Computational Investigation of Three-Dimensional Flow Effects on Micronozzles

2002 ◽  
Vol 39 (4) ◽  
pp. 642-644 ◽  
Author(s):  
R. D. D. Menzies ◽  
B. E. Richards ◽  
K. J. Badcock ◽  
J. Loseken ◽  
M. Kahl
Keyword(s):  
Three Dimensional ◽  
Computational Investigation ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Flow Effects

Three-Dimensional Flow Effects on Convective Heat Transfer From a Window Covered by a Simple Plane Blind With No Top Covering

2006 ◽  
Author(s):  
Patrick H. Oosthuizen
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Approximate Model ◽  
Conductive Heat ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Flow Effects

Most studies of convective heat transfer in window-blind systems assume that the flow over the window-blind arrangement is two-dimensional. In some cases, however, three-dimensional flow effects can become important. The present study was undertaken to determine how significant such effects can be for the particular case of a window covered by a simple plane blind. Only convective heat transfer has been considered. The situation considered is only an approximate model of the real window-blind situation. The window is represented by a rectangular vertical isothermal wall section embedded in a large vertical adiabatic plane wall surface and exposed to a large surrounding "room" in which the temperature is lower than the window temperature. The plane blind is represented by a thin vertical wall having the same size as the "window" which offers no resistance to heat transfer across it and in which conductive heat transfer is negligible. The gaps between the blind and the window at the sides and at the top of the window-blind system are assumed to be open. The flow has been assumed to be laminar and it has been assumed that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces. The solution has been obtained by numerically solving the three-dimensional governing equations written in dimensionless form. The effects of the dimensionless governing variables on the window Nusselt number have been numerically examined.

Three-Dimensional Flow Calculations of the Stator in a Highly Loaded Transonic Fan

1998 ◽  
Vol 120 (1) ◽  
pp. 141-146 ◽  
Author(s):  
P. R. Emmerson
Keyword(s):  
Three Dimensional ◽  
Flow Visualisation ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Efficiency Condition ◽  
Flow Effects ◽  
High Level ◽  
Transonic Fan ◽  
Very High ◽  
Highly Loaded

A three-dimensional viscous solver has been used to model the flow in the stator of a highly loaded single-stage transonic fan. The fan has a very high level of aerodynamic loading at the hub, which results in a severe hub endwall stall. Prediction of the flow at the 100 percent speed, peak efficiency condition has been carried out and comparisons are made with experiment, including stator exit traverses and fixed blade surface pressure tappings and flow visualisation. Comparisons are also made with an analysis of the rotor and stator rows using the DERA S1–S2 method. The three-dimensional predictions show good qualitative agreement with measurements in all regions of the flow field. Quantitatively the flow away from the hub region agreed the best. The general trends of the severe hub endwall stall were predicted, although the shape and size did not match experiment exactly. The S1–S2 system was unable to predict the hub endwall stall, since it arises from fully three-dimensional flow effects.

Molecular Tagging Fluorescence Velocimetry (MTFV) to Measure Meso- to Micro-Scale Thermal Flow Fields

2000 ◽  
Author(s):  
J. S. Park ◽  
K. D. Kihm ◽  
D. M. Pratt
Keyword(s):  
Capillary Flow ◽  
Three Dimensional ◽  
Surface Flow ◽  
Three Dimensional Flow ◽  
Molecular Tagging ◽  
Dimensional Flow ◽  
Thermally Driven ◽  
Thermocapillary Stress ◽  
Flow Effects ◽  
Capillary Pore

Abstract The development of a molecular tagging fluorescence velocimetry (MTFV) system is discussed and measurement results are presented for a meso-scale flow field of thermally driven capillary pore of 5-mm inner diameter that is tilted 5° from the horizon. The developed technique uses caged Dextran conjugates of caged fluorescene dyes of less than 10 nm in size for tracers. The frequency-tripled UV band (λ = 355 nm) of a pulsed Nd:YAG laser uncages the molecules by photo-cleaving that is decomposition of a caging chemical group and a fluorescence chemical group. Then a CW blue Argon-ion laser (λ = 488 nm) pumps the fluorescence of only those uncaged molecules, whose emmission band is centered at λ = 518 nm, and a sequential recording of the fluorescence images are digitally recorded and analyzed for Lagrangian velocity field mapping. The use of the technique allows detailed measurements of the thermally driven three-dimensional flow inside a heated capillary pore. The measurement shows that the meniscus surface flow is mainly driven by the thermocapillary stress field, occurring due to the surface temperature gradient, while the bulk flow inside the pore is driven largely by the natural convection buoyancy. The whole capillary flow is made by a combination of these two different flow effects. As to the heater position, above or below the interface, the three dimensional flow patterns are measured totally in the opposite way.

Three-Dimensional Potential Flow and Effects of Blade Dihedral in Axial Flow Propeller Pumps

1977 ◽  
Vol 99 (1) ◽  
pp. 167-175 ◽  
Author(s):  
R. Howells ◽  
B. Lakshminarayana
Keyword(s):  
Potential Flow ◽  
Three Dimensional ◽  
Axial Flow ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Pressure Distributions ◽  
Rotating Blade ◽  
Satisfactory Approximation ◽  
Flow Through ◽  
Flow Effects

A relatively simple and rapid method for predicting the three-dimensional flow effects in axial flow turbomachinery was investigated. Although the two-dimensional cascade is a satisfactory approximation for the design and analysis of some types of turbo-machines, the flow through devices, such as propeller pumps and inducers, may deviate significantly. A three-dimensional lifting surface theory was used to predict the potential flow around blades, represented by line vortices and sources, spanning an annulus. A rotor was designed, built, and tested (with air as the test medium) for comparison with the theory. Static pressure distributions on a rotating blade were measured. The effect of blade dihedral on these pressures was also measured. Deviation from cascade predictions caused by the three-dimensional flow effects is found to be appreciable for propeller pumps. No theory was developed, but variation of the experimental blade pressure distributions caused by dihedral was found to be considerable.

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