles and upper-air profiles taken during the summer of 1997–98. Despite the fact that the irregular topographical situation prohibits easy interpretation of the data, interesting features can still be identified. All terms in the momentum budget (katabatic forcing, synoptic pressure gradient, Coriolis force and friction) can be of the same order of magnitude, which indicates that the influence of each term depends largely on the prevailing conditions. More precisely, the relative importance of the various momentum terms varies strongly with altitude, location, time of day and prevailing synoptic conditions. For example, at the undisturbed snow slopes there is a very regular daily variation of katabatically forced flow during the night and a flow dominated by the synoptic pressure gradient during the day, causing a persistent diurnal cycle in surface wind direction. The interpretation of the flow characteristics in terms of the momentum budget agrees favourably with the conclusions drawn on the basis of a general description of the prevailing meteorological conditions, and can therefore be considered consistent.

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